Encyclopedia of Autographa californica Nucleopolyhedrovirus Genes

  • Cohen David P. A.,

    Affiliation Wageningen University, Laboratory of Virolo, Box 629, 6700AP wageningen, The Netherlands

  • Marek Martin,

    Affiliation Wageningen University, Laboratory of Virolo, Box 629, 6700AP wageningen, The Netherlands,
    Généthon, Department of Bioprocess Development, Evry, France

  • Davies Bryn G.,

    Affiliation University of York, YCR Cancer Research, Dept. of Biology, Heslington, York, United Kingdom

  • Vlak Just M.,

    Affiliation Wageningen University, Laboratory of Virolo, Box 629, 6700AP wageningen, The Netherlands

  • Monique M. van Oers

    Affiliation Wageningen University, Laboratory of Virolo, Box 629, 6700AP wageningen, The Netherlands

Encyclopedia of Autographa californica Nucleopolyhedrovirus Genes

  • Cohen David P. A., 
  • Marek Martin, 
  • Davies Bryn G., 
  • Vlak Just M., 
  • Monique M. van Oers
x

Abstract

The Autographa californica multiple capsid nucleopolyhedrovirus (AcMNPV) was the first baculovirus for which the complete nucleotide sequence became known. Since then 15 years lapsed and much research has been performed to elucidate putative functions of the annotated open reading frames of this virus and this endeavour is still ongoing. AcMNPV is the most well-known and well-studied baculovirus species, not in the least for its application as a vector for the high-level expression of foreign genes in insect cells. This article is the first monograph of a single baculovirus and gives a current overview of what is known about the 151 AcMNPV ORFs, including (putative) function and temporal and spatial presence of transcripts and protein. To date 60 ORFs have a proven function, another 19 ORFs have homologs for which functions are known in other baculoviruses and 72 ORFs are still enigmatic. This paper should assist the reader in quickly finding the essentials of AcMNPV.

Baculoviruses are viruses of invertebrates that are widely used as biopesticides for the protection of agricultural crops and forests against insect pests (59). This practice has already occurred for over 70 years and these viruses have a perfect safety record to date. More recently these baculoviruses have been used as vectors for the high-level expression of foreign genes (254) and for the transfer of foreign genes into vertebrate systems (40). A most notable characteristic of baculoviruses is the rod-shaped morphology of the virions, hence, the family name Baculoviridae (23). These rod-shaped virions are found occluded in large polyhedral shaped, proteinaceous capsules (polyhedra, 0.1-15 μm in diameter) or in smaller granular capsules (granula) 0.3 till 0.5 μm in length and 0.1 to 0.3 μm in diameter (43). These capsules are often collectively called occlusion bodies (OBs). Baculoviruses share this occlusion phenotype with the genetically unrelated cypoviruses (CPV) and entomopoxviruses (EPV).

The family Baculoviridae comprises four genera, Alphabaculovirus, Betabaculovirus, Gammabaculovirus and Deltabaculovirus (118). The Alphabaculovirus genus contains the nucleopolyhedroviruses (NPVs) of lepidopteran insects and the Betabaculovirus genus encompasses the granuloviruses (GVs) of lepidopteran hosts. The NPVs from hymenopterans form the genus Gammabaculovirus and the Deltabaculovirus genus encompasses the NPVs from dipteran hosts. The Alphabaculoviruses are further divided in group Ⅰ and group Ⅱ NPVs on the basis of phylogenetic analysis (99) and the type of envelope fusion protein (GP64 or F, respectively). The virions of NPVs as found in the occlusion bodies may contain single (S) or multiple (M) nucleopcapsids, but this is not a taxonomical denominator. Collectively about 700 baculoviruses have been described genetically, but only a minority have been characterised to the extent that they can be called a species. Baculoviruses occur in a very wide range of insect hosts, but each virus by itself in general has a narrow host range. The most notable example of a baculovirus with multiple hosts is Autographa californica MNPV, the type species of the Alphabaculoviruses, belonging to the group Ⅰ NPVs.

Baculoviruses have a complex 'life' cycle. They infect their larval host orally and the virions, upon release from the proteinaceous capsules (hence their name occlusion derived virions = ODVs), replicate in the epithelial cells of the larval midgut. Infectious virions (budded virions = BVs) are produced in these cells and released into the hemolymph and tracheal system to invade and infect other organs and tissues of the insect larva. Replication of the Gammabaculoviruses is restricted to the midgut (144). At the end of the infection virions are occluded into OBs, which are released into the environment from the insect body upon death. In the OB form baculoviruses can persist in the environment for many years. For some baculoviruses, notably AcMNPV, the replication cycle can also be completed in cell culture using BVs as inoculum and this has greatly enhanced our current understanding of the cell biology and genetics of baculovirus infections (for more details (279)).

Baculoviruses contain a double-stranded, circular and superhelical DNA molecule, which replicates in the cell nucleus. After synthesis the DNA is packaged in a number of proteins to form nucleocapsids. One or more nucleocapsids are wrapped in an envelope, which is de novo formed in the nucleus of infected cells. Single or multiple virion packages are occluded in GVs and NPVs, respectively. The size of baculovirus genomes depends on the species and ranges from 80 to 180 kilobasepairs (kbp), hence encompassing a variable numbers of ORFs (266). Gene homology, gene content and gene location can be used to construct reliable phylogenetic trees to show the relatedness among baculoviruses (99).

The transcription of baculoviruses occurs in a cascaded fashion and four classes of transcripts are discriminated. The immediate early (IE) transcripts are made by host RNA polymerases, a process independent of de novo protein synthesis. Delayed early (DE) transcripts require translation of IE viral transcripts for their synthesis. Late (L) transcripts are expressed after the onset of DNA replication and very late (VL) transcripts are those that are still expressed very late after infection, sometimes at very high levels (polyhedrin, p10). Baculovirus late and very late transcription occurs via a virus-encoded RNA polymerase, which is α-amanitin insensitive. Baculovirus genes are hence categorized as immediate-early, delayed-early, late and very late genes. Baculovirus transcripts may have 5'and 3' co-terminal ends and hence may overlap in sequence and time of expression. A canonical baculovirus transcription initiation motif (TAAG) is present in the promoter region of L and VL genes, whereas a more common motif (CAGT) is often associated with early baculovirus gene expression (recent review (213)).

The fact that for replication in cell culture only BVs are required and the ODV phenotype is dispensable allowed the development of the baculovirus expression system for production of recombinant protein in insect cells (254). Baculovirus VL genes are highly expressed but not required for virus propagation in cell culture, enabling their replacement with foreign genes. The promoters of the polyhedrin and p10 genes are extensively used as cassettes to drive the expression of single or multiple foreign genes in a baculovirus background. The development of an AcMNPV bacmid greatly facilitated the functional analysis of baculovirus genes, since it not only simplified the engineering of baculovirus expression vectors (172), but also made the construction of (knock-out) mutants much easier. The deletion of the cathepsin and the chitinase genes for instance, has improved the integrity of secreted recombinant proteins (120). The insertion of genes for the modification of glycoproteins in the Golgi system, has allowed the production of complex, mammalian-like glycoproteins in insect cells (115). AcMNPV can also be used as a delivery vector for mammalian cells and as gene therapy vector, either as a gene carrier or as a production system for other gene therapy vectors such as adeno-associated viruses (108, 174, 244). The baculovirus insect cell expression system is still being tailored and optimised to meet the demands of both the scientist as well as the commerce.

AcMNPV was isolated in 1969 by the late Dr. Patrick V. Vail and colleagues from a single virosed insect larva near Riverside (264). The insect was assigned as alfalfa looper or A. californica, but could also have been Trichoplusia ni as liquefied larvae are difficult to determine taxonomically. Later the late Dr. Lois K. Miller isolated an AcMNPV variant from A. californica on sunflower. The virus has an extremely wide host range, infecting insect species across several lepidopteran subfamilies (225). AcMNPV also replicates efficiently in cultured insect cells, such as Sf9, Sf21, Tn368, Tni High Five, and Se-UCR. Various clonal isolates of AcMNPV have been described (E2, L1, C6, HR). The genome of the AcMNPV C6 isolate was the first baculovirus genome that was sequenced completely in 1994 (GenBank: NC_001623) (9). The circular double stranded DNA genome is 133, 894 bp in size with a GC-content of 40.7 %. Partial resequencing of the AcMNPV genome ((92) led to a few modifications to the original sequence, which are not yet incorporated in the GenBank entry, resulting now in a total of 151 assigned open reading frames (ORFs). The encoded proteins range in size between 50 aa (normally set as the under limit for a baculovirus ORF) to 1221 aa (DNA helicase). All genes, except one (IE-0/IE-1), produce non-spliced transcripts. Over the years through collective effort of many laboratories around the world, functions have been assigned to many of the encoded gene products. However, the function of many ORFs -even some with orthologs in (many) other baculovirus species -remains enigmatic. At this moment in time nearly 50 baculovirus genomes have been completely sequenced and the genetic relatedness among the baculoviruses became apparent when further baculoviruses were being sequenced (266).

Eight regions with homologous repeats (hrs), each with a set of 28-mer imperfect palindromes, are present dispersed throughout the AcMNPV genome (9, 141). These hrs can act as origins of DNA replication in cell culture (135) and as enhancers of gene expression (33, 234, 271). Within the gene ac134 (p94), a sequence of direct and inverted repeats, palindromes and AT-rich regions different from the hrs is found and called the non-hr, which can also serve as an origin of DNA replication (134, 138). The non-hr region is also associated with the formation of "defective interfering particles" (DIs), which are generated as an artifact in cell culture and which interfere with the replication and production of infectious BVs (145, 222). These DI particles are baculoviruses with reduced size and genome content and a higher frequency of non-hr sequences. DIs are unable to propagate autonomously.

The purpose of this review is to provide an overview of the current knowledge on the function of AcMNPV ORFs and to serve as a starting point for researchers and students to gather further detailed information on particular ORFs. The overview will also assist researchers working with other baculoviruses, which carry homologous genes. In this review, all ORFs are listed in their order of appearance in the AcMNPV genome beginning wit the ptp gene (5'-3') and named according to the GenBank file (NC_ 001623). We choose for an encyclopaedic layout in which a short description of each ORF is presented, together with a small number of selected literature references referring to key publications, and/or review papers through which further relevant literature may be found. In the current paper the description of each ORF starts with the ORF number, e.g. ac1, where ac stands for AcMNPV and "1" for the number of the ORF as indicated in the database. This ORF number is followed by the name of the gene and by the name of the gene product. A genomic map of AcMNPV is given in Fig. 1, which serves to visualize the direction of transcription for individual ORFs and their genetic environment. The indicated sizes are the predicted molecular masses and the length in amino acids (aa) for the primary translation products. Post translational modifications can of course affect the actual size of the protein. A summary of the data is presented in Table 1. In this table the ORFs are also functionally categorized into four groups: genes for virion structure, DNA replication, transcription and auxiliary functions. Auxiliary genes are those that are not necessary for virus replication but give replication advantages for the virus at the level of the cell, the organism or the ecosystem (197).

thumbnail
Fig 1. Genetic and physical map of the AcMNPV genome. The different colors indicate the categorization of genes in four functional classes: genes for DNA replication and transcription, structural and auxiliary genes. The physical map is based on the EcoRI restriction sites.The figurewas adjusted from (258).

thumbnail
Table 1. ORFs of Autographa californica MNPV for which published information is available

In Table 2 and Table 3, AcMNPV gene orthologs are indicated for the 48 baculoviruses that have been completely sequenced (December 2008). The numbers correspond to their respective ORF number in the particular virus. Homologous genes have been found using Basic Local Alignment Tool (6) for proteins available through the website http://blast.ncbi.nlm.nih.gov/ with the following search set: non-redundant protein sequence database; organism: dsDNA viruses, no RNA stage; blast-p algorithm. Baculoviruses have a common set of 30 genes and these genes are designated as the baculovirus core genes (178, 179). Two Ac-MNPV genes have homologs in all baculoviruses except for the Deltabaculoviruses (ac25 and ac145), one AcMNPV gene has a homolog in all, except Gammabaculoviruses (ac23), twenty in all Alpha-and Betabaculoviruses and sixteen additional genes have homologs in all sequenced Alphabaculoviruses (Table 2 and Table 3).

thumbnail
Table 2. Homologues of AcMNPV in Alphabaculoviruses

thumbnail
Table 3. AcMNPV homologues in Beta-, Gamma and Deltabaculoviruses﹟

ORF DESCRIPTIONS

Ac1: ptp/bvp, protein tyrosine phosphatase or baculovirus phosphatase

This ORF encodes a protein (19.3 kDa; 168 aa) with a chimerical character as it has the characteristics of a protein tyrosine phosphatase (PTP), but it also has RNA-tri/diphosphatase activity (255). The preferred substrate for PTP is RNA and it crystallizes in a metazoan RNA capping enzyme fashion (27). Later it was renamed to baculovirus phosphatase (BVP), which is a protein only produced by group Ⅰ NPVs. The AcMNPV ptp/bvp gene appears to be associated with the wandering behaviour of infected larvae (107), similarly to the closely related Bombyx mori (Bm) NPV ptp gene (122). RNA-triphosphatase activity is also encoded by the AcMNPV lef-4 gene (ac90), which in addition encodes guanyltransferase activity (154).

Ac2: bro, baculovirus repeated ORF

This gene belongs to the baculovirus repeated ORF (bro) family, which has members in many other baculoviruses either as a single gene or in multiple copies. A similar gene is also present in entomopoxvirus (3, 11). The AcMNPV bro gene is present as a single copy and encodes a protein with a predicted mass of 37.8 kDa (328 aa) with unclear function. Disruption of the bro gene has no effect on virus replication in cultured cells or on the lethal dose in insect larvae when injected as BV or per os with ODV. However, disruption of the N-terminal part of the BRO protein reduced the number of OBs (15). In contrast to Ac-MNPV, BmNPV contains five bro genes, bro-a till bro-e. The BmNPV bro-d gene is essential for virus replication in cell culture and bro-a and bro-c genes can complement each other (124). However, the absence of bro genes in several baculoviruses suggests that the requirement for bro genes may depend on the host species (15). In BmNPV, the BRO proteins reside in the nucleus until 4 h post infection (p.i.). After that time point, the proteins are found in both cytoplasm and nucleus (123). Furthermore, mutation in the leucine-rich N-terminal part of the protein results in accumulation of proteins, which suggest that this region serves as a CRM1-dependent nuclear export signal (123).

Ac3: ctl, conotoxin-like peptide

The ctl gene encodes a conotoxin-like peptide, which has a molecular mass of 5.6 kDa (53 aa). Conotoxins are neurotoxins that are present in the venom of marine snails, belonging to the genus Conus (257). Ω-conotoxins block specific types of Ca2+-channels in neurons (180), while another sub-class of conotoxins have a behavioural and anticonvulsant effect in DBA/2 mice (114). Infection with a mutant AcMNPV virus – with either a disruption or a null mutant of the gene – was not significantly different in infectivity in Sf21 cells or in virulence S. frugiperda larvae (57).

Ac4: ac4, putative enhancer activity

ORF 4 of AcMNPV is an early gene and together with five other early genes of AcMNPV, ac102, he65 (ac105), ie-1 (ac147), ac152, and pe38 (ac153) respectively, is needed to accumulate G-actin into the nucleus of Tn-368 cells (202). The expression of ac4, ie-1, and pe38 starts before the expression of ac102 or he65. The gene ac4 codes for a protein of 17.6 kDa (83 aa.) which has not been characterized thoroughly, but it has enhancer activities for cellular and viral promoters (162).

Ac5: ac5, enhancer

In BmNPV, a region upstream of the polyhedrin promoter corresponding to the 5'-ends of ac4 and ac5 of AcMNPV was shown to have enhancer capabilities (1). This enhancer activity was confirmed as the homologous region in AcMNPV resulted in increased promoter activity in luciferase-assays in combination with several full or minimal promoters: hsp70, CMVm and p35 minimal promoter in insect cells (162). In AcMNPV ac5 encodes a hypothetical protein (12.4 kDa, 109 aa), however no transcripts have been detected (287).

Ac6: lef-2, late expression factor 2

The lef-2 gene codes for late expression factor-2 (LEF-2), (23.9 kDa, 210 aa). This protein is essential for the expression from vp39 and polh promoters (216). In addition, LEF-2 as well as five other gene products (IE-1, LEF-1 LEF-3, DNA polymerase, and helicase) are required for replication of plasmid DNA containing an AcMNPV origin of replication (133). Protein-protein interaction between LEF-1 and LEF-2 is essential for this DNA replication (61) and LEF-2 binds to DNA (187). A point mutation changing an aspartic acid into an asparagine residue at amino acid 178, showed no difference in plasmid replication between mutant and wild type virus infections but showed deficiency in very late gene expression (184). Lef-2 is a baculovirus core gene.

Ac7: orf603, ORF603 peptide

The orf603 gene encodes a hitherto uncharacterized protein of 23.6 kDa (201 aa). Partial deletion of the orf603 gene did not affect BV yield in cell culture nor the dose to kill insects (72). However, a truncation of ORF603 decreased the time to death in S. frugiperda larvae (224).

Ac8: polh, major occlusion body protein

The polh gene encodes the 28.6 kDa polyhedrin protein (245 aa), which is the major component of OBs in NPVs. It was the first baculovirus gene to be characterised (105). AcMNPV polyhedrin has a mosaic structure, which makes it unsuitable for phylogenetic analysis (117). polh is the most conserved gene in baculoviruses. The gene is described very late after infection from a canonical TAAG motif. The function of the polyhedra is to protect and spread the virus outside the host. Upon ingestion by the host, the polyhedra dissociate due to the alkaline environment of the midgut and release the virions (129). The gene is not essential for virus replication in cell culture and its promoter is used extensively to drive the expression of foreign genes. For a more detailed review see (236).

Ac9: orf1629, P78/83 capsid protein

The orf1629 gene codes for the essential P78/83 structural protein of BVs and ODVs (226). The protein with a calculated mass of 60.7 kDa (543 aa) has a phosphorylated and a non-phosphorylated isoform, and is present at one end of the mature nucleocapsid (272). P78/83 resembles Wiscott-Aldrich Syndrome proteins (WASP) and is, together with the host protein complex ARP2/3, responsible for actin polymerization in the nucleus of infected cells (74, 175). By deleting part of orf1629 from the AcMNPV genome, a new method was developed to obtain recombinant baculoviruses by dominant selection with almost 100% recombination efficiency (130).

Ac10: pk-1, protein kinase

The protein product of this gene, PK-1 (32.0 kDa, 272 aa), has high similarity to serine-threonine protein kinases and phosphorylates histone H1 in rabbit reticulocyte lysates (233). The gene is expressed from the beginning of the late throughout the very late phase of the viral infection (233). PK-1 is required for transcription of the very late polh gene, presumably through phosphorylation of LEF-8 (ac50), which is required in the (very) late transcription complex (190, 191). PK-1 interacts with PKIP (ac24), which stimulates PK-1 activity (62).

Ac11: ac11, unknown function

The ac11 gene encodes a hypothetical protein with a predicted mass of 40.1 kDa (340 aa). Homologs found in many Alphabaculoviruses (Table 2) together form the DUF1386 family (176), but no particular motifs point towards a specific function.

Ac12: ac12, unknown function

This ORF encodes a hypothetical protein of 25.4 kDa (217 aa) with unknown function (9). The gene is not conserved among the Alphabaculoviruses; only in the related virus Rachoplusia ou (Ro)MNPV and in Lymantria dispar (Ld)MNPV homologous genes can be found. In the former the homologous gene is 25 codons shorter than in AcMNPV (92). Microarray analysis revealed transcripts of the gene, but its function remains unknown (287).

Ac13: ac13, unknown function

Ac13 codes for a hypothetical protein with a predicted mass of 38.7 kDa (327 aa). Homologs are conserved among all Alphabaculoviruses and are present in a few granuloviruses (Table 2 and Table 3). Transcripts were found by microarray analysis (287), but no function was assigned.

Ac14: lef-1, late expression factor 1

The gene product LEF-1 with a calculated mass of a 30.8 kDa (266 aa) is essential for DNA replication (133) and forms a complex with LEF-2 (ac6) (61). This interaction is required as non-interacting mutants of LEF-1 and LEF-2 do not promote transient DNA replication (61). LEF-1 contains a primase-like motif (61) and its primase activity was confirmed (187) based on the oligonucleotide synthesis on a poly (dT) template, which then allowed initiation of DNA synthesis by an exogenous DNA polymerase (Klenow enzyme). Lef-1 is a baculovirus core gene.

Ac15: egt, ecdysteroid UDP-glucosyl transferase

The egt gene encodes the enzyme ecdysteroid UDP-glucosyl transferase (EGT) (23.6 kDa, 201 aa). The gene is lost in some baculovirus lineages (100). This enzyme prevents insect molting by inactivating ecdysteroid hormones through transfer of glucosyl groups to these hormones (199). The presence of EGT during infection leads the development of larger insects, a longer time to death and a higher yield of progeny virus (41). Deletion of the egt gene makes baculovirus-based insecticides more effective by an early reduction of the feeding damage (200).

Ac16: bv/odv-e26; structural protein

The ORF ac16 encodes a structural protein (25.9 kDa, 225 aa) present in the envelopes of BVs and ODVs, named BV/ODV-E26 or briefly E26 (14). Ac16 is an early gene and transcripts accumulate rapidly after infection (213). Ac16 transcription initiates from a cryptic promoter sequence (87). When the ac16 locus (previously called DA26) was disrupted-maintaining the N-terminus -a virus with a few polyhedra (FP) phenotype was produced, which was still infectious and showed no difference in protein synthesis when mutant and wild type virus were compared (201). However, deletion of the ac16 homolog in BmNPV (Bm8) was not successful, indicating that this ORF may be essential (24). Multiple isoforms of E26 are present in infected cells, one isoform associates with viral DNA or DNA-binding proteins, a second one associates with intracellular membranes, likely due to palmityolation (24).

More recently, it has been shown that Ac16 contains a subdomain within the acidic transcriptional activation domain for binding with IE0 and IE1. Deletion of the ac16 gene results in an increased ratio of IE0 to IE1, but there was no effect on temporal production of these proteins nor on BV production nor on DNA replication (195).

Ac17: ac17, unknown function

Ac17 gene transcripts are present from the early to the very late phases and the encoded protein (18.5 kDa, 164 aa) localized in the cytoplasm of infected cells from 6 h p.i. (7). The gene ac17, together with pe38 (ac153), he65 (ac105), gp64 (ac128), ie2 (ac151), ac16, ac25 and pcna (ac49), is activated by the transactivator IE1 in the mammalian cell line Vero E6 (161). The function of the gene remains unknown, although transcriptional control is most likely. Deletion mutants of ac17 are infectious (139).

Ac18: da41, unknown function

The ac18 gene (da41) is expressed as a 40.9 kDa (353 aa) protein. The gene is not essential for virus infection and replication at least in vitro as viable ac18 mutants are formed in bioreactors (139). The lethal dose was not affected by deleting ac18, but time to death was increased (275). Which role ac18 plays, is still unclear.

Ac19: ac19, unknown function

This gene encodes a hypothetical protein with a calculated mass of 12.2 kDa (108 aa). Although homologs are found in other baculoviruses (Table 2), the function of the gene product is unknown. This gene is represented in the transcriptome (287).

Ac20/21: actin rearrangement inducing factor-1

The gene ac20 was identified in 1994 (9) and had the potential to encode a partial homolog of ac21. Resequencing of these ORFs showed that ac20 and ac21 in fact form one ORF (92). The ac20/ac21 fusion gene codes for the 47.7 kDa (417 aa) actin rearrangement inducing factor 1 (ARIF-1). The gene is expressed after transactivation by IE-1, weakly from 2 h p.i., more abundantly after 4-6 h p.i., and not detectably at 12 h p.i. (237). ARIF-1 is a tyrosine phosphorylated protein and induces rearrangement of the actin skeleton (237) by interacting with filamentous actin (F-actin) at the plasma membrane (53). Deletion of ARIF-1 interfered with F-actin accumulation at the plasma membrane, but not with the formation of early actin cables and nuclear F-actin accumulation (53, 237). Homologs are only present in Alphabaculoviruses (Table 2).

Ac22: pif-2, per os infectivity factor 2

Ac22 encodes the 43.8 kDa (382 aa) PIF-2 protein conserved in all baculoviruses and essential for oral infectivity of midgut cells (223). Hence, PIF-2 is a per os infectivity factor. PIFs are not needed when the virus is injected into the hemolymph (as for all four known baculovirus PIF proteins). Proteomic analysis showed the presence of PIF-2 in ODVs (20) and it has a predicted N-terminal membrane anchor (249). PIF-2 is thought to be involved in binding of ODVs to midgut epithelial cells, and possibly associates with PIF-1 (203). PIF-2 is a highly conserved protein belonging to the baculovirus core genes and is often used in baculovirus phylogeny.

Ac23: ac23, copia-like envelope protein

The gene ac23 is a truncated, non-functional homolog of the baculovirus F-protein present in group Ⅱ NPVs of the Alphabaculoviruses and in Beta-, and Deltabaculoviruses. The F-protein homolog or F-like protein Ac23 (79.9 kDa, 690 aa) does not function as fusion protein, as it lacks a functional furin cleavage site, but it may have other functions (219). An AcMNPV-mutant lacking ac23 showed that the gene is not essential for either infection, virus propagation or BV production, but the mutant killed T. ni larvae slower than wild type virus, suggesting that the F-like Ac23 protein is a viral pathogenicity factor in vivo (173).

Ac24: pkip, protein kinase interacting protein

The gene ac24 or pkip is a late gene and encodes a protein kinase-interacting protein (PKIP; 19.2 kDa, 169 aa) (62). PKIP interacts with PK-1 (see ac10) in virus-infected cells and stimulates activity of PK-1 (62). A temperature sensitive pkip mutant showed neither BV production nor VL gene expression, but intracellular nucleocapsids of this mutant structurally resembled those of the wild type AcMNPV (182).

Ac25: dbp, ssDNA-binding protein

Homologs of the dbp gene have been identified in all sequenced baculovirus genomes, except the dipteran CuniNPV (205). DBP (36.6 kDa, 316 aa) is expressed as an early gene product (204), which is essential for the production of viable virions. However, it is not required for synthesis of viral DNA nor for expression of viral genes (231, 267). DBP has a tight association with subnuclear structures and has high affinity for ssDNA. It has both DNA unwinding and renaturation activities and may be involved in the processing of replication intermediates (188).

Ac26: ac26, unknown function

The ac26 gene encodes a protein with a theoretical molecular mass of 14.6 kDa (129 aa) and has a conserved domain with unknown function in the NCBI Conserved Domain Database (CDD) (176). The gene appears to be transcribed (287), but the function remains unclear. The majority of the homologs can be found in Alphabaculoviruses (Table 2).

Ac27: iap-1, inhibitor of apoptosis

The gene iap-1 encodes a protein (33.3 kDa, 286 aa) containing an imperfect 70-amino acid repeat, called a baculovirus IAP repeat (BIR) at the N-terminus and an additional Cys3-His-Cys4(C3HC4) zinc or RING-finger-like motif at the carboxyl-terminus (79). Ac27 was named iap-1 on the basis of homology to the Cydia pomonella (Cp) GV iap gene (43). Expression of iap-1 does not block the induction of apoptosis by AcMNPV p35 (ac135) deletion mutants (36). The gene is transcribed early and late after infection as a part of a bicistronic mRNA, which also includes lef-6 (ac28) sequences (214). Spontaneous deletion in the PstI-I fragment harbouring the iap-1 gene occurs during serial passage of the virus (139). Three spontaneous recombinant viruses with different mutations showed no abnormalities in the rate of replication and the amount of BV and ODV produced in cell culture (181). However, in competition-assays, the mutant lacking iap-1 has a replication advantage over wild type AcMNPV in TN-368, but not in Sf21 cells (181).

Ac28: lef-6, late expression factor 6

Lef-6 is transcribed into a monocistronic mRNA at 9 h p.i. and at 12 h p.i, but lef-6 is transcribed together with iap-1 as a bicistronic mRNA at 12 h p.i. (214). LEF-6 is most abundant between 12 and 24 h p.i. (156). Furthermore, LEF-6 (calculated mass 20.4 kDa, 173 aa) is localized in the nuclei of infected cells (156) and is involved in expression of L and VL genes (214). LEF-6 is not essential for viral reproduction, DNA replication or late transcription in Sf9 cells. However, late gene transcription and the production of BVs were delayed and reduced (156).

Ac29: ac29, unknown function

The gene ac29 encodes a hypothetical protein with calculated mass of 8.6 kDa (71 aa). The gene is transcribed (287), but its function is not described in the literature. Homologous genes are present in the majority of Alphabaculoviruses (Table 2).

Ac30: ac30, unknown function

The ac30 gene codes for a protein (54.7 kDa, 463 aa) with unknown function. Transcripts are present during viral infection (287). Homologous are present in some but not all Alpha-and Betabaculoviruses (Table 2 and Table 3).

Ac31: sod, superoxide dismutase

Transcription of the sod gene results in two RNAs of 1.4 and 1.5 kb which are detectable at 24-48 h and 12-48 h p.i., respectively (263). The encoded superoxide dismutase (16.2 kDa, 151 aa) is not essential for virus replication in cell culture or in larvae (263). Homologs are found in almost every Alphabaculovirus and in a few Betabaculoviruses (Table 2 and Table 3). The sod gene, therefore, may have an important function in the Alphabaculovirus' life cycle (109).

Ac32: fgf, fibroblast growth factor

The fgf gene encodes a fibroblast growth factor homolog (FGF; 20.6 kDa, 181 aa) and homologs are only present in baculoviruses that infect lepidopteran insects (Alpha-and Betabaculoviruses) (48). FGFs have an important role in angiogenesis, cell proliferation, differentiation, and cell migration (110). AcMNPV FGF is also functional in cell culture, as it is secreted and able to enhance cell migration (48). An fgf deletion mutant showed no differences in production of infectious BV nor in DNA replication in Sf21 cells nor did the mutant have a replication advantage (50). In insect larvae of S. frugiperda and T. ni death was delayed compared to the wild type virus with oral feeding, but not with intrahemocoelic injection (49). These results suggest that FGF plays a role in the systemic spread of the virus from the midgut (49).

Ac33: hisp, histidinol-phosphatase

The gene hisp codes for a protein (20.8 kDa, 182 aa) with putative histidinol-phosphatase activity due to the presence of a conserved haloacid dehalogenaselike hydrolase domain. The function of histidinolphosphatase is to catalyze the dephosphorylation of L-histidinol phosphate and such enzymes have been characterized mainly in prokaryotes (211). This gene is represented in the transcriptome (287).

Ac34: ac34, unknown function

The gene ac43 encodes a hypothetical protein of 24.9 kDa (215 aa) with a conserved domain with unknown function according to the CDD database (176). Homologs are found in all Alphabaculoviruses except Spodoptera litura (Splt) NPV (Table 2).

Ac35: v-ubi, viral ubiquitin

The gene v-ubi encodes the viral ubiquitin (V-UBI) protein (8.7 kDa, 77 aa). The protein has 70% identity to eukaryotic ubiquitin proteins and is produced at maximal levels between 14 and 18 h p.i., indicating that the gene is a late gene (82). The gene has been classified as an auxiliary gene and the encoded ubiquitin is likely involved in signaling the degradation of proteins by the 26S proteome (197). Homologs are present in all Alpha-and Betabaculoviruses except Leucania separate (Ls)NPV (Table 2 and Table 3).

Ac36: 39K/pp31, nuclear matrix associated phosp-hoprotein

The gene pp31 (also known as 39K) encodes a phosphoprotein (31.3 kDa, 112 aa) that can bind in a non-specific way to ssDNA and dsDNA with equal affinity and is essential for late gene expression, i.e. it serves as a late expression factor (22, 86). In addition, a pp31-null mutant was prepared of AcMNPV, and microarray and quantitative PCR showed that pp31 is not essential for viral DNA replication. However, the deletion resulted in a minor down-regulation of a subset of both early and late genes and, as for BmNPV (77), in decreased BV production (287).

Ac37: lef-11, late expression factor 11

Lef-11 codes for the late expression factor-11 (LEF-11) with a calculated mass of 13.1 kDa (112 aa). Its messenger RNA is present from 3 to 36 h p.i., while LEF-11 is detected until 72 h p.i. and localizes within a dense region of infected nuclei (158). LEF-11 is not essential for DNA replication in transient replication assays (169), but is necessary for the activity of late gene promoters (262). An AcMNPV lef-11 null mutant was not able to replicate in Sf9 cells and late gene transcription was absent (157).

Ac38: ac38, ADP-ribose pyrophosphatase

The Ac38 protein (25.3 kDa, 216 aa) has homology with proteins in the Nudix (nucleotide diphosphate X) superfamily of pyrophosphatases and contains the conserved Nudix motif: GX5EX7REUXEEX2U (U: I, L or V, and X: any amino acid). Within this superfamily, the Ac38 protein shows the closest phylogenetic relationship with ADP-ribose pyrophosphatases (ADPRases). Recombinant Ac38 indeed has in vitro ADPRase activity (70). Transcripts of ac38 are detectable from 2 h p.i. and the level increases during the late stage of infection. Deletion of ac38 decreases the yield of BV to less than 1% of the wild type virus (70). So far, the gene is conserved in all Alpha-and Betabaculoviruses (Table 2 and Table 3).

Ac39: p43, ODV protein of unknown function

The 43.5 kDa protein P43 (363 aa) encoded by the gene ac39, is present in the proteome of ODVs (20). No putative conserved domains have been detected and its function other than being an ODV protein is still enigmatic. Homologs are present in seven NPV genomes.

Ac40: p47, transcription regulator

The ac40 gene product has a molecular mass of 47.5 kDa (P47;401 aa) and belongs to the group of factors required for late gene expression (262). Moreover, the gene p47 together with three other genes ac50, ac62 and ac90 -coding for lef-8, lef-9 and lef-4, respectively -form a RNA polymerase complex that transcribes late and very late viral genes (88), while early genes are transcribed by the host RNA polymerase Ⅱ (106). P47 directly binds to all other subunits of the late viral RNA complex, as well as to itself, and P47 is required for the association of LEF-4 with LEF-8 (44). Ac40 is a baculovirus core gene.

Ac41: lef-12, late expression factor 12

Ac41 encodes late expression factor 12, LEF-12 (21.1 kDa, 181 aa), which stimulates late gene expression in transient assays in a cell type specific manner (167). In a virus context, lef-12 is neither essential for virus replication nor for expression of late genes, but it has a stimulatory affect on late gene expression levels and virus yield (85). Lef-12 expression depends on DNA replication and the mRNA is synthesized by 12 h p.i. LEF-12 protein is first detected 18 h p.i. and peaks at 24 to 36 h p.i., (85). The expression of lef-12 is diminished when it is not present in cis with sequences present within the nearby ORF ac45 (149).

Ac42: gta, global transactivator-like protein

The ac42 gene encodes a putative 59.1 kDa (506 aa) global transactivator-like protein (GTA) and homologs are found only in group Ⅰ NPVs (Table 2). Baculovirus GTA proteins contain conserved regions belonging to the SNF2-N terminal domain and the helicase C-terminal domain superfamilies (142). The presence of these domains suggests a role in ATP-dependent DNA unwinding. In Choristoneura fumiferana (Cf) MNPV, the region upstream of the gta gene has an early CAGT promoter motif and a transcript is detectable at 6 h p.i. (142). Baculovirus consensus promoter motifs are absent in the AcMNPV gta upstream sequence.

Ac43: ac43, unknown function

Ac43 represents a small ORF, that contains the code for a late gene product of 8.8 kDa (77 aa) (9). Microarray analysis showed transcripts from this part of the genome (287).

Ac44: ac44, zinc finger protein with unknown function

Ac44 is a putative early gene encoding a 15.0 kDa (131 aa) protein with a zinc finger motif (9), suggesting a role in DNA binding. Transcripts from this ORF have been demonstrated by microarray analysis (287). The homolog in BmNPV (Bm35) contains a region rich in C and H residues, resembling RING-finger motifs. Such motifs are found in ubiquitin-ligase (E3), but Bm35 may have a different function since it tested negative for E3 activity (111).

Ac45: ac45, unknown function

Ac45 encodes a predicted protein of 22.7 kDa (192 aa) with unknown function. The presence of the ac45 ORF stimulates expression of lef-12 (ac41) (149). This stimulatory effect is only observed when provided in cis, suggesting that the ac45 region acts either as an enhancer of lef-12 transcription or produces an as yet unobserved protein as a result of mRNA splicing, combining ac45 and lef-12 sequences (149).

Ac46: odv-e66, occlusion-derived virus envelope protein

ODV-E66 (predicted mass 79.1 kDa, 704 aa) is an integral ODV envelope protein that like ODV-E25 (ac94), is N-terminally anchored in the envelope (104, 239). ODV-E66 is not required for BV production (240). The N-terminal region of AcMNPV ODV-E66 enables trafficking of marker proteins to intranuclear membranes and the ODV envelope (104). This region has two features: () a hydrophobic sequence of 18 aa and () positively charged amino acids close to the C-terminal end of the hydrophobic sequence. The latter may comprise a sorting motif for selection of proteins to the inner nuclear membrane (21).

Ac47: ets, unknown function

The 88-codon ets ORF has the ability to encode a 10.5 kDa protein (88 aa), and shows sequence homology to a small part of the vesicular stomatitis virus RNA polymerase gene (similarity 50% for a 250 bp region) (42). The ets gene represents the smallest ORF in a polycistronic unit in the EcoRI-T fragment (hence its name). The other ORFS in this unit are with ORFs ac48 or etm, the medium-sized ORF, and ac49 (etl/pcl) for the largest ORF in the unit), as further described below in the context of ac49.

Ac48: etm, unknown function

The gene etm encodes a putative 12.9 kDa (113 aa) hydrophobic protein with unknown function (42). It is part of a polycistronic unit with ORFs ac48 and ac49, as outlined in detail under ac49.

Ac49: pcna, proliferating cell nuclear antigen

The pcna gene (previously etl) encodes a 28.6 kDa protein (256 aa) with 42% amino acid identity to rat proliferating cell nuclear antigen (198). The gene pcna forms the largest ORF in a putative polycistronic unit comprising pcna, etm (ac48) and ets (ac47). The largest and most predominant transcript from this region is an early 1.7 kb poly (A)+ RNA, which contains each of the three tandem, non-overlapping ORFs. Smaller (0.5 kb) heterogeneous transcripts are also observed from the cistron, corresponding to ets (ac47). Both the 1.7 and 0.5 kb transcripts are present at 4 h p.i.. Whilst the 1.7 kb transcripts are shut off at 12 h p.i., the levels of the smaller transcript persist until late after infection (42). Cellular PCNAs colocalize with viral DNA replication sites and complement viral PCNA in pcna-defective viruses (113). In transient replication assays, PCNA did not stimulate DNA replication (133, 149), nor is it essential for virus replication, at least in proliferating cell cultures (198).

Ac50: lef-8, late expression factor 8

The gene lef-8 encodes the late expression factor 8 (101.8 kDa, 876 aa), which is the largest subunit of the RNA polymerase complex (see ac40). LEF-8 harbors a conserved sequence motif GXKX4HGQ/ NKG found in DNA-directed RNA polymerases (217). LEF-8 directly associates with LEF-9 (ac62), the other protein with RNA polymerase motifs and with P47 (ac40) (44). LEF-8, like all other RNA poly-merase subunits, is encoded by a baculovirus core gene.

Ac51: ac51, BJDP (unknown function)

The early gene ac51 encodes a predicted (37.5 kDa, 318 aa) protein. A transcript has been demonstrated by microarray analysis, however its function remains unknown (287). The ortholog splt39 from SpltNPV is a late gene and encodes a protein described as baculovirus J domain protein (BJDP). It has a predicted coiled-coil domain and RNA recognition motif, and is present in both ODVs and BVs (273). AcMNPV ODVs do not contain detectable amounts of Ac51 protein (20), which appears to be in line with the early promoter motifs of this ORF.

Ac52: ac52, unknown function

The gene ac52 is putatively an early gene for a 14.9 kDa (123 aa) protein. A detectable mRNA transcript from this ORF was found in microarray analysis (287).

Ac53: ac53, unknown function

Ac53 is located in a gene cluster of five ORFs (ac53, lef-10 (ac53a), vp1054 (ac54), ac55 and ac56), which all have the same clock-wise orientation. This cluster is conserved in many group Ⅰ NPVs (160). In BmNPV many overlapping, 3'co-terminal mRNAs are transcribed from this region (2). Deletion of ac53 affects BV formation. Tubular, incomplete capsid-like structures lacking nucleic acids are present, although DNA replication is not affected (160). Therefore, the encoded 17.0 kDa (139 aa) protein is most likely involved in nucleocapsid assembly and may have a role in condensation or packaging of viral DNA. Its crucial role is reflected by the presence of ac53 orthologs in all sequenced lepidopteran and hymenopteran baculovirus genomes (Table 2 and Table 3). The homologous protein encoded by BmNPV (Bm42) is present in BVs, but is absent in ODVs (2).

Ac53a: lef-10, late expression factor 10

The gene lef-10 belongs to the group of 18 genes that support late gene expression (262). The exact function is unclear, but the LEF-10 protein (8.6 kDa, 78 aa) might be involved in promoter recognition, stabilization of late transcripts or could be associated with the virus-induced RNA polymerase complex (169). The gene has been classified as an auxiliary factor in the transcription process (97).

Ac54: vp1054, VP1054 viral capsid-associated protein

The vp1054 region produces multicistronic mRNAs from early to very late times after infection (209). VP1054 is a 42.1 kDa (365 aa) structural protein present in both BVs and ODVs required for nucleocapsid formation (209). VP1054 interacts with the 38K protein (ac98) in infected cells (281) and is encoded by a baculovirus core gene

Ac55: ac55, unknown function

Ac55 is an early gene for a hitherto unidentified 8.2 kDa (73 aa) protein without known domains. A mRNA from this ORF has been demonstrated (287).

Ac56: ac56, unknown function

Ac56 encodes a small putative protein of 9.9 kDa (84 aa) protein for which no conserved domains have been found. A transcript from this ORF was found by microarray analysis (287).

Ac57: ac57, unknown function

Ac57 is a putative early gene encoding a 19.0 kDa.(161 aa) protein. Microarray studies revealed a transcript from this ORF (287). The Ac57 protein and its orthologs in other Alphabaculoviruses form the DUF918 superfamily (176), but this gives no further clues concerning its function.

Ac58/59: ac58/59, ODV protein of unknown function:

In the closely related Rachoplusia ou (Ro)MNPV the ac58 and ac59 orthologs are fused into one ORF of 172 codons (92). This is also the case in e.g. BmNPV. Partial resequencing of the AcMNPV C6 strain confirmed that ac58 and ac59 are in fact one ORF (92).Ac58/59 encodes a 20.3 kDa (172 aa) protein. Ac58/59 specific peptides were found within or associated with the ODVs by proteomic analysis (20). Ac58/59 belongs to the ChaB superfamily, originally known in E. coli in combination with ChaA, a cation transporter. The role of ChaB proteins in baculoviruses is unclear.

Ac60: ac60, unknown function

Ac60 was predicted by sequence analysis to potentially encode a 10.1 kDa (87 aa) protein (9). Transcript levels from this ORF were reduced by 72% in a pp31 (ac36) deletion mutant (287). As in the Ac58/59 protein, Ac60 contains a ChaB superfamily domain.

Ac61: fp/25k, FP protein

FP25K (25.2 kDa, 214 aa) is a structural protein of BVs and ODVs (16). Ac61 mutants show a reduction in polyhedrin transcripts, but have wild type p10 expression levels (93). Mutations in FP25K also reduce ODV-e66 expression and transport of ODV-E66 protein to the nucleus is inhibited (16). A more general role has been proposed for FP25K in targeting and intracellular transport of viral proteins during infection (16). In BmNPV it has been shown that FP25K is required for maintaining transcriptional regulation and efficient secretion of V-CATH and maintaining a steady-state level expression during secretion (125).

During serial passage of AcMNPV in cultured insect cells spontaneous mutants occur having the "few polyhedral" (FP) phenotype. This is the result of frequent transposon insertions in this area (10). These mutants have typical characteristics (94), including a reduced number of occlusion bodies, no envelopment of nucleocapsids within the nucleus and enhanced BV production.

Ac62: lef-9, late expression factor 9

The protein LEF-9 has a molecular mass of 59.3 kDa (516 aa) and is required for late and very late gene expression (168). LEF-9 contains RNA polymerase motifs and is an essential subunit of the RNA polymerase complex encoded by AcMNPV. Mutations in the conserved RNA polymerase motif showed the requirement of conserved asparagine residues (44) LEF-9 and LEF-8 interact directly (44) (see also ac40).

Ac63: ac63, unknown function

The Ac63 protein has a predicted mass of 18.5 kDa (155 aa) and does not contain any known conserved domains. Homologs are present in several Alphabaculoviruses (Table 2).

Ac64: gp37, spindle body protein or GP37

ORF ac63 encodes a glycoprotein with a predicted molecular mass of 34.8 kDa (P34.8, 302 aa) and is a homolog of the OpMNPV spindlin, which in that virus is a component of OBs (80). Baculovirus GP37 proteins are homologous to entomopoxvirus fusolins (221). Disrupting the gene in AcMNPV showed that the gene is not essential for virus replication nor affects virulence or speed of kill (34).

Ac65: dnapol, DNA polymerase

The ac65 gene codes for DNA polymerase (114.3 kDa, 984 aa) and is conserved among all baculoviruses. It is disputable whether it is essential for DNA replication in transient replication assays (133) or only stimulatory (169). Vanarsdall et al. (269) have shown using quantitative PCR (qPCR) that an AcMNPV-bacmid lacking dnapol cannot replicate its DNA in Sf9 cells.

Ac66: ac66, desmoplakin-like (ODV protein of unknown function)

The gene ac66 encodes a protein of 94.0 kDa (808 aa) and contains two conserved domains: a viral desmoplakin N-terminal domain and a CorA-like Mg2+-transporter region, respectively. Desmoplakin is the major component of desmosomes (253), which have a strong adhesive nature. They are involved in intercellular adhesion and participate in cell proliferation, differentiation and morphology (69). The CorA family consists of a group of membrane transporters of metal ions, abundant in prokaryotes, which can also be found in humans and yeast (196). The protein has been found in ODV nucleocapsids, but the exact localization is unknown (20). An ac66-null mutation resulted in depleted BV production due to inefficient transport of nucleocapsids from the nucleus to the cytoplasm. However, ac66 is not required for the formation of the nucleocapsids, but appears to be involved in pre-occluded virion and occlusion body formation (126).

Ac67: lef-3, late expression factor 3

The lef-3 gene is essential for DNA replication in transient replication assays (133). The 44.6 kDa (385 aa) LEF-3 protein binds to ssDNA (90). LEF-3 forms, together with P143 (helicase; see ac95) and IE-1 (see ac147), complexes with viral chromatin in infected cells (112). It has been proposed that LEF-3 interacts with P143 to stabilize the formed ssDNA after unwinding by the P143 helicase (112). LEF-3 also mediates nuclear localization of P143 (284) due to a nuclear localization signal domain which is required for interaction between LEF-3 and P143 (8).

Ac68: ac68, unknown function

All baculovirus genomes sequenced to date carry a homolog of the AcMNPV ac68 gene (Table 2 and Table 3), suggesting that it performs an important role in baculovirus biology. The conserved sequence is assigned as DUF708 domain, with unknown function (176). Ac68 is transcribed from 3 to 96 h p.i. and the gene product (22.3 kDa, 192 aa) was detected from 36 to 96 h p.i. (148). Deletion of ac68 did not affect production of infectious BVs, nucleocapsid or OB formation, nor did deletion of ac68 change the time to kill in vivo (148).

Ac69: mtase1, MTase1

Ac69 is a late gene (283) and its 30.4 kDa (262 aa) product stimulates late gene expression in vitro (149). The protein is homologous to E. coli FtsJ (148), an RNA methyltransferase and also has an S-adenosylmethionine (AdoMet)-methyltransferase domain. The protein binds AdoMet in vitro and has (nucleoside 2′-O)-methyltransferase activity, allowing coupling of methyl groups to RNA (283). Disruption of the ac69 gene does not affect virus replication in single-step growth curves (283), but the effect in vivo has not been analyzed.

Ac70: hcf-1, host cell-specific factor 1

The gene hcf-1 encodes a 34.4 kDa (290 aa) protein involved in the expression of late and very late gene promoters. HCF-1 is absolutely required for virus replication and late gene expression in TN-368 cells, and its absence is accompanied by a block in cellular and viral protein synthesis (170). In T. ni larvae a hcf-1 mutant, shows a reduced speed of kill. In Sf21 cells and in S. frugiperda larvae replication of hcf-1 mutants is not different from that of the wild type virus, hence the name host cell-specific factor (170).

Ac71: iap-2, apoptosis inhibitor

The gene iap-2 encodes a putative apoptosis inhibitor (28.6 kDa, 249 aa). It contains the conserved RING-finger like-motifs present in all iap genes, but not a BIR repeat region (79). Deletion of either iap-1 (ac27) or iap-2, or the simultaneous deletion of both genes did not have an effect on the replication of the virus in Sf21 cells (79). Whether it has a role in inhibiting apoptosis remains unclear. In other NPVs IAPs have been shown to inhibit apoptosis (36).

Ac72: unknown function

Homologs of ac72 are only found in genomes of Alphabaculoviruses (Table 2). The role of this transcribed gene encoding a 7.1 kDa (60 aa) protein (287) is not known.

Ac73: ac73, unknown function

Homologs of the predicted gene ac73 (11.5 kDa, 99 aa protein) are present in genomes of several other members of the genus Alphabaculovirus (Table 2). Information about the (putative) function of ac73 in the viral life cycle is not available, but transcripts are made (287).

Ac74: ac74, unknown function

Homologs of ac74 (30.6 kDa, 265 aa) are present in many but not all Alphabaculoviruses (Table 2), but the function of ac74 remains unknown. RNA copies have been found for this ORF (287).

Ac75: ac75, unknown function

Homologs of ac75 can only be found in genomes of Alphabaculoviruses (Table 2). The predicted gene product has a molecular mass of 15.5 kDa (133 aa) and transcripts have been detected with micro-arrays (287). There is no publication about the role of ac75 in baculovirus biology.

Ac76; ac76, unknown function

Homologs of ac76 can be found in genomes of all Alphabaculoviruses (Table 2). The predicted gene is transcribed (287) and encodes a hypothetical protein of 9.4 kDa (84 aa). No data about the role of ac76 in the baculovirus replication cycle are available.

Ac77: vlf-1, very late expression factor 1

Ac77 or the vlf-1 gene is involved in the expression of the very late genes p10 and polh (183, 288). The gene is transcribed in the late phase of infection – from 15 to 24 h p.i. The VLF-1 protein (44.4 kDa, 379 aa) is localized in the nucleus of infected cells and in nucleocapsids of both BV and ODV (289). Deletion of the vlf-1 gene results in defective BV production, but this is not due to impaired DNA replication as the vlf-1 mutant is still able to replicate DNA, although at a lower level (268). When infected with a vlf-1 null mutant neither nucleocapsids nor occlusion bodies are produced (153). VLF-1 may be involved in viral DNA processing as the protein sequence of VLF-1 shows similarity to integrases and resolvases (153, 183). Integrases belong to a family of tyrosine recombinases, which can arrange DNA duplexes by site-specific recombination (60). DNA replication of most likely AcMNPV is based on concatemer formation (147) and if true, VLF-1 might be involved in processing the concatemers before the DNA is packaged into nucleocapsids (153). Ac77 is a baculovirus core gene.

Ac78: ac78, unknown function

The ac78 gene product is a hypothetical protein (12.5 kDa, 109 aa) with a conserved DUF912 domain (176), which occurs in homologous NPV proteins, but gives no indication for the function of ac78. The gene is conserved among all Alphabaculoviruses (Table 2).

Ac79: ac79, unknown function

The ac79 gene encodes a hypothetical protein (12.2 kDa, 104 aa) with a conserved endonuclease GIYYIG catalytic domain. This domain shows similarity with bacteriophage T4 segA-E genes and with group Ⅰ introns of fungi (245). The GIY-YIG motif belongs to the homing endonuclease family, members of which catalyze double-stranded breaks in DNA to facilitate homing of introns (235). Orthologs of ac79 are found in several Alphabaculoviruses (Table 2), but its function in baculovirus biology remains enigmatic.

Ac80: gp41, tegument protein

The gene gp41 is expressed as a late gene with transcripts starting within two consensus late transcription start sites (TAAG), located immediately upstream of the first ATG codon (276). The 41 kDa protein (predicted molecular mass 45.4 kDa, 409 aa) has O-glycosidically linked N-acetylglucosamine (GlcNAc) residues and is present between the envelope membrane and the nucleocapsids of ODVs (277). A thermosensitive (ts) gp41 mutant causes single-cell-infections, which progress through the very late phase including the formation of OBs. However, infection does not spread to neighboring cells (210), indicating that BV production is affected in the ts-mutant, although GP41 is only found in ODVs (277). Ac80 is conserved in all baculovirus genomes.

Ac81: ac81, unknown function

The ac81 gene is highly conserved and belongs to the baculovirus core genes. The gene product has a predicted mass of 26.9 kDa (238 aa) and the homologous protein in BmNPV (Bm67) is detected neither in BVs nor ODVs. Immunofluoresence analysis showed that the Bm67 protein is present in the cytoplasm and interacts with the host protein actin A3 (31). Bm67 is required for the production of infectious BV (71). Bm67 mutations negatively affect viral DNA synthesis and the stability of nascent viral DNA. Nucleocapsids with a wild type morphology are hardly found and nucleocapsids are only occasionally exported to the cytoplasm. The envelopment of nucleocapsids is also abnormal with these Bm67 mutants (71).

Ac82: tlp, telokin-like protein-20

The gene ac82 encodes a protein with a predicted molecular mass of 20 kDa (19.8 kDa, 180 aa). In Western blot analysis it shows a size of 28 kDa and reacts with an antibody specific against the smooth muscle protein telokin, hence the name telokin-like protein or TLP (232). However, no amino acid sequence similarity exists between TLP-20 and telokin. 3-D structure analysis of TLP-20 showed a seven-stranded antiparallel β-barrel flanked on the basis by two additional β-strands and on the top by an α-helix. As such, TLP-20 does not resemble the structure of any other known protein (101).

Ac83: p95, viral capsid associated protein, VP91

The gene p95 encodes a protein (96.2 kDa, 847 aa), with two conserved domains: a viral capsid protein 91 and a chitin-binding peritrophin-A domain, respectively. The p95 gene belongs to the baculovirus core genes (Table 2 and Table 3). VP91 is associated with the capsid and envelope of ODVs (240). The second conserved domain belongs to the family of chitin peritrophic binding proteins and is able to bind chitin, which is present in a matrix lining the gut of most insects (58, 246).

Ac84: ac84, unknown function

The gene ac84 codes for a hypothetical protein (21.7 kDa, 188 aa) without any known conserved domain. The gene is transcribed (287).

Ac85: ac85, unknown function

The ac85gene product is a hypothetical protein with a mass of 6.4 kDa (53 aa) and homologs are only present in RoMNPV and Plutella xylostella (Px) MNPV (Table 2). The ac85 gene is transcribed (287).

Ac86: pnk/pnl polynucleotide kinase/ligase

The gene pnk/pnl is an immediate early gene encoding a protein (80.8 kDa, 694 aa) that contains two conserved domains: a kinase and a T4 RNA ligase domain (55). Deletion of pnk/pnl has no effect on virus replication in Sf21 cells or on protein production (55). The effect in pathogenesis in larvae is unknown.

Ac87: p15, unknown function

The gene p15 codes for a 15.0 kDa protein (126 aa) of unknown function. The protein does not contain known conserved domains, but homologs can be found in eight other Alphabaculoviruses (Table 2). For BmNPV P15 a function as a viral capsid protein was proposed due to high similarity with other viral capsid proteins. The transcription of the bm70 gene is regulated in time with a short early and a longer late transcript (171).

Ac88: cg30; unknown function

The ac88 gene product (30.1 kDa, 264 aa) harbors a zinc-finger-like and a leucine zipper motif, a characteristic found in proteins involved in gene regulation (215). cg30 is transcribed as an early monocistronicRNA and as the second cistron of an abundant late bicistronicRNA together with vp39 (259), but a CG30-beta-galactosidase fusion proteinwasmainly observed early in the infection process (215). cg30 is not essential for virus replication in vitro and in vivo, but the wild type virus accumulated to slightly higher titers over the cg30 deletion mutant after several passages in cell culture (215).

Ac89: vp39, major viral capsid protein VP39

The VP39 (39.0 kDa, 357 aa) is the most abundant structural protein of the nucleocapsid (260) with monomers arranged in stacked rings around the nucleoprotein core as reviewed in (249). VP39 is involved in the rearrangement and polymerization of host actin (28, 29). Recent results have shown that VP39 interacts with the 38K protein in infected insect cells (281). The vp39 gene is transcribed at late time points in infection from a promoter sequence containing three A/GTAAG consensus motifs (maximal transcription 12-24 h p.i.) as a bicistronic mRNA together with cg30 (259, 260). Vp39 is a core gene.

Ac90: lef-4, late expression factor 4

The lef-4 gene encodes the 55 kDa late expression factor 4 (predicted molecular mass 53.9 kDa, 464 aa) (54). LEF-4 is a subunit of the AcMNPV RNA polymerase (88) (see ac40) and is essential for late gene expression (132). LEF-4 has guanylyltransferase (84), RNA 5'-triphosphatase and ATPase activities (119), and appears to be a complete mRNA capping enzyme. The lef-4 gene is present in all baculoviruses (Table 2 and Table 3).

Ac91: ac91, unknown function

Ac91 potentially encodes a 24.1 kDa (224 aa) protein expressed in the late phase of infection and the gene is transcribed (287). The protein has an N-terminus rich in hydrophobic amino acids, including a stretch of 7 isoleucine residues, and a large central domain consisting of mainly proline, threonine and serine residues. The C-terminal domain, which is preceded by a methionine, is also present in some other baculovi-ruses, suggesting that the protein encoding region may be smaller than the entire ORF (not published).

Ac92: ac92/p33, unknown function, P33

Ac92 is a baculovirus core gene encoding a 33 kDa (predicted 30.9 kDa, 259 aa) protein (P33). Inactivation of this gene is lethal for the virus, indicating that ac93 is an essential baculovirus gene (230). P33 forms a complex with the mammalian tumor suppressor protein P53, when AcMNPV is used as a p53 gene expression vector, P33 also enhances P53-mediated apoptosis in insect cells (230). Flag-tagged P33 displays a diffuse cytoplasmic localization and punctuate nuclear staining in the absence of P53. In the presence of P53, P33 has an entirely nuclear localization. An insect p53 homolog has been identified (208) and many DNA viruses encode a P53 binding protein. Mass spectrometry indicated that P33 may be present in ODV particles (20).

Ac93: ac93, unknown function

The ac93 ORF is transcribed (287) and encodes a 18.4 kDa (161 aa) protein of unknown function, also named P18 in other baculoviruses. The conserved region is addressed as a DUF628 domain in the CDD (176).

Ac94: odv-e25, occlusion-derived virus envelope protein

ODV-E25 (25.5 kDa, 228 aa) is an integral ODV envelope protein, that is N-terminally anchored in the envelope (249). ODV-E25 is also present in BVs, but is much less abundant there than in ODVs (239). The ODV-E25 protein is initially present at a low concentrations, but is present at a higher levels from 36 h p.i. onwards (239). The N-terminal amino acid sequence of the protein (24 amino acids) is highly hydrophobic and this hydrophobic domain is sufficient to direct ODV-E25 to virus-induced membrane micro-vesicles within the nucleus and the ODV viral envelope (104).

Ac95: helicase, DNA helicase

Ac95 is a baculovirus core gene and encodes a 143.2 kDa (1221 aa) polypeptide (P143) with a consensus NTP-binding site and six other motifs characteristic for helicase proteins. Ac95 is a delayed early gene, which is transactivated by IE-1 (ac147) and PE38 (ac153) with a stimulatory role of IE-2 (ac151) (163). A ts-mutant showed the essential role of P143 in viral DNA replication (165) and this was further confirmed by transient replication assays (133). The AcMNPV helicase shows specificity for AcMNPV replication and cannot be exchanged with the SeMNPV helicase in transient DNA replication assays (98).

Ac96: ac96, unknown function

Ac96 is a baculovirus core gene encoding a 19.8 kDa (173 aa) protein. The BmNPV homolog Bm79 encodes a larger, 28 kDa protein, which is located in the ODV-envelope (ODV-E28) (286). The conserved region of Ac96 is indicated as the baculovirus 19 kDa protein superfamily domain. AcMNPV ac96 is found within a four-gene cluster comprising of helicase, lef-5, ac96, and 38K (ac98). The relative positions of these genes are conserved in all baculovirus genomes (100).

Ac97: ac97, unknown function

Ac97 is predicted to be an early gene encoding a 6.5 kDa (56 aa) protein. A transcript overlaps this ORF (287). Homologs of this gene with unknown function have not been found in other baculoviruses (Table 2 and Table 3).

Ac98: 38k, 38K protein

The gene ac98 encodes the protein 38K (38.0 kDa, 320 aa) which is synthesized in the late phase of infection. The 38K protein is localized and distributed over the cylindrical sheath of the nucleocapsid of both BVs and ODVs and is required for nucleocapsid assembly, but not for DNA replication (281, 282). Furthermore, it interacts with the nucleocapsid proteins VP1054 (ac54), VP39 (ac89), VP80 (ac104) and itself (281). The ac98 belongs to the baculovirus core genes (Table 2 and Table 3).

Ac99: lef-5, Late expression factor 5

The gene ac99 codes for the late expression factor LEF-5 (31.0 kDa, 265 aa), which has significant sequence similarity in a stretch of 32 C-terminal amino acids with a zinc ribbon domain in the eukaryotic transcription elongation factor TFIIS (95). Unlike the cellular TFIIS, LEF-5 functions most likely as a transcription initiation factor and stimulates transcription mediated by baculovirus RNA polymerase from late and very late viral promoters at least in in vitro transcription assays (83).. The N terminal 194 amino acids are involved in LEF-5:LEF-5 self interactions and the 32 C-terminal amino acids of LEF-5 contain a putative Zn2+-ribbon domain (95). The acidic dipeptide DE within this domain is crucial for LEF-5 activity (83). Lef-5 is a core gene (Table 2 and Table 3).

Ac100: p6.9, major DNA-binding protein

The most abundant protein in the nucleoprotein core is a small (6.9 kDa, 55 aa), very basic (pI=12), protamine-like protein named: Basic Protein or P6.9. The positively charged arginine residues of P6.9 interact with the viral DNA genome to mediate DNA condensation in the nucleocapsid (127). In infected cells P6.9 is phosphorylated, but in nucleocapsid assembly this phosphorylation is inhibited by the presence of Zn2+(68). A model for this packaging has been proposed: during packaging of viral DNA, P6.9 is dephosphorylated by cellular phosphatases followed by DNA condensation. Phosphorylation of P6.9 by a capsid-associated kinase results in unpackaging of the nucleocapsid upon entry into cells, allowing the onset of the infection cycle (68). P6.9 is a baculovirus core gene.

Ac101: p40, BV/ODV-C42

The gene ac101 is transcribed at the late stage of infection. It encodes a 42 kDa protein (41.5 kDa predicted molecular mass, 361 aa), which is a component of the nucleocapsid of both BVs and ODVs (18). There is strong evidence that ODV-C42 is capable of direct interaction with the WASP-like protein P78/ 83 (ac9) and ODV-EC27 (ac144) (18). ODV-C42 probably binds to the viral protein P78/83 in the cytoplasm to form a protein complex, which then migrates to the nucleus during AcMNPV infection due to the nuclear localization signal in ODV-C42 (274). A mutant virus lacking ac101 is not able to propagate in cell culture as no mature nucleocapsids are formed, however, viral genome replication was not affected (270). Direct interaction between BV/ODV-C42 and a leucine zipper domain of EXON0 (ac141) enables egress of nucleocapsids from the nucleus to cytoplasm during the late phase of infection (64). Homologs of the gene ac101 are present in all sequenced baculovi-ruses except CuniNPV (249) (Table 2 and Table 3).

Ac102: p12, transport of G-actin

The transcription of the gene coding for the 12-kDa protein (13.3 kDa predicted, 122 aa) initiates from the consensus baculovirus late transcription start site (ATAAG) (166). Attempts to prepare a p12-mutant were not successful, suggesting that the gene is essential for virus replication in cell culture (166). Together with the products of the genes ie-1 (ac147), pe38 (ac153), he65 (ac105), ac4, and ac152, P12 is involved in transport of G-actin into the nucleus during baculovirus infection (202).

Ac103: p48, unknown function

The 5' end of the p48 transcript maps to consensus baculovirus late transcription start sites (ATAAG) (166). Attempts to prepare p48 mutant viruses were not successful suggesting that the gene is essential for virus replication in cell culture (166). More recently, detailed analysis of a p48 deletion mutant confirmed that this gene is essential for BV production and ODV envelopment (290). Homologs of ac103 can be found in the genomes of all Alpha-, Beta-and Gammabaculoviruses (Table 2 and Table 3).

Ac104: vp80, capsid-associated protein VP80

A late 2.1 kb transcript was mapped to ac104 which encodes a 79.9 kDa protein (691 aa). VP80 is a structural capsid-associated protein as confirmed with anti-BV sera (164). VP80 interacts with the viral protein, 38K (see ac98) (281). In BmNPV, VP80 is essential for BV production and nucleocapsid maturation. The BmNPV vp80 could not functionally be replaced by AcMNPV vp80 (256). In the case of Choristoneura fumiferana (Cf) MNPV, the VP80 protein appears as a 82 kDa protein in samples from ODVs and as an 72/82 kDa doublet from BVs (151). Homologs of the vp80 gene are only found in Alphabaculoviruses (Table 2).

Ac105: he65, HE65 protein

The designation he65 stems from the size of the predicted protein (65.6 kDa, 553 aa) and the genomic location of this ORF, being flanked by an EcoRI site and the hr4 left region. He65 is a delayed early gene and mRNA is detectable from 2 h p.i.. Transcript levels remain stable into the late phases of infection (12). HE65, together with Ac102, mediates nuclear localization of monomeric G-actin, a process promoting nuclear F-actin formation, which is required for progeny virus production (202). Localization of G-actin within the nucleus is a temporally regulated process. Transactivators encoded by ie-1 (ac147), pe38 (ac153), ac4 and ac152 are essential for expression of he65 and ac102 (202).

Ac106/107: ac106/107, unknown function

Partial resequencing of AcMNPV showed that the original ac106 and ac107 together form one ORF (92). The combined ORF encodes a 28.3 kDa (243 aa) protein and has homologs in all Alpha-and Betabaculoviruses (Table 2 and Table 3) (100). Together these homologs form the DUF816 superfamily (176), a family of baculovirus proteins with unknown function.

Ac108: ac108, P11 protein

Ac108 is a putative late gene, expressing a 11.8 kDa (105 aa) protein belonging to the baculovirus 11 kDa protein family according to the CDD database (176). Its homologs in Antheraea pernyi (Anpe)NPV and SpltNPV are ODV structural proteins, with envelope localization shown for SpltMNPV P11 (32, 247). Association with ODVs has not been found for Ac108 (20). P11 is transcribed from a late promoter motif in AnpeNPV and from an early promoter in SpltNPV, with concordant differences in initiation of transcription.

Ac109: ac109, occlusion derived structural protein

The ac109 gene belongs to the baculovirus core genes. It encodes a 44.8 kDa (390 aa) protein which is present within or associated with the ODV (20). Its homolog in Helicoverpa armigera (Hear)NPV (ha94) is a late gene encoding the structural ODV component ODV-EC43 (66). The conserved part of this protein is known as DUF673 domain according to the CDD database (176).

Ac110: ac110, unknown function

Ac110 codes for a small 6.8 kDa (56 aa) protein of unknown function. Homologs are present in all Alpha-baculoviruses and most Betabaculoviruses (Table 2 and Table 3) and the conserved part of the protein is designated as DUF1448 domain (176). Transcripts from this region have been reported (287).

Ac111: ac111, unknown function

The gene ac111 is probably an early gene encoding a 8.2 kDa (67 aa) protein with undetermined function. The ORF is represented in the transcriptome of Ac-MNPV (287). Homologs of this ORF form the baculovirus 8 kDa gene family (176) with members in various Alpha-and Betabaculoviruses (Table 2 and Table 3).

Ac112/113: ac112/113, unknown function

The ORF ac112 encodes a protein (30.9 kDa, 258 aa) with a zinc finger motif (9). Homologs are present in a few baculovirus genomes and in Fowl pox virus (FPF217) (4). The homologs of ac112 and ac113 are fused into one ORF in RoMNPV and re-sequencing showed that this is also the case in AcMNPV C6 (92). The function of this ORF is unknown.

Ac114: ac114, unknown function

The gene ac114 codes for a protein with a predicted mass of 49.3 kDa (424 aa). Ac114 was detected in the capsid of ODVs (20). The gene is unique for group Ⅰ NPVs and contains a conserved domain belonging to the DUF1098 superfamily of unknown function (176).

Ac 115: pif-3, per os infectivity factor 3

PIF-3 is a 23.0 kDa (204 aa) baculovirus core protein required for oral infectivity of larvae. It has a predicted N-terminal transmembrane domain and is located most likely on the inside of the ODV envelopes (249). PIF-3 does not affect ODV binding or envelope fusion with larval midgut cells, but may play a crucial role further downstream in the infection process (203).

Ac116: ac116, unknown function

The putative gene product encoded by ac116 is 6.4 kDa (58 aa) and homologs are only present in the closely related BmNPV, Plutella xylostella (Plxy) MNPV and RoMNPV (Table 2). The function of the transcribed ac116 gene (287) is unknown.

Ac117: ac117, unknown function

The gene is transcribed (287) and codes for a putative protein with a molecular mass of 11.0 kDa (95 aa). Homologs are present in several other members of the genus Alphabaculovirus (Table 2).The function of ac117 in the viral life cycle is not known.

Ac118: ac118, unknown function

The gene codes for a protein (18.7 kDa, 157 aa) with unknown function and an RNA copy was found (287). A homolog of ac118 is only present in the genomes of the closely related PlxyMNPV and RoMNPV (Table 2).

Ac119: pif-1, per os infectivity factor 1

PIF-1, previously called PIF, is a low-abundant 59.7 kDa (530 aa) baculovirus core protein essential for oral infectivity in insect larvae (249). The Spodoptera exigua (Se)MNPV PIF-1 protein is present in ODVs (128), most likely anchored in the membrane by a conserved N-terminal transmembrane region (249). PIF-1 was not found in a proteomic analysis of AcMNPV ODVs (20), suggesting a low abundance. Together with PIF-2 it mediates binding of ODVs to epithelial midgut cells (203).

Ac120: ac120, unknown function

The putative gene product encoded by ac120 has a molecular mass of 9.5 kDa (82 aa). There is no information about the role of the ac120 product in the baculovirus life cycle. Homologs of ac120 can only be found in genomes of several other members of the genus Alphabaculovirus (Table 2).

Ac121: ac121, unknown function

A homolog of ac121 is only present in the genome of BmNPV (Table 2) and encodes a 6.7 kDa (58 aa) protein. There is evidence that Ac121 stimulates expression of the viral protein 39K (ac36) by up-regulation of IE1 (ac147) expression (78). Ac121 does not influence late gene expression (149).

Ac122: ac122, unknown function

The predicted gene ac122 (7.2 kDa, 62 aa) is transcribed (287) and present in genomes of several other members of the genus Alphabaculovirus (Table 2). No information on its function is available.

Ac123: pk2, protein kinase 2

The gene pk2 is transcribed early as an 1.2 kb RNA and encodes the protein PK2 (24.9 kDa, 215 aa). PK2 contains six out of eleven motifs conserved among eukaryotic protein kinases (152). Truncation of the pk2 gene has no effect on the number, size, or appearance of viral plaques and on the kinetics of protein synthesis or protein phosphorylation profiles during virus infection in cultured Sf21 cells. PK2 mutants show no difference in infectivity or virulence in larval bioassays, neither in production of OBs as compared to wild type AcMNPV infection (152). PK2 prevents the phosphorylation of the eukaryotic translation initiation factor 2α (eIF2α). This phosphorylation is induced by stress, as caused by viral infection and inhibits protein synthesis in general (39). PK2 is a homolog of cellular eIF2α kinases, but is an inactive, truncated enzyme. By forming hetero-dimers with the cellular eIF2α kinases their phosphorylation activity is inhibited. Wild type AcMNPV shows a reduced eIF2α phosphorylation and increased translational activity, compared to a pk2 deletion mutant (51).

Ac124: ac124, unknown function

This gene encodes a protein (28.5 kDa, 247 aa) with unknown function. Homologs are present in several members of the genus Alphabaculovirus (Table 2). Ac124 is transcribed (287).

Ac125: lef-7, late expression factor 7

The lef-7 gene is transcribed early in infection from an initiation site 14 to 16 bp upstream of the putative translational start site and transcribed late in infection from a not determined initiation site more upstream (194). LEF-7 (26.6. kDa, 226 aa) is required for maximum late reporter gene expression (167). Deletion of lef-7 results in decreased BV and ODV production and DNA replication compared to the wild type virus infection (30). In BmNPV deletion of lef-7 also resulted in decreased levels of viral DNA replication (77). Furthermore, lef-7 is required for efficient homologous recombination in the presence of all other DNA replication genes (45).

Ac126: ac126, chitinase (ChiA)

The AcMNPV chitinase protein (ChiA) has a predicted molecular mass of 61.4 kDa (551 aa). ChiA accumulates in the endoplasmatic reticulum due to the presence of a signal peptide and a KDEL-retention signal (241, 261). Its release upon cell death is mediated by P10 (ac137) (261). ChiA is -together with the protease cathepsin (V-CATH; ac127) -required for disruption of the chitin skeleton of the host (96). The resulting liquefaction of the insect enables the efficient spread of viral occlusion bodies. ChiA is also prerequisite for processing of v-CATH from an inactive proenzyme (102). As a consequence deletion of chiA (+/-v-cath) from baculovirus expression vectors is used to reduce recombinant protein degradation (120). The chiA genes are present in many Alphabaculovi-ruses and some Betabaculoviruses and may have been picked up later in baculovirus evolution (Table 2 and Table 3).

Ac127: v-cath, cathepsin

The protease cathepsin (V-CATH) (predicted size 36.9 kDa, 323 aa) is activated from an inactive precursor by ChiA (ac126) and both proteins (V-CATH and ChiA) are required for the liquefaction of the insect host to allow efficient spread of OBs (96). V-CATH is also activated by chaotropic agents like SDS and its activity is inhibited by the protease inhibitor E64 (103). As, the chiA genes, the v-cath genes are also present in many Alphabaculoviruses and some Betabaculoviruses, but not all these viruses have both chiA and v-cath genes (Table 2 and Table 3).

Ac128: gp64, major budded virus envelope glycoprotein

In AcMNPV-infected Sf9 cells, the gene gp64 is transcribed both early and late in infection (116). GP64 (58.6 kDa predicted size, 512 aa) is absolutely essential for cell to cell spread of BVs. GP64 occurs as a covalently bonded trimer and is present on the surface of infected cells and is acquired by virions during budding through the plasma membrane, the final step in the release of BVs (212). GP64 is involved in host-receptor binding and is sufficient alone to mediate low-pH-triggered membrane fusion during intra-cellular trafficking (177). A domain in the N-terminal part (aa 21-159) is thought to be involved in host-receptor binding (292) and fusion and oligomerization domains have also been identified (192). The GP64 transmembrane region plays a crucial role in membrane fusion and is also required for GP64 trafficking and the budding process (154). The crystal structure of the GP64 post-fusion form revealed structural homology with the vesicular stomatitis virus G and herpes simplex virus type 1 gB proteins (121).

Ac129: p24, viral capsid protein

The gene ac129 is transcribed in the late phase of virus infection, initiated from a canonical late pro-moter sequence (GTAAG) situated immediately up-stream of the coding sequence (75). P24 (22.1 predicted molecular mass, 198 aa) is a capsid-associated protein, which is not N-glycosylated, but its precise function is unknown. Transposon-based interruption of the p24 gene did not affect viral propagation in cell culture (75, 242, 280). In SpltNPV, the homologous protein is associated with ODVs as a complex of 83 kDa (155). For Lymantria dispar (Ld)MNPV some natural variants lack p24 sequences (251).

Ac130: gp16, unknown function

Ac130 has the potential to encode a protein of 12.1 kDa (106 aa). In OpMNPV, the homologous protein GP16 was detected at 24 h p.i. and its levels increased through 120 h p.i. OpMNPV GP16 is N-glycosylated and not associated with purified BVs and ODVs. It localizes to cytoplasmic lamellar-like structures close to the nuclear membrane and to envelopes of viruses on their way from the nucleus to the cell surface (81). In AcMNPV, transcription of the gene ac130 could not be detected by microarray analysis (287).

Ac131: pp34, major polyhedral calyx protein

The phosphoprotein PP34 (38 kDa, predicted 29.1 kDa, 252 aa) is detected from 15 h p.i. and continues to be phosphorylated until 60-70 h p.i. inside infected insect cells. It is involved in the morphogenesis of the polyhedral envelope of baculoviruses and is part of the carbohydrate envelope of occlusion bodies called the calyx (278, 294). Electron-dense "spacers" present in wild-type AcMNPV-infected cells, are absent in pp34-null mutants (294).

Ac132: ac132, unknown function

The ac132 gene with a predicted product of 25.1 kDa (219 aa) is transcribed (287) and homologs are present in genomes of several other members of the genus Alphabaculovirus (Table 2), but no function has been associated with it.

Ac133: an, alkaline nuclease

All sequenced baculovirus genomes encode a homolog of alkaline nuclease (AN) (Table 2 and Table 3). The predicted molecular mass of the AcMNPV AN is 48.3 kDa (419 aa). AN protein is present in two forms, one full length (53 kDa) and a shorter form (43 kDa). Both forms are found at low levels from 12 h p.i., with maximal abundance at 24 h p.i. (150). AN associates with LEF-3, the baculovirus ssDNA-binding protein (185). AN has 5' to 3'exonuclease and 5' to 3' endonuclease activity. Both these enzyme functions are involved in DNA recombination and replication (185, 186). The first attempt to produce an AcMNPV an-null virus was not successful, suggesting that an is an essential gene (150). Transfection with an AcMNPV an-null bacmid shows no BV production and a reduced number of normal-appearing nucleo-capsids. Instead, numerous aberrant capsid-like structures are formed, indicating a defect in nucleocapsid maturation or in a DNA-processing step, that is necessary for encapsidation (206, 207).

Ac134: 94k, unknown function

The 94k gene encodes a protein of 94.5 kDa (803 aa). The function of the 94K is still unknown, but homologs can be found in several other baculoviruses (Table 2 and 3). In the closely related BmNPV only 151 bps correspond to ac134 suggesting the gene might not be essential and was lost by a deletion (76). Random transposon insertions into the 94k gene have confirmed that it is not essential for virus replication (32). The 94k gene harbors the non-hr origin of replication, which is characterized by palindromes-and AT-rich regions. These motifs are essential for its ability to act as origin of DNA replication and are conserved in BmNPV (134).

Ac135: 35k/p35, apoptosis inhibitor

The gene p35 encodes the 34.8 kDa (299 aa) protein P35, which is a strong inhibitor of apoptosis The function of P35 and IAP proteins is extensively reviewed e.g. (36). Mutations in the p35 gene result in apoptosis of infected Sf21 cells and abort infection (37, 146), but have a wild type appearance in Tn368 cells (38). P35 blocks apoptosis by inhibiting the activity of Sf-caspase-1 and as such works at a different point in the caspase cascade as IAPs, which block apoptosis further upstream in the pathway (5, 140). Crystal structures of the interaction between P35 and Sf-caspase-1 have been determined (56). P35 gene expression is transactivated by IE-1 the protein, which is also responsible for inducing apoptosis (243).

Ac136: p26, unknown function

The gene p26 encodes a dimeric protein (monomeric 27.2 kDa, 240 aa) with unknown function, which is located primarily in the cytoplasm. Transcripts accumulate between 2-12 h p.i. (73, 248). Although conserved in most Alphabaculoviruses (Table 2) and present as two copies in several group-Ⅱ NPVs, deletion of this ORF does not notably affect the virulence of the virus (248).

Ac137: p10, fibrillin or fibrous body protein

The p10 gene is a non-essential, hyper-expressed very late gene, encoding a 10.3 kDa protein (94 aa). P10 forms two cytoskeletal-like structures: microtubule-associated filaments through interaction with α-tubulin and perinuclear, tubular aggregates (25, 218). The formation of these structures requires the N-terminal heptad repeat/coiled-coil domain of P10 (52). Other domains include a pro-line rich region and a positively-charged C-terminus. The nuclear filaments may play a role in occlusion body maturation via interaction with the polyhedral envelope. P10 also triggers the release of individual polyhedra from the cell nucleus (265). The p10 promoter is-besides the polyhedrin promoter-exploited in baculovirus expression vectors.

Ac138: p74, occlusion-derived virus envelope protein

The AcMNPV P74 (73.9 kDa, 645 aa) was the first ODV-envelope protein found to be essential for primary infection in larval midguts (67) and is therefore also addressed as PIF-0 (review in (249)). The p74 gene belongs together with pif-1, pif-2 and pif-3 to the baculovirus core genes. In order to be active, P74 needs to be cleaved by trypsins in the insect gut (250). P74 is exposed at its N-terminus at the ODV surface and binds to midgut epithelium (89) through a receptor not yet characterized for AcMNPV. A double C-terminal membrane anchor allows insertion into membranes, as shown by rescue of P74 negative ODVs with recombinant P74 protein (293).

Ac139: me53, DNA synthesis regulator

The me53 ORF is an immediate-early gene abundantly transcribed as early as 1 h p.i. It encodes a protein of 53 kDa (52.6 kDa, 449 aa) with a C-terminal zinc finger motif (CX2CX13CX2C) suggesting a sequence-specific DNA binding capacity and the N-terminus contains a proline-rich region (131). Deletion of this essential gene prevents DNA replication (285).

Ac140; ac140, unknown function

The transcribed ac140 gene (287) is translated in a hypothetical protein of 7.1 kDa (60 aa) with unknown function. No homologs have been found in any other baculovirus (Table 2).

Ac141: exon0, unknown function

The gene exon0 is transcribed in the late phase of infection and encodes a 30.1 kDa (261 aa) protein with the following functional domains: The N-ter-minal halve of EXON-0 contains two acidic domains and a domain rich in charged amino acids, whereas the C-terminal part comprises a leucine zipper/coiled coil domain and a RING finger-like domain (46, 64). The protein EXON0 is not essential for virus replication or ODV production, but is required for the production of BVs, as it mediates the egress of nucleocapsids from the nucleus (46, 63). EXON0 interacts with the nucleocapsid protein BV/ODV-C42 and with FP25, enabling the escape of nucleocapsids from the nucleus to the cytoplasm (64). Recently, interaction of EXON0 with -tubulin was demonstrated (65). The ac141 ORF is located in the 4.5 kb part of the transcript that is removed by splicing to get the immediate early ie-0 mRNA (see ac147) (46). Some homologs are aberrantly referred to in literature as ie-0.

Ac142: 49k, 49 kDa protein

The ORF ac142 belongs to the core baculovirus genes and is a late gene, transcribed from 12 to 72 h p.i. The gene product, Ac142, is a 55.4 kDa (477-aa) protein with a putative transmembrane domain and is associated with the nucleopcapsids of BVs and ODVs (20, 178). ac142 is essential for infectious BV production and for effective envelopment of ODVs to allow the subsequent packaging into occlusion bodies (178).

Ac143: odv-e18, occlusion-derived virus envelope protein

The gene odv-e18 is transcribed from three late promoter motifs from 16 through 72 h p.i. ODV-E18 is a structural protein (6.6 kDa predicted, 62 aa) present in the ODV envelope and in virus-induced intranuclear membranes (19). Deletion of ac143 prohibits the production of infectious BVs, however, the level of DNA replication and occlusion body formation are not affected (179). Homologs are found in all baculovirus genomes (179).

Ac144: odv-ec27, occlusion-derived virus envelope/capsid protein

The odv-ec27 is a late gene, transcribed from the same promoter motifs as odv-e18 (ac143) and its product, ODV/EC27, is localized to the ODV envelope and capsid structures (19). The protein has a cyclin-like domain, suggesting a role in cell cycle de-regulation (13). Antibodies against ODV-EC27 recognized a 27 kDa protein (33.5 kDa predicted, 292 aa) in infected cells and proteins of 27 and 35 kDa in purified ODVs. The ODV-E35 protein appears to be the result of a translational shift during ribosomal reading of the bicistronic odv-e18/odv-27 mRNA (19). ODV-E27 interacts with ODV/BV-C42 and P78/83 (18). AcMNPV odv-e27 deletion mutants show a diminished production of infectious BVs. DNA replication is similar as for the wild-type virus but the mutant has a defect in nucleocapsid assembly (270). Odv-ec27 is a baculovirus core gene.

Ac145: ac145, unknown function

The gene ac145 is expressed at the late to very late phase of infection and encodes a small protein (8.9 kDa, 77 aa), present in both BVs and ODVs. Ac145 belongs to a family of proteins, which contain a C6 or peritrophin-A-like domain (CX7-18CX5CX6-11CX12CX5-11C, where X represents any amino acid residue other than cysteine) (143). The function of Ac145 is not clear although it plays a role in oral infection. Deletion of ac145 does not affect BV propagation, but leads to decreased in vivo infectivity compared to wild-type AcMNPV in a host dependent way (143). Homologs of the gene are conserved in all baculoviruses, except Deltabaculoviruses (Table 2 and Table 3).

Ac146: ac146, unknown function

The ac146 gene codes for a protein of 22.9 kDa (201 aa) and is found in the genomes of Alpha-and Betabaculoviruses. No information about the function of ac146 is available.

Ac147: ie-1, immediate early transactivator IE-1

During the early phase of infection, mRNAs of 1.9-kb and spliced 2.1-kb transcripts are present which encode IE-1 and IE-0, respectively (35). The ie-0 transcript is the only known spliced baculovirus mRNA. IE-1 contains 582 aa (66.9 kDa) arranged into different domains, including an acidic activation domain at the N-terminus, a DNA binding domain, and an oligomerization domain at the C-terminus (47, 136). Compared to IE-1, IE-0 has 52 extra N-terminal amino acids. IE-1 is a potent transcriptional transactivator and essential for virus replication (133). A virus lacking either ie-1 or ie-0 could be propagated in cell culture, but a double knock-out is not viable. The ie0-ie1 gene complex is essential for viral infection and is needed to obtain wild type levels of replication, late gene expression and BV and ODV production (243, 197). De novo synthesis of IE-1 leads to virus-induced apoptosis (252). IE-1 also transactivates the expression of the p35 gene, and in that way counteracts its own pro-apoptotic activity (243). Homologs are found in all Alphabaculoviruses (Table 2).

Ac148: odv-e56, occlusion-derived virus envelope protein

Transcription of the gene odv-e56 starts from a late ATAAG promoter and transcripts are detected from 16 to 72 h p.i. (17). ODV-E56 protein (predicted 40.9 kDa, 476 aa) is present in viral-induced intranuclear microvesicles, and consequently is incorporated into ODV envelopes (17). Mutation in the 3x-end of odv- e56 alters its location to the nucleocapsids instead of the ODV envelope, suggesting that an important localization sequence is present in the C-terminus of this protein (17).

Ac149: ac149, unknown function

The ac149 ORF encodes a putative protein of 12.4 kDa (107 aa) with unknown function. Homologs are present in a few related Alphabaculoviruses (Table 2).

Ac150: ac150, unknown function

The gene ac150 encodes an 11.2 kDa (99 aa) protein and is expressed in the late to very late phase of infection. The protein Ac150, is a member of a family containing peritrophin-A-like domains (see also ac145) -common among mucins, peritrophins and chitinases -and the protein contains an integrin-binding motif (143). Deletion of ac150 has no effect on infectivity of the virus for T. ni or H. virescens larvae, but the mutant is less efficient in establishing a primary infection in midgut cells, although the infectivity kinetics are the same as for the wild type virus (291). These results together suggest that ac150 can be considered as a putative per os infection factor (PIF) that mediates, but is not essential for, oral infection (291). This has been confirmed as a deletion of the homologous gene (bm126) in BmNPV shows no difference in BV production and mean lethal dose of OBs. However the median survival time in larvae is delayed (91).

Ac151: ie-2, immediate early transactivator 2

The ie-2 gene encodes the immediate early protein IE-2 (47.0 kDa, 408 aa), which functions as a transactivator of early baculovirus promoters in transient expression assays (26). Other functions of the protein are blocking the progression of the cell cycle in a variety of cell lines (229) and augmenting the replication and stability of reporter plasmids containing hr sequences in the presence of IE-1 and four other AcMNPV gene products (133, 167). Viruses with ie-2 mutations exhibit delays in viral DNA synthesis, late gene expression, BV production, and OB formation in Sf21 cells but not in TN-5B1-4 cells (227).

Ac152: ac152

The gene ac152 encodes a protein of 10.8 kDa (92 aa). The protein Ac152 is involved in nuclear localization of G-actin in TN-368 cells and is a transactivator (directly or indirectly) of both ac102 and he65 genes (202).

Ac153: pe38

The gene product of pe38, the protein PE38 (321 aa), is present during the early phase of infection as a nuclear 38 kDa protein, but during the late phase, it is modulated to or produced as a cytoplasmic 20 kDa protein in a process which is controlled by viral factors (137). PE38 is a protein with RING finger and leucine zipper motifs and is involved in transactivation of viral genes and augmenting viral DNA replication in transient replication assays (133, 137). Furthermore, PE38 is augments IE1-induced apoptosis, but is not able to induce apoptosis when expressed in Sf21 cells alone (228). PE38 is an important factor in viral DNA synthesis and BV production (189).

Ac154: ac154, unknown function

The gene ac154 encodes a protein (calculated mass 9.4 kDa, 81 aa) with unknown function. Transcripts of this gene have been identified (287). Only four homologs are present in other Alphabaculoviruses (Table 2).

CONCLUSION

The research towards elucidating the function of AcMNPV genes started in the early 1980s with the assignment of polyhedrin and p10, but was enhanced by the publication of the complete genome sequence in 1994 showing originally 154 ORFs (9) to which ac53a (lef-10) was added later. Partial re-sequencing of the AcMNPV C6 strain at a later date, demonstrated that four ORF pairs were actually fused (ac20/21, ac58/59, ac106/107, ac112/113), bringing the total to 151 ORFs (92). For many ORFs, we had little or no idea about their putative function. Overtime, many ORFs were assigned (see Table 1), mainly associated with transcription, DNA replication, virion structure and pathogenesis. Nevertheless, as of January 2009, 73 ORFs still remain with an unknown function. The most striking ORFs were those involved in the inhibition of apoptosis (p35) and in abrogation of the molt (egt). These observations provoked resonance far beyond baculovirology.

Functional studies in other, closely-related baculovi-ruses are sometimes useful to indicate which role an encoded AcMNPV protein might have. However, discrepancies have been found, which may reflect intrinsic differences in the viral protein under study. The discrepancies may also reflect dissimilarities in the presence or absence of other baculovirus gene products or in the interplay with host factors.

Many of the AcMNPV ORFs with unknown function encode relatively small proteins, sometimes with homologs in only a few baculoviruses, and therefore may not be functional or may not have a very crucial role. Others with unrevealed function, though, belong to the baculovirus core genes at the family level, or are represented in a whole genus, and must play key roles in baculovirus biology. Some of these genes may very well play a role in baculovirus ecology rather than in transcription, gene regulation, DNA replication, or in the assembly of BV and ODV particles. A systematic analysis of knock-out mutants would help in the further functional assignment of AcMNPV ORFs.

Detailed information on the molecular genetics and functional biology of AcMNPV ORFs will contribute to the further development, tailoring and improvement of baculoviruses as biocontrol agents, protein expression vectors and as vectors for gene therapy. This Encyclopedia of AcMNPV genes should be the starting point and further contribute to this venture.

The draft of this manuscript was almost completed when a web-based publication by George F. Rohrmann on "Baculovirus Molecular Biology" was made public.

Acknowledgments

David Cohen, Bryn Davis and Martin Marek were financed by the project BACULOGENES of the European Union (LSHB-CT-2006-037541). Monique van Oers was sponsored by the Netherlands Scientific Organisation (NWO) MEERVOUD program.

References

  1. 1. Acharya A, Gopinathan K P. 2001. Identification of an enhancer-like element in the polyhedrin gene upstream region of Bombyx mori nucleopolyhedrovirus. J Gen Virol, 82: 2811-2819.
  2. 2. Acharya A, Gopinathan K P. 2002. Transcriptional analysis and preliminary characterization of ORF Bm42 from Bombyx mori nucleopolyhedrovirus. Virology, 299: 213-24.
  3. 3. Afonso C L, Tulman E R, Lu Z, et al. 1999. The genome of Melanoplus sanguinipes entomopoxvirus. J Virol, 73: 533-552.
  4. 4. Afonso C L, Tulman E R, Lu Z, et al. 2000. The genome of Fowlpox virus. J Virol, 74: 3815-3831.
  5. 5. Ahmad M, Srinivasula S M, Wang L, et al. 1997. Spodoptera frugiperda caspase-1, a novel insect death protease that cleaves the nuclear immunophilin FKBP46, is the target of the baculovirus antiapoptotic protein p35. J Biol Chem, 272: 1421-1424.
  6. 6. Altschul S, Gish W, Miller W, et al. 1990. Basic local alignment search tool. J. Mol. Biol, 215: 403-410.
  7. 7. An S H, Xing L P, Shi W J, et al. 2006. Characterization of Autographa californica multiple nucleopolyhedrovirus ORF17. Acta Virol, 50: 17-23.
  8. 8. Au V, Yu M, Carstens E B. 2009. Characterization of a baculovirus nuclear localization signal domain in the late expression factor 3 protein. Virology, 385: 209-217.
  9. 9. Ayres M D, Howard S C, Kuzio J, et al. 1994. The complete DNA sequence of Autographa californica nuclear polyhedrosis virus. Virology, 202: 586-605.
  10. 10. Bauser C A, Elick T A, Fraser M J. 1996. Characterization of hitchhiker, a transposon insertion frequently associated with baculovirus FP mutants derived upon passage in the TN-368 cell line. Virology, 216: 235-237.
  11. 11. Bawden A L, Glassberg K J, Diggans J, et al. 2000. Complete genomic sequence of the Amsacta moorei entomopoxvirus: analysis and comparison with other poxviruses. Virology, 274: 120-139.
  12. 12. Becker D, Knebel-Mörsdorf D. 1993. Sequence and temporal appearance of the early transcribed baculovirus gene HE65. J Virol, 67: 5867-5872.
  13. 13. Belyavskyi M, Braunagel S C, Summers M D. 1998. The structural protein ODV-EC27 of Autographa cali-fornica nucleopolyhedrovirus is a multifunctional viral cyclin. Proc Natl Acad Sci USA, 95: 11205-11210.
  14. 14. Beniya H, Braunagel S C, Summers M D. 1998. Auto-grapha californica nuclear polyhedrosis virus: subcellular localization and protein trafficking of BV/ODV-E26 to intranuclear membranes and viral envelopes. Virology, 240: 64-75.
  15. 15. Bideshi D K, Renault S, Stasiak K, et al. 2003. Phy-logenetic analysis and possible function of bro-like genes, a multigene family widespread among large double-stranded DNA viruses of invertebrates and bacteria. J Gen Virol, 84: 2531-2544.
  16. 16. Braunagel S C, Burks J K, Rosas-Acosta G, et al. 1999. Mutations within the Autographa californica nucleopoly-hedrovirus FP25K gene decrease the accumulation of the ODV-E66 and alter its intranuclear transport. J Virol, 73: 8559-8570.
  17. 17. Braunagel S C, Elton D M, Ma H, et al. 1996. Identification and analysis of an Autographa californica nuclear polyhedrosis virus structural protein of the occlusion-derived virus envelope: ODV-E56. Virology, 217: 97-110.
  18. 18. Braunagel S C, Guidry P A, Rosas-Acosta G, et al. 2001. Identification of BV/ODV-C42, an Autographa californica nucleopolyhedrovirus orf101-encoded structural protein detected in infected-cell complexes with ODV-EC27 and p78/83. J Virol, 75: 12331-12338.
  19. 19. Braunagel S C, He H, Ramamurthy P, et al. 1996. Transcription, translation, and cellular localization of three Autographa californica nuclear polyhedrosis virus structural proteins: ODV-E18, ODV-E35, and ODV-EC27. Virology, 222: 100-114.
  20. 20. Braunagel S C, Russell W K, Rosas-Acosta G, et al. 2003. Determination of the protein composition of the occlusion-derived virus of Autographa californica nuc-leopolyhedrovirus. Proc Natl Acad Sci USA, 100: 9797-9802.
  21. 21. Braunagel S C, Williamson S T, Saksena S, et al. 2004. Trafficking of ODV-E66 is mediated via a sorting motif and other viral proteins: Facilitated trafficking to the inner nuclear membrane. Proc Natl Acad Sci USA, 101: 8372-8377.
  22. 22. Broussard D R, Guarino L A, Jarvis D L. 1996. Dynamic phosphorylation of Autographa californica nuclear polyhedrosis virus pp31. J Virol, 70: 6767-6774.
  23. 23. Büchen-Osmond C. 2006. ICTVdb-The universal virus database, version 4. Columbia University, New York, USA
  24. 24. Burks J K, Summers M D, Braunagel S C. 2007. BV/ ODV-E26: A palmitoylated, multifunctional structural protein of Autographa californica nucleopolyhedrovirus. Virology, 361: 194-203.
  25. 25. Carpentier D C J, Griffiths C M, King L A. 2008. The baculovirus P10 protein of Autographa californica nuc-leopolyhedrovirus forms two distinct cytoskeletal-like structures and associates with polyhedral occlusion bodies during infection. Virology, 371: 278-291.
  26. 26. Carson D D, Summers M D, Guarino L A. 1991. Molecular analysis of a baculovirus regulatory gene. Virology, 182: 279-286.
  27. 27. Changela A, Martins A, Shuman S, et al. 2005. Crystal structure of baculovirus RNA triphosphatase complexed with phosphate. J Biol Chem, 280: 17848-56.
  28. 28. Charlton C A, Volkman L E. 1993. Penetration of Autographa californica nuclear polyhedrosis virus nucleocapsids into IPLB Sf21 cells induces actin cable formation. Virology, 197: 245-254.
  29. 29. Charlton C A, Volkman L E. 1991. Sequential rear-rangement and nuclear polymerization of actin in baculovirus-infected Spodoptera frugiperda cells. J Virol, 65: 1219-1227.
  30. 30. Chen C-J, Thiem S M. 1997. Differential infectivity of two Autographa californica nucleopolyhedrovirus mutants on three permissive cell lines is the result of lef-7 deletion. Virology, 227: 88-95.
  31. 31. Chen H Q, Chen K P, Yao Q, et al. 2007. Characteri-zation of a late gene, ORF67 from Bombyx mori nucleopoly-hedrovirus. FEBS Lett, 581: 5836-5842.
  32. 32. Chen W, Li Z, Li S, et al. 2006. Identification of Spodoptera litura multicapsid nucleopolyhedrovirus ORF97, a novel protein associated with envelope of occlusion-derived virus. Virus Genes, 32: 79-84.
  33. 33. Chen Y, Yao B, Zhu Z, et al. 2004. A constitutive super-enhancer: homologous region 3 of Bombyx mori nucleopolyhedrovirus. Biochem. Biophys. Res.Commun, 318: 1039-1044.
  34. 34. Cheng X-W, Krell P J, Arif B M. 2001. P34. 8 (GP37) is not essential for baculovirus replication. J Gen Virol, 82: 299-305.
  35. 35. Chisholm G E, Henner D J. 1988. Multiple early transcripts and splicing of the Autographa californica nuclear polyhedrosis virus ie-1 gene. J Virol, 62: 3193-3200.
  36. 36. Clem R J. 2007. Baculoviruses and apoptosis: a diversity of genes and responses. Curr Drug Targets, 8: 1069-1074.
  37. 37. Clem R J, Fechheimer M, Miller L K. 1991. Prevention of apoptosis by a baculovirus gene during infection of insect cells. Science, 254: 1388-1390.
  38. 38. Clem R J, Miller L K. 1993. Apoptosis reduces both the in vitro replication and the in vivo infectivity of a baculovirus. J Virol, 67: 3730-3738.
  39. 39. Clemens M J. 2001. Initiation factor eIF2 alpha phosp-horylation in stress responses and apoptosis. Prog Mol Subcell Biol, 27: 57-89.
  40. 40. Condreay J P, Witherspoon S M, Clay W C, et al. 1999. Transient and stable gene expression in mammalian cells transduced with a recombinant baculovirus vector. Proc Natl Acad Sci USA, 96: 127-132.
  41. 41. Cory J S, Clarke E E, Brown M L, et al. 2004. Microparasite manipulation of an insect: the influence of the egt gene on the interaction between a baculovirus and its lepidopteran host. Funct Ecol, 18: 443-450.
  42. 42. Crawford A M, Miller L K. 1988. Characterization of an early gene accelerating expression of late genes of the baculovirus Autographa californica nuclear polyhedrosis virus. J Virol, 62: 2773-2781.
  43. 43. Crook N E, Jarrett P. 1991. Viral and bacterial patho-gens of insects. J Appl Bacteriol Symposium Sup-plement, 20: 91S-96S.
  44. 44. Crouch E A, Cox L T, Morales K G, et al. 2007. Inter-subunit interactions of the Autographa californica M nucleopolyhedrovirus RNA polymerase. Virology, 367: 265-274.
  45. 45. Crouch E A, Passarelli A L. 2002. Genetic requirements for homologous recombination in Autographa californica nucleopolyhedrovirus. J Virol, 76: 9323-9334.
  46. 46. Dai X, Stewart T M, Pathakamuri J A, et al. 2004. Autographa californica multiple nucleopolyhedrovirus exon0 (orf141), which encodes a RING finger protein, is required for efficient production of budded virus. J Virol, 78: 9633-9644.
  47. 47. Dai X, Willis L G, Huijskens I, et al. 2004. The acidic activation domains of the baculovirus transactivators IE1 and IE0 are functional for transcriptional activation in both insect and mammalian cells. J Gen Virol, 85: 573-582.
  48. 48. Detvisitsakun C, Berretta M F, Lehiy C, et al. 2005. Stimulation of cell motility by a viral fibroblast growth factor homolog: Proposal for a role in viral pathogenesis. Virology, 336: 308-317.
  49. 49. Detvisitsakun C, Cain E L, Passarelli A L. 2007. The Autographa californica M nucleopolyhedrovirus fibroblast growth factor accelerates host mortality. Virology, 365: 70-78.
  50. 50. Detvisitsakun C, Hutfless E L, Berretta M F, et al. 2006. Analysis of a baculovirus lacking a functional viral fibroblast growth factor homolog. Virology, 346: 258-265.
  51. 51. Dever T E, Sripriya R, McLachlin J R, et al. 1998. Disruption of cellular translational control by a viral truncated eukaryotic translation initiation factor 2 alpha kinase homolog. Proc Natl Acad Sci USA, 95: 4164-4169.
  52. 52. Dong C, Deng F, Li D, et al. 2007. The heptad repeats region is essential for AcMNPV P10 filament formation and not the proline-rich or the C-terminus basic regions. Virology, 365: 390-397.
  53. 53. Dreschers S, Roncarati R, Knebel-Morsdorf D. 2001. Actin rearrangement-inducing factor of baculoviruses is tyrosine phosphorylated and colocalizes to F-actin at the plasma membrane. J Virol, 75: 3771-3778.
  54. 54. Durantel D, Croizier G, Ravallec M, et al. 1998. Temporal expression of the AcMNPV lef-4 gene and subcellular localization of the protein. Virology, 241: 276-284.
  55. 55. Durantel D, Croizier L, Ayres M D, et al. 1998. The pnk/pnl gene (ORF 86) of Autographa californica nucleopolyhedrovirus is a non-essential, immediate early gene. J Gen Virol, 79: 629-637.
  56. 56. Eddins M J, Lemongello D, Friesen P D, et al. 2002. Crystallization and low-resolution structure of an effector-caspase/P35 complex: Similarities and differences to an initiator-caspase/P35 complex. Acta Crystallographica Section D: Biological Crystallography, 58: 299-302.
  57. 57. Eldridge R, Li Y, Miller L K. 1992. Characterization of a baculovirus gene encoding a small conotoxinlike poly-peptide. J Virol, 66: 6563-6571.
  58. 58. Elvin C M, Vuocolo T, Pearson R D, et al. 1996. Characterization of a major peritrophic membrane protein, peritrophin-44, from the larvae of Lucilia cuprina. J Biol Chem, 271: 8925-8935.
  59. 59. Erlandson M, Mahy B W J, van Regenmortel M H V. 2008. Insect pest control by viruses. Encyclopedia of Virology. Oxford: Academic Press: p125-133.
  60. 60. Esposito D, Scocca J J. 1997. The integrase family of tyrosine recombinases: evolution of a conserved active site domain. Nucleic Acids Res, 25: 3605-3614.
  61. 61. Evans J T, Leisy D J, Rohrmann G F. 1997. Characteri-zation of the interaction between the baculovirus repli-cation factors LEF-1 and LEF-2. J Virol, 71: 3114-3119.
  62. 62. Fan X, McLachlin J R, Weaver R F. 1998. Identi-fication and characterization of a protein kinase-interacting protein encoded by the Autographa californica nuclear polyhedrosis virus. Virology, 240: 175-182.
  63. 63. Fang M, Dai X, Theilmann D A. 2007. Autographa californica multiple nucleopolyhedrovirus EXON0 (ORF141) is required for efficient egress of nucleo-capsids from the nucleus. J Virol, 81: 9859-9869.
  64. 64. Fang M, Nie Y, Dai X, et al. 2008. Identification of AcMNPV EXON0 (ac141) domains required for efficient production of budded virus, dimerization and association with BV/ODV-C42 and FP25. Virology, 375: 265-276.
  65. 65. Fang M, Nie Y, Theilmann D A. 2009. AcMNPV EXON0 (AC141) which is required for the efficient egress of budded virus nucleocapsids interacts with -tubulin. Virology, 385(2): 496-504.
  66. 66. Fang M, Wang H, Wang H, et al. 2003. Open reading frame 94 of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus encodes a novel conserved occlusion-derived virion protein, ODV-EC43. J Gen Virol, 84: 3021-3027.
  67. 67. Faulkner P, Kuzio J, Williams G, et al. 1997. Analysis of p74, a PDV envelope protein of Autographa californica nucleopolyhedrovirus required for occlusion body infectivity in vivo. J Gen Virol, 78: 3091-3100.
  68. 68. Funk C J, Consigli R A. 1993. Phosphate cycling on the basic protein of Plodia interpunctella granulosis virus. Virology, 193: 396-402.
  69. 69. Garrod D, Chidgey M. 2008. Desmosome structure, composition and function. Biochim Biophys Acta, 1778: 572-587.
  70. 70. Ge J, Wei Z, Huang Y, et al. 2007. AcMNPV ORF38 protein has the activity of ADP-ribose pyrophosphatase and is important for virus replication. Virology, 361: 204-11.
  71. 71. Ge J Q, Yang Z N, Tang X D, et al. 2008. Characteri-zation of a nucleopolyhedrovirus with a deletion of the baculovirus core gene Bm67. J Gen Virol, 89: 766-774.
  72. 72. Gearing K L, Possee R D. 1990. Functional analysis of a 603 nucleotide open reading frame upstream of the polyhedrin gene of Autographa californica nuclear polyhedrosis virus. J Gen Virol, 71: 251-262.
  73. 73. Goenka S, Weaver R F. 2008. The p26 gene of the Autographa californica nucleopolyhedrovirus: timing of transcription, and cellular localization and dimerization of product. Virus Res, 131: 136-44.
  74. 74. Goley E D, Ohkawa T, Mancuso J, et al. 2006. Dynamic nuclear actin assembly by Arp2/3 complex and a baculovirus WASP-like protein. Science, 314: 464-467.
  75. 75. Gombart A F, Blissard G W, Rohrmann G F. 1989. Characterization of the genetic organization of the HindIII M region of the multicapsid nuclear polyhedrosis virus of Orgyia pseudotsugata reveals major differences among baculoviruses. J Gen Virol: 70.
  76. 76. Gomi S, Majima K, Maeda S. 1999. Sequence analysis of the genome of Bombyx mori nucleopolyhedrovirus. J Gen Virol, 80: 1323-1337.
  77. 77. Gomi S, Zhou C E, Yih W, et al. 1997. Deletion analysis of four of eighteen late gene expression factor gene homologues of the baculovirus, BmNPV. Virology, 230: 35-47.
  78. 78. Gong M, Jin J, Guarino L A. 1998. Mapping of ORF121, a factor that activates baculovirus early gene expression. Virology, 244: 495-503.
  79. 79. Griffiths C M, Barnett A L, Ayres M D, et al. 1999. In vitro host range of Autographa californica nucleopoly-hedrovirus recombinants lacking functional p35, iap1 or iap2. J Gen Virol, 80: 1055-1066.
  80. 80. Gross C H, Wolgamot G M, Russell R L, et al. 1993. A 37-kilodalton glycoprotein from a baculovirus of Orgyia pseudotsugata is localized to cytoplasmic inclusion bodies. J Virol, 67: 469-475.
  81. 81. Gross C H, Wolgamot G M, Russell R L Q, et al. 1993. A baculovirus encoded 16-kDa glycoprotein localizes near the nuclear membrane of infected cells. Virology, 192: 386-390.
  82. 82. Guarino L A. 1990. Identification of a viral gene encoding a ubiquitin-like protein. Proc Natl Acad Sci USA, 87: 409-413.
  83. 83. Guarino L A, Dong W, Jin J. 2002. In vitro activity of the baculovirus late expression factor LEF-5. J Virol, 76: 12663-12675.
  84. 84. Guarino L A, Jin J, Dong W. 1998. Guanylyltransferase activity of the LEF-4 subunit of baculovirus RNA polymerase. J Virol, 72: 10003-10010.
  85. 85. Guarino L A, Mistretta T-A, Dong W. 2002. Bacu-lovirus lef-12 is not required for viral replication. J Virol, 76: 12032-12043.
  86. 86. Guarino L A, Mistretta T-A, Dong W. 2002. DNA binding activity of the baculovirus late expression factor PP31. Virus Res, 90: 187-195.
  87. 87. Guarino L A, Summers M D. 1988. Functional mapping of Autographa california nuclear polyhedrosis virus genes required for late gene expression. J Virol, 62: 463-471.
  88. 88. Guarino L A, Xu B, Jin J, et al. 1998. A virus-encoded RNA polymerase purified from baculovirus-infected cells. J Virol, 72: 7985-7991.
  89. 89. Haas-Stapleton E J, Washburn J O, Volkman L E. 2004. P74 mediates specific binding of Autographa californica M bucleopolyhedrovirus occlusion-derived virus to primary cellular targets in the midgut epithelia of Heliothis virescens larvae. J Virol, 78: 6786-6791.
  90. 90. Hang X, Dong W, Guarino L A. 1995. The lef-3 gene of Autographa californica nuclear polyhedrosis virus encodes a single-stranded DNA-binding protein. J Virol, 69: 3924-3928.
  91. 91. Hao B, Huang J, Sun X, et al. 2009. Variants of open reading frame Bm126 in wild-type Bombyx mori nucleopoly-hedrovirus isolates exhibit functional differences. J Gen Virol, 90: 153-161.
  92. 92. Harrison R L, Bonning B C. 2003. Comparative analysis of the genomes of Rachiplusia ou and Auto-grapha californica multiple nucleopolyhedroviruses. J Gen Virol, 84: 1827-1842.
  93. 93. Harrison R L, Jarvis D L, Summers M D. 1996. The role of the AcMNPV 25K gene, 'FP25', in baculovirus polh and p10 expression. Virology, 226: 34-46.
  94. 94. Harrison R L, Summers M D. 1995. Mutations in the Autographa californica multinucleocapsid nuclear poly-hedrosis virus 25 kDa protein gene result in reduced virion occlusion, altered intranuclear envelopment and enhanced virus production. J Gen Virol, 76: 1451-1459.
  95. 95. Harwood S H, Li L, Shing Ho P, et al. 1998. AcMNPV late expression factor-5 interacts with itself and contains a zinc ribbon domain that is required for maximal late transcription activity and is homologous to elongation factor TFIIS. Virology, 250: 118-134.
  96. 96. Hawtin R E, Zarkowska T, Arnold K, et al. 1997. Liquefaction of Autographa californica nucleopoly-hedrovirus-infected insects is dependent on the integrity of virus-encoded chitinase and cathepsin genes. Virology, 238: 243-53.
  97. 97. Hefferon K L. 2004. Baculovirus late expression factors. J Mol Microbiol Biotechnol, 7: 89-101.
  98. 98. Heldens J G, Liu Y, Zuidema D, et al. 1997. Characteri-zation of a putative Spodoptera exigua multicapsid nucleopoly hedrovirus helicase gene. J Gen Virol, 78: 3101-3114.
  99. 99. Herniou E A, Jehle J A. 2007. Baculovirus phylogeny and evolution. Curr Drug Targets, 8: 1043-50.
  100. 100. Herniou E A, Olszewski J A, Cory J S, et al. 2003. The genome sequence and evolution of baculoviruses. Annu Rev Entomol, 48: 211-234.
  101. 101. Holden H M, Wesenberg G, Raynes D A, et al. 1996. Molecular structure of a proteolytic fragment of TLP20. Acta Crystallogr D Biol Crystallogr, 52: 1153-1160.
  102. 102. Hom L G, Volkman L E. 2000. Autographa californica M nucleopolyhedrovirus chiA is required for processing of V-CATH. Virology, 277: 178-183.
  103. 103. Hom L G, Volkman L E. 1998. Preventing proteolytic artifacts in the baculovirus expression system. Bio-Techniques, 25: 18-20.
  104. 104. Hong T, Summers M D, Braunagel S C. 1997. N-terminal sequences from Autographa californica nuclear polyhedrosis virus envelope proteins ODV-E66 and ODV-E25 are sufficient to direct reporter proteins to the nuclear envelope, intranuclear microvesicles and the envelope of occlusion derived virus. Proc Natl Acad Sci USA, 94: 4050-4055.
  105. 105. Hooft van Iddekinge B J L, Smith G E, Summers M D. 1983. Nucleotide sequence of the polyhedrin gene of Autographa californica nuclear polyhedrosis virus. Virology, 131: 561-565.
  106. 106. Hoopes R R, Rohrmann G F. 1991. In vitro transcription of baculovirus immediate early genes: accurate mRNA initiation by nuclear extracts from both insect and human cells. Proc Natl Acad Sci USA, 88: 4513-4517.
  107. 107. Hoover K, van Oers M M. 2008. Hypermobility and climbing behaviour induced by baculovirus infection are regulated by separate gene functions 41st Annual Meeting of the Society for Invertebrate Pathology and 9th International Conference on Bacillus thuringiensis, Warwick, United Kingdom.
  108. 108. Hu Y. 2006. Baculovirus vectors for gene therapy, p. 287-320. In Bonning B C, Maramorosch K, and Shatkin A J (ed. ), Adv. Virus Res. , vol. Volume 68. Academic Press.
  109. 109. Hu Z H, Arif B M, Sun J S, et al. 1998. Genetic organization of the HindⅢ-Ⅰ region of the single-nucleocapsid nucleopolyhedrovirus of Buzura suppressaria. Virus Res, 55: 71-82.
  110. 110. Huang P, Stern M J. 2005. FGF signaling in flies and worms: More and more relevant to vertebrate biology. Cytokine Growth Factor Rev, 16: 151-158.
  111. 111. Imai N, Matsuda N, Tanaka K, et al. 2003. Ubiquitin ligase activities of Bombyx mori nucleopolyhedrovirus RING finger proteins. J Virol, 77: 923-930.
  112. 112. Ito E, Sahri D, Knippers R, et al. 2004. Baculovirus proteins IE-1, LEF-3, and P143 interact with DNA in vivo: A formaldehyde cross-linking study. Virology, 329: 337-347.
  113. 113. Iwahori S, Ikeda M, Kobayashi M. 2004. Association of Sf9 cell proliferating cell nuclear antigen with the DNA replication site of Autographa californica multicapsid nucleopolyhedrovirus. J Gen Virol, 85: 2857-2862.
  114. 114. Jackson H C, Scheideler M A. 1996. Behavioural and anticonvulsant effects of Ca2+ channel toxins in DBA/2 mice. Psychopharmacology, 126: 85-90.
  115. 115. Jarvis D L. 2003. Developing baculovirus-insect cell expression systems for humanized recombinant glycoprotein production. Virology, 310: 1-7.
  116. 116. Jarvis D L, Garcia Jr A. 1994. Biosynthesis and processing of the Autographa californica nuclear poly-hedrosis virus gp64 protein. Virology, 205: 300-313.
  117. 117. Jehle J A. 2004. The mosaic structure of the polyhedrin gene of the Autographa californica nucleopolyhedrovirus (AcMNPV). Virus Genes, 29: 5-8.
  118. 118. Jehle J A, Blissard G W, Bonning B C, et al. 2006. On the classification and nomenclature of baculoviruses: a proposal for revision. Arch Virol, 151: 1257-1266.
  119. 119. Jin J, Dong W, Guarino L A. 1998. The LEF-4 subunit of baculovirus RNA polymerase has RNA 5'-triphosp-hatase and ATPase activities. J Virol, 72: 10011-10019.
  120. 120. Kaba S A, Salcedo A M, Wafula P O, et al. 2004. Development of a chitinase and v-cathepsin negative bacmid for improved integrity of secreted recombinant proteins. J Virol Methods, 122: 113-118.
  121. 121. Kadlec J, Loureiro S, Abrescia N G A, et al. 2008. The postfusion structure of baculovirus gp64 supports a unified view of viral fusion machines. Nat Struct Biol, 15: 1024-1030.
  122. 122. Kamita S G, Nagasaka K, Chua J W, et al. 2005. A baculovirus-encoded protein tyrosine phosphatase gene induces enhanced locomotory activity in a lepidopteran host. Proc Natl Acad Sci USA, 102: 2584-2589.
  123. 123. Kang W, Kurihara M, Matsumoto S. 2006. The BRO proteins of Bombyx mori nucleopolyhedrovirus are nuc-leocytoplasmic shuttling proteins that utilize the CRM1-mediated nuclear export pathway. Virology, 350: 184-191.
  124. 124. Kang W, Suzuki M, Zemskov E, et al. 1999. Characteri-zation of baculovirus repeated open reading frames (bro) in Bombyx mori nucleopolyhedrovirus. J Virol, 73: 10339-10345.
  125. 125. Katsuma S, Nakanishi T, Shimada T. 2009. Bombyx mori nucleopolyhedrovirus FP25K is essential for mai-ntaining a steady-state level of v-cath expression throug-hout the infection. Virus Res, 140: 155-160.
  126. 126. Ke J, Wang J, Deng R, et al. 2008. Autographa californica multiple nucleopolyhedrovirus ac66 is required for the efficient egress of nucleocapsids from the nucleus, general synthesis of preoccluded virions and occlusion body formation. Virology, 374: 421-431.
  127. 127. Kelly D C, Brown D A, Ayres M D, et al. 1983. Properties of the major nucleocapsid protein of Heliothis zea singly enveloped nuclear polyhedrosis virus. J Gen Virol, 64: 399-408.
  128. 128. Kikhno I, Gutiérrez S, Croizier L, et al. 2002. Characterization of pif, a gene required for the per os infectivity of Spodoptera littoralis nucleopolyhedrovirus. J Gen Virol, 83: 3013-3022.
  129. 129. King L K, Possee R D. 1992. The baculovirus expres-sion system: a laboratory guide. London: Chapman and Hall.
  130. 130. Kitts P A, Possee R D. 1993. A method for producing recombinant baculovirus expression vectors at high fre-quency. BioTechniques, 14: 810-817.
  131. 131. Knebel-Mörsdorf D, Kremer A, Jahnel F. 1993. Baculovirus gene ME53, which contains a putative zinc finger motif, is one of the major early-transcribed genes. J Virol, 67: 753-758.
  132. 132. Knebel-Mörsdorf D, Quadt I, Li Y, et al. 2006. Expression of baculovirus late and very late genes depends on LEF-4, a component of the viral RNA polymerase whose guanyltransferase function Is essential. J Virol, 80: 4168-4173.
  133. 133. Kool M, Ahrens C H, Goldbach R W, et al. 1994. Indentification of genes involved in DNA replication of the Autographa californica baculovirus. Proc Natl Acad Sci USA, 91: 11212-11216.
  134. 134. Kool M, Goldbach R W, Vlak J M. 1994. A putative non-hr origin of DNA replication in the HindII-K fragment of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus. J Gen Virol, 75: 3345-3352.
  135. 135. Kool M, van den Berg P M M M, Tramper J, et al. 1993. Location of two putative origins of DNA replication of Autographa californica nuclear polyhedrosis virus. Virology, 192: 94-101.
  136. 136. Kovacs G R, Choi J, Guarino L A, et al. 1992. Functional dissection of the Autographa californica nuclear polyhedrosis virus immediate-early 1 transcriptional regulatory protein. J Virol, 66: 7429-7437.
  137. 137. Krappa R, Roncarati R, Knebel-Mörsdorf D. 1995. Expression of PE38 and IE2, viral members of the C3HC4 finger family, during baculovirus infection: PE38 and IE2 localize to distinct nuclear regions. J Virol, 69: 5287-5293.
  138. 138. Krell P J. 1996. Passage effect of virus infection in insect cells. Insect cell cultures, Fundamental and applied aspects, vol. 2. Kluwer, Dordrecht, the Netherlands. p125-137.
  139. 139. Kumar S, Miller L K. 1987. Effects of serial passage of Autographa californica nuclear polyhedrosis virus in cell culture. Virus Res, 7: 335-349.
  140. 140. LaCount D J, Hanson S F, Schneider C L, et al. 2000. Caspase inhibitor P35 and inhibitor of apoptosis Op-IAP block in vivo proteolytic activation of an effector caspase at different steps. J Biol Chem, 275: 15657-15664.
  141. 141. Landais I, Vincent R, Bouton M, et al. 2006. Functional analysis of evolutionary conserved clustering of bZIP binding sites in the baculovirus homologous regions (hrs) suggests a cooperativity between host and viral transcription factors. Virology, 344: 421-431.
  142. 142. Lapointe R, Back D W, Ding Q, et al. 2000. Identi-fication and molecular characterization of the Choristoneura fumiferana multicapsid nucleopolyhedrovirus genomic region encoding the regulatory genes pkip, p47, lef-12, and gta. Virology, 271: 109-121.
  143. 143. Lapointe R, Popham H J R, Straschil U, et al. 2004. Characterization of two nucleopolyhedrovirus proteins, Ac145 and Ac150, which affect oral infectivity in a host-dependent manner. J Virol, 78: 6439-6448.
  144. 144. Lauzon H A M, Lucarotti C J, Krell P J, et al. 2004. Sequence and organization of the Neodiprion lecontei nucleopolyhedrovirus genome. J Virol, 78: 7023-7035.
  145. 145. Lee H, Krell P J. 1994. Reiterated DNA fragments in defective genomes of Autographa californica nuclear polyhedrosis virus are competent for AcMNPV-depen-dent DNA replication. Virology, 202: 418-29.
  146. 146. Lee J C, Chen H H, Chao Y C. 1998. Persistent baculovirus infection results from deletion of the apoptotic suppressor gene p35. J Virol, 72: 9157-9165.
  147. 147. Leisy D J, Rohrmann G F. 1993. Characterization of the replication of plasmids containing hr sequences in baculovirusinfected Spodoptera frugiperda cells. Virology, 196: 722-730.
  148. 148. Li G, Wang J, Deng R, et al. 2008. Characterization of AcMNPV with a deletion of ac68 gene. Virus Genes, 37: 119-127.
  149. 149. Li L, Harwood S H, Rohrmann G F. 1999. Identi-fication of additional genes that influence baculovirus late gene expression. Virology, 255: 9-19.
  150. 150. Li L, Rohrmann G F. 2000. Characterization of a baculovirus alkaline nuclease. J Virol, 74: 6401-6407.
  151. 151. Li X, Pang A, Lauzon H A M, et al. 1997. The gene encoding the capsid protein P82 of the Choristoneura fumiferana multicapsid nucleopolyhedrovirus: Sequencing, transcription and characterization by immunoblot analysis. J Gen Virol, 78: 2665-2673.
  152. 152. Li Y, Miller L K. 1995. Expression and functional analysis of a baculovirus gene encoding a truncated protein kinase homolog. Virology, 206: 314-323.
  153. 153. Li Y, Wang J, Deng R, et al. 2005. vlf-1 deletion brought AcMNPV to defect in nucleocapsid formation. Virus Genes, 31: 275-284.
  154. 154. Li Z, Blissard G W. 2008. Functional analysis of the transmembrane (TM) domain of the Autographa californica multicapsid nucleopolyhedrovirus GP64 protein: Substi-tution of heterologous TM domains. J Virol, 82: 3329-3341.
  155. 155. Li Z, Li C, Pan L, et al. 2005. Characterization of p24 gene of Spodoptera litura multicapsid nucleopolyhed-rovirus. Virus Genes, 30: 349-356.
  156. 156. Lin G, Blissard G W. 2002. Analysis of an Autographa californica multicapsid nucleopolyhedrovirus lef-6-null virus: LEF-6 is not essential for viral replication but appears to accelerate late gene transcription. J Virol, 76: 5503-5514.
  157. 157. Lin G, Blissard G W. 2002. Analysis of an Autographa californica nucleopolyhedrovirus lef-11 Knockout: LEF-11 is essential for viral DNA replication. J Virol, 76: 2770-2779.
  158. 158. Lin G, Slack J M, Blissard G W. 2001. Expression and localization of LEF-11 in Autographa californica nucleopoly-hedrovirus-infected Sf9 cells. J Gen Virol, 82: 2289-2294.
  159. 159. Liqun L, Rivkin H, Chejanovsky N. 2005. The immediate-early protein IE0 of the Autographa californica nucleopolyhedrovirus is not essential for viral replication. J Virol, 79: 10077-10082.
  160. 160. Liu C, Li Z, Wu W, et al. 2008. Autographa californica multiple nucleopolyhedrovirus ac53 plays a role in nucleocapsid assembly. Virology, 382: 59-68.
  161. 161. Liu C Y Y, Wang C H, Wang J C, et al. 2007. Stimulation of baculovirus transcriptome expression in mammalian cells by baculoviral transcriptional activators. J Gen Virol, 88: 2176-2184.
  162. 162. Lo H-R, Chou C-C, Wu T-Y, et al. 2002. Novel baculovirus DNA elements strongly stimulate activities of exogenous and endogenous promoters. J Biol Chem, 277: 5256-5264.
  163. 163. Lu A, Carstens E B. 1993. Immediate-early baculovirus genes transactivate the p143 gene promoter of Auto-grapha californica nuclear polyhedrosis virus. Virology, 195: 710-8.
  164. 164. Lu A, Carstens E B. 1992. Nucleotide sequence and transcriptional analysis of the p80 gene of Autographa californica nuclear polyhedrosis virus: a homologue of the Orgyia pseudotsugata nuclear polyhedrosis virus capsid-associated gene. Virology, 190: 201-209.
  165. 165. Lu A, Carstens E B. 1991. Nucleotide sequence of a gene essential for viral DNA replication in the baculovirus Autographa californica nuclear polyhedrosis virus. Virology, 181: 336-347.
  166. 166. Lu A, Craig A, Casselman R, et al. 1996. Nucleotide sequence, insertional mutagenesis, and transcriptional mapping of a conserved region of the baculovirus Autographa californica nuclear polyhedrosis virus (map unit 64. 8-66.9). Can J Microbiol, 42: 1267-1273.
  167. 167. Lu A, Miller L K. 1995. Differential requirements for baculovirus late expression factor genes in two cell lines. J Virol, 69: 6265-6272.
  168. 168. Lu A, Miller L K. 1994. Identification of three late expression factor genes within the 33. 8 to 43.4 map unit region of Autographa californica nuclear polyhedrosis virus. J Virol, 68: 6710-6718.
  169. 169. Lu A, Miller L K. 1995. The roles of eighteen baculovirus late expression factor genes in transcription and DNA replication. J Virol, 69: 975-982.
  170. 170. Lu A, Miller L K. 1996. Species-specific effects of the hcf-1 gene on baculovirus virulence. J Virol, 70: 5123-5130.
  171. 171. Lu M, Iatrou K. 1997. Characterization of a domain of the genome of BmNPV containing a functional gene for a small capsid protein and harboring deletions eliminating three open reading frames that are present in AcNPV. Gene, 185: 69-75.
  172. 172. Luckow V A, Lee S C, Barry G F, et al. 1993. Efficient generation of infectious recombinant baculoviruses by site-specific transposon-mediated insertion of foreign genes into a baculovirus genome propagated in Escheri-chia coli. J Virol, 67: 4566-4579.
  173. 173. Lung O Y, Cruz-Alvarez M, Blissard G W. 2003. Ac23, an envelope fusion protein homolog in the baculovirus Autographa californica multicapsid nucleopolyhedro-virus, is a viral pathogenicity factor. J Virol, 77: 328-339.
  174. 174. Luz-Madrigal A, Clapp C, Aranda J, et al. 2007. In vivo transcriptional targeting into the retinal vasculature using recombinant baculovirus carrying the human flt-1 promoter. Virol J, 4: 88.
  175. 175. Machesky L M, Insall R H. 2001. WASP homology sequences in baculoviruses. Trends Cell Biol, 11: 286-287.
  176. 176. Marchler-Bauer A, Anderson J B, Derbyshire M K, et al. 2007. CDD: a conserved domain database for in-teractive domain family analysis. Nucleic Acids Res, 35: D237-240.
  177. 177. Markovic I, Pulyaeva H, Sokoloff A, et al. 1998. Membrane fusion mediated by baculovirus gp64 involves assembly of stable gp64 trimers into multiprotein aggre-gates. J Cell Biol, 143: 1155-1166.
  178. 178. McCarthy C B, Dai X, Donly C, et al. 2008. Autographa californica multiple nucleopolyhedrovirus ac142, a core gene that is essential for BV production and ODV envelopment. Virology, 372: 325-339.
  179. 179. McCarthy C B, Theilmann D A. 2008. AcMNPV ac143 (odv-e18) is essential for mediating budded virus production and is the 30th baculovirus core gene. Virology, 375: 277-291.
  180. 180. McCleskey E W, Fox A P, Feldman D H. 1987. Omega-Conotoxin: Direct and persistent blockade of specific types of calcium channels in neurons but not muscle. Proc Natl Acad Sci USA, 84: 4327-4331.
  181. 181. McLachlin J R, Escobar J C, Harrelson J A, et al. 2001. Deletions in the Ac-iap1 gene of the baculovirus AcMNPV occur spontaneously during serial passage and confer a cell line-specific replication advantage. Virus Res, 81: 77-91.
  182. 182. McLachlin J R, Miller L K. 1998. A baculovirus mutant defective in PKIP, a protein which interacts with a virus-encoded protein kinase. Virology, 246: 379-391.
  183. 183. McLachlin J R, Miller L K. 1994. Identification and characterization of vlf-1, a baculovirus gene involved in very late gene expression. J Virol, 68: 7746-7756.
  184. 184. Merrington C L, Kitts P A, King L A, et al. 1996. An Autographa californica nucleopolyhedrovirus lef-2 mutant: consequences for DNA replication and very late gene expression. Virology, 217: 338-348.
  185. 185. Mikhailov V S, Okano K, Rohrmann G F. 2003. Bacu-lovirus alkaline nuclease possesses a 5'- > 3' exonuclease activity and associates with the DNA-binding protein LEF-3. J Virol, 77: 2436-2444.
  186. 186. Mikhailov V S, Okano K, Rohrmann G F. 2004. Specificity of the endonuclease activity of the baculovirus alkaline nuclease for single-stranded DNA. J Biol Chem, 279: 14734-14745.
  187. 187. Mikhailov V S, Rohrmann G F. 2002. Baculovirus replication factor LEF-1 is a DNA primase. J Virol, 76: 2287-2297.
  188. 188. Mikhailov V S, Vanarsdall A L, Rohrmann G F. 2008. Isolation and characterization of the DNA-binding protein (DBP) of the Autographa californica multiple nucleopoly-hedrovirus. Virology, 370: 415-429.
  189. 189. Milks M L, Washburn J O, Willis L G, et al. 2003. Deletion of pe38 attenuates AcMNPV genome replication, budded virus production, and virulence in Heliothis virescens. Virology, 310: 224-234.
  190. 190. Mishra G, Chadha P, Das R H. 2008. Serine/threonine kinase (pk-1) is a component of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) very late gene transcription complex and it phosphorylates a 102 kDa polypeptide of the complex. Virus Res, 137: 147-149.
  191. 191. Mishra G, Gautam H K, Das R H. 2007. Serine/ Threonine kinase dependent transcription from the poly-hedrin promoter of SpltNPV-I. Biochem Biophys Res Commun, 358: 942-947.
  192. 192. Monsma S A, Blissard G W. 1995. Identification of a membrane fusion domain and an oligomerization domain in the baculovirus GP64 envelope fusion protein. J Virol, 69: 2583-2595.
  193. 193. Monsma S A, Oomens A G, Blissard G W. 1996. The GP64 envelope fusion protein is an essential baculovirus protein required for cell-to-cell transmission of infection. J Virol, 70: 4607-4616.
  194. 194. Morris T D, Todd J W, Fisher B, et al. 1994. Identi-fication of lef-7: a baculovirus gene affecting late gene expression. Virology, 200: 260-269.
  195. 195. Nie Y, Fang M, Theilmann D A. 2009. AcMNPV AC16 (DA26, BV/ODV-E26) regulates the levels of IE0 and IE1 and binds to both proteins via a domain located within the acidic transcriptional activation domain. Virology, 385: 484-495.
  196. 196. Niegowski D, Eshaghi S. 2007. The CorA family: Structure and function revisited. Cell Mol Life Sci, 64: 2564-2574.
  197. 197. O'Reilly D R. 1997. Auxiliary genes of baculoviruses. In: The baculoviruses(Miller L K. ed.), New York: Plenum, p 267-300
  198. 198. O'Reilly D R, Crawford A M, Miller L K. 1989. Viral proliferating cell nuclear antigen. Nature, 337: 606.
  199. 199. O'Reilly D R, Miller L K. 1989. A baculovirus blocks insect molting by producing ecdysteroid UDP-glucosyl transferase. Science, 245: 1110-2.
  200. 200. O'Reilly D R, Miller L K. 1991. Improvement of a baculovirus pesticide by deletion of the egt gene. Nat. Biotechnol, 9: 1086-1089.
  201. 201. O'Reilly D R, Passarelli A L, Goldman I F, et al. 1990. Characterization of the da26 gene in a hypervariable region of the Autographa californica nuclear poly-hedrosis virus genome. J Gen Virol, 71: 1029-1037.
  202. 202. Ohkawa T, Rowe A R, Volkman L E. 2002. Identification of six Autographa californica multicapsid nucleopolyhedrovirus early genes that mediate nuclear localization of G-actin. J Virol, 76: 12281-12289.
  203. 203. Ohkawa T, Washburn J O, Sitapara R, et al. 2005. Specific binding of Autographa californica M nucleopoly-hedrovirus occlusion-derived virus to midgut cells of Heliothis virescens larvae is mediated by products of pif genes Ac119 and Ac022 but not by Ac115. J Virol, 79: 15258-15264.
  204. 204. Okano K, Mikhailov V S, Maeda S. 1999. Colocali-zation of baculovirus IE-1 and two DNA-binding proteins, DBP and LEF-3, to viral replication factories. J Virol, 73: 110-119.
  205. 205. Okano K, Vanarsdall A L, Mikhailov V S, et al. 2006. Conserved molecular systems of the Baculoviridae. Virology, 344: 77-87.
  206. 206. Okano K, Vanarsdall A L, Rohrmann G F. 2007. A baculovirus alkaline nuclease knockout construct produces fragmented DNA and aberrant capsids. Virology, 359: 46-54.
  207. 207. Okano K, Vanarsdall A L, Rohrmann G F. 2004. Characterization of a baculovirus lacking the alkaline nuclease gene. J Virol, 78: 10650-10656.
  208. 208. Ollmann M, Young L M, Di Como C J, et al. 2000. Drosophila p53 is a structural and functional homolog of the tumor suppressor p53. Cell, 101: 91-101.
  209. 209. Olszewski J, Miller L K. 1997. Identification and characterization of a baculovirus structural protein, VP1054, required for nucleocapsid formation. J Virol, 71: 5040-5050.
  210. 210. Olszewski J, Miller L K. 1997. A role for baculovirus GP41 in budded virus production. Virology, 233: 292-301.
  211. 211. Omi R, Goto M, Miyahara I, et al. 2007. Crystal structure of monofunctional histidinol phosphate phosphatase from Thermus thermophilus HB8. Biochemistry, 46: 12618-12627.
  212. 212. Oomens A G P, Blissard G W. 1999. Requirement for GP64 to drive efficient budding of Autographa cali-fornica multicapsid nucleopolyhedrovirus. Virology, 254: 297-314.
  213. 213. Passarelli A L, Guarino L A. 2007. Baculovirus late and very late gene regulation. Curr. Drug Targets, 8: 1103-1115.
  214. 214. Passarelli A L, Miller L K. 1994. Identification and transcriptional regulation of the baculovirus lef-6 gene. J Virol, 68: 4458-4467.
  215. 215. Passarelli A L, Miller L K. 1994. In vivo and in vitro analyses of recombinant baculoviruses lacking a func-tional cg30 gene. J Virol, 68: 1186-1190.
  216. 216. Passarelli A L, Miller L K. 1993. Three baculovirus genes involved in late and very late gene expression: ie-1, ie-n, and lef-2. J Virol, 67: 2149-2158.
  217. 217. Passarelli A L, Todd J W, Miller L K. 1994. A baculovirus gene involved in late gene expression predicts a large polypeptide with a conserved motif of RNA polymerases. J Virol, 68: 4673-4678.
  218. 218. Patmanidi A L, Possee R D, King L A. 2003. Formation of P10 tubular structures during AcMNPV infection depends on the integrity of host-cell microtubules. Virology, 317: 308-320.
  219. 219. Pearson M N, Russell R L Q, Rohrmann G F. 2001. Characterization of a baculovirus-encoded protein that is associated with infected-cell membranes and budded virions. Virology, 291: 22-31.
  220. 220. Pham D Q D, Hice R H, Sivasubramanian N, et al. 1993. The 1629-bp open reading frame of the Autographa californica multinucleocapsid nuclear polyhedrosis virus encodes a virion structural protein. Gene, 137: 275-280.
  221. 221. Phanis C G, Miller D P, Cassar S C, et al. 1999. Identification and expression of two baculovirus gp37 genes. J Gen Virol, 80: 1823-1831.
  222. 222. Pijlman G P, Dortmans J C F, Vermeesch A M G, et al. 2002. Pivotal role of the non-hr origin of DNA replication in the genesis of defective interfering baculoviruses. J Virol, 76: 5605-5611.
  223. 223. Pijlman G P, Pruijssers A J P, Vlak J M. 2003. Identification of pif-2, a third conserved baculovirus gene required for per os infection of insects. J Gen Virol, 84: 2041-2049.
  224. 224. Popham H J R, Pellock B J, Robson M, et al. 1998. Characterization of a variant of Autographa californica nuclear polyhedrosis virus with a non-functional ORF603. Biol Control, 12: 223-230.
  225. 225. Possee R D, Hirst M, Jones L D, et al. 1993. Field tests of genetically engineered baculoviruses. Britsh Crop Protection Council Monograph 55: Opportunities for Molecular Biology in crop production (Beadle D J, Bishop D H L, Copping L G, et al. ed. ), Churchill College, Cambridge, UK, p23-36.
  226. 226. Possee R D, Sun T-P, Howard S C, et al. 1991. Nucleotide sequence of the Autographa californica nuclear polyhedrosis 9.4 kbp EcoRI-I and -R (polyhedrin gene) region. Virology, 185: 229-241.
  227. 227. Prikhod'ko E A, Lu A, Wilson J A, et al. 1999. In vivo and in vitro analysis of baculovirus ie-2 mutants. J Virol, 73: 2460-2468.
  228. 228. Prikhod'ko E A, Miller L K. 1999. The baculovirus PE38 protein augments apoptosis induced by trans-activator IE1. J Virol, 73: 6691-6699.
  229. 229. Prikhod'ko E A, Miller L K. 1998. Role of baculovirus IE2 and its RING finger in cell cycle arrest. J Virol, 72: 684-692.
  230. 230. Prikhod'ko G G, Wang Y, Freulich E, et al. 1999. Baculovirus p33 binds human p53 and enhances p53-mediated apoptosis. J Virol, 73: 1227-1234.
  231. 231. Quadt I, Van Lent J W M, Knebel-Mörsdorf D. 2007. Studies of the silencing of baculovirus DNA binding protein. J Virol, 81: 6122-6127.
  232. 232. Raynes D A, Hartshorne D J, Guerriero V, J r. 1994. Sequence and expression of a baculovirus protein with antigenic similarity to telokin. J Gen Virol, 75: 1807-1809.
  233. 233. Reilly L M, Guarino L A. 1994. The pk-1 Gene of Autographa californica multinucleocapsid nuclear poly-hedrosis virus encodes a protein kinase. J Gen Virol, 75: 2999-3006.
  234. 234. Rodems S M, Friesen P D. 1993. The hr5 transcriptional enhancer stimulates early expression from the Autographa californica nuclear polyhedrosis virus genome but is not required for virus replication. J Virol, 67: 5776-5785.
  235. 235. Roey P V, Meehan L, Kowalski J C, et al. 2002. Catalytic domain structure and hypothesis for function of GIY-YIG intron endonuclease I-tevI. Nat Struct Biol, 9: 806-811.
  236. 236. Rohrmann G F. 1986. Polyhedrin Structure. J Gen Virol, 67: 1499-1513.
  237. 237. Roncarati R, Knebel-Mörsdorf D. 1997. Identification of the early actin-rearrangement-inducing factor gene, arif-1, from Autographa californica multicapsid nuclear polyhedrosis virus. J Virol, 71: 7933-7941.
  238. 238. Russell R L Q, Funk C J, Rohrmann G F. 1997. Association of a baculovirus-encoded protein with the capsid basal region. Virology, 227: 142-152.
  239. 239. Russell R L Q, Rohrmann G F. 1993. A 25-kDa protein is associated with the envelopes of occluded baculovirus virions. Virology, 195: 532-540.
  240. 240. Russell R L Q, Rohrmann G F. 1997. Characterization of P91, a protein associated with virions of an Orgyia pseudotsugata baculovirus. Virology, 233: 210-223.
  241. 241. Saville G P, Patmanidi A L, Possee R D, et al. 2004. Deletion of the Autographa californica nucleopoly-hedrovirus chitinase KDEL motif and in vitro and in vivo analysis of the modified virus. J Gen Virol, 85: 821-31.
  242. 242. Schetter C, Oellig C, Doerfler W. 1990. An insertion of insect cell DNA in the 81-map-unit segment of Auto-grapha californica nuclear polyhedrosis virus DNA. J Virol, 64: 1844-1850.
  243. 243. Schultz K L W, Wetter J A, Fiore D C, et al. 2009. Transactivator IE1 is required for baculovirus early replication events that trigger apoptosis in permissive and non-permissive cells. J Virol, 83: 262-272.
  244. 244. Shan L, Wang L, Yin J, et al. 2006. An OriP/EBNA-1-based baculovirus vector with prolonged and enhanced transgene expression. J Gene Med, 8: 1400-1406.
  245. 245. Sharma M, Ellis R L, Hinton D M. 1992. Identification of a family of bacteriophage T4 genes encoding proteins similar to those present in group Ⅰ introns of fungi and phage. Proc Natl Acad Sci USA, 89: 6658-6662.
  246. 246. Shen Z, Jacobs-Lorena M. 1998. A type Ⅰ peritrophic matrix protein from the malaria vector Anopheles gam-biae binds to chitin. J Biol Chem, 273: 17665-17670.
  247. 247. Shi S-L, Pan M-H, Lu C. 2007. Characterization of Antheraea pernyi nucleopolyhedrovirus p11 gene, a homologue of Autographa californica nucleopoly-hedrovirus orf108. Virus Genes, 35: 97-101.
  248. 248. Simon O, Williams T, Caballero P, et al. 2008. Effects of Acp26 on in vitro and in vivo productivity, patho-genesis and virulence of Autographa californica multiple nucleopolyhedrovirus. Virus Res, 136: 202-5.
  249. 249. Slack J, Arif B M. 2006. The baculoviruses occlusion-derived virus: virion structure and function. Adv Virus Res, 69: 99-165.
  250. 250. Slack J M, Lawrence S D, Krell P J, et al. 2008. Trypsin cleavage of the baculovirus occlusion-derived virus attachment protein P74 is prerequisite in per os infection. J Gen Virol, 89: 2388-97.
  251. 251. Slavicek J M, Hayes-Plazolles N. 2003. The Lymantria dispar nucleopolyhedrovirus contains the capsid-asso-ciated p24 protein gene. Virus Genes, 26: 15-18.
  252. 252. Stewart T M, Huijskens I, Willis L G, et al. 2005. The Autographa californica multiple nucleopolyhedrovirus ie0-ie1 gene complex is essential for wild-type virus replication, but either IE0 or IE1 can support virus growth. J Virol, 79: 4619-4629.
  253. 253. Stokes D L. 2007. Desmosomes from a structural perspective. Curr Opin Cell Biol, 19: 565-571.
  254. 254. Summers M D. 2006. Milestones leading to the genetic engineering of baculoviruses as expression vector systems and viral esticides. Adv Virus Res, 68: 3-73.
  255. 255. Takagi T, Taylor G S, Kusakabe T, et al. 1998. A protein tyrosine phosphatase-like protein from baculovirus has RNA 5'-triphosphatase and diphosphatase activities. Proc Natl Acad Sci USA, 95: 9808-9812.
  256. 256. Tang X-D, Xu Y-P, Yu L-l, et al. 2008. Characterization of a Bombyx mori nucleopolyhedrovirus with Bmvp80 disruption. Virus Res, 138: 81-88.
  257. 257. Terlau H, Olivera B M. 2004. Conus venoms: A rich source of novel ion channel-targeted peptides. Physiol. Rev, 84: 41-68.
  258. 258. Theilmann D A, Blissard G W. 2008. Baculoviruses: Molecular biology of nucleopolyhedroviruses. Ency-clopedia of Virology. Oxford: Academic Press: p254-265.
  259. 259. Thiem S M, Miller L K. 1989. A baculovirus gene with a novel transcription pattern encodes a polypeptide with a zinc finger and a leucine zipper. J Virol, 63: 4489-4497.
  260. 260. Thiem S M, Miller L K. 1989. Identification, sequence, and transcriptional mapping of the major capsid protein gene of the baculovirus Autographa californica nuclear polyhedrosis virus. J Virol, 63: 2008-2018.
  261. 261. Thomas C J, Brown H L, Hawes C R, et al. 1998. Localization of a baculovirus-induced chitinase in the insect cell endoplasmic reticulum. J Virol, 72: 10207-10212.
  262. 262. Todd J W, Passarelli A L, Miller L K. 1995. Eighteen baculovirus genes, including lef-11, p35, 39K, and p47, support late gene expression. J Virol, 69: 968-974.
  263. 263. Tomalski M D, Eldridge R, Miller L K. 1991. A baculovirus homolog of a Cu/Zn superoxide dismutase gene. Virology, 184: 149-161.
  264. 264. Vail P V, Sutter G, Jay D L, et al. 1971. Reciprocal infectivity of nuclear polyhedrosis viruses of the cabbage looper and alfalfa looper. J Invertebr Pathol, 17: 383-388.
  265. 265. van Oers M M, Vlak J M. 1997. The baculovirus 10-kDa protein. J Invertebr Pathol, 70: 1-17.
  266. 266. van Oers M M, Vlak J M. 2007. Baculovirus genomics. Curr Drug Targets, 8: 1051-1068.
  267. 267. Vanarsdall A L, Mikhailov V S, Rohrmann G F. 2007. Characterization of a baculovirus lacking the DBP (DNA-binding protein) gene. Virology, 364: 475-485.
  268. 268. Vanarsdall A L, Okano K, Rohrmann G F. 2004. Characterization of a baculovirus with a deletion of vlf-1. Virology, 326: 191-201.
  269. 269. Vanarsdall A L, Okano K, Rohrmann G F. 2005. Characterization of the replication of a baculovirus mutant lacking the DNA polymerase gene. Virology, 331: 175-180.
  270. 270. Vanarsdall A L, Pearson M N, Rohrmann G F. 2007. Characterization of baculovirus constructs lacking either the Ac101, Ac142, or the Ac144 open reading frame. Virology, 367: 187-195.
  271. 271. Venkaiah B, Viswanathan P, Habib S, et al. 2004. An additional copy of the homologous region (hr1) sequence in the Autographica californica multinucleocapsid poly-hedrosis virus genome promotes hyperexpression of foreign genes. Biochemistry, 43: 8143-8151.
  272. 272. Vialard J E, Richardson C D. 1993. The 1, 629-nucleotide open reading frame located downstream of the Autographa californica nuclear polyhedrosis virus polyhedrin gene encodes a nucleocapsid-associated phosp-hoprotein. J Virol, 67: 5859-5866.
  273. 273. Wang L, Yu J, Yin C, et al. 2002. Characterization of a J domain gene of Spodoptera litura multicapsid nuc-leopolyhedrovirus. Virus Genes, 25: 291-297.
  274. 274. Wang Y, Wang Q, Liang C, et al. 2008. Autographa californica multiple nucleopolyhedrovirus nucleocapsid protein BV/ODV-C42 mediates the nuclear entry of P78/ 83. J Virol, 82: 4554-4561.
  275. 275. Wang Y, Wu W, Li Z, et al. 2007. Ac18 is not essential for the propagation of Autographa californica multiple nucleopolyhedrovirus. Virology, 367: 71-81.
  276. 276. Whitford M, Faulkner P. 1992. Nucleotide sequence and transcriptional analysis of a gene encoding gp41, a structural glycoprotein of the baculovirus Autographa californica nuclear polyhedrosis virus. J Virol, 66: 4763-4768.
  277. 277. Whitford M, Faulkner P. 1992. A structural polypeptide of the baculovirus Autographa californica nuclear poly-hedrosis virus contains O-linked N-acetylglucosamine. J Virol, 66: 3324-3329.
  278. 278. Whitt M A, Manning J S. 1988. A phosphorylated 34-kDa protein and a subpopulation of polyhedrin are thiol linked to the carbohydrate layer surrounding a baculovirus occlusion body. Virology, 163: 33-42.
  279. 279. Williams G V, Faulkner P. 1997. Cytological changes and viral morphogenesis during baculovirus infection. In: The baculoviruses(Miller L K. ed. ), New York: Plenum Press, p61-107.
  280. 280. Wolgamot G M, Gross C H, Russell R L Q, et al. 1993. Immunocytochemical characterization of P24, a baculovirus capsid-associated protein. J Gen Virol, 74: 103-107.
  281. 281. Wu W, Liang H, Kan J, et al. 2008. Autographa californica multiple nucleopolyhedrovirus 38K is a novel nucleocapsid protein that interacts with VP1054, VP39, VP80, and itself. J Virol, 82: 12356-12364.
  282. 282. Wu W, Lin T, Pan L, et al. 2006. Autographa cali fornica multiple nucleopolyhedrovirus nucleocapsid assembly is interrupted upon deletion of the 38K gene. J Virol, 80: 11475-11485.
  283. 283. Wu X, Guarino L A. 2003. Autographa californica nucleopolyhedrovirus orf69 encodes an RNA cap (nucleoside-2'-O)-methyltransferase. J Virol, 77: 3430-3440.
  284. 284. Wu Y, Carstens E B. 1998. A baculovirus single-stranded DNA binding protein, LEF-3, mediates the nuclear localization of the putative helicase P143. Virology, 247: 32-40.
  285. 285. Xi Q, Wang J, Deng R, et al. 2007. Characterization of AcMNPV with a deletion of me53 gene. Virus Genes, 34: 223-232.
  286. 286. Xu H J, Yang Z N, Wang F, et al. 2006. Bombyx mori nucleopolyhedrovirus ORF79 encodes a 28-kDa structural protein of the ODV envelope. Arch Virol, 151: 681-695.
  287. 287. Yamagishi J, Burnett E D, Harwood S H, et al. 2007. The AcMNPV pp31 gene is not essential for productive AcMNPV replication or late gene transcription but appears to increase levels of most viral transcripts. Virology, 365: 34-47.
  288. 288. Yang S, Miller L K. 1998. Control of baculovirus poly-hedrin gene expression by very late factor 1. Virology, 248: 131-138.
  289. 289. Yang S, Miller L K. 1998. Expression and mutational analysis of the baculovirus very late factor 1 (vlf-1) gene. Virology, 245: 99-109.
  290. 290. Yuan M, Wu W, Liu C, et al. 2008. A highly conserved baculovirus gene p48 (ac103) is essential for BV production and ODV envelopment. Virology, 379: 87-96.
  291. 291. Zhang J-H, Ohkawa T, Washburn J O, et al. 2005. Effects of Ac150 on virulence and pathogenesis of Autographa californica multiple nucleopolyhedrovirus in noctuid hosts. J Gen Virol, 86: 1619-1627.
  292. 292. Zhou J, Blissard G W. 2008. Identification of a GP64 subdomain involved in receptor binding by budded virions of the baculovirus Autographica californica multicapsid nucleopolyhedrovirus. J Virol, 82: 4449-4460.
  293. 293. Zhou W, Yao L, Xu H, et al. 2005. The function of envelope protein p74 from Autographa californica multiple nucleopolyhedrovirus in primary infection to host. Virus Genes, 30: 139-150.
  294. 294. Zuidema D, Klinge-Roode E C, Van Lent J W M, et al. 1989. Construction and analysis of an Autographa californica nuclear polyhedrosis virus mutant lacking the polyhedral envelope. Virology, 173: 98-108.