Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
Getah virus (GETV) is a mosquito-borne virus of the genus Alphavirus in the family Togaviridae and, in recent years, it has caused several outbreaks in animals. The molecular basis for GETV pathogenicity is not well understood. Therefore, a reverse genetic system of GETV is needed to produce genetically modified viruses for the study of the viral replication and its pathogenic mechanism. Here, we generated a CMV-driven infectious cDNA clone based on a previously isolated GETV strain, GX201808 (pGETV-GX). Transfection of pGETV-GX into BHK-21 cells resulted in the recovery of a recombinant virus (rGETV-GX) which showed similar growth characteristics to its parental virus. Then three-day-old mice were experimentally infected with either the parental or recombinant virus. The recombinant virus showed milder pathogenicity than the parental virus in the mice. Based on the established CMV-driven cDNA clone, subgenomic promoter and two restriction enzyme sites (BamHI and EcoRI) were introduced into the region between E1 protein and 3'UTR. Then the green fluorescent protein (GFP), red fluorescent protein (RFP) and improved light-oxygen-voltage (iLOV) genes were inserted into the restriction enzyme sites. Transfection of the constructs carrying the reporter genes into BHK-21 cells proved the rescue of the recombinant reporter viruses. Taken together, the establishment of a reverse genetic system for GETV provides a valuable tool for the study of the virus life cycle, and to aid the development of genetically engineered GETVs as vectors for foreign gene expression.
Enteroviruses belonging to the family Picornaviridae are non-enveloped RNA viruses that cause hand-foot-mouth disease (HFMD), which can lead to severe neurological complications. Enteroviruses genomes represent a single open reading frame flanked by 5′-and 3′-untranslated terminal regions (UTRs), constituting the basis for classifying enteroviruses into groups A–D (Zaoutis et al., 1998). Current research is primarily focused on highly prevalent pathogens, including enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) of group A (Duan et al., 2021). However, group B viruses are also responsible for a significant number of infections that often cause histopathological changes in the heart, brain, and pancreas. For instance, coxsackievirus B5 (CV-B5) can induce aseptic meningitis, viral meningitis, acute flaccid paralysis, pancreatitis, and type I diabetes mellitus (Chen et al., 2020; Marcela et al., 2019; Hyöty et al., 2018). HFMD outbreaks caused by CV-B5 have been reported in China, Southeast Asia, and Europe. However, despite its clinical significance, little is known about its pathogenesis, and in-depth studies on the underlying mechanisms are urgently needed (Gao et al., 2018; Sciandra et al., 2020).
African swine fever (ASF) is a highly contagious and acute hemorrhagic viral disease with a high mortality approaching 100% in domestic pigs. ASF is an endemic in countries in sub-Saharan Africa. Now, it has been spreading to many countries, especially in Asia and Europe. Due to the fact that there is no commercial vaccine available for ASF to provide sustainable prevention, the disease has spread rapidly worldwide and caused great economic losses in swine industry. The knowledge gap of ASF virus (ASFV) pathogenesis and immune evasion is the main factor to limit the development of safe and effective ASF vaccines. Here, we will summarize the molecular mechanisms of how ASFV interferes with the host innate and adaptive immune responses. An in-depth understanding of ASFV immune evasion strategies will provide us with rational design of ASF vaccines.
Differential miRNA expression profiling of Highly Pathogenic Avian Influenza Virus H5N1 infected chicken lungs reveals critical microRNAs, biological pathways and genes involved in the molecular pathogenesis
Received: 24 January 2021 Accepted: 07 March 2022 Published: 09 March 2022
Avian influenza is a highly contagious viral infection affecting the respiratory system. MicroRNAs (miRNAs) are small, regulatory, endogenous, non-coding RNAs of ~22 nt that regulate the gene expression of the target mRNAs by cleavage or translational repression. miRNAs are connected with the host response during avian influenza virus (AIV) infection (Wang et al., 2009; Wang et al., 2012). In this study, we used miRNomics approach to understand the complex host-pathogen interaction during the HPAIV H5N1 infection in chicken.
The recent COVID-19 pandemic poses a global health emergency. Cellular entry of the causative agent SARS-CoV-2 is mediated by its spike protein interacting with cellular receptor-human angiotensin converting enzyme 2 (ACE2). Here, by using lentivirus based pseudotypes bearing spike protein, we demonstrated that entry of SARS-CoV-2 into host cells was dependent on clathrin-mediated endocytosis, and phosphoinositides played essential roles during this process. In addition, we showed that the intracellular domain and the catalytic activity of ACE2 were not required for efficient virus entry. Finally, we showed that the current predominant Delta variant, although with high infectivity and high syncytium formation, also entered cells through clathrin-mediated endocytosis. These results provide new insights into SARS-CoV-2 cellular entry and present proof of principle that targeting viral entry could be an effective way to treat different variant infections.
Consolidation treatment needed for sustained HBsAg-negative response induced by interferon-alpha in HBeAg positive chronic hepatitis B patients
Received: 21 October 2021 Accepted: 25 February 2022 Published: 04 March 2022
Hepatitis B surface antigen (HBsAg) clearance is considered as functional cure in patients with chronic hepatitis B (CHB). This study aimed to assess the durability of HBsAg clearance achieved by interferon-based therapies in patients with CHB who were originally positive for hepatitis B envelope antigen (HBeAg). In this prospective study, HBeAg-positive CHB patients with confirmed HBsAg loss under interferon-based therapies were enrolled within 12 weeks from end of treatment and followed up for 48 weeks. Virological markers, biochemical indicators, and liver imaging examinations were observed every 3–6 months. Sustained functional cure was analyzed as primary outcome. Factor associated with sustained HBsAg loss or reversion was also investigated. The rate of HBsAg loss sustainability was 91.8% (212/231). Patients receiving consolidation treatment for 12–24 weeks or ≥ 24 weeks had higher rates of sustained HBsAg negativity than those receiving consolidation treatment for < 12 weeks (98.3% and 91.2% vs. 86.7%, P = 0.068), and the former groups had significantly higher anti-HBs levels than the later (P < 0.05). The cumulative incidence of HBsAg reversion and HBV DNA reversion was 8.2% and 3.9%, respectively. Consolidation treatment of ≥ 12 weeks [odd ratio (OR) 3.318, 95% confidence interval (CI) 1.077–10.224, P = 0.037) was a predictor of sustained functional cure, and HBeAg-positivity at cessation of treatment (OR 12.271, 95% CI 1.076–139.919, P = 0.043) was a predictor of HBsAg reversion. Interferon-alpha induced functional cure was durable and a consolidation treatment of ≥ 12–24 weeks was needed after HBsAg loss in HBeAg-positive CHB patients.
African swine fever virus (ASFV), the sole member of the family Asfarviridae, is thecausative agent of African swine fever (ASF), a viral disease that leads to high mortality indomestic pigs. Since firstly identified in Kenya in the 1920s, ASFV has been prevalent inAfrica, Europe, and Russian Federation (Sanchez et al., 2019). Recently, ASFV wasintroduced to Asian countries including China, Mongolia, Vietnam, Cambodia, Laos andSouth Korea, which lead to huge economic losses to local pig industries (Li and Tian, 2018,Gaudreault and Richt, 2019). The first case of ASFV in China was reported in August 2018(Zhou et al., 2018). Since then, hundreds of cases in most provinces were officiallyannounced and more than 1 million pigs were slaughtered under the strict stamping-out policy(Miao et al., 2019).
Advancements in high-throughput sequencing (HTS) of antibody repertoires (Ig-Seq) have unprecedentedly improved our ability to characterize the antibody repertoires on a large scale. However, currently, only a few studies explored the influence of chronic HIV-1 infection on human antibody repertoires and many of them reached contradictory conclusions, possibly limited by inadequate sequencing depth and throughput. To better understand how HIV-1 infection would impact humoral immune system, in this study, we systematically analyzed the differences between the IgM (HIV-IgM) and IgG (HIV-IgG) heavy chain repertoires of HIV-1 infected patients, as well as between antibody repertoires of HIV-1 patients and healthy donors (HH). Notably, the public unique clones accounted for only a negligible proportion between the HIV-IgM and HIV-IgG repertoires libraries, and the diversity of unique clones in HIV-IgG remarkably reduced. In aspect of somatic mutation rates of CDR1 and CDR2, the HIV-IgG repertoire was higher than HIV-IgM. Besides, the average length of CDR3 region in HIV-IgM was significant longer than that in the HH repertoire, presumably caused by the great number of novel VDJ rearrangement patterns, especially a massive use of IGHJ6. Moreover, some of the B cell clonotypes had numerous clones, and somatic variants were detected within the clonotype lineage in HIV-IgG, indicating HIV-1 neutralizing activities. The in-depth characterization of HIV-IgG and HIV-IgM repertoires enriches our knowledge in the profound effect of HIV-1 infection on human antibody repertoires and may have practical value for the discovery of therapeutic antibodies.
Efficient assembly of a large fragment of monkeypox virus genome as a qPCR template using dual-selection based transformation-associated recombination
Received: 10 August 2021 Accepted: 23 February 2022 Published: 28 February 2022
Transformation-associated recombination (TAR) has been widely used to assemble large DNA constructs. One of the significant obstacles hindering assembly efficiency is the presence of error-prone DNA repair pathways in yeast, which results in vector backbone recircularization or illegitimate recombination products. To increase TAR assembly efficiency, we prepared a dual-selective TAR vector, pGFCS, by adding a PADH1-URA3 cassette to a previously described yeast-bacteria shuttle vector, pGF, harboring a PHIS3-HIS3 cassette as a positive selection marker. This new cassette works as a negative selection marker to ensure that yeast harboring a recircularized vector cannot propagate in the presence of 5-fluoroorotic acid. To prevent pGFCS bearing ura3 from recombining with endogenous ura3-52 in the yeast genome, a highly transformable Saccharomyces cerevisiae strain, VL6-48B, was prepared by chromosomal substitution of ura3-52 with a transgene conferring resistance to blasticidin. A 55-kb genomic fragment of monkeypox virus encompassing primary detection targets for quantitative PCR was assembled by TAR using pGFCS in VL6-48B. The pGFCS-mediated TAR assembly showed a zero rate of vector recircularization and an average correct assembly yield of 79% indicating that the dual-selection strategy provides an efficient approach to optimizing TAR assembly.
Human cytomegalovirus RNA2.7 inhibits RNA polymerase II (Pol II) Serine-2 phosphorylation by reducing the interaction between Pol II and phosphorylated cyclin-dependent kinase 9 (pCDK9)
Received: 12 August 2021 Accepted: 24 February 2022 Published: 28 February 2022
Human cytomegalovirus (HCMV) is a ubiquitous pathogen belongs to beta herpesvirus family. RNA2.7 is a highly conserved long non-coding RNA accounting for more than 20% of total viral transcripts. In our study, functions of HCMV RNA2.7 were investigated by comparison of host cellular transcriptomes between cells infected with HCMV clinical strain and RNA2.7 deleted mutant. It was demonstrated that RNA polymerase II (Pol II)-dependent host gene transcriptions were significantly activated when RNA2.7 was removed during infection. A 145 nt-in-length motif within RNA2.7 was identified to inhibit the phosphorylation of Pol II Serine-2 (Pol II S2) by reducing the interaction between Pol II and phosphorylated cyclin-dependent kinase 9 (pCDK9). Due to the loss of Pol II S2 phosphorylation, cellular DNA pre-replication complex (pre-RC) factors, including Cdt1 and Cdc6, were significantly decreased, which prevented more cells from entering into S phase and facilitated viral DNA replication. Our results provide new insights of HCMV RNA2.7 functions in regulation of host cellular transcription.
Apis mellifera filamentous virus (AmFV) is a large DNA virus that is endemic in honeybee colonies. The genome sequence of the AmFV Swiss isolate (AmFV CH-C05) has been reported but so far very few molecular studies have been conducted on this virus. We isolated and purified AmFV (AmFV CN) from Chinese honeybee (Apis mellifera) colonies and elucidated its genomics and proteomics. Electron microscopy showed ovoid purified virions with dimensions of 300–500 × 210–285 nm, wrapping a 3165 × 40 nm filamentous nucleocapsid in three figure-eight loops. Unlike AmFV CH-C05, which was reported to have a circular genome, our data suggest that AmFV CN has a linear genome of approximately 493 kb. A total of 197 ORFs were identified, among which 36 putative genes including18 homologs were annotated. The overall nucleotide similarity between the CN and CH-C05 isolates was 96.9%. Several ORFs were newly annotated in AmFV CN, including homologs of per os infectivity factor 4 (PIF4) and a putative integrase. Phylogenomic analysis placed AmFVs on a separate branch within the newly proposed virus class Naldaviricetes. Proteomic analysis revealed 47 AmFV virion-associated proteins, of which 14 had over 50% sequence coverage, suggesting that they are likely to be main structural proteins. In addition, all six of the annotated PIFs (PIF-0–5) were identified by proteomics, suggesting that they may function as entry factors in AmFV infection. This study provides fundamental information regarding the molecular biology of AmFV.
Rabies virus (RABV) is an enveloped, non-segmented, and single-stranded RNA virus that belongs to the genus Lyssavirus within the Rhabdoviridae family (Douglas et.al., 2013). RABV causes rabies, and although vaccines are available, rabies continues to be a global public health concern causing more than 60,000 human deaths each year (WHO, 2013). There is a high prevalence especially in developing countries in Asia and Africa (Hampson et al., 2015; Singh et al., 2017). In most cases, RABV is transmitted through the direct contact of broken skin or the mucous membrane with the saliva of infected dogs. Unless the wound is promptly cleaned and post-exposure prophylaxis is administered, the human victim may develop encephalitis that is nearly always fatal.
Enterovirus 71 (EV71) belongs to the genus Enterovirus, family Picornaviridae (Oberste et al., 1999). It was first isolated from patients with central nervous system diseases in California between 1969 and 1974 (Schmidt et al., 1974) and has spread worldwide (Solomon et al., 2010). EV71 infection usually causes mild, self-limiting hand, foot, and mouth disease in children. Acute EV71 infection may also cause severe polio-like neurological diseases and significant mortality. The spectrum of EV71-associated neurological diseases includes aseptic meningitis, brainstem and/or cerebellar encephalitis, acute flaccid paralysis (AFP), myocarditis, and rapid fatal pulmonary edema and hemorrhage (McMinn, 2002).
Multiple new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have constantly emerged, as the delta and omicron variants, which have developed resistance to currently gained neutralizing antibodies. This highlights a critical need to discover new therapeutic agents to overcome the variants mutations. Despite the availability of vaccines against coronavirus disease 2019 (COVID-19), the use of broadly neutralizing antibodies has been considered as an alternative way for the prevention or treatment of SARS-CoV-2 variants infection. Here, we show that the nasal delivery of two previously characterized broadly neutralizing antibodies (F61 and H121) protected K18-hACE2 mice against lethal challenge with SARS-CoV-2 variants. The broadly protective efficacy of the F61 or F61/F121 cocktail antibodies was evaluated by lethal challenge with the wild strain (WIV04) and multiple variants, including beta (B.1.351), delta (B.1.617.2), and omicron (B.1.1.529) at 200 or 1000 TCID50, and the minimum antibody administration doses (5–1.25 mg/kg body weight) were also evaluated with delta and omicron challenge. Fully prophylactic protections were found in all challenged groups with both F61 and F61/H121 combination at the administration dose of 20 mg/kg body weight, and corresponding mice lung viral RNA showed negative, with almost all alveolar septa and cavities remaining normal. Furthermore, low-dose antibody treatment induced significant prophylactic protection against lethal challenge with delta and omicron variants, whereas the F61/H121 combination showed excellent results against omicron infection. Our findings indicated the potential use of broadly neutralizing monoclonal antibodies as prophylactic and therapeutic agent for protection of current emerged SARS-CoV-2 variants infection.
The Getah virus (GETV), a mosquito-borne RNA virus, is widely distributed in Oceania and Asia. GETV is not only pathogenic to horses, pigs, cattle, foxes and boars, but it can also cause fever in humans. Since its first reported case in Chinese mainland in 2017, the number of GETV-affected provinces has increased to seventeen till now. Therefore, we performed an epidemiologic investigation of GETV in the Xinjiang region, located in northwestern China, during the period 2017–2020. ELISA was used to analyze 3299 serum samples collected from thoroughbred horse, local horse, sheep, goat, cattle, and pigs, with thoroughbred horse (74.8%), local horse (67.3%), goat (11.7%), sheep (10.0%), cattle (25.1%) and pigs (51.1%) being positive for anti-GETV antibodies. Interestingly, the neutralizing antibody titer in horses was much higher than in other species. Four samples from horses and pigs were positive for GETV according to RT-PCR. Furthermore, from the serum of a local horse, we isolated GETV which was designated as strain XJ-2019-07, and determined its complete genome sequence. From the phylogenetic relationships, it belongs to the Group III lineage. This is the first evidence of GETV associated to domestic animals in Xinjiang. Overall, GETV is prevalent in Xinjiang and probably has been for several years. Since no vaccine against GETV is available in China, detection and monitoring strategies should be improved in horses and pigs, especially imported and farmed, in order to prevent economic losses.
Bovine hepacivirus (BovHepV) is a novel virus that was recently discovered in Ghana and Germany in 2015. Until now, this virus has been identified in cattle population worldwide and is classified into subtypes A–G. To fully understand the epidemic situation and genetic characteristic of BovHepV in China, a total of 612 cattle serum samples were collected from 20 farms in seven provinces and municipality in China between 2018 and 2020 and were tested for the presence of BovHepV RNA via semi-nested PCR. The results demonstrated that 49 (8.0%) samples were BovHepV RNA-positive. It is noted that BovHepV infection in yak was confirmed for the first time. BovHepV was detected in all the seven provinces, with the positive rate ranging from 3.1% to 13.3%, which indicates a wide geographical distribution pattern of BovHepV in China. Sequencing results revealed that 5′ UTR of the 49 field BovHepV strains have a nucleotide similarity of 96.3%–100% between each other and 93.9%–100% with previously reported BovHepV strains. In addition, genetic analysis identified five critical nucleotide sites in 5′ UTR to distinguish different subtypes, which was further verified by genomic sequencing and nucleotide similarity analysis. All the 49 Chinese field BovHepV strains were classified into subtype G and this subtype is only determined in cattle in China currently. This study will provide insights for us to better understand the epidemiology and genetic diversity of BovHepV.
Bocaviruses are associated with many human infectious diseases, such as respiratory tract infections, gastroenteritis, and hepatitis. Rats are known to be reservoirs of bocaviruses, including rodent bocavirus and rat bocavirus. Recently, ungulate bocaparvovirus 4, a known porcine bocavirus, has also been found in rats. Thus, investigating bocaviruses in rats is important for determining the origin of the viruses and preventing and controlling their transmission. To the best of our knowledge, no study to date has investigated bocaviruses in the livers of rats. In this report, a total of 624 rats were trapped in southern China between 2014 and 2017. Liver and serum samples from rats were tested for the prevalence of bocaviruses using PCR. Sequences related to ungulate bocaparvovirus 4 and rodent bocavirus were detected in both liver and serum samples. Interestingly, the prevalence of ungulate bocaparvovirus 4 (reference strain: KJ622366.1) was higher than that of rodent bocavirus (reference strain: KY927868.1) in both liver (2.24% and 0.64%, respectively) and serum samples (2.19% and 0.44%, respectively). The NS1 regions of ungulate bocaparvovirus 4 and rodent bocavirus related sequences displayed over 84% and 88% identity at the nucleic and amino acid levels, respectively. Furthermore, these sequences had similar genomic structure, genomic features, and codon usage bias, and shared a common ancestor. These viruses also displayed greater adaptability to rats than pigs. Our results suggested that ungulate bocaparvovirus 4 and rodent bocavirus may originate from rats and may be different genotypes of the same bocavirus species.
COVID-19 caused by SARS-CoV-2, is still a big threat to human populations around the world. As of Jan 2022, over 292 million cases were reported worldwide with more than 5.4 million deaths. After it was first reported in China in December 2019, the virus kept circulating and evolving and several variants with different transmissibility emerged in different countries and regions (WHO, 2021a). Until now, six major variants have been reported including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), Lambda (C.37), and Omicron (B.1.1.529) and the infection caused by different variants has varied according to the surveillance data (WHO, 2021b).
Since its outbreak in 2019, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) keeps surprising the medical community by evolving diverse immune escape mutations in a rapid and effective manner. To gain deeper insight into mutation frequency and dynamics, we isolated ten ancestral strains of SARS-CoV-2 and performed consecutive serial incubation in ten replications in a suitable and common cell line and subsequently analysed them using RT-qPCR and whole genome sequencing. Along those lines we hoped to gain fundamental insights into the evolutionary capacity of SARS-CoV-2 in vitro. Our results identified a series of adaptive genetic changes, ranging from unique convergent substitutional mutations and hitherto undescribed insertions. The region coding for spike proved to be a mutational hotspot, evolving a number of mutational changes including the already known substitutions at positions S:484 and S:501. We discussed the evolution of all specific adaptations as well as possible reasons for the seemingly inhomogeneous potential of SARS-CoV-2 in the adaptation to cell culture. The combination of serial passage in vitro with whole genome sequencing uncovers the immense mutational potential of some SARS-CoV-2 strains. The observed genetic changes of SARS-CoV-2 in vitro could not be explained solely by selectively neutral mutations but possibly resulted from the action of directional selection accumulating favourable genetic changes in the evolving variants, along the path of increasing potency of the strain. Competition among a high number of quasi-species in the SARS-CoV-2 in vitro population gene pool may reinforce directional selection and boost the speed of evolutionary change.
Temperate bacteriophages are widely distributed in bacteria isolated from different natural environments (Howard-Varona et al., 2017). The phages normally lead to lysogenic infection and merge their genetic components into the bacterial chromosome. Among the temperate phages, linear plasmid phages are atypical because of their capability to reside in host cells as linear dsDNA with covalently closed ends, rather than being integrated in host genomes in the form of prophages (Ravin et al., 2000; Ravin, 2011). The life cycle of N15, the first isolated linear plasmid phage, has been thoroughly investigated in its host Escherichia coli (Ravin, 2011). The formation of the linear plasmid prophage is attributed to a protelomerase that is encoded by the telN gene. The protelomerase acts on an inverted repeat site (telRL) on the phage genome, and then forms two covalently closed ends (telR and telL) (Ravin, 2003). Similar to phage λ DNA, N15 phage DNA has two 12-bp single-stranded cohesive ends (cosR and cosL), which are also responsible for the formation of the linear plasmid prophage of N15 (Ravin, 2015). Additionally, a multifunctional replication protein, RepA, which combines primase, helicase and DNA-binding activities, is indispensable for the lytic replication of N15 (Ravin, 2015).
Arthropod-borne chikungunya virus (CHIKV) infection can cause a debilitating arthritic disease in human. However, there are no specific antiviral drugs and effective licensed vaccines against CHIKV available for clinical use. Here, we developed an mRNA-lipid nanoparticle (mRNA-LNP) vaccine expressing CHIKV E2-E1 antigen, and compared its immunogenicity with soluble recombinant protein sE2-E1 antigen expressed in S2 cells. For comparison, we first showed that recombinant protein antigens mixed with aluminum adjuvant elicit strong antigen-specific humoral immune response and a moderate cellular immune response in C57BL/6 mice. Moreover, sE2-E1 vaccine stimulated 12–23 folds more neutralizing antibodies than sE1 vaccine and sE2 vaccine. Significantly, when E2-E1 gene was delivered by an mRNA-LNP vaccine, not only the better magnitude of neutralizing antibody responses was induced, but also greater cellular immune responses were generated, especially for CD8+ T cell responses. Moreover, E2-E1-LNP induced CD8+ T cells can perform cytotoxic effect in vivo. Considering its better immunogenicity and convenience of preparation, we suggest that more attention should be placed to develop CHIKV E2-E1-LNP mRNA vaccine.
The coronavirus disease 2019 (COVID-19) outbreak, has spread across the world (Wu et al., 2020). The causative agent of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is highly pathogenic and infectious, which become a major public health hazard that has had a devastating social and economic impact worldwide (Li QQ et al., 2020).
The hepatitis B virus (HBV) is a global public health challenge due to its highly contagious nature. It is estimated that almost 300 million people live with chronic HBV infection annually. Although nucleoside analogs markedly reduce the risk of liver disease progression, the analogs do not fully eradicate the virus. As such, new treatment options and drugs are urgently needed. Psoralen is a nourishing monomer of Chinese herb and is known to inhibit virus replication and inactivate viruses. In this study, we evaluated the potential of psoralen as an anti-HBV agent. Quantitative PCR and Southern blot analysis revealed that psoralen inhibited HBV replication in HepG2.2.15 cells in a concentration-dependent manner. Moreover, psoralen was also active against the 3TC/ETV-dual-resistant HBV mutant. Further investigations revealed that psoralen suppressed both HBV RNA transcription and core protein expression. The transcription factor FOXO1, a known target for PGC1α co-activation, binds to HBV pre-core/core promoter enhancer II region and activates HBV RNA transcription. Co-immunoprecipitation showed that psoralen suppressed the expression of FOXO1, thereby decreasing the binding of FOXO1 co-activator PGC1α to the HBV promoter. Overall, our results demonstrate that psoralen suppresses HBV RNA transcription by down-regulating the expression of FOXO1 resulting in a reduction of HBV replication.
The nationwide COVID-19 epidemic ended in 2020, a few months after its outbreak in Wuhan, China at the end of 2019. Most COVID-19 cases occurred in Hubei Province, with a few local outbreaks in other provinces of China. A few studies have reported the early SARS-CoV-2 epidemics in several large cities or provinces of China. However, information regarding the early epidemics in small and medium-sized cities, where there are still traditionally large families and community culture is more strongly maintained and thus, transmission profiles may differ, is limited. In this study, we characterized 60 newly sequenced SARS-CoV-2 genomes from Anyang as a representative of small and medium-sized Chinese cities, compared them with more than 400 reference genomes from the early outbreak, and studied the SARS-CoV-2 transmission profiles. Genomic epidemiology revealed multiple SARS-CoV-2 introductions in Anyang and a large-scale expansion of the epidemic because of the large family size. Moreover, our study revealed two transmission patterns in a single outbreak, which were attributed to different social activities. We observed the complete dynamic process of single-nucleotide polymorphism development during community transmission and found that intrahost variant analysis was an effective approach to studying cluster infections. In summary, our study provided new SARS-CoV-2 transmission profiles representative of small and medium-sized Chinese cities as well as information on the evolution of SARS-CoV-2 strains during the early COVID-19 epidemic in China.
Coxsackievirus A10 (CVA10) is one of the major causative agents of hand, foot and mouth disease (HFMD). To investigate the epidemiological characteristics as well as genetic features of CVA10 currently circulating in Shanghai, China, we collected a total of 9,952 sporadic HFMD cases from January 2016 to December 2020. In the past five years, CVA10 was the fourth prevalent causatives associated with HFMD in Shanghai and the overall positive rate was 2.78%. The annual distribution experienced significant fluctuations over the past five years. In addition to entire VP1 sequencing, complete genome sequencing and recombination analysis of CVA10 isolates in Shanghai were further performed. A total of 64 near complete genomes and 11 entire VP1 sequences in this study combined with reference sequences publicly available were integrated into phylogenetic analysis. The CVA10 sequences in this study mainly belonged to genogroup C and presented 91%–100% nucleotide identity with other Chinese isolates based on VP1 region. For the first time, our study reported the appearance of CVA10 genogroup D in Chinese mainland, which had led to large-scale outbreaks in Europe previously. The recombination analysis showed the recombination break point located between 5,100 nt and 6,700 nt, which suggesting intertypic recombination with CVA16 genogroup D. To conclusion, CVA10 genogroup C was the predominant genogroup in Shanghai during 2016–2020. CVA10 recombinant genogroup D was firstly reported in circulating in Chinese mainland. Continuous surveillance is needed to better understand the evolution relationships and transmission pathways of CVA10 to help to guide disease control and prevention.
Porcine deltacoronavirus (PDCoV) is a novel discovered swine enteric coronavirus which can cause diarrhea and dehydration in pigs, particularly in neonatal piglets (Jung et al. 2016). At present, there are no commercial vaccines available for PDCoV. To control PDCoV transmission and perform antiviral therapy efficiently, a rapid and accurate diagnostic method to detect PDCoV is needed. PDCoV nucleocapsid (N) protein is the most abundant protein in the virus particle and plays essential roles in several stages of the viral lifecycle. It can produce high levels of antibodies at the early stage of PDCoV infection (Xu et al. 2013; Dinesh et al. 2020; Van Elslande et al. 2021). However, the characterization of epitopes on PDCoV N protein remains largely unknown.
Since the anti-inflammatory effect of hydrogen has been widely known, it was supposed that hydrogen could suppress tissue damage by inhibiting virus-related inflammatory reactions. However, hydrogen is slightly soluble in water, which leads to poor effect of oral hydrogen-rich water therapy. In this study, the nano-bubble hydrogen water (nano-HW) (about 0.7 ppm) was prepared and its therapeutic effect against viral infection was investigated by utilizing spring viraemia of carp virus (SVCV)-infected zebrafish as model. Three-month-old zebrafish were divided into nano-HW treatment–treated group and aquaculture water treated group (control group). The results revealed that the cumulative mortality rate of SVCV-infected zebrafish was reduced by 40% after treatment with nano-bubble hydrogen water, and qRT-PCR results showed that SVCV replication was significantly inhibited. Histopathological examination staining showed that SVCV infection caused tissue damage was greatly alleviated after treatment with nano-bubble hydrogen water. Futhermore, SVCV infection caused reactive oxygen species (ROS) accumulation was significantly reduced upon nano-HW treatment. The level of proinflammatory cytokines IL-1β, IL-8, and TNF-α was remarkably reduced in the nano-HW-treated group in vivo and in vitro. Taken together, our data demonstrated for the first time that nano-HW could inhibit the inflammatory response caused by viral infection in zebrafish, which suggests that nano-HW can be applied to antiviral research，and provides a novel therapeutic strategy for virus-caused inflammation related disease.
Molecular analysis of Coxsackievirus A24 variant isolates from three outbreaks of acute hemorrhagic conjunctivitis in 1988, 1994 and 2007 in Beijing, China
Received: 28 January 2021 Accepted: 14 January 2022 Published: 22 January 2022
Coxsackievirus A24 variant (CVA24v) is a major pathogen that causes continued outbreaks and pandemics of acute hemorrhagic conjunctivitis (AHC). In China, the first confirmed outbreak of CVA24v-related AHC occurred in Beijing in 1988, followed by another two significant outbreaks respectively in 1994 and 2007, which coincides with the three-stage dynamic distribution of AHC in the world after 1970s. To illustrate the genetic characteristics of CVA24v in different periods, a total of 23 strains were isolated from those three outbreaks and the whole genome of those isolations were sequenced and analyzed. Compared with the prototype strain, the 23 strains shared four nucleotide deletions in the 5′ UTR except the 0744 strain isolated in 2007. And at the 98th site, one nucleotide insertion was found in all the strains collected from 2007. From 1994 to 2007, amino acid polarity in the VP1 region at the 25th and the 32nd site were changed. Both the 3C and VP1 phylogenetic tree indicated that isolates from 1988 and 1994 belonged to Genotype III (GIII), and 2007 strains to Genotype IV (GIV). According to the Bayesian analysis based on complete genome sequence, the most recent common ancestors for the isolates in 1988, 1994 and 2007 were respectively estimated around October 1987, February 1993 and December 2004. The evolutionary rate of the CVA24v was estimated to be 7.45 × 10−3 substitutions/site/year. Our study indicated that the early epidemic of CVA24v in Chinese mainland was the GIII. Point mutations and amino acid changes in different genotypes of CVA24v may generate intensity differences of the AHC outbreak. CVA24v has been evolving constantly with a relatively rapid rate.
Subgroup J avian leukosis virus (ALV-J) is a highly oncogenic retrovirus that has been devastating the global poultry industry since the late 1990s. The major infection model of ALV-J is vertical transmission, which is responsible for the congenital infection of progeny from generation to generation. Increasing evidence has suggested that extracellular vesicles (EVs) derived from virus-infected cells or biological fluids have been thought to be vehicles of transmission for viruses. However, the role of EVs in infection and transmission of ALV-J remains obscure. In the present study, semen extracellular vesicles (SE) were isolated and purified from ALV-J-infected rooster seminal plasma (SE-ALV-J), which was shown to contain ALV-J genomic RNA and partial viral proteins, as determined by RNA sequencing, reverse transcription-quantitative PCR and Western blotting. Furthermore, SE-ALV-J was proved to be able to transmit ALV-J infection to host cells and establish productive infection. More importantly, artificial insemination experiments showed that SE-ALV-J transmitted ALV-J infection to SPF hens, and subsequently mediated vertical transmission of ALV-J from the SPF hens to the progeny chicks. Taken together, the results of the present study suggested that ALV-J utilized host semen extracellular vesicles as a novel means for vertical transmission, enhancing our understanding on mechanisms underlying ALV-J transmission.
Hepaciviruses, members of the family Flaviviridae, are enveloped viruses containing a single-stranded positive-sense RNA genome of approximately 8.9–10.5 kb in size (Simmonds et al., 2017). To date, 15 species (Hepacivirus A–N, and P) have been documented within the Hepacivirus genus that show distinct host ranges, including primates, bats, horses, donkeys, cows, and various rodents (Hartlage et al., 2016). Seven rodent-associated hepaciviruses have been characterized, including hepacivirus E, I, G and H infecting rodents of Muridae, hepacivirus F and J infecting rodents of Cricetidae (de Souza et al., 2019), and heapcivirus P infecting rodents of Xerinae (Li et al., 2019). Additional unclassified rodent hapaciviruses have been described in diverse rodents from Dormouse, Echimyidae, Heteromyidae, and Spalacidae. Mongolian gerbils (Meriones unguiculatus) are small rodents belonging to the family Muridae and are widely distributed in the desert grasslands and steppes of northern China, Mongolia, and Russia (Liu et al., 2007). They have been reported as a major host of Yersinia pestis causing plagues in China in recent decades (Riehm et al., 2011). Moreover, Mongolian gerbil is known to be susceptible to various viruses and is a commonly used animal model for virus research (Li et al., 2009). Despite this, the natural virome of wild Meriones unguiculatus has not been described. Herein, we reported the first hepacivirus detected in Mongolian gerbils captured in Dingbian County of Shaanxi Province, one of the plague zones in China.
During 2018–2019, a severe human adenovirus (HAdV) infection outbreak occurred in southern China. Here, we screened 18 respiratory pathogens in 1,704 children (≤14 years old) hospitalized with acute respiratory illness in Guangzhou, China, in 2019. In total, 151 patients had positive HAdV test results; 34.4% (52/151) of them exhibited severe illness. HAdV infection occurred throughout the year, with a peak in summer. The median patient age was 3.0 (interquartile range: 1.1–5.0) years. Patients with severe HAdV infection exhibited increases in 12 clinical indexes (P ≤ 0.019) and decreases in four indexes (P ≤ 0.007), compared with patients exhibiting non-severe infection. No significant differences were found in age or sex distribution according to HAdV infection severity (P > 0.05); however, the distributions of comorbid disease and HAdV co-infection differed according to HAdV infection severity (P < 0.05). The main epidemic types were HAdV-3 (47.0%, 71/151) and HAdV-7 (46.4%, 70/151). However, the severe illness rate was significantly higher in patients with HAdV-7 (51.4%) than in patients with HAdV-3 (19.7%) and other types of HAdV (20%) (P < 0.001). Sequencing analysis of genomes/capsid genes of 13 HAdV-7 isolates revealed high similarity to previous Chinese isolates. A representative HAdV-7 isolate exhibited a similar proliferation curve to the curve described for the epidemic HAdV-3 strain Guangzhhou01 (accession no. DQ099432) (P > 0.05); the HAdV-7 isolate exhibited stronger virulence and infectivity, compared with HAdV-3 (P < 0.001). Overall, comorbid disease, HAdV co-infection, and high virulence and infectivity of HAdV-7 were critical risk factors for severe HAdV infection; these data can facilitate treatment, control, and prevention of HAdV infection.
Pegivirus (family Flaviviridae) is a genus of small enveloped RNA viruses that mainly causes blood infections in various mammals including human. Herein, we carried out an extensive survey of pegiviruses from a wide range of wild animals mainly sampled in the Qinghai-Tibet Plateau of China. Three novel pegiviruses, namely Passer montanus pegivirus, Leucosticte brandti pegivirus and Montifringilla taczanowskii pegivirus, were identified from different wild birds, and one new rodent pegivirus, namely Phaiomys leucurus pegivirus, was identified from Blyth's vole. Interestingly, the pegiviruses of non-mammalian origin discovered in this study substantially broaden the host range of Pegivirus to avian species. Co-evolutionary analysis showed virus-host co-divergence over long evolutionary timescales, and indicated that pegiviruses largely followed a virus-host co-divergence relationship. Overall, this work extends the biodiversity of the Pegivirus genus to those infecting wild birds and hence revises the host range and evolutionary history of genus Pegivirus.
Severe acute respiratory syndrome (SARS) is a highly contagious zoonotic disease caused by SARS coronavirus (SARS-CoV). Since its outbreak in Guangdong Province of China in 2002, SARS has caused 8096 infections and 774 deaths by December 31st, 2003. Although there have been no more SARS cases reported in human populations since 2004, the recent emergence of a novel coronavirus disease (COVID-19) indicates the potential of the recurrence of SARS and other coronavirus disease among humans. Thus, developing a rapid response SARS vaccine to provide protection for human populations is still needed. Spike (S) protein of SARS-CoV can induce neutralizing antibodies, which is a pivotal immunogenic antigen for vaccine development. Here we constructed a recombinant chimeric vesicular stomatitis virus (VSV) VSVΔG-SARS, in which the glycoprotein (G) gene is replaced with the SARS-CoV S gene. VSVΔG-SARS maintains the bullet-like shape of the native VSV, with the heterogeneous S protein incorporated into its surface instead of G protein. The results of safety trials revealed that VSVΔG-SARS is safe and effective in mice at a dose of 1 × 106 TCID50. More importantly, only a single-dose immunization of 2 × 107 TCID50 can provide high-level neutralizing antibodies and robust T cell responses to non-human primate animal models. Thus, our data indicate that VSVΔG-SARS can be used as a rapid response vaccine candidate. Our study on the recombinant VSV-vectored SARS-CoV vaccines can accumulate experience and provide a foundation for the new coronavirus disease in the future.
Vol 37, No 1 (February, 2022)
Editor in Chief: Zheng-Li Shi
2020 Impact Factor 4.327
2020 Journal Citation Reports