2015 Vol.30(3)
Immunofl uorescence microscopy of a chimeric mouse liver repopulated with human hepatocytes. Productive infection of human hepatocytes within a chimeric mouse by hepatitis C virus (HCV) reveals antagonism of the RIGI- like receptor pathway. Due to cleavage of the central adaptor protein MAVS, HCV (green) infected hepatocytes do not exhibit nuclear translocation of the innate immune activating transcription factor IRF3 (red). Evasion of the innate immune system is a central event in HCV establishing chronic infection and inducing hepatocellular carcinoma. Read more about the RIG-I-like receptors signaling in the innate antiviral immunity from the review article wrote by John Errett and Michael Gale (p163-173). (Image courtesy of Nanette Crochet from the Gale laboratory.)
|
Emerging complexity and new roles for the RIG-I-like receptors in innate antiviral immunity
2015, 30(3): 163 doi: 10.1007/s12250-015-3604-5
Received: 05 May 2015
Accepted: 13 May 2015
Published: 19 May 2015
Innate immunity is critical for the control of virus infection and operates to restrict viral susceptibility and direct antiviral immunity for protection from acute or chronic viral-associated diseases including cancer. RIG-I like receptors (RLRs) are cytosolic RNA helicases that function as pathogen recognition receptors to detect RNA pathogen associated molecular patterns (PAMPs) of virus infection. The RLRs include RIG-I, MDA5, and LGP2. They function to recognize and bind to PAMP motifs within viral RNA in a process that directs the RLR to trigger downstream signaling cascades that induce innate immunity that controls viral replication and spread. Products of RLR signaling also serve to modulate the adaptive immune response to infection. Recent studies have additionally connected RLRs to signaling cascades that impart inflammatory and apoptotic responses to virus infection. Viral evasion of RLR signaling supports viral outgrowth and pathogenesis, including the onset of viral-associated cancer.
mTOR regulates TLR-induced c-fos and Th1 responses to HBV and HCV vaccines
2015, 30(3): 174 doi: 10.1007/s12250-015-3606-3
Received: 11 May 2015
Accepted: 11 June 2015
Published: 11 June 2015
Although IL-12 plays a critical role in priming Th1 and cytotoxic T lymphocyte (CTL) responses, Toll-like receptor (TLR) signaling only induces low amounts of IL-12 in dendritic cells and macrophages, implying the existence of stringent regulatory mechanisms. In this study, we sought to uncover the mechanisms underlying TLR-induced IL-12 expression and the Th1 response. By systemic screening, we identified a number of protein kinases involved in the regulation of TLRinduced IL-12 expression. In particular, PI3K, ERK, and mTOR play critical roles in the TLR-induced Th1 response by regulating IL-12 and IL-10 production in innate immune cells. Moreover, we identified c-fos as a key molecule that mediates mTOR-regulated IL-12 and IL-10 expression in TLR signaling. Mechanistically, mTOR plays a crucial role in c-fos expression, thereby modulating NFκB binding to promoters of IL-12 and IL-10. By controlling the expression of a special innate gene program, mTOR can specifically regulate the TLR-induced T cell response in vivo. Furthermore, blockade of mTOR by rapamycin efficiently boosted TLR-induced antigen-specific T and B cell responses to HBV and HCV vaccines. Taken together, these results reveal a novel mechanism through which mTOR regulates TLR-induced IL-12 and IL-10 production, contributing new insights for strategies to improve vaccine efficacy.
A respiratory syncytial virus persistent-infected cell line system reveals the involvement of SOCS1 in the innate antiviral response
2015, 30(3): 190 doi: 10.1007/s12250-015-3597-0
Received: 18 April 2015
Accepted: 12 June 2015
Published: 19 June 2015
HEp-2 cells persistently infected with respiratory syncytial virus (RSV) are a heterogeneous mixture of viral antigen-positive and -negative variants; however, the mechanism through which viral replication becomes latent remains unclear. In this study, we investigated the potential mechanism by which RSV escapes from innate immune surveillance. Persistent-infected RSV HEp- 2 cells were isolated and cell clones were passaged. The RSV-persistent cells produced viruses at a lower titer, resisted wild-type RSV re-infection, and secreted high levels of interferon-β (IFN-β), macrophage inflammatory protein-1α (Mip-1α), interleukin-8 (IL-8), and Rantes. Toll-like receptor 3 (TLR3), retinoic acid inducible gene-I (RIG-I), and suppressor of cytokine signaling 1 (SOCS1) levels were upregulated in these cells. The silencing of TLR3 mRNA decreased the expression of SOCS1 protein and the secretion of cytokines. RSV-persistent cells are in an inflammatory state; upregulation of SOCS1 is related to the TLR3 signaling pathway, which could be associated with the mechanism of viral persistence.
Design of a heterosubtypic epitope-based peptide vaccine fused with hemokinin-1 against influenza viruses
2015, 30(3): 200 doi: 10.1007/s12250-014-3504-0
Received: 13 September 2014
Accepted: 31 March 2015
Published: 15 April 2015
Influenza viruses continue to emerge and re-emerge, posing new threats for public health. Control and treatment of influenza depends mainly on vaccination and chemoprophylaxis with approved antiviral drugs. Identification of specific epitopes derived from influenza viruses has significantly advanced the development of epitope-based vaccines. Here, we explore the idea of using HLA binding data to design an epitope-based vaccine that can elicit heterosubtypic T-cell responses against circulating H7N9, H5N1, and H9N2 subtypes. The hemokinin-1 (HK-1) peptide sequence was used to induce immune responses against the influenza viruses. Five conserved high score cytotoxic T lymphocyte (CTL) epitopes restricted to HLA-A*0201-binding peptides within the hemagglutinin (HA) protein of the viruses were chosen, and two HA CTL/HK-1 chimera protein models designed. Using in silico analysis, which involves interferon epitope scanning, protein structure prediction, antigenic epitope determination, and model quality evaluation, chimeric proteins were designed. The applicability of one of these proteins as a heterosubtypic epitopebased vaccine candidate was analyzed.
Monoclonal neutralizing antibodies against EV71 screened from mice immunized with yeast-produced virus-like particles
2015, 30(3): 208 doi: 10.1007/s12250-015-3573-8
Received: 14 February 2015
Accepted: 11 May 2015
Published: 29 May 2015
Periodic outbreaks of hand, foot and mouth disease (HFMD) occur in children under 5 years old, and can cause death in some cases. The C4 strain of enterovirus 71 (EV71) is the main pathogen that causes HFMD in China. Although no drugs against EV71 are available, some studies have shown that candidate vaccines or viral capsid proteins can produce anti-EV71 immunity. In this study, female BABL/c mice (6–8 weeks old) were immunized with virus-like particles (VLPs) of EV71 produced in yeast to screen for anti-EV71 antibodies. Two hybridomas that could produce neutralizing antibodies against EV71 were obtained. Both neutralizing mAbs (D4 and G12) were confirmed to bind the VP1 capsid protein of EV71, and could protect > 95% cells from 100 TCID50 EV71 infection at 25 μg/mL solution (lowest concentration). Those two neutralizing mAbs identified in the study may be promising candidates in development for mAbs to treat EV71 infection, and utilized as suitable reagents for use in diagnostic tests and biological studies.
Taken together with our previous report, current results provide cursory evidence that the sinecatechins’ mechanism of action likely entails some degree of modulation of inflammatory and apoptotic processes, in particular, the NF-κB-pathway. It is possible that sinecatechins also upregulate the host immune response, since the only gene to be significantly upregulated in VR is the pro-lymphocytic IL2; however, further studies are needed to examine the exact pattern of immune regulation. Moreover, since no DEGs were identified in VNR in the prior report, the present study provides putative insight into the expression patterns of patients who are not responsive to sinecatechins.
Our results suggest that TTV is extremely common in the general Chinese population, including infants, providing further evidence that TTV is highly prevalent in the general population worldwide(Mancuso et al., 2013). Furthermore, the overall prevalence of TTV infection based on UTR-PCR in healthy infants, healthy adults, and patients with liver disease was almost 2–3 times higher than that obtained by N22-PCR(p < 0.01, Table 1), which highlights both the considerable influence of the PCR primers on the detection of TTV DNA and the benefits of using UTR-PCR to establish the true overall prevalence of TTV infection. On the other h and , our results also indicate the lack of a clear association of TTV infection with chronic viral hepatitis, which strongly suggests that TTV has little potential for causing hepatitis. However, the virulence and pathogenesis of the different genotypes or strains of TTV remain unclear and require further investigation.
Cats as a potential source of emerging influenza virus infections
2015, 30(3): 221 doi: 10.1007/s12250-015-3580-9
Published: 05 May 2015
Based on the findings of the present study, we conclude that cats can be infected with human influenza viruses as well as avian influenza viruses. Actually, the recent study has shown that both human-type(α2, 6-linked sialic acid) and avian-type(α2, 3-linked sialic acid)influenza virus receptors were extensively detected in the respiratory organs such as trachea, bronchus, and lung of the domestic cats(Wang et al., 2013). Therefore, cats may act as a vector for human influenza virus transmission within households, posing a potential public health concern. Furthermore, we detected both H5N1 and human virus-seropositive cats in neighboring areas at similar sampling times, suggesting that cats can be simultaneously infected with both avian and human viruses in H5N1 virus-endemic areas. Thus, cats, like pigs, may act as an intermediate host for the emergence of new, potentially p and emic viruses.
Evidence for the antisense transcription in the proviral R29-127 strain of bovine immunodefciency virus
2015, 30(3): 224 doi: 10.1007/s12250-015-3559-6
Published: 21 April 2015
In summary, this report documents the generation of antisense transcripts from clone127 of the R29 strain of BIV. An antisense ORF was predicted, and antisense transcripts were detected in 293T cells transfected with DNA containing the BIV127 proviral sequence. More importantly, the antisense transcript was detected in BIVE cells infected with BIV127. It should be noted that this research attempted to demonstrate the presence of antisense transcripts in BIV-127 of the R29 strain; thus, the results do not address whether the antisense transcripts exist in other BIV strains.
In this study, we developed a real-time PCR assay for RHDV detection and quantitation. With this method, the distribution of RHDV in the internal organs and body fluids of infected rabbits was analyzed. The highest viral RNA load was found in the spleen, followed by that in the liver. The virus is shed mainly through the oral, nasal, and urethral routes. Through testing of clinical samples, we found that most farmed rabbits that had been immunized had low levels of RHDV in their tissues. These findings may be useful for further research on the pathogenic mechanism of RHDV and potential RHDV receptors in organs.
Characterization of an infectious pancreatic necrosis virus from rainbow trout fry (Onhorhynchus mykiss) in West Ukraine
2015, 30(3): 231 doi: 10.1007/s12250-014-3513-z
Published: 20 March 2015
In this report, an aquatic birnavirus was isolated from rainbow trout fry, Onhorhynchus mykiss, during a fish health inspection in fish-farms in the west region of Ukraine near the rivers Siret and Cheremosh(Chernivtsi region). Preliminary examination of infected fish revealed a range of lesions, particularly in pancreatic tissue. Morphological changes, such as vacuole enlargement and cell rounding, were caused by viruses in appropriate cell lines. Investigation by electron microscopy demonstrated that the isolated virus was ultrastructurally similar to infectious pancreatic necrosis virus(IPNV). In addition, the nucleotide sequences of the 1120 bp VP2 gene fragments were analyzed and the identity of the isolated IPNV to strain Sp was revealed. The identity of nucleotide sequences was 97%–99%; the isolates of Sp strains most closely related to the Ukrainian IPNV isolate were found in Norway.
Are developing countries prepared to face Ebola-like outbreaks?
2015, 30(3): 234 doi: 10.1007/s12250-015-3564-9
Published: 19 June 2015
Many developing countries lack a functional health care system, especially African countries. Such a system is not only important to monitor emergencies but also to develop an integrated response; otherwise, any epidemic can spread rapidly(as was observed in the case of Ebola) and pose huge problems worldwide. According to WHO reports, the basic health care system in most countries affected by Ebola is very fragile(http://www.who.int/healthsystems); substantial investments are needed to improve the infrastructure and bring reforms. This is not only important for African countries; in fact, most developing countries need additional investments to improve the healthcare sector.
