Search

Abstract Background Chicken anemia virus (CAV) infection of newly hatched chickens induces generalized lymphoid atrophy and causes immunosuppressive. VP3, also known as Apoptin, is non-structural protein of CAV. Apoptin specifically induces apoptosis in transformed or tumor cells but not in normal cells. In particular, there are no known cellular homologues of Apoptin hindering genetic approaches to elucidate its cellular function. Although a number of Apoptin-interacting molecules have been identified, the molecular mechanism underlying Apoptin's action is still poorly understood. To learn more about the molecular mechanism of Apoptin's action, we searched for Apoptin associated proteins. Results Using yeast two-hybrid and colony-life filter approaches we got five positive yeast clones. Through sequencing and BLASTed against NCBI, one of the clones was confirmed containing Gallus heat shock cognate protein 70 (Hsc70). Hsc70 gene was clone into pRK5-Flag plasmid, coimmunoprecipitation assay show both exogenous Hsc70 and endogenous Hsc70 can interact with Apoptin. Truncated Apoptin expression plasmids were made and coimmunoprecipitation were performed, the results show the binding domain of Apoptin with Hsc70 is located between amino acids 30-60. Truncated expression plasmids of Hsc70 were also constructed and coimmunoprecipitation were performed, the results show the peptide-binding and variable domains of Hsc70 are responsible for the binding to Apoptin. Confocal assays were performed and results show that under physiological condition Hsc70 is predominantly distributed in cytoplasm, whereas Hsc70 is translocated into the nuclei and colocalized with Apoptin in the presence of Apoptin in DF-1 cell. Functional studies show that Apoptin markedly down-regulate the mRNA level of RelA/p65 in DF-1 cell. To explore the effect of Hsc70 on Apoptin-mediated RelA/p65 gene expression, we have searched two Hsc70 RNAi sequences, and found that all of them dramatically inhibited the expression of endogenous Hsc70, with the #2 Hsc70 RNAi sequence being the most effective. Knockdown of Hsc70 show Apoptin-inhibited RelA/p65 expression was abolished. Our data demonstrate that Hsc70 is responsible for the down-regulation of Apoptin induced RelA/p65 gene expression. Conclusion We identified Gallus Hsc70 as an Apoptin binding protein and showed the translocation of Hsc70 into the nuclei of DF-1 cells treated with Apoptin. Hsc70 regulates RelA/p65 gene expression induced by Apoptin.

Infectious bursal disease (IBD) is an acute, highly contagious and immunosuppressive avian disease caused by IBD virus (IBDV). Cell apoptosis triggered by IBDV contributes to the dysfunction of immune system in host. VP2 of IBDV is known to induce cell death but the underlying mechanism remains unclear. Here we demonstrate that VP2 interacts with the oral cancer overexpressed 1 (ORAOV1), a potential oncoprotein. Infection by IBDV or ectopic expression of VP2 causes a reduction of cellular ORAOV1 and induction of apoptosis, so does knockdown of ORAOV1. In contrast, over-expression of ORAOV1 leads to the inhibition of VP2- or IBDV-induced apoptosis, accompanied with the decreased viral release (p < 0.05). Thus, VP2-induced apoptosis during IBDV infection is mediated by interacting with and reducing ORAOV1, a protein that appears to act as an antiapoptotic molecule and restricts viral release early during IBDV infection. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Pullorum (S. pullorum) causes pullorum disease in poultry and results in great economic losses to the poultry industry. Although an eradication program has been successfully performed in some countries, it remains a major threat to countries with poor poultry disease surveillance. Currently there are no effective control measures for pullorum disease except eradication. In particular, the pathogenesis of S. pullorum infection is still largely unknown. Here we identified bacterioferritin (Bfr) as a major antigen of S. pullorum to elicit a humoral immune response. Furthermore, we demonstrate that Bfr induces activation of IFN-β promoter and mRNA expression in DF-1 cells, and that the amino acids 1-50 form a critical domain involved in IFN-β expression. Moreover, we found that the p38 MAPK signaling pathway was essential for Bfr-induced IFN-β expression. Importantly, S. pullorum-induced IFN-β expression was totally abolished by deficiency of Bfr in the bacteria, indicating that Bfr plays a critical role in S. pullorum induced IFN-β expression in DF-1 cells. Our findings provide new insights into the molecular mechanisms of the host response to S. pullorum infection. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Microbiology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Staphylococcus sciuri (S. sciuri) is a rare pathogen in humans, but it can cause a wide array of human infections. Recently a S. sciuri isolate (HBXX06) was reported to cause fatal exudative epidermitis (EE) in piglets and thus considered as a potential zoonotic agent. To investigate the pathogenicity of this bacterium, we cloned exfoliative toxin C (ExhC), a major toxin of the S. sciuri isolate and performed functional analysis of the recombinant ExhC-his (rExhC) protein using in vitro cell cultures and newborn mice as models. We found that rExhC could induce necrosis in multiple cell lines and peritoneal macrophages as well as skin lesions in newborn mice, and that the rExhC-induced necrosis in cells or skin lesions in newborn mice could be completely abolished if amino acids 79-128 of rExhC were deleted or blocked with a monoclonal antibody (3E4), indicating aa 79-128 portion as an essential necrosis-inducing domain. This information contributes to further understandings of the mechanisms underlying S. sciuri infection. [ABSTRACT FROM AUTHOR]

Background: Chicken anemia virus (CAV) infection of newly hatched chickens induces generalized lymphoid atrophy and causes immunosuppressive. VP3, also known as Apoptin, is non-structural protein of CAV. Apoptin specifically induces apoptosis in transformed or tumor cells but not in normal cells. In particular, there are no known cellular homologues of Apoptin hindering genetic approaches to elucidate its cellular function. Although a number of Apoptin-interacting molecules have been identified, the molecular mechanism underlying Apoptin's action is still poorly understood. To learn more about the molecular mechanism of Apoptin's action, we searched for Apoptin associated proteins. Results: Using yeast two-hybrid and colony-life filter approaches we got five positive yeast clones. Through sequencing and BLASTed against NCBI, one of the clones was confirmed containing Gallus heat shock cognate protein 70 (Hsc70). Hsc70 gene was clone into pRK5-Flag plasmid, coimmunoprecipitation assay show both exogenous Hsc70 and endogenous Hsc70 can interact with Apoptin. Truncated Apoptin expression plasmids were made and coimmunoprecipitation were performed, the results show the binding domain of Apoptin with Hsc70 is located between amino acids 30-60. Truncated expression plasmids of Hsc70 were also constructed and coimmunoprecipitation were performed, the results show the peptide-binding and variable domains of Hsc70 are responsible for the binding to Apoptin. Confocal assays were performed and results show that under physiological condition Hsc70 is predominantly distributed in cytoplasm, whereas Hsc70 is translocated into the nuclei and colocalized with Apoptin in the presence of Apoptin in DF-1 cell. Functional studies show that Apoptin markedly down-regulate the mRNA level of RelA/p65 in DF-1 cell. To explore the effect of Hsc70 on Apoptin-mediated RelA/ p65 gene expression, we have searched two Hsc70 RNAi sequences, and found that all of them dramatically inhibited the expression of endogenous Hsc70, with the #2 Hsc70 RNAi sequence being the most effective. Knockdown of Hsc70 show Apoptin-inhibited RelA/p65 expression was abolished. Our data demonstrate that Hsc70 is responsible for the down-regulation of Apoptin induced RelA/p65 gene expression. Conclusion: We identified Gallus Hsc70 as an Apoptin binding protein and showed the translocation of Hsc70 into the nuclei of DF-1 cells treated with Apoptin. Hsc70 regulates RelA/p65 gene expression induced by Apoptin. [ABSTRACT FROM AUTHOR]

Fowl adenovirus serotype 4 (FAdV-4) causes hepatitis-hydropericardium syndrome (HHS), leading to severe economic losses in the poultry industry. Although the pathogenesis of FAdV-4 infection has caused much attention, the underlying molecular mechanisms remain poorly understood. Here, we identified chaperonin containing TCP-1 subunit eta (CCT7) as an interacting partner of the FAdV-4 capsid protein hexon. We found that ectopic expression of CCT7 in leghorn male hepatocellular (LMH) cells enhanced hexon expression in pRK5-flag-hexon transfected cells. On the contrary, knockdown of cellular CCT7 by RNAi markedly reduced hexon expression in FAdV-4-infected cells and suppressed viral replication. These data suggest that CCT7 is required for FAdV-4 replication and may serve as a potential target for controlling FAdV-4 infection. [ABSTRACT FROM AUTHOR]

Nuclear receptors are ligand-activated transcription factors that play an important role in regulating innate antiviral immunity and other biological processes. However, the role of nuclear receptors in the host response to infectious bursal disease virus (IBDV) infection remains elusive. In this study, we show that IBDV infection or poly(I­C) treatment of DF-1 or HD11 cells markedly decreased nuclear receptor subfamily 2 group F member 2 (NR2F2) expression. Surprisingly, knockdown, knockout, or inhibition of NR2F2 expression in host cells remarkably inhibited IBDV replication and promoted IBDV/poly(I­C)-induced type I interferon and interferon-stimulated genes expression. Furthermore, our data show that NR2F2 negatively regulates the antiviral innate immune response by promoting the suppressor of cytokine signaling 5 (SOCS5) expression. Thus, reduced NR2F2 expression in the host response to IBDV infection inhibited viral replication by enhancing the expression of type I interferon by targeting SOCS5. These findings reveal that NR2F2 plays a crucial role in antiviral innate immunity, furthering our understanding of the mechanism underlying the host response to viral infection. [ABSTRACT FROM AUTHOR]

Avian reovirus (ARV) causes viral arthritis, chronic respiratory diseases, retarded growth, and malabsorption syndrome. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression posttranscriptionally by silencing or degrading their targets, thus playing important roles in the host response to pathogenic infection. However, the role of miRNAs in host response to ARV infection is still not clear. In this study, we show that ARV infection markedly increased gga-miR-30c-5p expression in DF-1 cells and that transfection of cells with gga-miR-30c-5p inhibited ARV replication while knockdown of endogenous gga-miR-30c-5p enhanced viral growth in cells. Importantly, we identified the autophagy related 5 (ATG5), an important proautophagic protein, as a bona fide target of gga-miR-30c-5p. Transfection of DF-1 cells with gga-miR-30c-5p markedly reduced ATG5 expression accompanied with reduced conversion of ARV-induced-microtubule-associated protein 1 light chain 3 II (LC3-II) from LC3-I, an indicator of autophagy in host cell, while knockdown of endogenous gga-miR-30c-5p enhanced ATG5 expression as well as ARV-induced conversion of LC3-II, facilitating viral growth in cells. Furthermore, knockdown of ATG5 by RNA interference (RNAi) or treatment of cells with autophagy inhibitors (3-MA and wortmannin) markedly reduced ARV-induced LC3-II and syncytium formation, suppressing viral growth in cells, while overexpression of ATG5 increased ARV-induced LC3-II and syncytium formation, promoting viral growth in cells. Thus, gga-miR-30c-5p suppressed viral replication by inhibition of ARV-induced autophagy via targeting ATG5. These findings unraveled the mechanism of how host cells combat against ARV infection by self-encoded small RNA and furthered our understanding of the role of microRNAs in host response to pathogenic infection. IMPORTANCE Avian reovirus (ARV) is an important poultry pathogen causing viral arthritis, chronic respiratory diseases, and retarded growth, leading to considerable economic losses to the poultry industry across the globe. Elucidation of the pathogenesis of ARV infection is crucial to guiding the development of novel vaccines or drugs for the effective control of these diseases. Here, we investigated the role of miRNAs in host response to ARV infection. We found that infection of host cells by ARV remarkably upregulated gga-miR-30c-5p expression. Importantly, gga-miR-30c-5p suppressed ARV replication by inhibition of ARV-induced autophagy via targeting autophagy related 5 (ATG5) accompanied by suppression of virus-induced syncytium formation, thus serving as an important antivirus factor in host response against ARV infection. These findings will further our understanding of how host cells combat against ARV infection by self-encoded small RNAs and may be used as a potential target for intervening ARV infection. [ABSTRACT FROM AUTHOR]

Recognition of viral RNAs by melanoma differentiation associated gene-5 (MDA5) initiates chicken antiviral response by producing type I interferons. Our previous studies showed that chicken microRNA-155-5p (gga-miR-155-5p) enhanced IFN-b expression and suppressed the replication of infectious burse disease virus (IBDV), a doublestranded RNA (dsRNA) virus causing infectious burse disease in chickens. However, the mechanism underlying IBDV-induced gga-miR-155-5p expression in host cells remains elusive. Here, we show that IBDV infection or poly(I:C) treatment of DF-1 cells markedly increased the expression of GATA-binding protein 3 (GATA3), a master regulator for TH2 cell differentiation, and that GATA3 promoted gga-miR-155-5p expression in IBDV-infected or poly(I:C)-treated cells by directly binding to its promoter. Surprisingly, ectopic expression of GATA3 significantly reduced IBDV replication in DF-1 cells, and this reduction could be completely abolished by treatment with gga-miR-155-5p inhibitors, whereas knockdown of GATA3 by RNA interference enhanced IBDV growth, and this enhancement could be blocked with gga-miR-155-5p mimics, indicating that GATA3 suppressed IBDV replication by gga-miR-155-5p. Furthermore, our data show that MDA5 is required for GATA3 expression in host cells with poly(I:C) treatment, so are the adaptor protein TBK1 and transcription factor IRF7, suggesting that induction of GATA3 expression in IBDV-infected cells relies on MDA5-TBK1-IRF7 signaling pathway. These results uncover a novel role for GATA3 as an antivirus transcription factor in innate immune response by promoting miR- 155 expression, further our understandings of host response against pathogenic infection, and provide valuable clues to the development of antiviral reagents for public health. IMPORTANCE Gga-miR-155-5p acts as an important antivirus factor against IBDV infection, which causes a severe immunosuppressive disease in chicken. Elucidation of the mechanism regulating gga-miR-155-5p expression in IBDV-infected cells is essential to our understandings of the host response against pathogenic infection. This study shows that transcription factor GATA3 initiated gga-miR-155-5p expression in IBDV-infected cells by directly binding to its promoter, suppressing viral replication. Furthermore, induction of GATA3 expression was attributable to the recognition of dsRNA by MDA5, which initiates signal transduction via TBK1 and IRF7. Thus, it is clear that IBDV induces GATA3 expression via MDA5-TBK1-IRF7 signaling pathway, thereby suppressing IBDV replication by GATA3-mediated gga-miR-155-5p expression. This information remarkably expands our knowledge of the roles for GATA3 as an antivirus transcription factor in host innate immune response particularly at an RNA level and may prove valuable in the development of antiviral drugs for public health. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression posttranscriptionally by silencing or degrading their targets and play important roles in the host response to pathogenic infection. Although infectious bursal disease virus (IBDV)-induced apoptosis in host cells has been established, the underlying molecular mechanism is not completely unraveled. Here, we show that infection of DF-1 cells by IBDV induced gga-miR-16-5p (chicken miR-16-5p) expression via demethylation of the pre-miR-16-2 (gga-miR-16-5p precursor) promoter. We found that ectopic expression of gga-miR-16-5p in DF-1 cells enhanced IBDVinduced apoptosis by directly targeting the cellular antiapoptotic protein B-cell lymphoma 2 (Bcl-2), facilitating IBDV replication in DF-1 cells. In contrast, inhibition of endogenous miR-16-5p markedly suppressed apoptosis associated with enhanced Bcl-2 expression, arresting viral replication in DF-1 cells. Furthermore, infection of DF-1 cells with IBDV reduced Bcl-2 expression, and this reduction could be abolished by inhibition of gga-miR-16-5p expression. Moreover, transfection of DF-1 cells with gga-miR-16-5p mimics enhanced IBDV-induced apoptosis associated with increased cytochrome c release and caspase-9 and -3 activation, and inhibition of caspase-3 decreased IBDV growth in DF-1 cells. Thus, epigenetic upregulation of gga-miR-16-5p expression by IBDV infection enhances IBDV-induced apoptosis by targeting the cellular antiapoptotic protein Bcl-2, facilitating IBDV replication in host cells. [ABSTRACT FROM AUTHOR]

Avian reovirus (ARV) causes viral arthritis, chronic respiratory diseases, retarded growth, and malabsorption syndrome. The ARV p10 protein, a viroporin responsible for the induction of cell syncytium formation and apoptosis, is rapidly degraded in host cells. Our previous report demonstrated that cellular lysosome-associated membrane protein 1 (LAMP-1) interacted with p10 and was involved in its degradation. However, the molecular mechanism underlying LAMP-1-mediated p10 degradation remains elusive. We report here that the E3 ubiquitin ligase seven in absentia homolog 1 (Siah-1) is critical for p10 ubiquitylation. Our data show that Siah-1 ubiquitylated p10 and targeted it for proteasome degradation. Furthermore, the ubiquitylation of p10 by Siah-1 required the participation of LAMP-1 by forming a multicomponent complex. Thus, LAMP-1 promotes the proteasomal degradation of p10 via interacting with both p10 and the E3 ligase Siah-1. These data establish a novel host defense mechanism where LAMP-1 serves as a scaffold for both Siah-1 and p10 that allows the E3 ligase targeting p10 for ubiquitylation and degradation to suppress ARV infection. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression posttranscriptionally through silencing or degrading their targets, thus playing important roles in the immune response. However, the role of miRNAs in the host response against infectious bursal disease virus (IBDV) infection is not clear. In this study, we show that the expression of a series of miRNAs was significantly altered in DF-1 cells after IBDV infection. We found that the miRNA gga-miR-130b inhibited IBDV replication via targeting the specific sequence of IBDV segment A and enhanced the expression of beta interferon (IFN-β) by targeting suppressors of cytokine signaling 5 (SOCS5) in host cells. These findings indicate that gga-miR-130b-3p plays a crucial role in host defense against IBDV infection. [ABSTRACT FROM AUTHOR]

Hepatitis-pericardial syndrome (HHS) is an acute highly infectious avian disease caused by fowl adenovirus serotype 4 (FAdV-4), characterized by fulminant hepatitis and hydropericardium in broilers. Since 2015, a widespread epidemic has occurred in China due to the emergence of hypervirulent FAdV-4 (HPFAdV-4), causing huge losses to the stakeholders. However, the pathogenesis of HPFAdV-4 and the host responses to its infection remain elusive. Here, we show that infection of leghorn male hepatocellular (LMH) cells by HPFAdV-4 induced complete autophagy in cells and that the autophagy induced by recombinant HPFAdV-4-ON1 (rHPFAdV-4-ON1), a viral strain generated by replacing the hexon gene of wild-type HPFAdV-4 (HPFAdV-4-WT) with the one of nonpathogenic strain FAdV-4-ON1, was remarkably mitigated compared to that of the rHPFAdV-4-WT control, suggesting that HPFAdV-4 hexon is responsible for virus-induced autophagy. Importantly, we found that hexon interacted with a cellular protein, BAG3, a host protein that initiates autophagy, and that BAG3 expression increased in cells infected with HPFAdV-4. Furthermore, knockdown of BAG3 by RNA interference (RNAi) significantly inhibited HPFAdV-4- or hexon-induced autophagy and suppressed viral replication. On the contrary, expression of hexon markedly upregulated the expression of BAG3 via activating the P38 signaling pathway, triggering autophagy. Thus, these findings reveal that HPFAdV-4 hexon interacts with the host protein BAG3 and promotes BAG3 expression by activating P38 signaling pathway, thereby inducing autophagy and enhancing viral proliferation, which immensely furthers our understanding of the pathogenesis of HPFAdV-4 infection. IMPORTANCE HHS, mainly caused by HPFAdV-4, has caused large economic losses to the stakeholders in recent years. Infection of leghorn male hepatocellular (LMH) cells by HPFAdV-4 induced complete autophagy that is essential for HPFAdV-4 replication. By a screening strategy, the viral protein hexon was found responsible for virus-induced autophagy in cells. Importantly, hexon was identified as a factor promoting viral replication by interaction with BAG3, an initiator of host cell autophagy. These findings will help us to better understand the host response to HPFAdV-4 infection, providing a novel insight into the pathogenesis of HPFAdV-4 infection. [ABSTRACT FROM AUTHOR]

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Our previous report indicates that IBDV VP5 induces apoptosis via interaction with voltage-dependent anion channel 2 (VDAC2). However, the underlying molecular mechanism is still unclear. We report here that receptor of activated protein kinase C 1 (RACK1) interacts with both VDAC2 and VP5 and that they could form a complex. We found that overexpression of RACK1 inhibited IBDV-induced apoptosis in DF-1 cells and that knockdown of RACK1 by small interfering RNA induced apoptosis associated with activation of caspases 9 and 3 and suppressed IBDV growth. These results indicate that RACK1 plays an antiapoptotic role during IBDV infection via interaction with VDAC2 and VP5, suggesting that VP5 sequesters RACK1 and VDAC2 in the apoptosis-inducing process. [ABSTRACT FROM AUTHOR]

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Although IBDV-induced immunosuppression has been well established, the underlying exact molecular mechanism for such induction is not very clear. We report here the identification of IBDV VP4 as an interferon suppressor by interaction with the glucocorticoid-induced leucine zipper (GILZ) in host cells. We found that VP4 suppressed the expression of type I interferon in HEK293T cells after tumor necrosis factor alpha (TNF-α) treatment or Sendai virus (SeV) infection and in DF-1 cells after poly(I·C) stimulation. In addition, the VP4-induced suppression of type I interferon could be completely abolished by knockdown of GILZ by small interfering RNA (siRNA). Furthermore, knockdown of GILZ significantly inhibited IBDV growth in host cells, and this inhibition could be markedly mitigated by anti-alpha/beta interferon antibodies in the cell cultures (P < 0.001). Thus, VP4-induced suppression of type I interferon is mediated by interaction with GILZ, a protein that appears to inhibit cell responses to viral infection. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, oligothiophenes (thiophene) n (n=2–7) were optimized by using Hartree–Fock and restricted configuration interaction/singles (CIS) for their ground states (S0) and first singlet excited states (S1) geometries. This was followed by conformational and optical properties investigations using ab initio method in combination with CIS, TD-B3LYP and ZINDO approaches. It is found that bithiophene (BTP) and terthiophene (TTP) are nonplanar in the S0 states, whereas they almost reach planarity in the S1 states. The geometry relaxation after excitation contribute much to the Stokes shift observed in their absorption and emission spectra. The global potential energy surface (PES) studies show BTP and TTP have high inter-ring trosional flexibilities, in both the ground-states (S0) and first excited-states (S1); the cis-conformers should have evident contribution to the absorption and emission spectra of BTP and TTP molecules. These conclusions are also applicable to larger oligomers by a basic study extended to (thiophene) n (n=4–7). [Copyright &y& Elsevier]

An abstract of the article "Critical Role for Voltage-Dependent Anion Channel 2 in Infectious Bursal Disease Virus-Induced Apoptosis in Host Cells via Interaction with VP5," by Hong Cao and colleagues is presented.

Pyroptosis is an inflammatory type of programmed cell death predominantly driven by the formation of plasma membrane pores by the N-terminus generated from the cleaved Gasdermin (GSDM) family proteins. Examination of membrane-attached GSDM- NT by Western Blot is the most commonly used method for evaluating pyroptosis. However, it is difficult to differentiate cells with pyroptosis from other forms of cell death using this method. In this study, Infectious Bursal Disease Virus (IBDV)-infected DF-1 cells were employed as a model to quantify the proportion of cells undergoing pyroptosis by flow cytometry, utilizing specific antibodies against the N-terminal fragment of chicken GSDME (chGSDME- NT ) and propidium iodide (PI) staining. The chGSDME- NT -positive cells were readily detectable by flow cytometry using Alexa Fluor 647-labeled anti-chGSDME- NT antibodies. Moreover, the proportion of chGSDME- NT /PI double-positive cells in IBDV-infected cells (around 33%) was significantly greater than in mock-infected controls (P < 0.001). These findings indicate that examination of membrane-bound chGSDME- NT by flow cytometry is an effective approach for determining pyroptotic cells among cells undergoing cell death.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression posttranscriptionally through silencing or degrading their targets, thus playing important roles in the immune response. However, the role of miRNAs in the host response against infectious bursal disease virus (IBDV) infection is not clear. In this study, we show that the expression of a series of miRNAs was significantly altered in DF-1 cells after IBDV infection. We found that the miRNA gga-miR-130b inhibited IBDV replication via targeting the specific sequence of IBDV segment A and enhanced the expression of beta interferon (IFN-β) by targeting suppressors of cytokine signaling 5 (SOCS5) in host cells. These findings indicate that gga-miR-130b-3p plays a crucial role in host defense against IBDV infection. IMPORTANCE This work shows that gga-miR-130b suppresses IBDV replication via directly targeting the viral genome and cellular SOCS5, the negative regulator for type I interferon expression, revealing the mechanism underlying gga-miR-130-induced inhibition of IBDV replication. This information will be helpful for the understanding of how host cells combat pathogenic infection by self-encoded small RNA and furthers our knowledge of the role of microRNAs in the cell response to viral infection., (Copyright © 2017 American Society for Microbiology.)

Infectious bursal disease (IBD) is an acute, highly contagious and immunosuppressive poultry disease caused by IBD virus (IBDV). The consequent immunosuppression increases susceptibility to other infectious diseases and the risk of subsequent vaccination failure as well. Since the genome of IBDV is relatively small, it has a limited number of proteins inhibiting the cellular antiviral responses and acting as destroyers to the host defense system. Thus, these virulence factors must be multifunctional in order to complete the viral replication cycle in a host cell. Insights into the roles of these viral proteins along with their multiple cellular targets in different pathways will give rise to a rational design for safer and effective vaccines. Here we summarize the recent findings that focus on the virus-cell interactions during IBDV infection at the protein level., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

In order to develop monoclonal antibodies (McAbs) against the gp90 protein of reticuloendotheliosis virus (REV), the His-tagged gp90 protein of REV was used to immunize BALB/c mice. Hybridomas were generated by fusing mouse myeloma cells SP2/0 with the splenocytes from the immunized mice. After screening and 3 rounds of cloning process, 3 hybridomas (3G5-B8, 3G5-A10 and 1G12) that stably secreted McAbs against the REV-gp90 were obtained. The isotypes of the McAbs were determined to be IgG1, IgG1 and IgG2b. The McAbs specifically bound to gp90 in REV-infected DF-1 cells, as demonstrated by Western blotting and indirect immunofluorescence assay. The recognition regions on gp90 that were recognized by 3G5-B8/3G5-A10 and 1G12 were located between amino acids 200 to 245 and 230 to 235, respectively, as demonstrated by Western blotting analysis. These McAbs will be useful in the diagnosis and pathogenesis study of REV.

Infectious bursal disease virus (IBDV) VP4 plays an important role in immunosuppression of host. In order to develop monoclonal antibodies (McAbs) against VP4, we vaccinated BALB/c mice with His-VP4, screened and subcloned positive clones. We established 4 hybridoma cell lines that stably secreted McAbs against VP4 and named these cell lines 3B3, 3H11, 4C8 and 4G6, respectively. We tested the dissociation constant (Kd) of these McAbs, and found that their K(d)s were 4.61 x 10(-11), 1.71 x 10(-10), 4.26 x 10(-11), 5.02 x 10(-11), respectively. The isotypes of these McAbs were determined to be IgG1, IgG1, IgG2b and IgG1. These McAbs specifically bound to VP4 in IBDV infected DF-1 cells as demonstrated by Western blotting analysis and fluorescence antibody assay. These McAbs would help to detect IBDV infection and to analyze the biological activities of IBDV VP4.

Staphylococcus sciuri causes multiple infections in humans. Recently, a strain of S. sciuri (HBXX06) carrying exfoliative toxin C (ExhC) was reported to cause fatal exudative epidermal skin pathology in piglets and might be considered as a potential zoonotic agent. However, little is known about the pathogenicity of this bacterium. In this study, we examined the activity of recombinant ExhC-his (rExhC) protein using newborn mice as the model and investigated the effect of rExhC on macrophage functions. Interestingly, we found that both rExhC and S. sciuri ExhC existed as dimers and that rExhC inhibited the phagocytosis of RAW264.7 cell lines but enhanced the production of proinflammatory mediators, such as interleukin-6, interleukin-12, tumor necrosis factor α, and nitric oxide, by murine peritoneal macrophages and RAW264.7 cells. These results suggest that ExhC may play an important role in innate immune response against S. sciuri infection.