97 research outputs found

    Trim21 regulates Nmi-IFI35 complex-mediated inhibition of innate antiviral response

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    In this study, using an immunoprecipitation coupled with mass spectrometry approach, we have identified the E3 ubiquitin ligase Trim21 as an interacting partner of IFI35 and Nmi. We found that this interaction leads to K63-linked ubiquitination on K22 residue of Nmi, but not IFI35. Using domain deletion analysis, we found that the interaction is mediated via the coiled-coil domain of Nmi and the carboxyl-terminal SPRY domain of Trim21. Furthermore, we show that depletion of Trim21 leads to significantly reduced interaction of Nmi with IFI35, which results in the abrogation of the negative regulatory function of the Nmi-IFI35 complex on innate antiviral signaling. Thus, Trim21 appears to be a critical regulator of the functions of the Nmi-IFI35 complex. Overall, the results presented here uncover a new mechanism of regulation of the Nmi-IFI35 complex by Trim21, which may have implications for various autoimmune diseases associated uncontrolled antiviral signaling

    Host Cell Functions In Vesicular Stomatitis Virus Replication

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    Vesicular stomatitis virus (VSV), the prototypic rhabdovirus, has been used as an excellent paradigm for understanding the mechanisms of virus replication, pathogenesis, host response to virus infection and also for myriads of studies on cellular and molecular biology. Biochemical studies as well as high-throughput genomics, proteomics, and chemical approaches have revealed a plethora of cellular factors and pathways that regulate replication of VSV. These factors include those that support virus replication and also those that restrict its replication. This chapter discusses the role(s) of many of these host cell factors and pathways involved in VSV replication. Although mechanistic understanding of the roles of some of these factors in VSV replication has been obtained, the roles of many others need to be investigated for a better understanding of the virus-host cell interactions

    Host Cell Functions In Vesicular Stomatitis Virus Replication

    Get PDF
    Vesicular stomatitis virus (VSV), the prototypic rhabdovirus, has been used as an excellent paradigm for understanding the mechanisms of virus replication, pathogenesis, host response to virus infection and also for myriads of studies on cellular and molecular biology. Biochemical studies as well as high-throughput genomics, proteomics, and chemical approaches have revealed a plethora of cellular factors and pathways that regulate replication of VSV. These factors include those that support virus replication and also those that restrict its replication. This chapter discusses the role(s) of many of these host cell factors and pathways involved in VSV replication. Although mechanistic understanding of the roles of some of these factors in VSV replication has been obtained, the roles of many others need to be investigated for a better understanding of the virus-host cell interactions

    Visualization of Intracellular Transport of Vesicular Stomatitis Virus Nucleocapsids in Living Cells

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    The phosphoprotein (P) of vesicular stomatitis virus (VSV) is a subunit of the viral RNA polymerase. In previous studies, we demonstrated that insertion of 19 amino acids in the hinge region of the protein had no significant effect on P protein function. In the present study, we inserted full-length enhanced green fluorescent protein (eGFP) in frame into the hinge region of P and show that the fusion protein (PeGFP) is functional in viral genome transcription and replication, albeit with reduced activity. A recombinant vesicular stomatitis virus encoding PeGFP in place of the P protein (VSV-PeGFP), which possessed reduced growth kinetics compared to the wild-type VSV, was recovered. Using the recombinant VSV-PeGFP, we show that the viral replication proteins and the de novo-synthesized RNA colocalize to sites throughout the cytoplasm, indicating that replication and transcription are not confined to any particular region of the cytoplasm. Real-time imaging of the cells infected with the eGFP-tagged virus revealed that, following synthesis, the nucleocapsids are transported toward the cell periphery via a microtubule (MT)-mediated process, and the nucleocapsids were seen to be closely associated with mitochondria. Treatment of cells with nocodazole or Colcemid, drugs known to inhibit MT polymerization, resulted in accumulation of the nucleocapsids around the nucleus and also led to inhibition of infectious-virus production. These findings are compatible with a model in which the progeny viral nucleocapsids are transported toward the cell periphery by MT and the transport may be facilitated by mitochondria

    Heterogeneous Nuclear Ribonucleoprotein K Supports Vesicular Stomatitis Virus Replication by Regulating Cell Survival and Cellular Gene Expression

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    The heterogeneous nuclear ribonucleoprotein K (hnRNP K) is a member of the family of hnRNPs and was recently shown in a genome-wide small interfering RNA (siRNA) screen to support vesicular stomatitis virus (VSV) growth. To decipher the role of hnRNP K in VSV infection, we conducted studies which suggest that the protein is required for VSV spreading. Virus binding to cells, entry, and nucleocapsid uncoating steps were not adversely affected in the absence of hnRNP K, whereas viral genome transcription and replication were reduced slightly. These results indicate that hnRNP K is likely involved in virus assembly and/or release from infected cells. Further studies showed that hnRNP K suppresses apoptosis of virus-infected cells, resulting in increased cell survival during VSV infection. The increased survival of the infected cells was found to be due to the suppression of proapoptotic proteins such as Bcl-X5 and Bik in a cell-type-dependent manner. Additionally, depletion of hnRNP K resulted in not only significantly increased levels of T-cell-restricted intracellular antigen 1 (TIA1) but also switching of the expression of the two isoforms of the protein (TIA1a and TIA1b), both of which inhibited VSV replication. hnRNP K was also found to support expression of several cellular proteins known to be required for VSV infection. Overall, our studies demonstrate hnRNP K to be a multifunctional protein that supports VSV infection via its role(s) in suppressing apoptosis of infected cells, inhibiting the expression of antiviral proteins, and maintaining the expression of proteins required for the virus

    A single amino acid change resulting in loss of fluorescence of eGFP in a viral fusion protein confers fitness and growth advantage to the recombinant vesicular stomatitis virus

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    Using a recombinant vesicular stomatitis virus encoding eGFP fused in-frame with an essential viral replication protein, the phosphoprotein P, we show that during passage in culture, the virus mutates the nucleotide C289 within eGFP of the fusion protein PeGFP to A or T, resulting in R97S/C amino acid substitution and loss of fluorescence. The resultant non-fluorescent virus exhibits increased fitness and growth advantage over its fluorescent counterpart. The growth advantage of the non-fluorescent virus appears to be due to increased transcription and replication activities of the PeGFP protein carrying the R97S/C substitution. Further, our results show that the R97S/C mutation occurs prior to accumulation of mutations that can result in loss of expression of the gene inserted at the G-L gene junction. These results suggest that fitness gain is more important for the recombinant virus than elimination of expression of the heterologous gene

    STUDIES ON THE PRODUCTIVE AND REPRODUCTIVE PERFORMANCES OF SOVIET CHINCHILLA AND NEW ZEALAND WHITE BREEDS OF RABBIT UNDER THE SUBTROPICAL CONDITION OF TRIPURA

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    ABSTRACT Productive and reproductive performances of New Zealand White and Soviet Chinchilla breeds of rabbit were studied under the sub-tropical climate of Tripura in India. Data from 261 litters were collected and studied. Both the breeds under study performed equally well. Only the number of service per conception and inter kindling interval were significantly (p<0.01) higher in New Zealand White than Soviet Chinchilla. Both the breed and sex of the rabbit had no significant effect on individual body weight at weaning (d-42) as well as at day of slaughter (d-90). Season of kindling exerted highly significant (p<0.01) effect on service period, kindling interval, and individual weight at weaning (d-42) and at slaughtering age (d-90). Winter season (November-March) was the most favourable season for kindling in terms of both their productive as well as reproductive efficiency where as summer season (April-June) turned to be the most unfavourable season. Age at first fertile service, age at first kindling, gestation period, litter size at birth did not influence by the season of kindling

    A single amino acid change resulting in loss of fluorescence of eGFP in a viral fusion protein confers fitness and growth advantage to the recombinant vesicular stomatitis virus

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    Using a recombinant vesicular stomatitis virus encoding eGFP fused in-frame with an essential viral replication protein, the phosphoprotein P, we show that during passage in culture, the virus mutates the nucleotide C289 within eGFP of the fusion protein PeGFP to A or T, resulting in R97S/C amino acid substitution and loss of fluorescence. The resultant non-fluorescent virus exhibits increased fitness and growth advantage over its fluorescent counterpart. The growth advantage of the non-fluorescent virus appears to be due to increased transcription and replication activities of the PeGFP protein carrying the R97S/C substitution. Further, our results show that the R97S/C mutation occurs prior to accumulation of mutations that can result in loss of expression of the gene inserted at the G-L gene junction. These results suggest that fitness gain is more important for the recombinant virus than elimination of expression of the heterologous gene
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