Genetic diversity in the capsid protein gene of porcine circovirus type 3 in Vietnam from 2018 to 2019.

Porcine circovirus type 3 (PCV3) was first detected in 2016 and has been reported in many pig-producing countries around the world, including Vietnam. PCV3 has been found in complex cases with multiple clinical syndromes in swine. In this study, we investigated the genetic diversity of PCV3 strains circulating in Vietnam.

Porcine circovirus genotypes and their copathogens in pigs with respiratory disease in southern provinces of Vietnam.

This study was conducted to investigate the genetic diversity of porcine circovirus type 2 (PCV2) and its coinfecting pathogens in pigs with respiratory disease in Vietnam. Samples from 127 clinical cases were obtained from different southern provinces of Vietnam from January 2018 to January 2020 for PCR and sequence analysis. The infection rate of PCV2 was 78.

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

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.

Interferon-inducible protein IFI35 negatively regulates RIG-I antiviral signaling and supports vesicular stomatitis virus replication.

Unlabelled: In a genome-wide small interfering RNA (siRNA) screen, we recently identified the interferon (IFN)-inducible protein 35 (IFI35; also known as IFP35) as a factor required for vesicular stomatitis virus (VSV) infection. Studies reported here were conducted to further understand the role and requirement of IFI35 in VSV infection. Consistent with the siRNA screening data, we found that depletion of IFI35 led to reduced VSV replication at the level of viral gene expression.

Heterogeneous nuclear ribonucleoprotein K supports vesicular stomatitis virus replication by regulating cell survival and cellular gene expression.

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.

Manipulation of cellular processing bodies and their constituents by viruses.

The processing bodies (PBs) are a form of cytoplasmic aggregates that house the cellular RNA decay machinery as well as many RNA-binding proteins and mRNAs. The PBs are constitutively present in eukaryotic cells and are involved in maintaining cellular homeostasis by regulating RNA metabolism, cell signaling, and survival. Virus infections result in modification of the PBs and their constituents.

Induction of stress granule-like structures in vesicular stomatitis virus-infected cells.

Previous studies from our laboratory revealed that cellular poly(C) binding protein 2 (PCBP2) downregulates vesicular stomatitis virus (VSV) gene expression. We show here that VSV infection induces the formation of granular structures in the cytoplasm containing cellular RNA-binding proteins, including PCBP2, T-cell-restricted intracellular antigen 1 (TIA1), and TIA1-related protein (TIAR). Depletion of TIA1 via small interfering RNAs (siRNAs), but not depletion of TIAR, results in enhanced VSV growth and gene expression.

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.

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.

Posttranslational modification of vesicular stomatitis virus glycoprotein, but not JNK inhibition, is the antiviral mechanism of SP600125.

Vesicular stomatitis virus (VSV), a negative-sense single-stranded-RNA rhabdovirus, is an extremely promising oncolytic agent for cancer treatment. Since oncolytic virotherapy is moving closer to clinical application, potentially synergistic combinations of oncolytic viruses and molecularly targeted antitumor agents are becoming a meaningful strategy for cancer treatment. Mitogen-activated protein kinase (MAPK) inhibitors have been shown to impair liver cell proliferation and tumor development, suggesting their potential use as therapeutic agents for hepatocellular carcinoma (HCC).

RNAi screening reveals requirement for host cell secretory pathway in infection by diverse families of negative-strand RNA viruses.

Negative-strand (NS) RNA viruses comprise many pathogens that cause serious diseases in humans and animals. Despite their clinical importance, little is known about the host factors required for their infection. Using vesicular stomatitis virus (VSV), a prototypic NS RNA virus in the family Rhabdoviridae, we conducted a human genome-wide siRNA screen and identified 72 host genes required for viral infection.

Cellular poly(c) binding proteins 1 and 2 interact with porcine reproductive and respiratory syndrome virus nonstructural protein 1β and support viral replication.

Porcine reproductive and respiratory syndrome virus (PRRSV) infection of swine results in substantial economic losses to the swine industry worldwide. Identification of cellular factors involved in PRRSV life cycle not only will enable a better understanding of virus biology but also has the potential for the development of antiviral therapeutics. The PRRSV nonstructural protein 1 (nsp1) has been shown to be involved in at least two important functions in the infected hosts: (i) mediation of viral subgenomic (sg) mRNA transcription and (ii) suppression of the host's innate immune response mechanisms.

Antagonistic effects of cellular poly(C) binding proteins on vesicular stomatitis virus gene expression.

Immunoprecipitation and subsequent mass spectrometry analysis of the cellular proteins from cells expressing the vesicular stomatitis virus (VSV) P protein identified the poly(C) binding protein 2 (PCBP2) as one of the P protein-interacting proteins. To investigate the role of PCBP2 in the viral life cycle, we examined the effects of depletion or overexpression of this protein on VSV growth. Small interfering RNA-mediated silencing of PCBP2 promoted VSV replication.

Glycosylation of minor envelope glycoproteins of porcine reproductive and respiratory syndrome virus in infectious virus recovery, receptor interaction, and immune response.

The role of N-glycosylation of the three minor envelope glycoproteins (GP2, GP3, and GP4) of porcine reproductive and respiratory syndrome virus (PRRSV) on infectious virus production, interactions with the receptor CD163, and neutralizing antibody production in infected pigs was examined. By mutation of the glycosylation sites in these proteins, the studies show that glycan addition at N184 of GP2, N42, N50 and N131 of GP3 is necessary for infectious virus production. Although single-site mutants of GP4 led to infectious virus production, mutation of any two sites in GP4 was lethal.

Induction of interferon and interferon signaling pathways by replication of defective interfering particle RNA in cells constitutively expressing vesicular stomatitis virus replication proteins.

We show here that replication of defective interfering (DI) particle RNA in HEK293 cells stably expressing vesicular stomatitis virus (VSV) replication proteins potently activates interferon (IFN) and IFN signaling pathways through upregulation of IFN-beta promoter, IFN-stimulated response element (ISRE) promoter, and NF-kappaB promoter activities. Replication of DI particle RNA, not mere expression of the viral replication proteins, was found to be critical for induction of IFN and IFN signaling. The stable cells supporting replication of DI RNA described in this report will be useful in further examining the innate immune signaling pathways and the host cell functions in viral genome replication.

The minor envelope glycoproteins GP2a and GP4 of porcine reproductive and respiratory syndrome virus interact with the receptor CD163.

Porcine reproductive and respiratory syndrome virus (PRRSV) contains the major glycoprotein, GP5, as well as three other minor glycoproteins, namely, GP2a, GP3, and GP4, on the virion envelope, all of which are required for generation of infectious virions. To study their interactions with each other and with the cellular receptor for PRRSV, we have cloned each of the viral glycoproteins and CD163 receptor in expression vectors and examined their expression and interaction with each other in transfected cells by coimmunoprecipitation (co-IP) assay using monospecific antibodies. Our results show that a strong interaction exists between the GP4 and GP5 proteins, although weak interactions among the other minor envelope glycoproteins and GP5 have been detected.