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Showing papers on "NSP1 published in 2011"


Journal ArticleDOI
TL;DR: RVs have evolved functionally distinct approaches for subverting the host antiviral response, a property consistent with the immense sequence variation noted for NSP1 proteins.
Abstract: Studies involving limited numbers of rotavirus (RV) strains have shown that the viral gene 5 product, NSP1, can antagonize beta interferon (IFN-β) expression by inducing the degradation of IFN-regulatory factors (IRFs) (IRF3, IRF5, and IRF7) or a component of the E3 ubiquitin ligase complex responsible for activating NF-κB (β-transducin repeat-containing protein [β-TrCP]). To gain a broader perspective of NSP1 activities, we examined various RV strains for the ability to inhibit IFN-β expression in human cells. We found that all strains encoding wild-type NSP1 impeded IFN-β expression but not always through IRF3 degradation. To identify other degradation targets involved in suppressing IFN-β expression, we used transient expression vectors to test the abilities of a diverse collection of NSP1 proteins to target IRF3, IRF5, IRF7, and β-TrCP for degradation. The results indicated that human RVs rely predominantly on the NSP1-induced degradation of IRF5 and IRF7 to suppress IFN signaling, whereas NSP1 proteins of animal RVs tended to target IRF3, IRF5, and IRF7, allowing the animal viruses a broader attack on the IFN-β signaling pathway. The results also suggested that the NSP1-induced degradation of β-TrCP is an uncommon mechanism of subverting IFN-β signaling but is one that can be shared with NSP1 proteins that induce IRF degradation. Our analysis reveals that the activities of NSP1 proteins are diverse, with no obvious correlations between degradations of pairs of target proteins. Thus, RVs have evolved functionally distinct approaches for subverting the host antiviral response, a property consistent with the immense sequence variation noted for NSP1 proteins.

83 citations


Journal ArticleDOI
TL;DR: Overall, the results presented here point toward an important role for PCBP1 and PCBP2 in regulating PRRSV RNA synthesis.
Abstract: 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. To further our understanding of the role of the viral nsp1 in these processes, using nsp1β, a proteolytically processed functional product of nsp1 as bait, we have identified the cellular poly(C)-binding proteins 1 and 2 (PCBP1 and PCBP2) as two of its interaction partners. The interactions of PCBP1 and PCBP2 with nsp1β were confirmed both by coimmunoprecipitation in infected cells and/or in plasmid-transfected cells and also by in vitro binding assays. During PRRSV infection of MARC-145 cells, the cytoplasmic PCBP1 and PCBP2 partially colocalize to the viral replication-transcription complexes. Furthermore, recombinant purified PCBP1 and PCBP2 were found to bind the viral 5' untranslated region (5'UTR). Small interfering RNA (siRNA)-mediated silencing of PCBP1 and PCBP2 in cells resulted in significantly reduced PRRSV genome replication and transcription without adverse effect on initial polyprotein synthesis. Overall, the results presented here point toward an important role for PCBP1 and PCBP2 in regulating PRRSV RNA synthesis.

54 citations


Journal ArticleDOI
TL;DR: Findings demonstrate that inhibition of RIG-I mediated type I IFN responses by NSP1 may contribute to the immune evasion of rotavirus.
Abstract: Background The nonstructural protein 1 (NSP1) of rotavirus has been reported to block interferon (IFN) signaling by mediating proteasome-dependent degradation of IFN-regulatory factors (IRFs) and (or) the β-transducin repeat containing protein (β-TrCP). However, in addition to these targets, NSP1 may subvert innate immune responses via other mechanisms.

42 citations


Journal ArticleDOI
TL;DR: The data indicate that systemic rotavirus strain-specific replication in the murine biliary tract is determined by both viral entry mediated by VP4 and viral antagonism of the host innate immune response mediated by NSP1.
Abstract: Rotavirus replication and virulence are strongly influenced by virus strain and host species. The rotavirus proteins VP3, VP4, VP7, NSP1, and NSP4 have all been implicated in strain and species restriction of replication; however, the mechanisms have not been fully determined. Simian (RRV) and bovine (UK) rotaviruses have distinctive replication capacities in mouse extraintestinal organs such as the biliary tract. Using reassortants between UK and RRV, we previously demonstrated that the differential replication of these viruses in mouse embryonic fibroblasts is determined by the respective NSP1 proteins, which differ substantially in their abilities to degrade interferon (IFN) regulatory factor 3 (IRF3) and suppress the type I IFN response. In this study, we used an in vivo model of rotavirus infection of mouse gallbladder with UK × RRV reassortants to study the genetic and mechanistic basis of systemic rotavirus replication. We found that the low-replication phenotype of UK in biliary tissues was conferred by UK VP4 and that the high-replication phenotype of RRV was conferred by RRV VP4 and NSP1. Viruses with RRV VP4 entered cultured mouse cholangiocytes more efficiently than did those with UK VP4. Reassortants with RRV VP4 and UK NSP1 genes induced high levels of expression of IRF3-dependent p54 in biliary tissues, and their replication was increased 3-fold in IFN-α/β and -γ receptor or STAT1 knockout (KO) mice compared to wild-type mice. Our data indicate that systemic rotavirus strain-specific replication in the murine biliary tract is determined by both viral entry mediated by VP4 and viral antagonism of the host innate immune response mediated by NSP1.

39 citations


Journal ArticleDOI
TL;DR: Both structural and nonstructural genes of the Western Indian rotavirus strains shared nucleotide and amino acid substitutions with the Bangladeshi strain, Dhaka16-03 (G1P[8]) in the year 2003, which suggests that the rotav virus VP6, NSP1 and NSP5 genes of Wa-like rotaviruses are more prone to temporal mutations.

38 citations


Journal ArticleDOI
TL;DR: Biochemical analysis shows that deterGents abolish nsP1 GTase activity, whereas nonionic detergents do not affect MTase activity and purified protein contains the metal-ion dependent GTase, whereas MTase does not require a metal ion.

33 citations


Journal ArticleDOI
TL;DR: Findings suggested that the G6P[9] human rotavirus detected in Japan may have occurred through reassortment among uncommon bovine-like human rotAViruses and human/feline AU-1-like rotaviruses.
Abstract: A rare genotype G6P[9] was identified in two human group A rotavirus strains designated as KF14 and KF17, that were detected in stool specimens from children with diarrhea in Japan. VP7 gene sequences of these two strains were identical and genetically closely related to G6 human rotavirus strains reported in European countries and the United States. To our knowledge, this is the first report of detection of a G6 human rotavirus in Japan. For further genetic analysis to elucidate the origin of the G6 rotavirus, nearly full-length sequences of all 11 RNA segments were determined for the KF17 strain. The complete genomic constellation of KF17 was determined as G6-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3, a novel genotype constellation for human rotavirus. Phylogenetic analysis indicated that VP6, VP1-3, and NSP2 genes of KF17 clustered with bovine-like G6 human strains and some animal strains into sub-lineages distinct from those of common DS-1-like G2 human rotaviruses. On the other hand, KF17 genes encoding VP4, NSP1, and NSP3-5 showed high sequence identities to the human G3P[9] strain AU-1, and clustered with AU-1 and some feline strains within the same lineage. These findings suggested that the G6P[9] human rotavirus detected in Japan may have occurred through reassortment among uncommon bovine-like human rotaviruses and human/feline AU-1-like rotaviruses.

30 citations


Journal ArticleDOI
TL;DR: It is indicated that the papain-like cysteine protease activity of nsp1α was necessary for nSp1 to inhibit IFN-β induction.
Abstract: Porcine reproductive and respiratory syndrome virus nonstructural protein 1 (nsp1) could be auto-cleaved into nsp1α and nsp1β, both of which had the papain-like cysteine protease activities. Previous studies have shown that porcine reproductive and respiratory syndrome virus nsp1 was an interferon (IFN) antagonist. However, the mechanism by which nsp1 inhibited IFN-β production was unclear. Here, we used site-directed mutagenesis that inactivated the papain-like cysteine protease activities of nsp1 to explore whether the papain-like cysteine protease activities were required for nsp1 to disrupt IFN-β production. The results showed that mutations that inactivated papain-like cysteine protease activity of nsp1α made nsp1 lose its IFN antagonism activity, whereas mutations that inactivated papain-like cysteine protease activity of nsp1β did not influence the IFN antagonism activity of nsp1. In conclusion, our present work indicated that the papain-like cysteine protease activity of nsp1α was necessary for nsp1 to inhibit IFN-β induction.

26 citations


Journal ArticleDOI
TL;DR: Rotavirus ts mutation groups are now mapped to 9 of the 11 rotavirus genome segments, and possible segment locations of the two remaining unmapped ts mutant groups are discussed.
Abstract: Four rotavirus SA11 temperature-sensitive (ts) mutants and seven rotavirus RRV ts mutants, isolated at the National Institutes of Health (NIH) and not genetically characterized, were assigned to reassortment groups by pairwise crosses with the SA11 mutant group prototypes isolated and characterized at Baylor College of Medicine (BCM). Among the NIH mutants, three of the RRV mutants and all four SA11 mutants contained mutations in single reassortment groups, and four RRV mutants contained mutations in multiple groups. One NIH mutant [RRVtsK(2)] identified the previously undefined 11th reassortment group (K) expected for rotavirus. Three NIH single mutant RRV viruses, RRVtsD(7), RRVtsJ(5), and RRVtsK(2), were in reassortment groups not previously mapped to genome segments. These mutants were mapped using classical genetic methods, including backcrosses to demonstrate reversion or suppression in reassortants with incongruent genotype and temperature phenotype. Once located to specific genome segments by genetic means, the mutations responsible for the ts phenotype were identified by sequencing. The reassortment group K mutant RRVtsK(2) maps to genome segment 9 and has a Thr280Ileu mutation in the capsid surface glycoprotein VP7. The group D mutant RRVtsD(7) maps to segment 5 and has a Leu140Val mutation in the nonstructural interferon (IFN) antagonist protein NSP1. The group J mutant RRVtsJ(5) maps to segment 11 and has an Ala182Gly mutation affecting only the NSP5 open reading frame. Rotavirus ts mutation groups are now mapped to 9 of the 11 rotavirus genome segments. Possible segment locations of the two remaining unmapped ts mutant groups are discussed.

11 citations


Journal ArticleDOI
TL;DR: The role of NSP1 appears to be to modulate the impact of the NSP3-based inhibition of cellular translation by binding to the 5′ end of viral mRNAs.
Abstract: The role of the rotavirus non-structural proteins NSP1 and NSP3 in regulating cellular and viral mRNA translation has been investigated by examining the effect of added recombinant NSP3 on protein translation in a T7-based in vitro coupled transcription-translation system. Addition of purified NSP3 to assays primed solely with cellular mRNA was found to have no effect on the translation efficiency of the mRNA. However, as expected, the addition of viral mRNA to such assays competitively inhibited the synthesis of cellular protein, and interestingly, this inhibition was enhanced by the addition of NSP3. Treatment of NSP3 with antisera raised against the purified protein abrogated its function, but only when used prior to mixing the protein with viral mRNA. Addition of partially purified NSP1 to the coupled system was able to alleviate the enhancement of the inhibition of cellular mRNA translation caused by NSP3. The role of NSP1 in this process appears to be to modulate the impact of the NSP3-based inhibition of cellular translation by binding to the 5′ end of viral mRNAs.

10 citations


Journal ArticleDOI
Y Lie, S Chen, CD Wang, Z Zhang, W Guo, X Wang, L Guo, Q Yan 
TL;DR: Phylogenetic analysis showed that giant panda rotavirus VP6 gene was closely related to porcine and human rotav virus, and this results may improve the understanding of the evolution, pathogenesis and functional studies of Giant pandaRotavirus.
Abstract: Rotavirus (family Reoviridae ) is the leading cause of severe gastroenteritis in human and animals worldwide. The genome of rotavirus comprises of 11 segments of dsRNA and encodes six structural proteins (VP1 to VP4, VP6 and VP7) and six non structural proteins (NSP1 to NSP6). VP6 is a group of antigen of rotavirus (according to the disparation of VP6, rotavirus is classified into seven groups: A to G), and the major structural protein of inner capsid particles (ICP), and also specific antigen of mucosa immunization that mediate specific immunological reaction. In this report, sequence analysis of VP6 gene of giant panda rotavirus was carried out. Full-length VP6 gene encoding for ICP of giant panda rotavirus was amplified by RT-PCR and the amplicons (1356 bp) were cloned and sequenced. Comparative sequence analysis revealed an open reading frame of 1194 nucleotides (nt) encoding a polypeptide of 397 amino acids (aa). Porcine and human rotaviruses VP6 were highly related giant panda rotavirus VP6 with sequence identity of 98.7 and 97% at the aa level, respectively. Further, they showed 62.9 to 95.1% sequence identity at the nt level with other species of rotavirus. Phylogenetic analysis also showed that giant panda rotavirus VP6 gene was closely related to porcine and human rotavirus. Together, these results may improve our understanding of the evolution, pathogenesis and functional studies of giant panda rotavirus, as well as contribute significantly to giant panda rotavirus research and possibly studies with other species rotaviruses. Key words : Giant panda rotavirus, VP6 gene, molecular cloning, sequence analysis.

01 Jan 2011
TL;DR: Cation of cellular factors involved in PRRSV life cyclenot not only will enable a better understanding of virus biology but also has the potential for the development ofantiviral therapeutics.
Abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) infection of swine results in substantialeconomic losses to the swine industry worldwide. Identification of cellular factors involved in PRRSV life cyclenot only will enable a better understanding of virus biology but also has the potential for the development ofantiviral therapeutics. The PRRSV nonstructural protein 1 (nsp1) has been shown to be involved in at least twoimportant functions in the infected hosts: (i) mediation of viral subgenomic (sg) mRNA transcription and (ii)suppression of the host’s innate immune response mechanisms. To further our understanding of the role of theviral nsp1 in these processes, using nsp1

Journal ArticleDOI
TL;DR: To better understand the rotavirus CH-1 strain isolated from diarrheic faeces of giant panda in 2008, cloned the non-structural protein (NSP) 1~5 complete coding sequence of the giant p Panda rotav virus (GPRV) and sequenced NSP1~5 genes, and phylogenetic analysis revealed that GPRV NSP 1 ~5 genes were close to that of porcine rotvirus, bovine rotav
Abstract: Rotavirus (RV), a member of the genus Rotavirus of the family Reoviridae, is an important causative agent of diarrhoea diseases of human and animals worldwide. The Asian Rotavirus Surveillance Network reported that overall 45% of diarrhoea admissions in Asian region were positive for rotavirus in nine countries and regions of Asia (2008). But very limited knowledge about animal diarrhoea diseases caused by rotavirus was published until now. Valuation of genetic relations between human and animal rotavirus isolates is very limited. To better understand the rotavirus CH-1 strain isolated from diarrheic faeces of giant panda in 2008, we cloned the non-structural protein (NSP) 1~5 complete coding sequence of the giant panda rotavirus (GPRV), and sequenced NSP1~5 genes (GenBank accession number: NSP1, GU205762; NSP2, GU188281; NSP3, GU329525; NSP4, GU188282; NSP5, GU329526). Based on these information and data from GenBank of other genus of RV NSP1~5 genes, phylogenetic analysis were realized. The phylogenetic tree revealed that GPRV NSP1~5 genes were close to that of porcine rotavirus, bovine rotavirus and human rotavirus. This research may provide some useful information helping us understanding giant panda rotavirus. Key words: Giant panda rotavirus isolate strain CH-1, NSP1~5 genes, cloning, phylogenetic analysis.