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Wang R, Yang L, Zhang Y, Li J, Xu L, Xiao Y, Zhang Q, Bai L, Zhao S, Liu E, Zhang YJ. Porcine reproductive and respiratory syndrome virus induces HMGB1 secretion via activating PKC-delta to trigger inflammatory response. Virology 2018. [PMID: 29522984 DOI: 10.1016/j.virol.2018.02.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) causes inflammatory injuries in infected pigs. PRRSV induces secretion of high mobility group box 1 (HMGB1) that enhances inflammatory response. However, the mechanism of PRRSV-induced HMGB1 secretion is unknown. Here, we discovered PRRSV induced HMGB1 secretion via activating protein kinase C-delta (PKCδ). HMGB1 secretion was positively correlated with PKCδ activation in PRRSV-infected cells in a dose and time-dependent manner. Suppression of PKCδ with inhibitor and siRNA significantly blocked PRRSV-induced HMGB1 translocation and secretion, which indicates PKCδ activation is essential for the PRRSV-mediated HMGB1 secretion. In addition, PKCδ knockdown in PRRSV-infected cells led to downregulation of inflammatory cytokines, including IL-1beta and IL-6. Moreover, PRRSV E and pORF5a proteins were found to activate PKCδ and consequent HMGB1 secretion. These results demonstrate PRRSV activates PKCδ to induce HMGB1 secretion via E and pORF5a. This finding provides insights on the inflammatory response and pathogenesis of PRRSV infection.
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Affiliation(s)
- Rong Wang
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Liping Yang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine, University of Maryland, College Park, MD, USA
| | - Yali Zhang
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Junyan Li
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Liran Xu
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Yueqiang Xiao
- Shandong Binzhou Animal Science and Veterinary Medicine Academy, Binzhou, Shandong, China
| | - Qian Zhang
- Shandong Binzhou Animal Science and Veterinary Medicine Academy, Binzhou, Shandong, China
| | - Liang Bai
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Sihai Zhao
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Enqi Liu
- Laboratory Animal Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
| | - Yan-Jin Zhang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine, University of Maryland, College Park, MD, USA.
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52
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Xin Y, Wang D, Huang M, Yu J, Fang L, Xiao S. Proteome analysis of differential protein expression in porcine alveolar macrophages regulated by porcine reproductive and respiratory syndrome virus nsp1β protein. Virus Genes 2018; 54:385-396. [PMID: 29508239 DOI: 10.1007/s11262-018-1547-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/01/2018] [Indexed: 11/27/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV), an acute infectious disease agent in swine, causes enormous economic losses to the global swine industry. PRRSV nonstructural protein 1β (nsp1β) plays a critical role in viral subgenomic mRNA synthesis and host immune regulation. However, the global changes of cellular gene expression in natural target cells regulated by the nsp1β have not yet been identified. Here, isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography-tandem mass spectrometry were used to quantitatively identify cellular proteins in porcine alveolar macrophage (PAM) 3D4/21 cells transduced with recombinant lentivirus expressing PRRSV nsp1β that are differentially expressed compared with PAM 3D4/21 cells transduced with recombinant lentivirus expressing GFP. Of the 425 cellular proteins detected as differentially expressed, 186 were upregulated and 239 were downregulated. Based on the identities of the differentially expressed cellular proteins and the essential role of nsp1β in interferon (IFN) activation and inflammatory factor antagonism during PRRSV infection, we propose a potential mechanism in which nsp1β inhibits IFN induction and nuclear factor κB (NF-κB) signaling pathways. Our results suggest that mitochondrial antiviral signaling (MAVS) protein and translocases of outer membrane complex 70 (TOM70), involved in type I IFN induction, were downregulated, while protein phosphatase 1A (PPM1A), related to the inhibition of NF-κB pathway activation, was upregulated in nsp1β-overexpressed PAM 3D4/21 cells. These data provide valuable information for better understanding the potential biological function of nsp1β during PRRSV infection and the mechanism of virus escape from host immune surveillance of viral replication.
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Affiliation(s)
- Yinghao Xin
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, People's Republic of China
| | - Dang Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, People's Republic of China
| | - Meijin Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, People's Republic of China
| | - Jinjin Yu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, People's Republic of China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, People's Republic of China
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
- The Key Laboratory of Preventive Veterinary Medicine in Hubei Province, Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, People's Republic of China.
- Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, 1 Shi-zi-shan Street, Wuhan, 430070, Hubei, People's Republic of China.
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53
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Cortey M, Arocena G, Ait-Ali T, Vidal A, Li Y, Martín-Valls G, Wilson AD, Archibald AL, Mateu E, Darwich L. Analysis of the genetic diversity and mRNA expression level in porcine reproductive and respiratory syndrome virus vaccinated pigs that developed short or long viremias after challenge. Vet Res 2018; 49:19. [PMID: 29448955 PMCID: PMC5815215 DOI: 10.1186/s13567-018-0514-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 02/08/2018] [Indexed: 11/10/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSv) infection alters the host’s cellular and humoral immune response. Immunity against PRRSv is multigenic and vary between individuals. The aim of the present study was to compare several genes that encode for molecules involved in the immune response between two groups of vaccinated pigs that experienced short or long viremic periods after PRRSv challenge. These analyses include the sequencing of four SLA Class I, two Class II allele groups, and CD163, plus the analysis by quantitative realtime qRT-PCR of the constitutive expression of TLR2, TLR3, TLR4, TLR7, TLR8 and TLR9 mRNA and other molecules in peripheral blood mononuclear cells.
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Affiliation(s)
- Martí Cortey
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain.
| | - Gaston Arocena
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain
| | - Tahar Ait-Ali
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK
| | - Anna Vidal
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain
| | - Yanli Li
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain
| | - Gerard Martín-Valls
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain
| | - Alison D Wilson
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK
| | - Allan L Archibald
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK
| | - Enric Mateu
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain.,IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain
| | - Laila Darwich
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain.,IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193, Cerdanyola Del Vallès, Spain
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54
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Nonstructural proteins nsp2TF and nsp2N of porcine reproductive and respiratory syndrome virus (PRRSV) play important roles in suppressing host innate immune responses. Virology 2018; 517:164-176. [PMID: 29325778 PMCID: PMC5884420 DOI: 10.1016/j.virol.2017.12.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 12/24/2022]
Abstract
Recently, we identified a unique -2/-1 ribosomal frameshift mechanism in PRRSV, which yields two truncated forms of nonstructural protein (nsp) 2 variants, nsp2TF and nsp2N. Here, in vitro expression of individual PRRSV nsp2TF and nsp2N demonstrated their ability to suppress cellular innate immune responses in transfected cells. Two recombinant viruses were further analyzed, in which either nsp2TF was C-terminally truncated (vKO1) or expression of both nsp2TF and nsp2N was knocked out (vKO2). Host cellular mRNA profiling showed that a panel of cellular immune genes, in particular those involved in innate immunity, was upregulated in cells infected with vKO1 and vKO2. Compared to the wild-type virus, vKO1 and vKO2 expedited the IFN-α response and increased NK cell cytotoxicity, and subsequently enhanced T cell immune responses in infected pigs. Our data strongly implicate nsp2TF/nsp2N in arteriviral immune evasion and demonstrate that nsp2TF/nsp2N-deficient PRRSV is less capable of counteracting host innate immune responses. In vitro expression of PRRSV nsp2TF/nsp2N affects cellular innate immune response. Nsp2TF/nsp2N suppressed immune genes expression in PRRSV-infected cells. Nsp2TF/nsp2N-deficient mutants showed attenuated growth in vivo. Nsp2TF/nsp2N-deficient mutants induced augmented immune responses in infected pigs.
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55
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Bailey-Elkin BA, Knaap RCM, Kikkert M, Mark BL. Structure and Function of Viral Deubiquitinating Enzymes. J Mol Biol 2017; 429:3441-3470. [PMID: 28625850 PMCID: PMC7094624 DOI: 10.1016/j.jmb.2017.06.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 06/12/2017] [Accepted: 06/13/2017] [Indexed: 01/12/2023]
Abstract
Post-translational modification of cellular proteins by ubiquitin regulates numerous cellular processes, including innate and adaptive immune responses. Ubiquitin-mediated control over these processes can be reversed by cellular deubiquitinating enzymes (DUBs), which remove ubiquitin from cellular targets and depolymerize polyubiquitin chains. The importance of protein ubiquitination to host immunity has been underscored by the discovery of viruses that encode proteases with deubiquitinating activity, many of which have been demonstrated to actively corrupt cellular ubiquitin-dependent processes to suppress innate antiviral responses and promote viral replication. DUBs have now been identified in diverse viral lineages, and their characterization is providing valuable insights into virus biology and the role of the ubiquitin system in host antiviral mechanisms. Here, we provide an overview of the structural biology of these fascinating viral enzymes and their role innate immune evasion and viral replication.
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Affiliation(s)
- Ben A Bailey-Elkin
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - Robert C M Knaap
- Department of Medical Microbiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Marjolein Kikkert
- Department of Medical Microbiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Brian L Mark
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada.
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56
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Dinan AM, Atkins JF, Firth AE. ASXL gain-of-function truncation mutants: defective and dysregulated forms of a natural ribosomal frameshifting product? Biol Direct 2017; 12:24. [PMID: 29037253 PMCID: PMC5644247 DOI: 10.1186/s13062-017-0195-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/04/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Programmed ribosomal frameshifting (PRF) is a gene expression mechanism which enables the translation of two N-terminally coincident, C-terminally distinct protein products from a single mRNA. Many viruses utilize PRF to control or regulate gene expression, but very few phylogenetically conserved examples are known in vertebrate genes. Additional sex combs-like (ASXL) genes 1 and 2 encode important epigenetic and transcriptional regulatory proteins that control the expression of homeotic genes during key developmental stages. Here we describe an ~150-codon overlapping ORF (termed TF) in ASXL1 and ASXL2 that, with few exceptions, is conserved throughout vertebrates. RESULTS Conservation of the TF ORF, strong suppression of synonymous site variation in the overlap region, and the completely conserved presence of an EH[N/S]Y motif (a known binding site for Host Cell Factor-1, HCF-1, an epigenetic regulatory factor), all indicate that TF is a protein-coding sequence. A highly conserved UCC_UUU_CGU sequence (identical to the known site of +1 ribosomal frameshifting for influenza virus PA-X expression) occurs at the 5' end of the region of enhanced synonymous site conservation in ASXL1. Similarly, a highly conserved RG_GUC_UCU sequence (identical to a known site of -2 ribosomal frameshifting for arterivirus nsp2TF expression) occurs at the 5' end of the region of enhanced synonymous site conservation in ASXL2. CONCLUSIONS Due to a lack of appropriate splice forms, or initiation sites, the most plausible mechanism for translation of the ASXL1 and 2 TF regions is ribosomal frameshifting, resulting in a transframe fusion of the N-terminal half of ASXL1 or 2 to the TF product, termed ASXL-TF. Truncation or frameshift mutants of ASXL are linked to myeloid malignancies and genetic diseases, such as Bohring-Opitz syndrome, likely at least in part as a result of gain-of-function or dominant-negative effects. Our hypothesis now indicates that these disease-associated mutant forms represent overexpressed defective versions of ASXL-TF. REVIEWERS This article was reviewed by Laurence Hurst and Eugene Koonin.
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Affiliation(s)
- Adam M Dinan
- Department of Pathology, Division of Virology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - John F Atkins
- School of Biochemistry and Cell Biology, University College Cork, T12 YT57, Cork, Ireland.,Department of Human Genetics, University of Utah, Salt Lake City, UT, 84112, USA
| | - Andrew E Firth
- Department of Pathology, Division of Virology, University of Cambridge, Cambridge, CB2 1QP, UK.
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57
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The T-cell leukemia-associated ribosomal RPL10 R98S mutation enhances JAK-STAT signaling. Leukemia 2017; 32:809-819. [PMID: 28744013 PMCID: PMC5669462 DOI: 10.1038/leu.2017.225] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 06/16/2017] [Accepted: 07/04/2017] [Indexed: 01/15/2023]
Abstract
Several somatic ribosome defects have recently been discovered in cancer, yet their oncogenic mechanisms remain poorly understood. Here we investigated the pathogenic role of the recurrent R98S mutation in ribosomal protein L10 (RPL10 R98S) found in T-cell acute lymphoblastic leukemia (T-ALL). The JAK-STAT signaling pathway is a critical controller of cellular proliferation and survival. A proteome screen revealed overexpression of several Jak-Stat signaling proteins in engineered RPL10 R98S mouse lymphoid cells, which we confirmed in hematopoietic cells from transgenic Rpl10 R98S mice and T-ALL xenograft samples. RPL10 R98S expressing cells displayed JAK-STAT pathway hyper-activation upon cytokine stimulation, as well as increased sensitivity to clinically used JAK-STAT inhibitors like pimozide. A mutually exclusive mutation pattern between RPL10 R98S and JAK-STAT mutations in T-ALL patients further suggests that RPL10 R98S functionally mimics JAK-STAT activation. Mechanistically, besides transcriptional changes, RPL10 R98S caused reduction of apparent programmed ribosomal frameshifting at several ribosomal frameshift signals in mouse and human Jak-Stat genes, as well as decreased Jak1 degradation. Of further medical interest, RPL10 R98S cells showed reduced proteasome activity and enhanced sensitivity to clinical proteasome inhibitors. Collectively, we describe modulation of the JAK-STAT cascade as a novel cancer-promoting activity of a ribosomal mutation, and expand the relevance of this cascade in leukemia.
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58
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Tsai TW, Yang H, Yin H, Xu S, Wang Y. High-Efficiency "-1" and "-2" Ribosomal Frameshiftings Revealed by Force Spectroscopy. ACS Chem Biol 2017; 12:1629-1635. [PMID: 28437082 PMCID: PMC5477775 DOI: 10.1021/acschembio.7b00028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
Ribosomal frameshifting is a rare
but ubiquitous process that is
being studied extensively. Meanwhile, frameshifting motifs without
any secondary mRNA structures were identified but rarely studied experimentally.
We report unambiguous observation of highly efficient “–1”
and “–2” frameshiftings on a GA7G
slippery mRNA without the downstream secondary structure, using force-induced
remnant magnetization spectroscopy combined with unique probing schemes.
The result represents the first experimental evidence of multiple
frameshifting steps. It is also one of the rare reports of the “–2”
frameshifting. Our assay removed the ambiguity of transcriptional
slippage involvement in other frameshifting assays. Two significant
insights for the frameshifting mechanism were revealed. First, EF-G·GTP
is indispensable to frameshifting. Although EFG·GDPCP has been
shown to prompt translocation before, we found that it could not induce
frameshifting. This implies that the GTP hydrolysis is responsible
for the codon–anticodon re-pairing in frameshifting, which
corroborates our previous mechanical force measurement of EF-G·GTP.
Second, translation in all three reading frames of the slippery sequence
can be induced by the corresponding in-frame aminoacyl tRNAs. Although
A-site tRNA is known to affect the partition between “0”
and “–1” frameshifting, it has not been reported
that all three reading frames can be translated by their corresponding
tRNAs. The in vitro results were confirmed by toe-printing
assay and protein sequencing.
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Recombination in JXA1-R vaccine and NADC30-like strain of porcine reproductive and respiratory syndrome viruses. Vet Microbiol 2017; 204:110-120. [PMID: 28532789 DOI: 10.1016/j.vetmic.2017.04.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 04/20/2017] [Accepted: 04/20/2017] [Indexed: 11/21/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is considered one of the most devastating swine diseases worldwide, resulting in immense economic losses. PRRS virus (PRRSV) has undergone rapid evolution since its first recognition in 1990s. In the present study, a PRRSV strain named FJXS15 causing high morbidity and mortality was isolated from piglets and sows from a farm participating in vaccination in China. Phylogenetic and molecular evolutionary analyses revealed that FJXS15 was highly similar to the JXA1-R vaccine strain (a live attenuated virus vaccine strain derived from the highly pathogenic PRRSV JXA1) in the ORF1a (nt 901-)-ORF4 (-nt 419) coding regions, as well as to FJZ03 (lineage 1, NADC30-like) in the 5'-UTR, ORF5a-ORF7 coding regions, and 3'-UTR, suggestive of a natural recombination event. Recombination analyses showed that recombination events occurred in two inter-lineage recombination events between Lineages 1 and 8 based on based on classification system (Shi et al., 2010), and two recombination breakpoints at positions 1-1092 and 13771-15537 of the sequence alignment (with reference to the VR-2332 strain). Animal experiments demonstrated that FJXS15-infected animals had more severe histopathological lung lesions than did JXA1-R-infected and control groups. A 25% mortality rate was found in FJXS15-infected piglets, which was similar to that found with other Chinese HP-PRRSV strains. Thus, the recombinant virus is a highly virulent PRRSV. Moreover, this report provides evidence for inter-subgenotypic recombination between the JXA1-R vaccine virus and a circulating Lineage 1 virus.
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Atypical RNA Elements Modulate Translational Readthrough in Tobacco Necrosis Virus D. J Virol 2017; 91:JVI.02443-16. [PMID: 28148800 DOI: 10.1128/jvi.02443-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 01/27/2017] [Indexed: 12/13/2022] Open
Abstract
Tobacco necrosis virus, strain D (TNV-D), is a positive-strand RNA virus in the genus Betanecrovirus and family Tombusviridae The production of its RNA-dependent RNA polymerase, p82, is achieved by translational readthrough. This process is stimulated by an RNA structure that is positioned immediately downstream of the recoding site, termed the readthrough stem-loop (RTSL), and a sequence in the 3' untranslated region of the TNV-D genome, called the distal readthrough element (DRTE). Notably, a base pairing interaction between the RTSL and the DRTE, spanning ∼3,000 nucleotides, is required for enhancement of readthrough. Here, some of the structural features of the RTSL, as well as RNA sequences and structures that flank either the RTSL or DRTE, were investigated for their involvement in translational readthrough and virus infectivity. The results revealed that (i) the RTSL-DRTE interaction cannot be functionally replaced by stabilizing the RTSL structure, (ii) a novel tertiary RNA structure positioned just 3' to the RTSL is required for optimal translational readthrough and virus infectivity, and (iii) these same activities also rely on an RNA stem-loop located immediately upstream of the DRTE. Functional counterparts for the RTSL-proximal structure may also be present in other tombusvirids. The identification of additional distinct RNA structures that modulate readthrough suggests that regulation of this process by genomic features may be more complex than previously appreciated. Possible roles for these novel RNA elements are discussed.IMPORTANCE The analysis of factors that affect recoding events in viruses is leading to an ever more complex picture of this important process. In this study, two new atypical RNA elements were shown to contribute to efficient translational readthrough of the TNV-D polymerase and to mediate robust viral genome accumulation in infections. One of the structures, located close to the recoding site, could have functional equivalents in related genera, while the other structure, positioned 3' proximally in the viral genome, is likely limited to betanecroviruses. Irrespective of their prevalence, the identification of these novel RNA elements adds to the current repertoire of viral genome-based modulators of translational readthrough and provides a notable example of the complexity of regulation of this process.
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61
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Domain Organization and Evolution of the Highly Divergent 5' Coding Region of Genomes of Arteriviruses, Including the Novel Possum Nidovirus. J Virol 2017; 91:JVI.02096-16. [PMID: 28053107 DOI: 10.1128/jvi.02096-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 12/27/2016] [Indexed: 12/31/2022] Open
Abstract
In five experimentally characterized arterivirus species, the 5'-end genome coding region encodes the most divergent nonstructural proteins (nsp's), nsp1 and nsp2, which include papain-like proteases (PLPs) and other poorly characterized domains. These are involved in regulation of transcription, polyprotein processing, and virus-host interaction. Here we present results of a bioinformatics analysis of this region of 14 arterivirus species, including that of the most distantly related virus, wobbly possum disease virus (WPDV), determined by a modified 5' rapid amplification of cDNA ends (RACE) protocol. By combining profile-profile comparisons and phylogeny reconstruction, we identified an association of the four distinct domain layouts of nsp1-nsp2 with major phylogenetic lineages, implicating domain gain, including duplication, and loss in the early nsp1 evolution. Specifically, WPDV encodes highly divergent homologs of PLP1a, PLP1b, PLP1c, and PLP2, with PLP1a lacking the catalytic Cys residue, but does not encode nsp1 Zn finger (ZnF) and "nuclease" domains, which are conserved in other arteriviruses. Unexpectedly, our analysis revealed that the only catalytically active nsp1 PLP of equine arteritis virus (EAV), known as PLP1b, is most similar to PLP1c and thus is likely to be a PLP1b paralog. In all non-WPDV arteriviruses, PLP1b/c and PLP1a show contrasting patterns of conservation, with the N- and C-terminal subdomains, respectively, being enriched with conserved residues, which is indicative of different functional specializations. The least conserved domain of nsp2, the hypervariable region (HVR), has its size varied 5-fold and includes up to four copies of a novel PxPxPR motif that is potentially recognized by SH3 domain-containing proteins. Apparently, only EAV lacks the signal that directs -2 ribosomal frameshifting in the nsp2 coding region.IMPORTANCE Arteriviruses comprise a family of mammalian enveloped positive-strand RNA viruses that include some of the most economically important pathogens of swine. Most of our knowledge about this family has been obtained through characterization of viruses from five species: Equine arteritis virus, Simian hemorrhagic fever virus, Lactate dehydrogenase-elevating virus, Porcine respiratory and reproductive syndrome virus 1, and Porcine respiratory and reproductive syndrome virus 2 Here we present the results of comparative genomics analyses of viruses from all known 14 arterivirus species, including the most distantly related virus, WPDV, whose genome sequence was completed in this study. Our analysis focused on the multifunctional 5'-end genome coding region that encodes multidomain nonstructural proteins 1 and 2. Using diverse bioinformatics techniques, we identified many patterns of evolutionary conservation that are specific to members of distinct arterivirus species, both characterized and novel, or their groups. They are likely associated with structural and functional determinants important for virus replication and virus-host interaction.
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62
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Han M, Ke H, Zhang Q, Yoo D. Nuclear imprisonment of host cellular mRNA by nsp1β protein of porcine reproductive and respiratory syndrome virus. Virology 2017; 505:42-55. [PMID: 28235682 PMCID: PMC7111332 DOI: 10.1016/j.virol.2017.02.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/03/2017] [Accepted: 02/08/2017] [Indexed: 02/07/2023]
Abstract
Positive-strand RNA genomes function as mRNA for viral protein synthesis which is fully reliant on host cell translation machinery. Competing with cellular protein translation apparatus needs to ensure the production of viral proteins, but this also stifles host innate defense. In the present study, we showed that porcine reproductive and respiratory syndrome virus (PRRSV), whose replication takes place in the cytoplasm, imprisoned host cell mRNA in the nucleus, which suggests a novel mechanism to enhance translation of PRRSV genome. PRRSV nonstructural protein (nsp) 1β was identified as the nuclear protein playing the role for host mRNA nuclear retention and subversion of host protein synthesis. A SAP (SAF-A/B, Acinus, and PIAS) motif was identified in nsp1β with the consensus sequence of 126-LQxxLxxxGL-135. In situ hybridization unveiled that SAP mutants were unable to cause nuclear retention of host cell mRNAs and did not suppress host protein synthesis. In addition, these SAP mutants reverted PRRSV-nsp1β-mediated suppression of interferon (IFN) production, IFN signaling, and TNF-α production pathway. Using reverse genetics, a series of SAP mutant PRRS viruses, vK124A, vL126A, vG134A, and vL135A were generated. No mRNA nuclear retention was observed during vL126A and vL135A infections. Importantly, vL126A and vL135A did not suppress IFN production. For other arteriviruses, mRNA nuclear accumulation was also observed for LDV-nsp1β and SHFV-nsp1β. EAV-nsp1 was exceptional and did not block the host mRNA nuclear export. PRRS virus blocks host mRNA nuclear export to the cytoplasm. PRRSV nsp1β is the viral protein responsible for host mRNA nuclear retention. SAP domain in nsp1β is essential for host mRNA nuclear retention and type I interferon suppression. Mutation in the SAP domain of nsp1β causes the loss of function. Host mRNA nuclear retention by nsp1β is common in the family Arteriviridae, except equine arteritis virus.
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Affiliation(s)
- Mingyuan Han
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA.
| | - Hanzhong Ke
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA
| | - Qingzhan Zhang
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA
| | - Dongwan Yoo
- Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA.
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63
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Liu JK, Zhou X, Zhai JQ, Li B, Wei CH, Dai AL, Yang XY, Luo ML. Emergence of a novel highly pathogenic porcine reproductive and respiratory syndrome virus in China. Transbound Emerg Dis 2017; 64:2059-2074. [PMID: 28198110 DOI: 10.1111/tbed.12617] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Indexed: 01/26/2023]
Abstract
From 2014 to 2015, four novel highly pathogenic PRRS virus (HP-PRRSV) strains named 14LY01-FJ, 14LY02-FJ 15LY01-FJ, and 15LY02-FJ were isolated from high morbidity (100%) and mortality (40%-80%) in piglets and sows in Fujian Province. To further our knowledge about these novel virus strains, we characterized their complete genomes and determined their pathogenicity in piglets. Full-length genome sequencing analysis showed that these four isolates were closely related to type 2 (North American type, NA-type) isolates, with 88.1%-96.3% nucleotide similarity, but only 60.6%-60.8% homology to the Lelystad virus (LV) (European type, EU-type). The full length of the four isolates was determined to be 15017 or 15018 nucleotides (nt), excluding the poly(A) tail. Furthermore, the four isolates had three discontinuous deletions (aa 322-432, aa 483, and aa 504-522) within hypervariable region II (HV-II) of Nsp2, as compared to the reference strain VR-2332. This deletion pattern in the four isolates is consistent with strain MN184 and strain NADC30 isolated from America. Phylogenetic and molecular evolutionary analyses indicated that these virulent strains originated from a natural recombination event between the JXA1-like HP-PRRSV (JXA-1 is one of the earliest Chinese HP-PRRSV strains; sublineage 8.7) and the NADC30-like (lineage 1) PRRSV. Animal experiments demonstrated that these four strains caused significant weight loss and severe histopathological lung lesions as compared to the negative control group. High mortality rate (40% or 80%) was found in piglets infected with any one of the four strains, similar to that found with other Chinese HP-PRRSV strains. This study showed that the novel variant PRRSV was HP-PRRSV, and it is therefore critical to monitor PRRSV evolution in China and develop a method for controlling PRRS.
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Affiliation(s)
- J-K Liu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, China.,College of Life Sciences of Longyan University, Longyan, Fujian Province, China.,Fujian Provincial Key Laboratory for the Prevention and Control of Animal Infectious Diseases and Biotechnology, Fujian Province, China
| | - X Zhou
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, China
| | - J-Q Zhai
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, China
| | - B Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, China
| | - C-H Wei
- College of Life Sciences of Longyan University, Longyan, Fujian Province, China.,Fujian Provincial Key Laboratory for the Prevention and Control of Animal Infectious Diseases and Biotechnology, Fujian Province, China
| | - A-L Dai
- College of Life Sciences of Longyan University, Longyan, Fujian Province, China.,Fujian Provincial Key Laboratory for the Prevention and Control of Animal Infectious Diseases and Biotechnology, Fujian Province, China
| | - X-Y Yang
- College of Life Sciences of Longyan University, Longyan, Fujian Province, China.,Fujian Provincial Key Laboratory for the Prevention and Control of Animal Infectious Diseases and Biotechnology, Fujian Province, China
| | - M-L Luo
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province, China
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64
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Posthuma CC, Te Velthuis AJW, Snijder EJ. Nidovirus RNA polymerases: Complex enzymes handling exceptional RNA genomes. Virus Res 2017; 234:58-73. [PMID: 28174054 PMCID: PMC7114556 DOI: 10.1016/j.virusres.2017.01.023] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/24/2017] [Accepted: 01/26/2017] [Indexed: 12/22/2022]
Abstract
Coronaviruses and arteriviruses are distantly related human and animal pathogens that belong to the order Nidovirales. Nidoviruses are characterized by their polycistronic plus-stranded RNA genome, the production of subgenomic mRNAs and the conservation of a specific array of replicase domains, including key RNA-synthesizing enzymes. Coronaviruses (26-34 kilobases) have the largest known RNA genomes and their replication presumably requires a processive RNA-dependent RNA polymerase (RdRp) and enzymatic functions that suppress the consequences of the typically high error rate of viral RdRps. The arteriviruses have significantly smaller genomes and form an intriguing package with the coronaviruses to analyse viral RdRp evolution and function. The RdRp domain of nidoviruses resides in a cleavage product of the replicase polyprotein named non-structural protein (nsp) 12 in coronaviruses and nsp9 in arteriviruses. In all nidoviruses, the C-terminal RdRp domain is linked to a conserved N-terminal domain, which has been coined NiRAN (nidovirus RdRp-associated nucleotidyl transferase). Although no structural information is available, the functional characterization of the nidovirus RdRp and the larger enzyme complex of which it is part, has progressed significantly over the past decade. In coronaviruses several smaller, non-enzymatic nsps were characterized that direct RdRp function, while a 3'-to-5' exoribonuclease activity in nsp14 was implicated in fidelity. In arteriviruses, the nsp1 subunit was found to maintain the balance between genome replication and subgenomic mRNA production. Understanding RdRp behaviour and interactions during RNA synthesis and subsequent processing will be key to rationalising the evolutionary success of nidoviruses and the development of antiviral strategies.
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Affiliation(s)
- Clara C Posthuma
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, the Netherlands.
| | - Aartjan J W Te Velthuis
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom; Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, the Netherlands
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Zhong Z, Yang L, Zhang H, Shi J, Vandana JJ, Lam DTUH, Olsthoorn RCL, Lu L, Chen G. Mechanical unfolding kinetics of the SRV-1 gag-pro mRNA pseudoknot: possible implications for -1 ribosomal frameshifting stimulation. Sci Rep 2016; 6:39549. [PMID: 28000744 PMCID: PMC5175198 DOI: 10.1038/srep39549] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/24/2016] [Indexed: 12/19/2022] Open
Abstract
Minus-one ribosomal frameshifting is a translational recoding mechanism widely utilized by many RNA viruses to generate accurate ratios of structural and catalytic proteins. An RNA pseudoknot structure located in the overlapping region of the gag and pro genes of Simian Retrovirus type 1 (SRV-1) stimulates frameshifting. However, the experimental characterization of SRV-1 pseudoknot (un)folding dynamics and the effect of the base triple formation is lacking. Here, we report the results of our single-molecule nanomanipulation using optical tweezers and theoretical simulation by steered molecular dynamics. Our results directly reveal that the energetic coupling between loop 2 and stem 1 via minor-groove base triple formation enhances the mechanical stability. The terminal base pair in stem 1 (directly in contact with a translating ribosome at the slippery site) also affects the mechanical stability of the pseudoknot. The -1 frameshifting efficiency is positively correlated with the cooperative one-step unfolding force and inversely correlated with the one-step mechanical unfolding rate at zero force. A significantly improved correlation was observed between -1 frameshifting efficiency and unfolding rate at forces of 15-35 pN, consistent with the fact that the ribosome is a force-generating molecular motor with helicase activity. No correlation was observed between thermal stability and -1 frameshifting efficiency.
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Affiliation(s)
- Zhensheng Zhong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Lixia Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Haiping Zhang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Jiahao Shi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - J. Jeya Vandana
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
| | - Do Thuy Uyen Ha Lam
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
- St Andrew’s Junior College, 5 Sorby Adams Drive, 357691 Singapore
| | - René C. L. Olsthoorn
- Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore
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66
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Rappe JCF, García-Nicolás O, Flückiger F, Thür B, Hofmann MA, Summerfield A, Ruggli N. Heterogeneous antigenic properties of the porcine reproductive and respiratory syndrome virus nucleocapsid. Vet Res 2016; 47:117. [PMID: 27871316 PMCID: PMC5118883 DOI: 10.1186/s13567-016-0399-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 10/27/2016] [Indexed: 12/21/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is an arterivirus responsible for a widespread contagious disease of domestic pigs with high economic impact. Switzerland is one of the rare PRRSV-free countries in Europe, although sporadic outbreaks have occurred in the past. The PRRSV isolate IVI-1173 from the short outbreak in Switzerland in 2012 was entirely sequenced, and a functional full-length cDNA clone was constructed. Genetic and antigenic characterization of IVI-1173 revealed the importance of amino acid 90 of the nucleocapsid protein N as part of a conformational epitope. IVI-1173 was not detected by SDOW17, a monoclonal antibody against N widely used to detect PRRSV-infected cells. Substitution of alanine at position 90 of N [N(A90)] with a threonine [N(T90)] restored reactivity of vIVI1173-N(T90) to SDOW17 completely. The relevance of this amino acid for the conformational SDOW17 epitope of PRRSV N was further confirmed by the opposite substitution in a functional cDNA clone of the genotype 2 isolate RVB-581. Finally, N proteins from ten genotype 1 strains differing from threonine at position 90 were analysed for reactivity with SDOW17. N(A90) totally disrupted or severely affected the epitope in 7 out of 8 strains tested. Based on these findings, 225 genotype 1 strains were screened for the prevalence of N(A90). N(A90) is rare in classical subtype 1 and in subtype 3 strains, but is frequent in Russian subtype 1 (70%) and in subtype 2 (45%) isolates. In conclusion, this study highlights the variable antigenic properties of N among genotype 1 PRRSV strains.
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Affiliation(s)
- Julie C F Rappe
- The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | | | | | - Barbara Thür
- The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Office for Consumer Protection, Canton Aargau, Obere Vorstadt 14, 5000, Aarau, Switzerland
| | - Martin A Hofmann
- The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland
| | - Artur Summerfield
- The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.,Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Nicolas Ruggli
- The Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.
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67
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Complete genomic characterization of two European-genotype porcine reproductive and respiratory syndrome virus isolates in Fujian province of China. Arch Virol 2016; 162:823-833. [PMID: 27858288 DOI: 10.1007/s00705-016-3136-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 10/26/2016] [Indexed: 01/22/2023]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is considered one of the most devastating swine diseases worldwide, resulting in immense economic losses. PRRS virus (PRRSV) is divided into two major genotypes, European (type 1) and the North American (type 2). Type 1 PRRSV have recently emerged in Fujian province (South China), and this might have a significant impact on the Chinese pig industry. From 2013 to 2014, two type 1 PRRSV strains, named FJEU13 and FJQEU14, were isolated from piglets and sows with respiratory problems and reproductive disorders in Fujian province. The full genome length of the two isolates was 14,869-15,062 nucleotides (nt), excluding the poly(A) tail. These isolates shared 86.0-89.9% sequence identity with the prototypic strains Lelystad virus (LV) and 82.8-92% with Chinese type 1 PRRSV strains, but only 59.9-60.1% with the North American reference strain VR-2332. However, they were 82.9% identical to each other. Nonstructural protein 2 (Nsp2) and ORF3-ORF5 were the most variable regions when compared to other type 1 PRRSV strains. Nsp2 and ORF3 contained multiple discontinuous deletions and a 204-bp deletion in NSP2 in isolate FJQEU14, which has never been described in other Chinese type 1 PRRSV strains. All of these results might be useful for understanding the epidemic status of type 1 PRRSV in China.
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68
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Wang X, Mu G, Dang R, Yang Z. Up-regulation of IL-10 upon PRRSV vaccination impacts on the immune response against CSFV. Vet Microbiol 2016; 197:68-71. [PMID: 27938685 DOI: 10.1016/j.vetmic.2016.11.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 11/07/2016] [Accepted: 11/09/2016] [Indexed: 10/20/2022]
Abstract
Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection negatively impacts the efficacy of classical swine fever virus (CSFV) vaccine. This paper investigates whether the PRRSV vaccine also impacts the CSFV vaccine and if the impact is time-related. Forty-eight piglets born from four sows were divided into five groups (G1-G5). The piglets in G1 to G4 were given PRRSV vaccine at 14, 21, 28 and 35days of age. The G5 group was not vaccinated with the PRRSV. All pigs were given the CSFV vaccine at 35days of age. Immune responses to the CSFV vaccine were evaluated by testing CSFV-specific sera antibodies, lymphocyte proliferation and cytokine secretion. The results demonstrate that the PRRSV vaccine significantly reduces the immune responses of the CSFV vaccination when immunised both vaccines at the same time or with only a one week interval. The PRRSV vaccination induced higher levels of IL-10 expression in the first week and this may be why the CSFV vaccination is immunosuppressed. The findings indicate that a time interval of more than one week is necessary for vaccinated CSF after the PRRSV immunisation.
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Affiliation(s)
- Xinglong Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, China.
| | - Guohui Mu
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, China
| | - Ruiyi Dang
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, China
| | - Zengqi Yang
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, China.
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69
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Chung CJ, Cha SH, Grimm AL, Chung G, Gibson KA, Yoon KJ, Parish SM, Ho CS, Lee SS. Recognition of Highly Diverse Type-1 and -2 Porcine Reproductive and Respiratory Syndrome Viruses (PRRSVs) by T-Lymphocytes Induced in Pigs after Experimental Infection with a Type-2 PRRSV Strain. PLoS One 2016; 11:e0165450. [PMID: 27798650 PMCID: PMC5087905 DOI: 10.1371/journal.pone.0165450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/12/2016] [Indexed: 11/18/2022] Open
Abstract
Background/Aim Live attenuated vaccines confer partial protection in pigs before the appearance of neutralizing antibodies, suggesting the contribution of cell-mediated immunity (CMI). However, PRRSV-specific T-lymphocyte responses and protective mechanisms need to be further defined. To this end, the hypothesis was tested that PRRSV-specific T-lymphocytes induced by exposure to type-2 PRRSV can recognize diverse isolates. Methods An IFN-gamma ELISpot assay was used to enumerate PRRSV-specific T-lymphocytes from PRRSVSD23983-infected gilts and piglets born after in utero infection against 12 serologically and genetically distinct type-1 and -2 PRRSV isolates. The IFN-gamma ELISpot assay using synthetic peptides spanning all open reading frames of PRRSVSD23983 was utilized to localize epitopes recognized by T-lymphocytes. Virus neutralization tests were carried out using the challenge strain (type-2 PRRSVSD23983) and another strain (type-2 PRRSVVR2332) with high genetic similarity to evaluate cross-reactivity of neutralizing antibodies in gilts after PRRSVSD23983 infection. Results At 72 days post infection, T-lymphocytes from one of three PRRSVSD23983-infected gilts recognized all 12 diverse PRRSV isolates, while T-lymphocytes from the other two gilts recognized all but one isolate. Furthermore, five of nine 14-day-old piglets infected in utero with PRRSVSD23983 had broadly reactive T-lymphocytes, including one piglet that recognized all 12 isolates. Overlapping peptides encompassing all open reading frames of PRRSVSD23983 were used to identify ≥28 peptides with T-lymphocyte epitopes from 10 viral proteins. This included one peptide from the M protein that was recognized by T-lymphocytes from all three gilts representing two completely mismatched MHC haplotypes. In contrast to the broadly reactive T-lymphocytes, neutralizing antibody responses were specific to the infecting PRRSVSD23983 isolate. Conclusion These results demonstrated that T-lymphocytes recognizing antigenically and genetically diverse isolates were induced by infection with a type 2 PRRSV strain (SD23983). If these reponses have cytotoxic or other protective functions, they may help overcome the suboptimal heterologous protection conferred by conventional vaccines.
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Affiliation(s)
- Chungwon J. Chung
- VMRD Inc., Pullman, WA 99163, United States of America
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99163, United States of America
- * E-mail:
| | - Sang-Ho Cha
- Department of Virology, Animal and Plant Quarantine Agency, Anyang, Republic of Korea
| | | | - Grace Chung
- VMRD Inc., Pullman, WA 99163, United States of America
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99163, United States of America
| | - Kathleen A. Gibson
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, United States of America
| | - Kyoung-Jin Yoon
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, United States of America
| | - Steven M. Parish
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99163, United States of America
| | - Chak-Sum Ho
- Gift of Life Michigan, Ann Arbor, MI 48108, United States of America
| | - Stephen S. Lee
- Department of Statistics, University of Idaho, Moscow, ID 83844, United States of America
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70
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Balka G, Dreckmann K, Papp G, Kraft C. Vaccination of piglets at 2 and 3 weeks of age with Ingelvac PRRSFLEX® EU provides protection against heterologous field challenge in the face of homologous maternally derived antibodies. Porcine Health Manag 2016; 2:24. [PMID: 28405450 PMCID: PMC5382426 DOI: 10.1186/s40813-016-0037-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 07/14/2016] [Indexed: 01/13/2023] Open
Abstract
Background Due to difficulties in eradicating porcine reproductive and respiratory syndrome (PRRS) linked to biosecurity challenges, transmission of the virus and the lack of efficient DIVA vaccines, successful control of PRRS requires a combination of strict management measures and vaccination of both sows and piglets. The present study aimed to assess the efficacy of a recently developed MLV vaccine (Ingelvac PRRSFLEX® EU) in piglets at 2 and 3-weeks of age in the presence of homologous maternally derived antibodies as the dams were vaccinated with the same vaccine strain (ReproCyc® PRRS EU). Methods The study was carried out on a Hungarian farrow to finish farm naturally infected with PRRSv. The study was designed as a blind, placebo controlled side by side trial. ORF5 sequence similarity of the vaccine strain and the resident field strain was 87.8 %. PRRS specific real-time quantitative PCR was performed from serum samples to measure both the viral load and the frequency of virus positive animals. Results At the time of the natural infection observed in the control group at 10–12 weeks of age, the number of viraemic animals did not increase significantly in the vaccinated group. To understand the infection dynamics, positive PCR samples with low Ct values were sequenced (ORF5) and the data analysis indicated the circulation of wild type virus in both groups, however wild type virus was only found in non-vaccinated animals. Conclusions Our data indicate that piglets vaccinated at as early as 2 weeks of age with Ingelvac PRRSFLEX® EU were protected both in terms of proportion of viraemic animals and viraemia levels. It has to be highlighted that these results were achieved in piglets with high levels of homologous maternally derived antibodies (MDA) at the time of vaccination.
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Affiliation(s)
- Gyula Balka
- Department of Pathology, University of Veterinary Medicine, István u. 2, H-1078 Budapest, Hungary
| | - Karla Dreckmann
- Boehringer Ingelheim Veterinary Research Center GmbH & Co. KG, Bemeroder Str. 31, 30559 Hannover, Germany
| | - György Papp
- Jászapáti 2000 Mezőgazdasági Zrt., H-5130 Jászapáti, Hungary
| | - Christian Kraft
- Boehringer Ingelheim Veterinary Research Center GmbH & Co. KG, Bemeroder Str. 31, 30559 Hannover, Germany
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71
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Jan E, Mohr I, Walsh D. A Cap-to-Tail Guide to mRNA Translation Strategies in Virus-Infected Cells. Annu Rev Virol 2016; 3:283-307. [PMID: 27501262 DOI: 10.1146/annurev-virology-100114-055014] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although viruses require cellular functions to replicate, their absolute dependence upon the host translation machinery to produce polypeptides indispensable for their reproduction is most conspicuous. Despite their incredible diversity, the mRNAs produced by all viruses must engage cellular ribosomes. This has proven to be anything but a passive process and has revealed a remarkable array of tactics for rapidly subverting control over and dominating cellular regulatory pathways that influence translation initiation, elongation, and termination. Besides enforcing viral mRNA translation, these processes profoundly impact host cell-intrinsic immune defenses at the ready to deny foreign mRNA access to ribosomes and block protein synthesis. Finally, genome size constraints have driven the evolution of resourceful strategies for maximizing viral coding capacity. Here, we review the amazing strategies that work to regulate translation in virus-infected cells, highlighting both virus-specific tactics and the tremendous insight they provide into fundamental translational control mechanisms in health and disease.
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Affiliation(s)
- Eric Jan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - Ian Mohr
- Department of Microbiology and New York University Cancer Institute, New York University School of Medicine, New York, NY 10016;
| | - Derek Walsh
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611;
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72
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Atkins JF, Loughran G, Bhatt PR, Firth AE, Baranov PV. Ribosomal frameshifting and transcriptional slippage: From genetic steganography and cryptography to adventitious use. Nucleic Acids Res 2016; 44:7007-78. [PMID: 27436286 PMCID: PMC5009743 DOI: 10.1093/nar/gkw530] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/26/2016] [Indexed: 12/15/2022] Open
Abstract
Genetic decoding is not ‘frozen’ as was earlier thought, but dynamic. One facet of this is frameshifting that often results in synthesis of a C-terminal region encoded by a new frame. Ribosomal frameshifting is utilized for the synthesis of additional products, for regulatory purposes and for translational ‘correction’ of problem or ‘savior’ indels. Utilization for synthesis of additional products occurs prominently in the decoding of mobile chromosomal element and viral genomes. One class of regulatory frameshifting of stable chromosomal genes governs cellular polyamine levels from yeasts to humans. In many cases of productively utilized frameshifting, the proportion of ribosomes that frameshift at a shift-prone site is enhanced by specific nascent peptide or mRNA context features. Such mRNA signals, which can be 5′ or 3′ of the shift site or both, can act by pairing with ribosomal RNA or as stem loops or pseudoknots even with one component being 4 kb 3′ from the shift site. Transcriptional realignment at slippage-prone sequences also generates productively utilized products encoded trans-frame with respect to the genomic sequence. This too can be enhanced by nucleic acid structure. Together with dynamic codon redefinition, frameshifting is one of the forms of recoding that enriches gene expression.
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Affiliation(s)
- John F Atkins
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland School of Microbiology, University College Cork, Cork, Ireland Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Gary Loughran
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Pramod R Bhatt
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Andrew E Firth
- Division of Virology, Department of Pathology, University of Cambridge, Hills Road, Cambridge CB2 0QQ, UK
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Nsp4 Cleaves VISA to Impair Antiviral Responses Mediated by RIG-I-like Receptors. Sci Rep 2016; 6:28497. [PMID: 27329948 PMCID: PMC4916416 DOI: 10.1038/srep28497] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/02/2016] [Indexed: 11/08/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most significant etiological agents in the swine industry worldwide. It has been reported that PRRSV infection can modulate host immune responses, and innate immune evasion is thought to play a vital role in PRRSV pathogenesis. In this study, we demonstrated that highly pathogenic PRRSV (HP-PRRSV) infection specifically down-regulated virus-induced signaling adaptor (VISA), a unique adaptor molecule that is essential for retinoic acid induced gene-I (RIG-I) and melanoma differentiation associated gene 5 (MDA5) signal transduction. Moreover, we verified that nsp4 inhibited IRF3 activation induced by signaling molecules, including RIG-I, MDA5, VISA, and TBK1, but not IRF3. Subsequently, we demonstrated that HP-PRRSV nsp4 down-regulated VISA and suppressed type I IFN induction. Importantly, VISA was cleaved by nsp4 and released from mitochondrial membrane, which interrupted the downstream signaling of VISA. However, catalytically inactive mutant of nsp4 abolished its ability to cleave VISA. Interestingly, nsp4 of typical PRRSV strain CH-1a had no effect on VISA. Taken together, these findings reveal a strategy evolved by HP-PRRSV to counteract anti-viral innate immune signaling, which complements the known PRRSV-mediated immune-evasion mechanisms.
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Hori N, Denesyuk NA, Thirumalai D. Salt Effects on the Thermodynamics of a Frameshifting RNA Pseudoknot under Tension. J Mol Biol 2016; 428:2847-59. [PMID: 27315694 DOI: 10.1016/j.jmb.2016.06.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 12/24/2022]
Abstract
Because of the potential link between -1 programmed ribosomal frameshifting and response of a pseudoknot (PK) RNA to force, a number of single-molecule pulling experiments have been performed on PKs to decipher the mechanism of programmed ribosomal frameshifting. Motivated in part by these experiments, we performed simulations using a coarse-grained model of RNA to describe the response of a PK over a range of mechanical forces (fs) and monovalent salt concentrations (Cs). The coarse-grained simulations quantitatively reproduce the multistep thermal melting observed in experiments, thus validating our model. The free energy changes obtained in simulations are in excellent agreement with experiments. By varying f and C, we calculated the phase diagram that shows a sequence of structural transitions, populating distinct intermediate states. As f and C are changed, the stem-loop tertiary interactions rupture first, followed by unfolding of the 3'-end hairpin (I⇌F). Finally, the 5'-end hairpin unravels, producing an extended state (E⇌I). A theoretical analysis of the phase boundaries shows that the critical force for rupture scales as (logCm)(α) with α=1(0.5) for E⇌I (I⇌F) transition. This relation is used to obtain the preferential ion-RNA interaction coefficient, which can be quantitatively measured in single-molecule experiments, as done previously for DNA hairpins. A by-product of our work is the suggestion that the frameshift efficiency is likely determined by the stability of the 5'-end hairpin that the ribosome first encounters during translation.
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Affiliation(s)
- Naoto Hori
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Natalia A Denesyuk
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - D Thirumalai
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA.
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Napthine S, Treffers EE, Bell S, Goodfellow I, Fang Y, Firth AE, Snijder EJ, Brierley I. A novel role for poly(C) binding proteins in programmed ribosomal frameshifting. Nucleic Acids Res 2016; 44:5491-503. [PMID: 27257056 PMCID: PMC4937337 DOI: 10.1093/nar/gkw480] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 05/18/2016] [Indexed: 01/16/2023] Open
Abstract
Translational control through programmed ribosomal frameshifting (PRF) is exploited widely by viruses and increasingly documented in cellular genes. Frameshifting is induced by mRNA secondary structures that compromise ribosome fidelity during decoding of a heptanucleotide 'slippery' sequence. The nsp2 PRF signal of porcine reproductive and respiratory syndrome virus is distinctive in directing both -2 and -1 PRF and in its requirement for a trans-acting protein factor, the viral replicase subunit nsp1β. Here we show that the the trans-activation of frameshifting is carried out by a protein complex composed of nsp1β and a cellular poly(C) binding protein (PCBP). From the results of in vitro translation and electrophoretic mobility shift assays, we demonstrate that a PCBP/nsp1β complex binds to a C-rich sequence downstream of the slippery sequence and here mimics the activity of a structured mRNA stimulator of PRF. This is the first description of a role for a trans-acting cellular protein in PRF. The discovery broadens the repertoire of activities associated with poly(C) binding proteins and prototypes a new class of virus-host interactions.
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Affiliation(s)
- Sawsan Napthine
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Emmely E Treffers
- Department of Medical Microbiology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Susanne Bell
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Ian Goodfellow
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Ying Fang
- College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5705, USA
| | - Andrew E Firth
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Eric J Snijder
- Department of Medical Microbiology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Ian Brierley
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
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Fang J, Wang H, Bai J, Zhang Q, Li Y, Liu F, Jiang P. Monkey Viperin Restricts Porcine Reproductive and Respiratory Syndrome Virus Replication. PLoS One 2016; 11:e0156513. [PMID: 27232627 PMCID: PMC4883763 DOI: 10.1371/journal.pone.0156513] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 05/16/2016] [Indexed: 01/12/2023] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen which causes huge economic damage globally in the swine industry. Current vaccination strategies provide only limited protection against PRRSV infection. Viperin is an interferon (IFN) stimulated protein that inhibits some virus infections via IFN-dependent or IFN-independent pathways. However, the role of viperin in PRRSV infection is not well understood. In this study, we cloned the full-length monkey viperin (mViperin) complementary DNA (cDNA) from IFN-α-treated African green monkey Marc-145 cells. It was found that the mViperin is up-regulated following PRRSV infection in Marc-145 cells along with elevated IRF-1 gene levels. IFN-α induced mViperin expression in a dose- and time-dependent manner and strongly inhibits PRRSV replication in Marc-145 cells. Overexpression of mViperin suppresses PRRSV replication by blocking the early steps of PRRSV entry and genome replication and translation but not inhibiting assembly and release. And mViperin co-localized with PRRSV GP5 and N protein, but only interacted with N protein in distinct cytoplasmic loci. Furthermore, it was found that the 13–16 amino acids of mViperin were essential for inhibiting PRRSV replication, by disrupting the distribution of mViperin protein from the granular distribution to a homogeneous distribution in the cytoplasm. These results could be helpful in the future development of novel antiviral therapies against PRRSV infection.
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Affiliation(s)
- Jianyu Fang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Haiyan Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Juan Bai
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Qiaoya Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yufeng Li
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Fei Liu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ping Jiang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China
- * E-mail:
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Zhang Q, Xu X, You S, Li Y, Wang H, Bai J, Jiang P. Emerging of two new subgenotypes of porcine reproductive and respiratory syndrome viruses in Southeast China. Microb Pathog 2016; 97:27-33. [PMID: 27224859 DOI: 10.1016/j.micpath.2016.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 05/11/2016] [Accepted: 05/17/2016] [Indexed: 11/16/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the leading swine pathogens and causes major economic loss to the global swine industry. In this study, a total of 49 PRRSV isolates were collected from different swine herds in seven provinces in Southeast China from 2014 to 2015. All the ORF5 genes and some Nsp2 genes were sequenced. Phylogenetic analysis showed that all the isolates belonged to the North America genotype. Among them, five isolates formed a new subgenotype IV derived from highly pathogenic PRRSV (HP-PRRSV). Six isolates formed subgenotype III, which were closely related to the NADC30 strain in the US. These isolates formed 13 putative N-linked glycosylation site (NGS) patterns based on N30, 33, 34, 35, 44 and 51. There were fewer NGSs of isolates in subgenotype IV than in subgenotype III. This indicates that the two new subgenotypes of PRRSV strains with different NGS patterns were spreading in those regions of China. The genetic diversity should be considered for the control and prevention of this disease.
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Affiliation(s)
- Qiaoya Zhang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xiaojie Xu
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Shumei You
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yufeng Li
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Haiyan Wang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Juan Bai
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ping Jiang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
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Porcine Reproductive and Respiratory Syndrome Virus Nucleocapsid Protein Interacts with Nsp9 and Cellular DHX9 To Regulate Viral RNA Synthesis. J Virol 2016; 90:5384-5398. [PMID: 27009951 DOI: 10.1128/jvi.03216-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 03/15/2016] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Porcine reproductive and respiratory syndrome virus (PRRSV) nucleocapsid (N) protein is the main component of the viral capsid to encapsulate viral RNA, and it is also a multifunctional protein involved in the regulation of host cell processes. Nonstructural protein 9 (Nsp9) is the RNA-dependent RNA polymerase that plays a critical role in viral RNA transcription and replication. In this study, we demonstrate that PRRSV N protein is bound to Nsp9 by protein-protein interaction and that the contacting surface on Nsp9 is located in the two predicted α-helixes formed by 48 residues at the C-terminal end of the protein. Mutagenesis analyses identified E646, E608, and E611 on Nsp9 and Q85 on the N protein as the pivotal residues participating in the N-Nsp9 interaction. By overexpressing the N protein binding fragment of Nsp9 in infected Marc-145 cells, the synthesis of viral RNAs, as well as the production of infectious progeny viruses, was dramatically inhibited, suggesting that Nsp9-N protein association is involved in the process of viral RNA production. In addition, we show that PRRSV N interacts with cellular RNA helicase DHX9 and redistributes the protein into the cytoplasm. Knockdown of DHX9 increased the ratio of short subgenomic mRNAs (sgmRNAs); in contrast, DHX9 overexpression benefited the synthesis of longer sgmRNAs and the viral genomic RNA (gRNA). These results imply that DHX9 is recruited by the N protein in PRRSV infection to regulate viral RNA synthesis. We postulate that N and DHX9 may act as antiattenuation factors for the continuous elongation of nascent transcript during negative-strand RNA synthesis. IMPORTANCE It is unclear whether the N protein of PRRSV is involved in regulation of the viral RNA production process. In this report, we demonstrate that the N protein of the arterivirus PRRSV participates in viral RNA replication and transcription through interacting with Nsp9 and its RdRp and recruiting cellular RNA helicase to promote the production of longer viral sgmRNAs and gRNA. Our data here provide some new insights into the discontinuous to continuous extension of PRRSV RNA synthesis and also offer a new potential anti-PRRSV strategy targeting the N-Nsp9 and/or N-DHX9 interaction.
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Porcine Reproductive and Respiratory Syndrome Virus Utilizes Nanotubes for Intercellular Spread. J Virol 2016; 90:5163-5175. [PMID: 26984724 DOI: 10.1128/jvi.00036-16] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/09/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Intercellular nanotube connections have been identified as an alternative pathway for cellular spreading of certain viruses. In cells infected with porcine reproductive and respiratory syndrome virus (PRRSV), nanotubes were observed connecting two distant cells with contiguous membranes, with the core infectious viral machinery (viral RNA, certain replicases, and certain structural proteins) present in/on the intercellular nanotubes. Live-cell movies tracked the intercellular transport of a recombinant PRRSV that expressed green fluorescent protein (GFP)-tagged nsp2. In MARC-145 cells expressing PRRSV receptors, GFP-nsp2 moved from one cell to another through nanotubes in the presence of virus-neutralizing antibodies. Intercellular transport of viral proteins did not require the PRRSV receptor as it was observed in receptor-negative HEK-293T cells after transfection with an infectious clone of GFP-PRRSV. In addition, GFP-nsp2 was detected in HEK-293T cells cocultured with recombinant PRRSV-infected MARC-145 cells. The intercellular nanotubes contained filamentous actin (F-actin) with myosin-associated motor proteins. The F-actin and myosin IIA were identified as coprecipitates with PRRSV nsp1β, nsp2, nsp2TF, nsp4, nsp7-nsp8, GP5, and N proteins. Drugs inhibiting actin polymerization or myosin IIA activation prevented nanotube formation and viral clusters in virus-infected cells. These data lead us to propose that PRRSV utilizes the host cell cytoskeletal machinery inside nanotubes for efficient cell-to-cell spread. This form of virus transport represents an alternative pathway for virus spread, which is resistant to the host humoral immune response. IMPORTANCE Extracellular virus particles transmit infection between organisms, but within infected hosts intercellular infection can be spread by additional mechanisms. In this study, we describe an alternative pathway for intercellular transmission of PRRSV in which the virus uses nanotube connections to transport infectious viral RNA, certain replicases, and certain structural proteins to neighboring cells. This process involves interaction of viral proteins with cytoskeletal proteins that form the nanotube connections. Intercellular viral spread through nanotubes allows the virus to escape the neutralizing antibody response and may contribute to the pathogenesis of viral infections. The development of strategies that interfere with this process could be critical in preventing the spread of viral infection.
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80
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The non-structural protein Nsp2TF of porcine reproductive and respiratory syndrome virus down-regulates the expression of Swine Leukocyte Antigen class I. Virology 2016; 491:115-24. [DOI: 10.1016/j.virol.2016.01.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 01/28/2016] [Accepted: 01/30/2016] [Indexed: 11/19/2022]
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Influence of the amino acid residues at 70 in M protein of porcine reproductive and respiratory syndrome virus on viral neutralization susceptibility to the serum antibody. Virol J 2016; 13:51. [PMID: 27004554 PMCID: PMC4802621 DOI: 10.1186/s12985-016-0505-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 03/14/2016] [Indexed: 01/11/2023] Open
Abstract
Background Porcine reproductive and respiratory syndrome virus (PRRSV) is mainly responsible for the significant economic losses in pig industry in the world. The adaptive immune responses of the host act as an important source of selective pressure in the evolutionary process of the virus. In the previous study, we confirmed that the amino acid (aa) residues at 102 and 104 sites in GP5 played an important role in escaping from the neutralizing antibodies (NAbs) against highly pathogenic PRRSV (HP-PRRSV). In this study, we further analyzed the aa mutants affecting neutralization susceptibility of NAbs in other structure proteins in NAbs resistant variants. Methods Based on the different aa residues of the structural proteins between the resistant virus BB20s and the parent virus BB, 12 recombinant PRRSV strains containing these aa residue substitutions were constructed using reverse genetic techniques. The neutralizing antibody (NA) titers of the recombinant strains were tested on MARC-145 and porcine alveolar macrophages (PAMs). And the NAbs binding abilities of parent and rescued viruses were tested by using ELISA method. Results By using the neutralization assay, it was revealed that the NA titer of N4 serum with rBB/Ms was significantly lower than that with rBB. Meanwhile, NA titer of the serum with rBB20s/M was significantly higher than that with rBB20s. The ELISA binding results showed that rBB/Ms had higher binding inability to N4 than did rBB. And alignment of M protein revealed that the variant aa residue lysine (K) at 70 was also existed in field type 2 and vaccine PRRSV strains. Conclusions The aa residue at 70 in M protein of PRRSV played an important role in regulating neutralization susceptibility to the porcine serum NAbs. It may be helpful for monitoring the antigen variant strains in the field and developing new vaccine against PRRSV in the future. Electronic supplementary material The online version of this article (doi:10.1186/s12985-016-0505-7) contains supplementary material, which is available to authorized users.
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Lee SC, Choi HW, Nam E, Noh YH, Lee S, Lee YJ, Park GS, Shin JH, Yoon IJ, Kang SY, Lee C. Pathogenicity and genetic characteristics associated with cell adaptation of a virulent porcine reproductive and respiratory syndrome virus nsp2 DEL strain CA-2. Vet Microbiol 2016; 186:174-88. [PMID: 27016772 DOI: 10.1016/j.vetmic.2016.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/03/2016] [Accepted: 03/03/2016] [Indexed: 02/06/2023]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is the most common and world-widespread viral pathogen of swine. We previously reported genomic sequences and pathogenicity of type 2 Korean PRRSV strains belonging to the virulent lineage 1 family, which contain remarkable amino acid deletions in nonstructural protein 2 (nsp2 DEL) compared to VR-2332. Here, a virulent type 2 Korean PRRSV nsp2 DEL strain, CA-2, was serially propagated in MARC-145 cells for up to 100 passages (CA-2-P100). As the passage number increased, the phenotypic characteristics of cell-adapted CA-2 strains were altered, in terms of higher viral titers and larger plaque sizes compared to the parental virus. Pro-inflammatory cytokine genes, including TNF-α, IL-8, MCP-1, and MCP-2, were found to be significantly down-regulated in PAM cells with the CA-2-P100 strain compared to its parental nsp2 DEL virus. Animal inoculation studies demonstrated that the virulence of CA-2-P100 was reduced significantly, with showing normal weight gain, body temperatures, and lung lesions comparable to the control group. Furthermore, high-passage CA-2-P100 showed declined and transient viremia kinetics, as well as delayed and low PRRSV-specific antibody responses in infected pigs. In addition, we determined whole genome sequences of low to high-passage derivatives of CA-2. The nsp2 DEL pattern was conserved for 100 passages, whereas no other deletions or insertions arose during the cell adaptation process. However, CA-2-P100 possessed 54 random nucleotide substitutions that resulted in 27 amino acid changes distributed throughout the genome, suggesting that these genetic drifts provide a possible molecular basis correlated with the cell-adapted features in vitro and the attenuated phenotype in vivo. Taken together, our data indicate that the cell-attenuated CA-2-P100 strain is a promising candidate for developing a safe and effective live PRRSV vaccine.
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Affiliation(s)
- Seung-Chul Lee
- Choongang Vaccine Laboratory, Daejeon 34055, Republic of Korea; College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - Hwan-Won Choi
- Choongang Vaccine Laboratory, Daejeon 34055, Republic of Korea
| | - Eeuri Nam
- Choongang Vaccine Laboratory, Daejeon 34055, Republic of Korea
| | - Yun-Hee Noh
- Choongang Vaccine Laboratory, Daejeon 34055, Republic of Korea
| | - Sunhee Lee
- Animal Virology Laboratory, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Yoo Jin Lee
- Animal Virology Laboratory, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Gun-Seok Park
- School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jae-Ho Shin
- School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - In-Joong Yoon
- Choongang Vaccine Laboratory, Daejeon 34055, Republic of Korea
| | - Shien-Young Kang
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Republic of Korea.
| | - Changhee Lee
- Animal Virology Laboratory, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu 41566, Republic of Korea.
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Abstract
Theiler's murine encephalomyelitis virus (TMEV) is a member of the genus Cardiovirus in the Picornaviridae, a family of positive-sense single-stranded RNA viruses. Previously, we demonstrated that in the related cardiovirus, Encephalomyocarditis virus, a programmed −1 ribosomal frameshift (−1 PRF) occurs at a conserved G_GUU_UUU sequence within the 2B-encoding region of the polyprotein open reading frame (ORF). Here we show that −1 PRF occurs at a similar site during translation of the TMEV genome. In addition, we demonstrate that a predicted 3′ RNA stem-loop structure at a noncanonical spacing downstream of the shift site is required for efficient frameshifting in TMEV and that frameshifting also requires virus infection. Mutating the G_GUU_UUU shift site to inhibit frameshifting results in an attenuated virus with reduced growth kinetics and a small-plaque phenotype. Frameshifting in the virus context was found to be extremely efficient at 74 to 82%, which, to our knowledge, is the highest frameshifting efficiency recorded to date for any virus. We propose that highly efficient −1 PRF in TMEV provides a mechanism to escape the confines of equimolar expression normally inherent in the single-polyprotein expression strategy of picornaviruses. IMPORTANCE Many viruses utilize programmed −1 ribosomal frameshifting (−1 PRF) to produce different protein products at a defined ratio, or to translate overlapping ORFs to increase coding capacity. With few exceptions, −1 PRF occurs on specific “slippery” heptanucleotide sequences and is stimulated by RNA structure beginning 5 to 9 nucleotides (nt) downstream of the slippery site. Here we describe an unusual case of −1 PRF in Theiler's murine encephalomyelitis virus (TMEV) that is extraordinarily efficient (74 to 82% of ribosomes shift into the alternative reading frame) and, in stark contrast to other examples of −1 PRF, is dependent upon a stem-loop structure beginning 14 nt downstream of the slippery site. Furthermore, in TMEV-based reporter constructs in transfected cells, efficient frameshifting is critically dependent upon virus infection. We suggest that TMEV evolved frameshifting as a novel mechanism for removing ribosomes from the message (a “ribosome sink”) to downregulate synthesis of the 3′-encoded replication proteins.
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Mutations in a Highly Conserved Motif of nsp1β Protein Attenuate the Innate Immune Suppression Function of Porcine Reproductive and Respiratory Syndrome Virus. J Virol 2016; 90:3584-99. [PMID: 26792733 DOI: 10.1128/jvi.03069-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/11/2016] [Indexed: 01/31/2023] Open
Abstract
UNLABELLED Porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural protein 1β (nsp1β) is a multifunctional viral protein, which is involved in suppressing the host innate immune response and activating a unique -2/-1 programmed ribosomal frameshifting (PRF) signal for the expression of frameshifting products. In this study, site-directed mutagenesis analysis showed that the R128A or R129A mutation introduced into a highly conserved motif ((123)GKYLQRRLQ(131)) reduced the ability of nsp1β to suppress interferon beta (IFN-β) activation and also impaired nsp1β's function as a PRF transactivator. Three recombinant viruses, vR128A, vR129A, and vRR129AA, carrying single or double mutations in the GKYLQRRLQ motif were characterized. In comparison to the wild-type (WT) virus, vR128A and vR129A showed slightly reduced growth abilities, while the vRR129AA mutant had a significantly reduced growth ability in infected cells. Consistent with the attenuated growth phenotype in vitro, pigs infected with nsp1β mutants had lower levels of viremia than did WT virus-infected pigs. Compared to the WT virus in infected cells, all three mutated viruses stimulated high levels of IFN-α expression and exhibited a reduced ability to suppress the mRNA expression of selected interferon-stimulated genes (ISGs). In pigs infected with nsp1β mutants, IFN-α production was increased in the lungs at early time points postinfection, which was correlated with increased innate NK cell function. Furthermore, the augmented innate response was consistent with the increased production of IFN-γ in pigs infected with mutated viruses. These data demonstrate that residues R128 and R129 are critical for nsp1β function and that modifying these key residues in the GKYLQRRLQ motif attenuates virus growth ability and improves the innate and adaptive immune responses in infected animals. IMPORTANCE PRRSV infection induces poor antiviral innate IFN and cytokine responses, which results in weak adaptive immunity. One of the strategies in next-generation vaccine construction is to manipulate viral proteins/genetic elements involved in antagonizing the host immune response. PRRSV nsp1β was identified to be a strong innate immune antagonist. In this study, two basic amino acids, R128 and R129, in a highly conserved GKYLQRRLQ motif were determined to be critical for nsp1β function. Mutations introduced into these two residues attenuated virus growth and improved the innate and adaptive immune responses of infected animals. Technologies developed in this study could be broadly applied to current commercial PRRSV modified live-virus (MLV) vaccines and other candidate vaccines.
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85
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Advani VM, Dinman JD. Reprogramming the genetic code: The emerging role of ribosomal frameshifting in regulating cellular gene expression. Bioessays 2015; 38:21-6. [PMID: 26661048 PMCID: PMC4749135 DOI: 10.1002/bies.201500131] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Reading frame maintenance is a critical property of ribosomes. However, a number of genetic elements have been described that can induce ribosomes to shift on mRNAs, the most well understood of which are a class that directs ribosomal slippage by one base in 5' (‐1) direction. This is referred to as programmed ‐1 ribosomal frameshifting (‐1 PRF). Recently, a new ‐1 PRF promoting element was serendipitously discovered in a study examining the effects of stretches of adenosines in the coding sequences of mRNAs. Here, we discuss this finding, recent studies describing how ‐1 PRF is used to control gene expression in eukaryotes, and how ‐1 PRF is itself regulated. The implications of dysregulation of ‐1 PRF on human health are examined, as are possible new areas in which novel ‐1 PRF promoting elements might be discovered. Also watch the https://youtu.be/1mPXIINCRcY.
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Affiliation(s)
- Vivek M Advani
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
| | - Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA
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86
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Lunney JK, Fang Y, Ladinig A, Chen N, Li Y, Rowland B, Renukaradhya GJ. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): Pathogenesis and Interaction with the Immune System. Annu Rev Anim Biosci 2015; 4:129-54. [PMID: 26646630 DOI: 10.1146/annurev-animal-022114-111025] [Citation(s) in RCA: 458] [Impact Index Per Article: 50.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review addresses important issues of porcine reproductive and respiratory syndrome virus (PRRSV) infection, immunity, pathogenesis, and control. Worldwide, PRRS is the most economically important infectious disease of pigs. We highlight the latest information on viral genome structure, pathogenic mechanisms, and host immunity, with a special focus on immune factors that modulate PRRSV infections during the acute and chronic/persistent disease phases. We address genetic control of host resistance and probe effects of PRRSV infection on reproductive traits. A major goal is to identify cellular/viral targets and pathways for designing more effective vaccines and therapeutics. Based on progress in viral reverse genetics, host transcriptomics and genomics, and vaccinology and adjuvant technologies, we have identified new areas for PRRS control and prevention. Finally, we highlight the gaps in our knowledge base and the need for advanced molecular and immune tools to stimulate PRRS research and field applications.
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Affiliation(s)
- Joan K Lunney
- Animal Parasitic Diseases Laboratory, BARC ARS USDA, Beltsville, Maryland 20705;
| | - Ying Fang
- College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5600; , ,
| | - Andrea Ladinig
- University of Veterinary Medicine, Vienna 1210, Austria;
| | - Nanhua Chen
- College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5600; , , .,College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China;
| | - Yanhua Li
- College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5600; , ,
| | - Bob Rowland
- College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5600; , ,
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87
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Gao F, Simon AE. Multiple Cis-acting elements modulate programmed -1 ribosomal frameshifting in Pea enation mosaic virus. Nucleic Acids Res 2015; 44:878-95. [PMID: 26578603 PMCID: PMC4737148 DOI: 10.1093/nar/gkv1241] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 11/02/2015] [Indexed: 11/13/2022] Open
Abstract
Programmed -1 ribosomal frameshifting (-1 PRF) is used by many positive-strand RNA viruses for translation of required products. Despite extensive studies, it remains unresolved how cis-elements just downstream of the recoding site promote a precise level of frameshifting. The Umbravirus Pea enation mosaic virus RNA2 expresses its RNA polymerase by -1 PRF of the 5'-proximal ORF (p33). Three hairpins located in the vicinity of the recoding site are phylogenetically conserved among Umbraviruses. The central Recoding Stimulatory Element (RSE), located downstream of the p33 termination codon, is a large hairpin with two asymmetric internal loops. Mutational analyses revealed that sequences throughout the RSE and the RSE lower stem (LS) structure are important for frameshifting. SHAPE probing of mutants indicated the presence of higher order structure, and sequences in the LS may also adapt an alternative conformation. Long-distance pairing between the RSE and a 3' terminal hairpin was less critical when the LS structure was stabilized. A basal level of frameshifting occurring in the absence of the RSE increases to 72% of wild-type when a hairpin upstream of the slippery site is also deleted. These results suggest that suppression of frameshifting may be needed in the absence of an active RSE conformation.
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Affiliation(s)
- Feng Gao
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA
| | - Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD 20742, USA
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88
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Lee YJ, Lee C. Ivermectin inhibits porcine reproductive and respiratory syndrome virus in cultured porcine alveolar macrophages. Arch Virol 2015; 161:257-68. [PMID: 26518309 DOI: 10.1007/s00705-015-2653-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/18/2015] [Indexed: 11/28/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is a devastating viral pathogen of swine that causes huge financial losses in the pig industry worldwide. Ivermectin is known to be a potent inhibitor of importin α/β-mediated nuclear transport and exhibits antiviral activity towards several RNA viruses by blocking the nuclear trafficking of viral proteins. Although PRRSV replication occurs exclusively in the cytoplasm of infected cells, the nucleocapsid (N) protein has been shown to distinctly localize in the nucleus and nucleolus throughout infection. Here, we sought to assess whether ivermectin suppresses PRRSV replication in cultured porcine alveolar macrophage (PAM) cells and to investigate the effect of ivermectin on the subcellular localization of the PRRSV N protein. Our data demonstrate that ivermectin treatment inhibits PRRSV infection in PAM-pCD163 cells in a dose-dependent manner. The antiviral activity of ivermectin on PRRSV replication was most effective when cells were treated during the early stage of infection. Treatment of PRRSV-infected cells with ivermectin significantly suppressed viral RNA synthesis, viral protein expression, and progeny virus production. However, immunofluorescence and cell fractionation assays revealed that ivermectin was incapable of disrupting the nuclear localization of the N protein, both in PRRSV-infected PAM-pCD163 cells and in PAM cells stably expressing the PRRSV N protein. This finding suggests that an alternative mechanism of action accounts for the ability of ivermectin to diminish PRRSV replication. Taken together, our results suggest that ivermectin is an invaluable therapeutic or preventative agent against PRRSV infection.
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Affiliation(s)
- Yoo Jin Lee
- Animal Virology Laboratory, School of Life Sciences, College of Natural Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - Changhee Lee
- Animal Virology Laboratory, School of Life Sciences, College of Natural Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 702-701, Republic of Korea.
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89
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Belew AT, Dinman JD. Cell cycle control (and more) by programmed -1 ribosomal frameshifting: implications for disease and therapeutics. Cell Cycle 2015; 14:172-8. [PMID: 25584829 PMCID: PMC4615106 DOI: 10.4161/15384101.2014.989123] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Like most basic molecular mechanisms, programmed –1 ribosomal frameshifting (−1 PRF) was first identified in viruses. Early observations that global dysregulation of −1 PRF had deleterious effects on yeast cell growth suggested that −1 PRF may be used to control cellular gene expression, and the cell cycle in particular. Collection of sufficient numbers of viral −1 PRF signals coupled with advances in computer sciences enabled 2 complementary computational approaches to identify −1 PRF signals in free living organisms. The unexpected observation that almost all −1 PRF events on eukaryotic mRNAs direct ribosomes to premature termination codons engendered the hypothesis that −1 PRF signals post-transcriptionally regulate gene expression by functioning as mRNA destabilizing elements. Emerging research suggests that some human diseases are associated with global defects in −1 PRF. The recent discovery of −1 PRF signal-specific trans-acting regulators may provide insight into novel therapeutic strategies aimed at treating diseases caused by changes in gene expression patterns.
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Affiliation(s)
- Ashton T Belew
- a Department of Cell Biology and Molecular Genetics ; University of Maryland ; College Park , MD USA
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90
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Baranov PV, Atkins JF, Yordanova MM. Augmented genetic decoding: global, local and temporal alterations of decoding processes and codon meaning. Nat Rev Genet 2015; 16:517-29. [PMID: 26260261 DOI: 10.1038/nrg3963] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The non-universality of the genetic code is now widely appreciated. Codes differ between organisms, and certain genes are known to alter the decoding rules in a site-specific manner. Recently discovered examples of decoding plasticity are particularly spectacular. These examples include organisms and organelles with disruptions of triplet continuity during the translation of many genes, viruses that alter the entire genetic code of their hosts and organisms that adjust their genetic code in response to changing environments. In this Review, we outline various modes of alternative genetic decoding and expand existing terminology to accommodate recently discovered manifestations of this seemingly sophisticated phenomenon.
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Affiliation(s)
- Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Ireland
| | - John F Atkins
- 1] School of Biochemistry and Cell Biology, University College Cork, Ireland. [2] Department of Human Genetics, University of Utah, 15 N 2030 E Rm. 7410, Salt Lake City, Utah 84112-5330, USA
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91
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Gao L, Wang L, Huang C, Yang L, Guo XK, Yu Z, Liu Y, Yang P, Feng WH. HP-PRRSV is attenuated by de-optimization of codon pair bias in its RNA-dependent RNA polymerase nsp9 gene. Virology 2015; 485:135-44. [PMID: 26247624 DOI: 10.1016/j.virol.2015.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 05/21/2015] [Accepted: 07/16/2015] [Indexed: 10/23/2022]
Abstract
There is an urgent need to develop new vaccines against highly pathogenic PRRS virus (HP-PRRSV) variant in China. The actual use of each codon pairs is more or less frequent than that of the statistical prediction and codon pair bias (CPB) usage affects gene translation. We "shuffled" the existing codons in HP-PRRSV genes GP5, M, nsp2 and nsp9, so that the CPB of these genes could be more negative. De-optimization of nsp9, the RNA-dependent RNA polymerase, significantly decreased PRRSV replication in porcine alveolar macrophages (PAMs). In vitro study showed that HV-nsp9(min) and HV-nsp29(min) were remarkably attenuated in PAMs, and inoculation of pigs with 2 ml⁎10(5.0) TCID50/ml of HV-nsp9(min) or HV-nsp29(min) did not cause PRRS. Importantly, pigs immunized with HV-nsp29(min) were fully protected against different HP-PRRSV strains׳ lethal challenges. Our results imply that the CPB de-optimized HV-nsp29(min) has the potential to be used as a live vaccine candidate against HP-PRRSV.
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Affiliation(s)
- Li Gao
- China Academy of Medicine Sciences, Peking Union Medical College, Institute of Medicinal Plant Development, Beijing 100193, China
| | - Lianghai Wang
- State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Chen Huang
- State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Longlong Yang
- The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709-2137, USA
| | - Xue-Kun Guo
- State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zhibin Yu
- State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yihao Liu
- State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Peng Yang
- Beijing Senkang Biotech Development Co., Ltd, Beijing 101400, China
| | - Wen-Hai Feng
- State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
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92
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Olspert A, Chung BYW, Atkins JF, Carr JP, Firth AE. Transcriptional slippage in the positive-sense RNA virus family Potyviridae. EMBO Rep 2015; 16:995-1004. [PMID: 26113364 PMCID: PMC4552492 DOI: 10.15252/embr.201540509] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/05/2015] [Accepted: 06/08/2015] [Indexed: 11/15/2022] Open
Abstract
The family Potyviridae encompasses ~30% of plant viruses and is responsible for significant economic losses worldwide. Recently, a small overlapping coding sequence, termed pipo, was found to be conserved in the genomes of all potyvirids. PIPO is expressed as part of a frameshift protein, P3N-PIPO, which is essential for virus cell-to-cell movement. However, the frameshift expression mechanism has hitherto remained unknown. Here, we demonstrate that transcriptional slippage, specific to the viral RNA polymerase, results in a population of transcripts with an additional "A" inserted within a highly conserved GAAAAAA sequence, thus enabling expression of P3N-PIPO. The slippage efficiency is ~2% in Turnip mosaic virus and slippage is inhibited by mutations in the GAAAAAA sequence. While utilization of transcriptional slippage is well known in negative-sense RNA viruses such as Ebola, mumps and measles, to our knowledge this is the first report of its widespread utilization for gene expression in positive-sense RNA viruses.
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Affiliation(s)
- Allan Olspert
- Division of Virology, Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Betty Y-W Chung
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - John F Atkins
- Schools of Biochemistry and Microbiology, University College Cork, Cork, Ireland Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - John P Carr
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Andrew E Firth
- Division of Virology, Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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93
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Renukaradhya GJ, Meng XJ, Calvert JG, Roof M, Lager KM. Live porcine reproductive and respiratory syndrome virus vaccines: Current status and future direction. Vaccine 2015; 33:4069-80. [PMID: 26148878 DOI: 10.1016/j.vaccine.2015.06.092] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 06/16/2015] [Accepted: 06/23/2015] [Indexed: 10/23/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) was reported in the late 1980s. PRRS still is a huge economic concern to the global pig industry with a current annual loss estimated at one billion US dollars in North America alone. It has been 20 years since the first modified live-attenuated PRRSV vaccine (PRRSV-MLV) became commercially available. PRRSV-MLVs provide homologous protection and help in reducing shedding of heterologous viruses, but they do not completely protect pigs against heterologous field strains. There have been many advances in understanding the biology and ecology of PRRSV; however, the complexities of virus-host interaction and PRRSV vaccinology are not yet completely understood leaving a significant gap for improving breadth of immunity against diverse PRRS isolates. This review provides insights on immunization efforts using infectious PRRSV-based vaccines since the 1990s, beginning with live PRRSV immunization, development and commercialization of PRRSV-MLV, and strategies to overcome the deficiencies of PRRSV-MLV through use of replicating viral vectors expressing multiple PRRSV membrane proteins. Finally, powerful reverse genetics systems (infectious cDNA clones) generated from more than 20 PRRSV isolates of both genotypes 1 and 2 viruses have provided a great resource for exploring many innovative strategies to improve the safety and cross-protective efficacy of live PRRSV vaccines. Examples include vaccines with diminished ability to down-regulate the immune system, positive and negative marker vaccines, multivalent vaccines incorporating antigens from other porcine pathogens, vaccines that carry their own cytokine adjuvants, and chimeric vaccine viruses with the potential for broad cross-protection against heterologous strains. To combat this devastating pig disease in the future, evaluation and commercialization of such improved live PRRSV vaccines is a shared goal among PRRSV researchers, pork producers and biologics companies.
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Affiliation(s)
- Gourapura J Renukaradhya
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH, United States.
| | - Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | | | - Michael Roof
- Boehringer Ingelheim Vetmedica, Inc., Ames, IA, United States
| | - Kelly M Lager
- Virus and Prion Research Unit, National Animal Disease Center, U.S. Department of Agriculture, Ames, IA, United States.
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94
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Dunkle JA, Dunham CM. Mechanisms of mRNA frame maintenance and its subversion during translation of the genetic code. Biochimie 2015; 114:90-6. [PMID: 25708857 PMCID: PMC4458409 DOI: 10.1016/j.biochi.2015.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 02/11/2015] [Indexed: 01/26/2023]
Abstract
Important viral and cellular gene products are regulated by stop codon readthrough and mRNA frameshifting, processes whereby the ribosome detours from the reading frame defined by three nucleotide codons after initiation of translation. In the last few years, rapid progress has been made in mechanistically characterizing both processes and also revealing that trans-acting factors play important regulatory roles in frameshifting. Here, we review recent biophysical studies that bring new molecular insights to stop codon readthrough and frameshifting. Lastly, we consider whether there may be common mechanistic themes in -1 and +1 frameshifting based on recent X-ray crystal structures of +1 frameshift-prone tRNAs bound to the ribosome.
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Affiliation(s)
- Jack A Dunkle
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Suite G223, Atlanta, GA 30322, USA
| | - Christine M Dunham
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Suite G223, Atlanta, GA 30322, USA.
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95
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Yordanova MM, Wu C, Andreev DE, Sachs MS, Atkins JF. A Nascent Peptide Signal Responsive to Endogenous Levels of Polyamines Acts to Stimulate Regulatory Frameshifting on Antizyme mRNA. J Biol Chem 2015; 290:17863-17878. [PMID: 25998126 PMCID: PMC4505036 DOI: 10.1074/jbc.m115.647065] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Indexed: 01/06/2023] Open
Abstract
The protein antizyme is a negative regulator of cellular polyamine concentrations from yeast to mammals. Synthesis of functional antizyme requires programmed +1 ribosomal frameshifting at the 3′ end of the first of two partially overlapping ORFs. The frameshift is the sensor and effector in an autoregulatory circuit. Except for Saccharomyces cerevisiae antizyme mRNA, the frameshift site alone only supports low levels of frameshifting. The high levels usually observed depend on the presence of cis-acting stimulatory elements located 5′ and 3′ of the frameshift site. Antizyme genes from different evolutionary branches have evolved different stimulatory elements. Prior and new multiple alignments of fungal antizyme mRNA sequences from the Agaricomycetes class of Basidiomycota show a distinct pattern of conservation 5′ of the frameshift site consistent with a function at the amino acid level. As shown here when tested in Schizosaccharomyces pombe and mammalian HEK293T cells, the 5′ part of this conserved sequence acts at the nascent peptide level to stimulate the frameshifting, without involving stalling detectable by toe-printing. However, the peptide is only part of the signal. The 3′ part of the stimulator functions largely independently and acts at least mostly at the nucleotide level. When polyamine levels were varied, the stimulatory effect was seen to be especially responsive in the endogenous polyamine concentration range, and this effect may be more general. A conserved RNA secondary structure 3′ of the frameshift site has weaker stimulatory and polyamine sensitizing effects on frameshifting.
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Affiliation(s)
- Martina M Yordanova
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Cheng Wu
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Matthew S Sachs
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - John F Atkins
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland; Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112-5330.
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96
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Mathew SF, Crowe-McAuliffe C, Graves R, Cardno TS, McKinney C, Poole ES, Tate WP. The highly conserved codon following the slippery sequence supports -1 frameshift efficiency at the HIV-1 frameshift site. PLoS One 2015; 10:e0122176. [PMID: 25807539 PMCID: PMC4373837 DOI: 10.1371/journal.pone.0122176] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 02/08/2015] [Indexed: 01/18/2023] Open
Abstract
HIV-1 utilises -1 programmed ribosomal frameshifting to translate structural and enzymatic domains in a defined proportion required for replication. A slippery sequence, U UUU UUA, and a stem-loop are well-defined RNA features modulating -1 frameshifting in HIV-1. The GGG glycine codon immediately following the slippery sequence (the 'intercodon') contributes structurally to the start of the stem-loop but has no defined role in current models of the frameshift mechanism, as slippage is inferred to occur before the intercodon has reached the ribosomal decoding site. This GGG codon is highly conserved in natural isolates of HIV. When the natural intercodon was replaced with a stop codon two different decoding molecules-eRF1 protein or a cognate suppressor tRNA-were able to access and decode the intercodon prior to -1 frameshifting. This implies significant slippage occurs when the intercodon is in the (perhaps distorted) ribosomal A site. We accommodate the influence of the intercodon in a model of frame maintenance versus frameshifting in HIV-1.
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Affiliation(s)
- Suneeth F. Mathew
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | | | - Ryan Graves
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Tony S. Cardno
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Cushla McKinney
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Elizabeth S. Poole
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
| | - Warren P. Tate
- Department of Biochemistry, University of Otago, Dunedin, 9054, New Zealand
- * E-mail:
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97
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Kappes MA, Miller CL, Faaberg KS. Porcine reproductive and respiratory syndrome virus nonstructural protein 2 (nsp2) topology and selective isoform integration in artificial membranes. Virology 2015; 481:51-62. [PMID: 25768891 DOI: 10.1016/j.virol.2015.01.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 01/15/2015] [Accepted: 01/30/2015] [Indexed: 11/28/2022]
Abstract
The membrane insertion and topology of nonstructural protein 2 (nsp2) of porcine reproductive and respiratory syndrome virus (PRRSV) strain VR-2332 was assessed using a cell free translation system in the presence or absence of artificial membranes. Expression of PRRSV nsp2 in the absence of all other viral factors resulted in the genesis of both full-length nsp2 as well as a select number of C-terminal nsp2 isoforms. Addition of membranes to the translation stabilized the translation reaction, resulting in predominantly full-length nsp2 as assessed by immunoprecipitation. Analysis further showed full-length nsp2 strongly associates with membranes, along with two additional large nsp2 isoforms. Membrane integration of full-length nsp2 was confirmed through high-speed density fractionation, protection from protease digestion, and immunoprecipitation. The results demonstrated that nsp2 integrated into the membranes with an unexpected topology, where the amino (N)-terminal (cytoplasmic) and C-terminal (luminal) domains were orientated on opposite sides of the membrane surface.
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Affiliation(s)
- Matthew A Kappes
- Virus and Prion Research Unit, USDA-ARS-National Animal Disease Center, Ames, IA, USA; Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Cathy L Miller
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Kay S Faaberg
- Virus and Prion Research Unit, USDA-ARS-National Animal Disease Center, Ames, IA, USA.
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98
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Kappes MA, Faaberg KS. PRRSV structure, replication and recombination: Origin of phenotype and genotype diversity. Virology 2015; 479-480:475-86. [PMID: 25759097 PMCID: PMC7111637 DOI: 10.1016/j.virol.2015.02.012] [Citation(s) in RCA: 223] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/23/2015] [Accepted: 02/09/2015] [Indexed: 11/26/2022]
Abstract
Porcine reproductive and respiratory disease virus (PRRSV) has the intrinsic ability to adapt and evolve. After 25 years of study, this persistent pathogen has continued to frustrate efforts to eliminate infection of herds through vaccination or other elimination strategies. The purpose of this review is to summarize the research on the virion structure, replication and recombination properties of PRRSV that have led to the extraordinary phenotype and genotype diversity that exists worldwide. Review of structure, replication and recombination of porcine reproductive and respiratory syndrome virus. Homologous recombination to produce conventional subgenomic messenger RNA as well as heteroclite RNA. Discussion of structure, replication and recombination mechanisms that have yielded genotypic and phenotypic diversity.
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Affiliation(s)
- Matthew A Kappes
- Virus and Prion Research Unit, USDA-ARS-National Animal Disease Center, Ames, IA, USA
| | - Kay S Faaberg
- Virus and Prion Research Unit, USDA-ARS-National Animal Disease Center, Ames, IA, USA.
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Rascón-Castelo E, Burgara-Estrella A, Mateu E, Hernández J. Immunological features of the non-structural proteins of porcine reproductive and respiratory syndrome virus. Viruses 2015; 7:873-86. [PMID: 25719944 PMCID: PMC4379552 DOI: 10.3390/v7030873] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/08/2015] [Accepted: 02/15/2015] [Indexed: 12/18/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is currently one of the most important viruses affecting the swine industry worldwide. Despite the large number of papers published each year, the participation of non-structural proteins (nsps) in the immune response is not completely clear. nsps have been involved in the host innate immune response, specifically, nsp1α/β, nsp2, nsp4 and nsp11 have been associated with the immunomodulation capability of the virus. To date, only participation by nsp1, nsp2, nsp4 and nsp7 in the humoral immune response has been reported, with the role of other nsps being overlooked. Furthermore, nsp1, nsp2, nsp5, nsp7 nsp9, nsp10, nsp11 have been implicated in the induction of IFN-γ and probably in the development of the cell-mediated immune response. This review discusses recent reports involving the participation of nsps in the modulation of the innate immune response and their role in the induction of both the humoral and cellular immune responses.
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Affiliation(s)
- Edgar Rascón-Castelo
- Laboratorio de Inmunología, Centro de Investigación en Alimentación y Desarrollo A.C (CIAD) Carretera a la Victoria Km 0.6, C.P. 83304 Hermosillo, Sonora, Mexico.
| | - Alexel Burgara-Estrella
- Laboratorio de Inmunología, Centro de Investigación en Alimentación y Desarrollo A.C (CIAD) Carretera a la Victoria Km 0.6, C.P. 83304 Hermosillo, Sonora, Mexico.
| | - Enric Mateu
- Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
- Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
| | - Jesús Hernández
- Laboratorio de Inmunología, Centro de Investigación en Alimentación y Desarrollo A.C (CIAD) Carretera a la Victoria Km 0.6, C.P. 83304 Hermosillo, Sonora, Mexico.
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Li Y, Tas A, Sun Z, Snijder EJ, Fang Y. Proteolytic processing of the porcine reproductive and respiratory syndrome virus replicase. Virus Res 2014; 202:48-59. [PMID: 25557977 DOI: 10.1016/j.virusres.2014.12.027] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/19/2014] [Accepted: 12/22/2014] [Indexed: 01/16/2023]
Abstract
The porcine reproductive and respiratory syndrome virus (PRRSV) replicase polyproteins pp1a and pp1ab are proteolytically processed by four proteases encoded in ORF1a. In this study, a large set of PRRSV replicase cleavage products were identified and pp1a cleavage sites were verified by using a combination of bioinformatics, proteomics, immunoprecipitation, and site-directed mutagenesis. For genotype 1 PRRSV (isolate SD01-08), proteomic analysis identified H180/S181, G385/A386, and G1446/A1447 as the cleavage sites separating nsp1α/1β, nsp1β/nsp2, and nsp2/nsp3, respectively. Transient expression of nsp2-8, nsp3-8, nsp4-8, nsp5-8 (using the recombinant vaccinia virus/T7 RNA polymerase system) and immunoprecipitation identified the cleavage end products nsp2, nsp3, nsp4, nsp7α and nsp7β, and various processing intermediates. Our studies also revealed the existence of alternative proteolytic processing pathways for the processing of the nsp3-8 region, depending on the presence or absence of nsp2 as a co-factor. The identity of most cleavage products was further corroborated by site-directed mutagenesis of individual cleavage sites in constructs expressing nsp3-8 or nsp4-8. This study constitutes the first in-depth experimental analysis of PRRSV replicase processing and the data are discussed against the background of the processing scheme previously derived for the arterivirus prototype, the distantly related equine arteritis virus (EAV). Despite several differences between the two viruses, of which the functional significance remains to be studied, our study demonstrates the general conservation of the replicase pp1a processing scheme between EAV and PRRSV, and likely also the other members of the arterivirus family.
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Affiliation(s)
- Yanhua Li
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, USA; Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Ali Tas
- Department of Medical Microbiology, Center for Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Zhi Sun
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, USA
| | - Eric J Snijder
- Department of Medical Microbiology, Center for Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands.
| | - Ying Fang
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, USA; Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
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