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Castells M, Benítez-Galeano MJ, Marandino A, Caffarena RD, Casaux ML, Pérez R, Giannitti F, Colina R. Detection and Genetic Characterization of Bovine Torovirus in Uruguay. Viruses 2024; 16:835. [PMID: 38932127 PMCID: PMC11209243 DOI: 10.3390/v16060835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 05/20/2024] [Accepted: 05/20/2024] [Indexed: 06/28/2024] Open
Abstract
Bovine torovirus (BToV) is an enteric pathogen that may cause diarrhea in calves and adult cattle, which could result in economic losses due to weight loss and decreased milk production. This study aimed to report the presence, the genetic characterization and the evolution of BToV in calves in Uruguay. BToV was detected in 7.9% (22/278) of fecal samples, being identified in dairy (9.2%, 22/239) but not beef (0.0%, 0/39) calves. BToV was detected in both diarrheic (14%, 6/43) and non-diarrheic (13.2%, 5/38) dairy calves. In addition, BToV was detected in the intestinal contents of 14.9% (7/47) of naturally deceased dairy calves. A complete genome (28,446 nucleotides) was obtained, which was the second outside Asia and the first in Latin America. In addition, partial S gene sequences were obtained to perform evolutionary analyses. Nucleotide and amino acid substitutions within and between outbreaks/farms were observed, alerting the continuous evolution of the virus. Through Bayesian analysis using BEAST, a recent origin (mid-60s) of BToV, possibly in Asia, was estimated, with two introductions into Uruguay from Asia and Europe in 2004 and 2013, respectively. The estimated evolutionary rate was 1.80 × 10-3 substitutions/site/year. Our findings emphasize the importance of continued surveillance and genetic characterization for the effective management and understanding of BToV's global epidemiology and evolution.
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Affiliation(s)
- Matías Castells
- Laboratorio de Virología Molecular, Departamento de Ciencias Biológicas, Centro Universitario Regional (CENUR) Litoral Norte, Universidad de la República, Salto 50000, Uruguay
| | - María José Benítez-Galeano
- Unidad de Genómica y Bioinformática, Departamento de Ciencias Biológicas, Centro Universitario Regional (CENUR) Litoral Norte, Universidad de la República, Salto 50000, Uruguay
| | - Ana Marandino
- Sección Genética Evolutiva, Departamento de Biología Animal, Instituto de Biología, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay
| | - Rubén Darío Caffarena
- Plataforma de Investigación en Salud Animal, Estación Experimental La Estanzuela, Instituto Nacional de Investigación Agropecuaria (INIA), Colonia 70006, Uruguay
- Unidad Académica Salud de Rumiantes, Departamento de Producción y Salud de los Sistemas Productivos, Facultad de Veterinaria, Universidad de la República, Montevideo 13000, Uruguay
| | - María Laura Casaux
- Plataforma de Investigación en Salud Animal, Estación Experimental La Estanzuela, Instituto Nacional de Investigación Agropecuaria (INIA), Colonia 70006, Uruguay
| | - Ruben Pérez
- Sección Genética Evolutiva, Departamento de Biología Animal, Instituto de Biología, Facultad de Ciencias, Universidad de la República, Montevideo 11400, Uruguay
| | - Federico Giannitti
- Plataforma de Investigación en Salud Animal, Estación Experimental La Estanzuela, Instituto Nacional de Investigación Agropecuaria (INIA), Colonia 70006, Uruguay
| | - Rodney Colina
- Laboratorio de Virología Molecular, Departamento de Ciencias Biológicas, Centro Universitario Regional (CENUR) Litoral Norte, Universidad de la República, Salto 50000, Uruguay
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Liao Y, Wang H, Liao H, Sun Y, Tan L, Song C, Qiu X, Ding C. Classification, replication, and transcription of Nidovirales. Front Microbiol 2024; 14:1291761. [PMID: 38328580 PMCID: PMC10847374 DOI: 10.3389/fmicb.2023.1291761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 11/06/2023] [Indexed: 02/09/2024] Open
Abstract
Nidovirales is one order of RNA virus, with the largest single-stranded positive sense RNA genome enwrapped with membrane envelope. It comprises four families (Arterividae, Mesoniviridae, Roniviridae, and Coronaviridae) and has been circulating in humans and animals for almost one century, posing great threat to livestock and poultry,as well as to public health. Nidovirales shares similar life cycle: attachment to cell surface, entry, primary translation of replicases, viral RNA replication in cytoplasm, translation of viral proteins, virion assembly, budding, and release. The viral RNA synthesis is the critical step during infection, including genomic RNA (gRNA) replication and subgenomic mRNAs (sg mRNAs) transcription. gRNA replication requires the synthesis of a negative sense full-length RNA intermediate, while the sg mRNAs transcription involves the synthesis of a nested set of negative sense subgenomic intermediates by a discontinuous strategy. This RNA synthesis process is mediated by the viral replication/transcription complex (RTC), which consists of several enzymatic replicases derived from the polyprotein 1a and polyprotein 1ab and several cellular proteins. These replicases and host factors represent the optimal potential therapeutic targets. Hereby, we summarize the Nidovirales classification, associated diseases, "replication organelle," replication and transcription mechanisms, as well as related regulatory factors.
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Affiliation(s)
- Ying Liao
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Huan Wang
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Huiyu Liao
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Yingjie Sun
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Lei Tan
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Cuiping Song
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Xusheng Qiu
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Chan Ding
- Department of Avian Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
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Ávila-Pérez G, Rejas MT, Chichón FJ, Guerra M, Fernández JJ, Rodríguez D. Architecture of torovirus replicative organelles. Mol Microbiol 2021; 117:837-850. [PMID: 34967475 DOI: 10.1111/mmi.14875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 11/29/2022]
Abstract
Plus-stranded RNA viruses replicate in the cytosol of infected cells, in membrane-bound replication complexes. We previously identified double membrane vesicles (DMVs) in the cytoplasm of cells infected with Berne virus (BEV), the prototype member of Torovirus genus (Nidovirales Order). Our previous analysis by transmission electron microscopy suggested that the DMVs form a reticulovesicular network (RVN) analogous those described for the related severe acute respiratory syndrome coronavirus (SARS-CoV-1). Here, we used serial sectioning and electron tomography to characterize the architecture of torovirus replication organelles, and to learn about their biogenesis and dynamics during the infection. The formation of a RVN in BEV infected cells was confirmed, where the outer membranes of the DMVs are interconnected with each other and with the ER. Paired or zippered ER membranes connected with the DMVs were also observed, and likely represent early structures that evolve to give rise to DMVs. Also, paired membranes forming small spherule-like invaginations were observed at late time post-infection. Although resembling in size, the tomographic analysis show that these structures are clearly different from the true spherules described previously for coronaviruses. Hence, BEV shows important similarities, but also some differences, in the architecture of the replication organelles with other nidoviruses.
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Affiliation(s)
- Ginés Ávila-Pérez
- Department of Molecular and Cellular Biology, Centro de Biología Molecular Severo Ochoa, CSIC, C/Nicolás Cabrera 1, 28049, Madrid, Spain
| | - María Teresa Rejas
- Servicio de Microscopía Electrónica, Centro de Biología Molecular Severo Ochoa, CSIC, C/Nicolás Cabrera 1, 28049, Madrid, Spain
| | - Francisco Javier Chichón
- Servicio de Criomicroscopía Electrónica (cryoEM-CSIC) and Department of Macromolecular Structures, Centro Nacional de Biotecnología, CSIC, C/Darwin 3, 28049, Madrid, Spain
| | - Milagros Guerra
- Servicio de Microscopía Electrónica, Centro de Biología Molecular Severo Ochoa, CSIC, C/Nicolás Cabrera 1, 28049, Madrid, Spain
| | - José Jesús Fernández
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), CINN-CSIC, Av Hospital Universitario s/n, 33011, Oviedo, Spain
| | - Dolores Rodríguez
- Department of Molecular and Cellular Biology, Centro de Biología Molecular Severo Ochoa, CSIC, C/Nicolás Cabrera 1, 28049, Madrid, Spain
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Abstract
Historically part of the coronavirus (CoV) family, torovirus (ToV) was recently classified into the new family Tobaniviridae. While reverse genetics systems have been established for various CoVs, none exist for ToVs. Herein, we developed a reverse genetics system using an infectious full-length cDNA clone of bovine ToV (BToV) in a bacterial artificial chromosome (BAC). Recombinant BToV harboring genetic markers had the same phenotype as wild-type (wt) BToV. To generate two types of recombinant virus, the hemagglutinin-esterase (HE) gene was edited, as cell-adapted wtBToV generally loses full-length HE (HEf), resulting in soluble HE (HEs). First, recombinant viruses with HEf and HA-tagged HEf or HEs genes were rescued. These exhibited no significant differences in their effect on virus growth in HRT18 cells, suggesting that HE is not essential for viral replication in these cells. Thereafter, we generated recombinant virus (rEGFP), wherein HE was replaced by the enhanced green fluorescent protein (EGFP) gene. The rEGFP expressed EGFP in infected cells, but showed significantly lower viral growth compared to wtBToV. Moreover, the rEGFP readily deleted the EGFP gene after one passage. Interestingly, rEGFP variants with two mutations (C1442F and I3562T) in non-structural proteins (NSPs) that emerged during passages exhibited improved EGFP expression, EGFP gene retention, and viral replication. An rEGFP into which both mutations were introduced displayed a similar phenotype to these variants, suggesting that the mutations contributed to EGFP gene acceptance. The current findings provide new insights into BToV, and reverse genetics will help advance the current understanding of this neglected pathogen. Importance ToVs are diarrhea-causing pathogens detected in various species, including humans. Through the development of a BAC-based BToV, we introduced the first reverse genetics system for Tobaniviridae. Utilizing this system, recombinant BToVs with a full-length HE gene were generated. Remarkably, although clinical BToVs generally lose the HE gene after a few passages, some recombinant viruses generated in the current study retained the HE gene for up to 20 passages while accumulating mutations in NSPs, which suggested that these mutations may be involved in HE gene retention. The EGFP gene of recombinant viruses was unstable, but rEGFP into which two NSP mutations were introduced exhibited improved EGFP expression, gene retention, and viral replication. These data suggested the existence of an NSP-based acceptance or retention mechanism for exogenous RNA or HE genes. Recombinant BToVs and reverse genetics are powerful tools for understanding fundamental viral processes, infection pathogenesis, and BToV vaccine development.
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Parrish K, Kirkland PD, Skerratt LF, Ariel E. Nidoviruses in Reptiles: A Review. Front Vet Sci 2021; 8:733404. [PMID: 34621811 PMCID: PMC8490724 DOI: 10.3389/fvets.2021.733404] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/19/2021] [Indexed: 12/17/2022] Open
Abstract
Since their discovery in 2014, reptile nidoviruses (also known as serpentoviruses) have emerged as significant pathogens worldwide. They are known for causing severe and often fatal respiratory disease in various captive snake species, especially pythons. Related viruses have been detected in other reptiles with and without respiratory disease, including captive and wild populations of lizards, and wild populations of freshwater turtles. There are many opportunities to better understand the viral diversity, species susceptibility, and clinical presentation in different species in this relatively new field of research. In captive snake collections, reptile nidoviruses can spread quickly and be associated with high morbidity and mortality, yet the potential disease risk to wild reptile populations remains largely unknown, despite reptile species declining on a global scale. Experimental studies or investigations of disease outbreaks in wild reptile populations are scarce, leaving the available literature limited mostly to exploring findings of naturally infected animals in captivity. Further studies into the pathogenesis of different reptile nidoviruses in a variety of reptile species is required to explore the complexity of disease and routes of transmission. This review focuses on the biology of these viruses, hosts and geographic distribution, clinical signs and pathology, laboratory diagnosis and management of reptile nidovirus infections to better understand nidovirus infections in reptiles.
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Affiliation(s)
- Kate Parrish
- Virology Laboratory, Elizabeth Macarthur Agricultural Institute, New South Wales (NSW) Department of Primary Industries, Menangle, NSW, Australia.,College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
| | - Peter D Kirkland
- Virology Laboratory, Elizabeth Macarthur Agricultural Institute, New South Wales (NSW) Department of Primary Industries, Menangle, NSW, Australia.,College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
| | - Lee F Skerratt
- Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Melbourne, VIC, Australia
| | - Ellen Ariel
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
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Dai X, Lu S, Shang G, Zhu W, Yang J, Liu L, Xu J. Characterization and Identification of a Novel Torovirus Associated With Recombinant Bovine Torovirus From Tibetan Antelope in Qinghai-Tibet Plateau of China. Front Microbiol 2021; 12:737753. [PMID: 34552576 PMCID: PMC8451951 DOI: 10.3389/fmicb.2021.737753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/10/2021] [Indexed: 11/25/2022] Open
Abstract
Toroviruses (ToVs) are enteric pathogens and comprise three species, equine torovirus (EToV), bovine torovirus (BToV), and porcine torovirus (PToV). In this study, a novel torovirus (antelope torovirus, AToV) was discovered from fecal samples of Tibetan antelopes (Pantholops hodgsonii) with viral loads of 2.10×109 to 1.76×1010 copies/g. The genome of AToV is 28,438 nucleotides (nt) in length encoding six open reading frames (ORFs) with 11 conserved domains in pp1ab and a putative slippery sequence (14171UUUAAAC14177) in the overlapping region of ORF1a and ORF1b. Phylogenetic analysis illustrated strains of AToV form a unique clade within ToVs and comparative analysis showed AToV share relatively low sequence identity with other ToVs in six ORFs (68.2–91.6% nucleotide identity). These data suggested that AToV represents a novel and distinct species of ToVs. Based on the M genes, evolutionary analysis with BEAST of AToV and other ToVs led to a most recent common ancestor estimate of 366years ago. Remarkably, recombination analysis revealed AToV was the unknown parental ToV that once involving in the recombinant events of HE genes of two Dutch strains of BToV (B150 and B155), which indicated that AToV occurred cross-species transmission and existed both in the Netherlands and China. This study revealed a novel torovirus, a natural reservoir host (Tibetan antelope) of toroviruses for the first time, and appealed to further related studies to better understand the diversity of toroviruses.
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Affiliation(s)
- Xiaoyi Dai
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, China.,State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Shan Lu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.,Shanghai Public Health Clinical Center, Fudan University, Shanghai, China.,Research Units of Discovery of Unknown Bacteria and Function, Chinese Academy of Medical Sciences, Beijing, China
| | - Guobao Shang
- Haixi Prefecture Center for Disease Control and Prevention, Qinghai, China
| | - Wentao Zhu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jing Yang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.,Shanghai Public Health Clinical Center, Fudan University, Shanghai, China.,Research Units of Discovery of Unknown Bacteria and Function, Chinese Academy of Medical Sciences, Beijing, China
| | - Liyun Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jianguo Xu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.,Shanghai Public Health Clinical Center, Fudan University, Shanghai, China.,Research Units of Discovery of Unknown Bacteria and Function, Chinese Academy of Medical Sciences, Beijing, China
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Abstract
Livestock products supply about 13 percent of energy and 28 percent of protein in diets consumed worldwide. Diarrhea is a leading cause of sickness and death of beef and dairy calves in their first month of life and also affecting adult cattle, resulting in large economic losses and a negative impact on animal welfare. Despite the usual multifactorial origin, viruses are generally involved, being among the most important causes of diarrhea. There are several viruses that have been confirmed as etiological agents (i.e., rotavirus and coronavirus), and some viruses that are not yet confirmed as etiological agents. This review summarizes the viruses that have been detected in the enteric tract of cattle and tries to deepen and gather knowledge about them.
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8
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Zhao L, Shao G, Tang C, Yue H. Development and use of a reverse transcription insulated isothermal PCR assay for detection and characterization of bovine torovirus in yaks. Arch Virol 2021; 166:2017-2025. [PMID: 33881617 PMCID: PMC8058584 DOI: 10.1007/s00705-021-05047-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/05/2021] [Indexed: 11/25/2022]
Abstract
Bovine torovirus (BToV) is an important diarrhea-causing pathogen affecting bovines. To facilitate BToV detection, a reverse transcription insulated isothermal PCR (RT-iiPCR) assay was developed that targets the BToV M gene with high specificity and reproducibility. The assay has a limit of detection of 23 copies/μL. Out of 69 diarrheic fecal samples from yaks collected on six farms in Tibet and Sichuan provinces in China, 11.59% (8/69) tested positive for BToV using this assay. The full-length spike (S) and hemagglutinin-esterase (HE) genes of three positive samples were subsequently sequenced. Notably, an identical recombination event was identified in the S1 subunit of the S protein of three isolates. All of the HE genes were found to belong to genotype III and shared the same unique aa variation (P44S) in the esterase domain. This study is the first confirmation of BToV in yaks and the first report of an S gene recombination event in BToV. Our findings will enhance the current understanding of the molecular characteristics and genetic evolution of BToV.
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Affiliation(s)
- Long Zhao
- College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu, China
| | - Guoqing Shao
- College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu, China
| | - Cheng Tang
- College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu, China.,Key Laboratory of Veterinary Medicine of Universities of Sichuan Province, Chengdu, China
| | - Hua Yue
- College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu, China. .,Key Laboratory of Veterinary Medicine of Universities of Sichuan Province, Chengdu, China. .,Key Laboratory of Qinghai Tibetan Plateau Animal Genetic Resource Reservation and Utilization, College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu, 610041, China.
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Ujike M, Taguchi F. Recent Progress in Torovirus Molecular Biology. Viruses 2021; 13:435. [PMID: 33800523 PMCID: PMC7998386 DOI: 10.3390/v13030435] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/24/2021] [Accepted: 02/24/2021] [Indexed: 11/16/2022] Open
Abstract
Torovirus (ToV) has recently been classified into the new family Tobaniviridae, although it belonged to the Coronavirus (CoV) family historically. ToVs are associated with enteric diseases in animals and humans. In contrast to CoVs, which are recognised as pathogens of veterinary and medical importance, little attention has been paid to ToVs because their infections are usually asymptomatic or not severe; for a long time, only one equine ToV could be propagated in cultured cells. However, bovine ToVs, which predominantly cause diarrhoea in calves, have been detected worldwide, leading to economic losses. Porcine ToVs have also spread globally; although they have not caused serious economic losses, coinfections with other pathogens can exacerbate their symptoms. In addition, frequent inter- or intra-recombination among ToVs can increase pathogenesis or unpredicted host adaptation. These findings have highlighted the importance of ToVs as pathogens and the need for basic ToV research. Here, we review recent progress in the study of ToV molecular biology including reverse genetics, focusing on the similarities and differences between ToVs and CoVs.
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Affiliation(s)
- Makoto Ujike
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan;
- Research Center for Animal Life Science, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan
| | - Fumihiro Taguchi
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan;
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Ujike M, Kawachi Y, Matsunaga Y, Etho Y, Asanuma H, Kamitani W, Taguchi F. Characterization of Localization and Export Signals of Bovine Torovirus Nucleocapsid Protein Responsible for Extensive Nuclear and Nucleolar Accumulation and Their Importance for Virus Growth. J Virol 2021; 95:e02111-20. [PMID: 33177195 PMCID: PMC7925113 DOI: 10.1128/jvi.02111-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 11/20/2022] Open
Abstract
Torovirus (ToV) has recently been classified into the new family Tobaniviridae, although historically, it belonged to the Coronavirus (CoV) family. The nucleocapsid (N) proteins of CoVs are predominantly localized in the cytoplasm, where the viruses replicate, but in some cases the proteins are partially located in the nucleolus. Many studies have investigated the subcellular localization and nucleocytoplasmic trafficking signals of the CoV N proteins, but little is known about ToV N proteins. Here, we studied the subcellular localization of the bovine ToV (BToV) N protein (BToN) and characterized its nucleocytoplasmic trafficking signals. Unlike other CoVs, BToN in infected cells was transported mainly to the nucleolus during early infection but was distributed predominantly in the nucleoplasm rather than in the nucleolus during late infection. Interestingly, a small quantity of BToN was detected in the cytoplasm during infection. Examination of a comprehensive set of substitution or deletion mutants of BToN fused with enhanced green fluorescent protein (EGFP) revealed that clusters of arginine (R) residues comprise nuclear/nucleolar localization signals (NLS/NoLS), and the C-terminal region served as a chromosomal maintenance 1 (CRM1)-independent nuclear export signal (NES). Moreover, recombinant viruses with mutations in the NLS/NoLS, but retaining nuclear accumulation, were successfully rescued and showed slightly reduced growth ability, while the virus that lost the NLS/NoLS-mediated nuclear accumulation of BToN was not rescued. These results indicate that BToN uniquely accumulates mainly in nuclear compartments during infection, regulated by an R-rich NLS/NoLS and a CRM1-independent NES, and that the BToN accumulation in the nuclear compartment driven by NLS/NoLS is important for virus growth.IMPORTANCE ToVs are diarrhea-causing pathogens detected in many species, including humans. BToV has spread worldwide, leading to economic loss, and there is currently no treatment or vaccine available. Positive-stranded RNA viruses, including ToVs, replicate in the cytoplasm, and their structural proteins generally accumulate in the cytoplasm. Interestingly, BToN accumulated predominantly in the nucleus/nucleolus during all infectious processes, with only a small fraction accumulating in the cytoplasm despite being a major structural protein. Furthermore, we identified unique nucleocytoplasmic trafficking signals and demonstrated the importance of NLS/NoLS for virus growth. This study is the first to undertake an in-depth investigation of the subcellular localization and intracellular trafficking signals of BToN. Our findings additionally suggest that the NLS/NoLS-mediated nuclear accumulation of BToN is important for virus replication. An understanding of the unique features of BToV may provide novel insights into the assembly mechanisms of not only ToVs but also other positive-stranded RNA viruses.
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Affiliation(s)
- Makoto Ujike
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
- Research Center for Animal Life Science, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Yukako Kawachi
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Yui Matsunaga
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Yuka Etho
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Hideki Asanuma
- Influenza Virus Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Wataru Kamitani
- Department of Infectious Diseases and Host Defense, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Fumihiro Taguchi
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
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11
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Faisal HMN, Katti KS, Katti DR. Differences in Interactions Within Viral Replication Complexes of SARS-CoV-2 (COVID-19) and SARS-CoV Coronaviruses Control RNA Replication Ability. JOM (WARRENDALE, PA. : 1989) 2021; 73:1684-1695. [PMID: 33907361 PMCID: PMC8061462 DOI: 10.1007/s11837-021-04662-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/25/2021] [Indexed: 05/04/2023]
Abstract
UNLABELLED COVID-19 has become a global pandemic caused by the SARS-CoV-2 coronavirus. SARS-CoV-2 shares many similarities with SARS coronavirus (SARS-CoV). A viral replication complex containing non-structural proteins (nsps) is the toolbox for RNA replication and transcription of both coronaviruses. In both cases, the RNA-dependent RNA polymerase (RdRp) domain of the coronaviral replication complex dictates the primary polymerase activity by cooperating with cofactors. The higher transmissibility and mortality due to SARS-CoV-2 are related to its higher RNA replication activity compared to SARS-CoV. The discrepancy between the RNA replication efficiency of SARS-CoV and SARS-CoV-2 can be understood by exploring interactions within their viral replication complexes. Our modeling of molecular interactions within the viral replication complexes of SARS-CoV and SARS-CoV-2 using molecular dynamics simulations suggests that in contrast to SARS-CoVnsp12, SARS-CoV2nsp12 prefers helices as the dominant interacting secondary motifs. The relative differences in nonbonded interactions between nsps could suggest viral RNA replication ability in coronaviruses. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11837-021-04662-6.
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Affiliation(s)
- H. M. Nasrullah Faisal
- Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58105 USA
| | - Kalpana S. Katti
- Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58105 USA
- Center for Engineered Cancer Testbeds, North Dakota State University, Fargo, ND 58105 USA
| | - Dinesh R. Katti
- Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58105 USA
- Center for Engineered Cancer Testbeds, North Dakota State University, Fargo, ND 58105 USA
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Characterization of Self-Processing Activities and Substrate Specificities of Porcine Torovirus 3C-Like Protease. J Virol 2020; 94:JVI.01282-20. [PMID: 32727876 DOI: 10.1128/jvi.01282-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 07/24/2020] [Indexed: 12/17/2022] Open
Abstract
The 3C-like protease (3CLpro) of nidovirus plays an important role in viral replication and manipulation of host antiviral innate immunity, which makes it an ideal antiviral target. Here, we characterized that porcine torovirus (PToV; family Tobaniviridae, order Nidovirales) 3CLpro autocatalytically releases itself from the viral precursor protein by self-cleavage. Site-directed mutagenesis suggested that PToV 3CLpro, as a serine protease, employed His53 and Ser160 as the active-site residues. Interestingly, unlike most nidovirus 3CLpro, the P1 residue plays a less essential role in N-terminal self-cleavage of PToV 3CLpro Substituting either P1 or P4 residue of substrate alone has little discernible effect on N-terminal cleavage. Notably, replacement of the two residues together completely blocks N-terminal cleavage, suggesting that N-terminal self-cleavage of PToV 3CLpro is synergistically affected by both P1 and P4 residues. Using a cyclized luciferase-based biosensor, we systematically scanned the polyproteins for cleavage sites and identified (FXXQ↓A/S) as the main consensus sequences. Subsequent homology modeling and biochemical experiments suggested that the protease formed putative pockets S1 and S4 between the substrate. Indeed, mutants of both predicted S1 (D159A, H174A) and S4 (P62G/L185G) pockets completely lost the ability of cleavage activity of PToV 3CLpro In conclusion, the characterization of self-processing activities and substrate specificities of PToV 3CLpro will offer helpful information for the mechanism of nidovirus 3C-like proteinase's substrate specificities and the rational development of the antinidovirus drugs.IMPORTANCE Currently, the active-site residues and substrate specificities of 3C-like protease (3CLpro) differ among nidoviruses, and the detailed catalytic mechanism remains largely unknown. Here, porcine torovirus (PToV) 3CLpro cleaves 12 sites in the polyproteins, including its N- and C-terminal self-processing sites. Unlike coronaviruses and arteriviruses, PToV 3CLpro employed His53 and Ser160 as the active-site residues that recognize a glutamine (Gln) at the P1 position. Surprisingly, mutations of P1-Gln impaired the C-terminal self-processing but did not affect N-terminal self-processing. The "noncanonical" substrate specificity for its N-terminal self-processing was attributed to the phenylalanine (Phe) residue at the P4 position in the N-terminal site. Furthermore, a double glycine (neutral) substitution at the putative P4-Phe-binding residues (P62G/L185G) abolished the cleavage activity of PToV 3CLpro suggested the potential hydrophobic force between the PToV 3CLpro and P4-Phe side chains.
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13
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Serpentoviruses: More than Respiratory Pathogens. J Virol 2020; 94:JVI.00649-20. [PMID: 32641481 DOI: 10.1128/jvi.00649-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 07/02/2020] [Indexed: 12/27/2022] Open
Abstract
In recent years, nidoviruses have emerged as important respiratory pathogens of reptiles, affecting captive python populations. In pythons, nidovirus (recently reclassified as serpentovirus) infection induces an inflammation of the upper respiratory and alimentary tract which can develop into a severe, often fatal proliferative pneumonia. We observed pyogranulomatous and fibrinonecrotic lesions in organ systems other than the respiratory tract during full postmortem examinations on 30 serpentovirus reverse transcription-PCR (RT-PCR)-positive pythons of varying species originating from Switzerland and Spain. The observations prompted us to study whether this not yet reported wider distribution of lesions is associated with previously unknown serpentoviruses or changes in the serpentovirus genome. RT-PCR and inoculation of Morelia viridis cell cultures served to recruit the cases and obtain virus isolates. Immunohistochemistry and immunofluorescence staining against serpentovirus nucleoprotein demonstrated that the virus infects not only a broad spectrum of epithelia (respiratory and alimentary epithelium, hepatocytes, renal tubules, pancreatic ducts, etc.), but also intravascular monocytes, intralesional macrophages, and endothelial cells. With next-generation sequencing we obtained a full-length genome for a novel serpentovirus species circulating in Switzerland. Analysis of viral genomes recovered from pythons showing serpentovirus infection-associated respiratory or systemic disease did not reveal sequence association to phenotypes; however, functional studies with different strains are needed to confirm this observation. The results indicate that serpentoviruses have a broad cell and tissue tropism, further suggesting that the course of infection could vary and involve lesions in a broad spectrum of tissues and organ systems as a consequence of monocyte-mediated viral systemic spread.IMPORTANCE During the last years, python nidoviruses (now reclassified as serpentoviruses) have become a primary cause of fatal disease in pythons. Serpentoviruses represent a threat to captive snake collections, as they spread rapidly and can be associated with high morbidity and mortality. Our study indicates that, different from previous evidence, the viruses do not only affect the respiratory tract, but can spread in the entire body with blood monocytes, have a broad spectrum of target cells, and can induce a variety of lesions. Nidovirales is an order of animal and human viruses that comprises important zoonotic pathogens such as Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and SARS-CoV-2. Serpentoviruses belong to the same order as the above-mentioned human viruses and show similar characteristics (rapid spread, respiratory and gastrointestinal tropism, etc.). The present study confirms the relevance of natural animal diseases to better understand the complexity of viruses of the order Nidovirales.
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Shi Z, Wang W, Chen C, Zhang X, Wang J, Xu Z, Lan Y. First report and genetic characterization of bovine torovirus in diarrhoeic calves in China. BMC Vet Res 2020; 16:272. [PMID: 32758221 PMCID: PMC7404080 DOI: 10.1186/s12917-020-02494-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 07/27/2020] [Indexed: 01/03/2023] Open
Abstract
Background Coronaviruses are notorious pathogens that cause diarrheic and respiratory diseases in humans and animals. Although the epidemiology and pathogenicity of coronaviruses have gained substantial attention, little is known about bovine coronavirus in cattle, which possesses a close relationship with human coronavirus. Bovine torovirus (BToV) is a newly identified relevant pathogen associated with cattle diarrhoea and respiratory diseases, and its epidemiology in the Chinese cattle industry remains unknown. Results In this study, a total of 461 diarrhoeic faecal samples were collected from 38 different farms in three intensive cattle farming regions and analysed. Our results demonstrated that BToV is present in China, with a low prevalence rate of 1.74% (8/461). The full-length spike genes were further cloned from eight clinical samples (five farms in Henan Province). Phylogenetic analysis showed that two different subclades of BToV strains are circulating in China. Meanwhile, the three BToV strains identified from dairy calves, 18,307, 2YY and 5YY, all contained the amino acid variants R614Q, I801T, N841S and Q885E. Conclusions This is the first report to confirm the presence of BToV in beef and dairy calves in China with diarrhea, which extend our understanding of the epidemiology of BToVs worldwide.
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Affiliation(s)
- Zhihai Shi
- Institute of Animal Husbandry and Veterinary Medicine, Henan Academy of Agricultural Sciences, Zhengzhou, 450002, Henan, China.,Henan Key Laboratory of Farm Animal Breeding and Nutritional Regulation, Zhengzhou, 450002, Henan, China
| | - Wenjia Wang
- College of Veterinary Medicine and Pharmaceutical Engineering, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, Henan, China
| | - Chaoxi Chen
- College of Life Science and Technology, Southwest University for Nationalities, Chengdu, 610041, Sichuan, China
| | - Xiaozhan Zhang
- College of Veterinary Medicine and Pharmaceutical Engineering, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, Henan, China.
| | - Jing Wang
- Institute of Animal Husbandry and Veterinary Medicine, Henan Academy of Agricultural Sciences, Zhengzhou, 450002, Henan, China
| | - Zhaoxue Xu
- Institute of Animal Husbandry and Veterinary Medicine, Henan Academy of Agricultural Sciences, Zhengzhou, 450002, Henan, China.,Henan Key Laboratory of Farm Animal Breeding and Nutritional Regulation, Zhengzhou, 450002, Henan, China
| | - Yali Lan
- Institute of Animal Husbandry and Veterinary Medicine, Henan Academy of Agricultural Sciences, Zhengzhou, 450002, Henan, China.
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15
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Li H, Zhang B, Yue H, Tang C. First detection and genomic characteristics of bovine torovirus in dairy calves in China. Arch Virol 2020; 165:1577-1583. [PMID: 32388597 PMCID: PMC7210800 DOI: 10.1007/s00705-020-04657-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/12/2020] [Indexed: 12/22/2022]
Abstract
Bovine torovirus (BToV) is a diarrhea-causing pathogen. In this study, 92 diarrheic fecal samples from five farms in four provinces in China were collected and tested for BToV using a RT-PCR assay, and 21.73% samples were found to be BToV positive. Moreover, two complete BToV genome sequences (MN073058 and MN073059) were obtained from the clinical samples, which were 28,297 and 28,301 nucleotides in length, respectively. Sequence analysis showed that the two isolates shared 10 identical amino acid mutations in the S protein compared to the complete S sequences of BToV available in the GenBank database. In addition, seven consecutive amino acid mutations were found from aa 1,486 to 1,492 in the S protein of isolate MN073058. Moreover, the two isolates shared one identical amino acid mutation in the receptor binding sites of the HE protein. To the best of our knowledge, this is the first report on the epidemic and genomic characterization of BToV in China, which is helpful for further understanding the genetic evolution of BToV.
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Affiliation(s)
- Hao Li
- College of Life Science and Technology, Southwest Minzu University, No. 16, South 4th Section 1st Ring Road, Chengdu, 610041, China
| | - Bin Zhang
- College of Life Science and Technology, Southwest Minzu University, No. 16, South 4th Section 1st Ring Road, Chengdu, 610041, China
- Innovation Team of Beef Cattle, Chengdu, Sichuan, China
| | - Hua Yue
- College of Life Science and Technology, Southwest Minzu University, No. 16, South 4th Section 1st Ring Road, Chengdu, 610041, China
| | - Cheng Tang
- College of Life Science and Technology, Southwest Minzu University, No. 16, South 4th Section 1st Ring Road, Chengdu, 610041, China.
- Innovation Team of Beef Cattle, Chengdu, Sichuan, China.
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16
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Blahak S, Jenckel M, Höper D, Beer M, Hoffmann B, Schlottau K. Investigations into the presence of nidoviruses in pythons. Virol J 2020; 17:6. [PMID: 31952524 PMCID: PMC6969405 DOI: 10.1186/s12985-020-1279-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 01/09/2020] [Indexed: 01/17/2023] Open
Abstract
Background Pneumonia and stomatitis represent severe and often fatal diseases in different captive snakes. Apart from bacterial infections, paramyxo-, adeno-, reo- and arenaviruses cause these diseases. In 2014, new viruses emerged as the cause of pneumonia in pythons. In a few publications, nidoviruses have been reported in association with pneumonia in ball pythons and a tiger python. The viruses were found using new sequencing methods from the organ tissue of dead animals. Methods Severe pneumonia and stomatitis resulted in a high mortality rate in a captive breeding collection of green tree pythons. Unbiased deep sequencing lead to the detection of nidoviral sequences. A developed RT-qPCR was used to confirm the metagenome results and to determine the importance of this virus. A total of 1554 different boid snakes, including animals suffering from respiratory diseases as well as healthy controls, were screened for nidoviruses. Furthermore, in addition to two full-length sequences, partial sequences were generated from different snake species. Results The assembled full-length snake nidovirus genomes share only an overall genome sequence identity of less than 66.9% to other published snake nidoviruses and new partial sequences vary between 99.89 and 79.4%. Highest viral loads were detected in lung samples. The snake nidovirus was not only present in diseased animals, but also in snakes showing no typical clinical signs. Conclusions Our findings further highlight the possible importance of snake nidoviruses in respiratory diseases and proof multiple circulating strains with varying disease potential. Nidovirus detection in clinical healthy individuals might represent testing during the incubation period or reconvalescence. Our investigations show new aspects of nidovirus infections in pythons. Nidoviruses should be included in routine diagnostic workup of diseased reptiles.
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Affiliation(s)
- Silvia Blahak
- Chemical and Veterinary Investigation Office, Westerfeldstraße 1, D-32758, Detmold, Germany
| | - Maria Jenckel
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, D-17493, Greifswald-Insel Riems, Germany.,Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, 2601, Australia
| | - Dirk Höper
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, D-17493, Greifswald-Insel Riems, Germany
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, D-17493, Greifswald-Insel Riems, Germany
| | - Bernd Hoffmann
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, D-17493, Greifswald-Insel Riems, Germany
| | - Kore Schlottau
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, D-17493, Greifswald-Insel Riems, Germany.
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17
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Ávila-Pérez G, Diaz-Beneitez E, Cubas-Gaona LL, Nieves-Molina G, Rodríguez JR, Rodríguez JF, Rodríguez D. Activation of the autophagy pathway by Torovirus infection is irrelevant for virus replication. PLoS One 2019; 14:e0219428. [PMID: 31306441 PMCID: PMC6629058 DOI: 10.1371/journal.pone.0219428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 06/24/2019] [Indexed: 11/19/2022] Open
Abstract
Autophagy is a conserved eukaryotic process that mediates lysosomal degradation of cytoplasmic macromolecules and damaged organelles, also exerting an important role in the elimination of intracellular pathogens. Despite the antiviral role of autophagy, many studies suggest that some positive-stranded RNA viruses exploit this pathway to facilitate their own replication. In this study, we demonstrate that the equine torovirus Berne virus (BEV), the prototype member of the Torovirus genus (Coronaviridae Family, Nidovirales Order), induces autophagy at late times post-infection. Conversion of microtubule associated protein 1B light chain 3 (LC3) from cytosolic (LC3 I) to the membrane associated form (LC3 II), a canonical marker of autophagosome formation, is enhanced in BEV infected cells. However, neither autophagy induction, via starvation, nor pharmacological blockade significantly affect BEV replication. Similarly, BEV infection is not altered in autophagy deficient cells lacking either Beclin 1 or LC3B protein expression. Unexpectedly, the cargo receptor p62, a selective autophagy receptor, aggregates within the region where the BEV main protease (Mpro) localizes. This finding, coupled with observation that BEV replication also induces ER stress at the time when selective autophagy is taking place, suggests that the autophagy pathway is activated in response to the hefty accumulation of virus-encoded polypeptides during the late phase of BEV infection.
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Affiliation(s)
- Ginés Ávila-Pérez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin, Madrid, Spain
| | - Elisabet Diaz-Beneitez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin, Madrid, Spain
| | - Liliana L. Cubas-Gaona
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin, Madrid, Spain
| | - Gliselle Nieves-Molina
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin, Madrid, Spain
| | | | - José F. Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin, Madrid, Spain
| | - Dolores Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin, Madrid, Spain
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Abstract
Hepatitis E virus (HEV) possesses many of the features of other positive-stranded RNA viruses but also adds HEV-specific nuances, making its virus-host interactions unique. Slow virus replication kinetics and fastidious growth conditions, coupled with the historical lack of an efficient cell culture system to propagate the virus, have left many gaps in our understanding of its structure and replication cycle. Recent advances in culturing selected strains of HEV and resolving the 3D structure of the viral capsid are filling in knowledge gaps, but HEV remains an extremely understudied pathogen. Many steps in the HEV life cycle and many aspects of HEV pathogenesis remain unknown, such as the host and viral factors that determine cross-species infection, the HEV-specific receptor(s) on host cells, what determines HEV chronicity and the ability to replicate in extrahepatic sites, and what regulates processing of the open reading frame 1 (ORF1) nonstructural polyprotein.
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Affiliation(s)
- Scott P Kenney
- Food Animal Health Research Program, The Ohio State University, Wooster, Ohio 44691
| | - Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
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19
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Stewart H, Brown K, Dinan AM, Irigoyen N, Snijder EJ, Firth AE. Transcriptional and Translational Landscape of Equine Torovirus. J Virol 2018; 92:e00589-18. [PMID: 29950409 PMCID: PMC6096809 DOI: 10.1128/jvi.00589-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/13/2018] [Indexed: 12/15/2022] Open
Abstract
The genus Torovirus (subfamily Torovirinae, family Coronaviridae, order Nidovirales) encompasses a range of species that infect domestic ungulates, including cattle, sheep, goats, pigs, and horses, causing an acute self-limiting gastroenteritis. Using the prototype species equine torovirus (EToV), we performed parallel RNA sequencing (RNA-seq) and ribosome profiling (Ribo-seq) to analyze the relative expression levels of the known torovirus proteins and transcripts, chimeric sequences produced via discontinuous RNA synthesis (a characteristic of the nidovirus replication cycle), and changes in host transcription and translation as a result of EToV infection. RNA sequencing confirmed that EToV utilizes a unique combination of discontinuous and nondiscontinuous RNA synthesis to produce its subgenomic RNAs (sgRNAs); indeed, we identified transcripts arising from both mechanisms that would result in sgRNAs encoding the nucleocapsid. Our ribosome profiling analysis revealed that ribosomes efficiently translate two novel CUG-initiated open reading frames (ORFs), located within the so-called 5' untranslated region. We have termed the resulting proteins U1 and U2. Comparative genomic analysis confirmed that these ORFs are conserved across all available torovirus sequences, and the inferred amino acid sequences are subject to purifying selection, indicating that U1 and U2 are functionally relevant. This study provides the first high-resolution analysis of transcription and translation in this neglected group of livestock pathogens.IMPORTANCE Toroviruses infect cattle, goats, pigs, and horses worldwide and can cause gastrointestinal disease. There is no treatment or vaccine, and their ability to spill over into humans has not been assessed. These viruses are related to important human pathogens, including severe acute respiratory syndrome (SARS) coronavirus, and they share some common features; however, the mechanism that they use to produce sgRNA molecules differs. Here, we performed deep sequencing to determine how equine torovirus produces sgRNAs. In doing so, we also identified two previously unknown open reading frames "hidden" within the genome. Together these results highlight the similarities and differences between this domestic animal virus and related pathogens of humans and livestock.
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Affiliation(s)
- Hazel Stewart
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Brown
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Adam M Dinan
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Nerea Irigoyen
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew E Firth
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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20
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Dervas E, Hepojoki J, Laimbacher A, Romero-Palomo F, Jelinek C, Keller S, Smura T, Hepojoki S, Kipar A, Hetzel U. Nidovirus-Associated Proliferative Pneumonia in the Green Tree Python (Morelia viridis). J Virol 2017; 91:e00718-17. [PMID: 28794044 PMCID: PMC5640870 DOI: 10.1128/jvi.00718-17] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 07/24/2017] [Indexed: 12/20/2022] Open
Abstract
In 2014 we observed a noticeable increase in the number of sudden deaths among green tree pythons (Morelia viridis). Pathological examination revealed the accumulation of mucoid material within the airways and lungs in association with enlargement of the entire lung. We performed a full necropsy and histological examination on 12 affected green tree pythons from 7 different breeders to characterize the pathogenesis of this mucinous pneumonia. By histology we could show a marked hyperplasia of the airway epithelium and of faveolar type II pneumocytes. Since routine microbiological tests failed to identify a causative agent, we studied lung tissue samples from a few diseased snakes by next-generation sequencing (NGS). From the NGS data we could assemble a piece of RNA genome whose sequence was <85% identical to that of nidoviruses previously identified in ball pythons and Indian pythons. We then employed reverse transcription-PCR to demonstrate the presence of the novel nidovirus in all diseased snakes. To attempt virus isolation, we established primary cultures of Morelia viridis liver and brain cells, which we inoculated with homogenates of lung tissue from infected individuals. Ultrastructural examination of concentrated cell culture supernatants showed the presence of nidovirus particles, and subsequent NGS analysis yielded the full genome of the novel virus Morelia viridis nidovirus (MVNV). We then generated an antibody against MVNV nucleoprotein, which we used alongside RNA in situ hybridization to demonstrate viral antigen and RNA in the affected lungs. This suggests that in natural infection MVNV damages the respiratory tract epithelium, which then results in epithelial hyperplasia, most likely as an exaggerated regenerative attempt in association with increased epithelial turnover.IMPORTANCE Novel nidoviruses associated with severe respiratory disease were fairly recently identified in ball pythons and Indian pythons. Herein we report on the isolation and identification of a further nidovirus from green tree pythons (Morelia viridis) with fatal pneumonia. We thoroughly characterized the pathological changes in the infected individuals and show that nidovirus infection is associated with marked epithelial proliferation in the respiratory tract. We speculate that this and the associated excess mucus production can lead to the animals' death by inhibiting normal gas exchange in the lungs. The virus was predominantly detected in the respiratory tract, which renders transmission via the respiratory route likely. Nidoviruses cause sudden outbreaks with high rates of mortality in breeding collections, and most affected snakes die without prior clinical signs. These findings, together with those of other groups, indicate that nidoviruses are a likely cause of severe pneumonia in pythons.
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Affiliation(s)
- Eva Dervas
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Jussi Hepojoki
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- University of Helsinki, Medicum, Department of Virology, Helsinki, Finland
| | - Andrea Laimbacher
- Institute of Virology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Fernando Romero-Palomo
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Christine Jelinek
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Saskia Keller
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Teemu Smura
- University of Helsinki, Medicum, Department of Virology, Helsinki, Finland
| | - Satu Hepojoki
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Anja Kipar
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Udo Hetzel
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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21
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A Naturally Occurring Recombinant Enterovirus Expresses a Torovirus Deubiquitinase. J Virol 2017; 91:JVI.00450-17. [PMID: 28490584 DOI: 10.1128/jvi.00450-17] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 04/26/2017] [Indexed: 11/20/2022] Open
Abstract
Enteroviruses (EVs) are implicated in a wide range of diseases in humans and animals. In this study, a novel enterovirus (enterovirus species G [EVG]) (EVG 08/NC_USA/2015) was isolated from a diagnostic sample from a neonatal pig diarrhea case and identified by using metagenomics and complete genome sequencing. The viral genome shares 75.4% nucleotide identity with a prototypic EVG strain (PEV9 UKG/410/73). Remarkably, a 582-nucleotide insertion, flanked by 3Cpro cleavage sites at the 5' and 3' ends, was found in the 2C/3A junction region of the viral genome. This insertion encodes a predicted protease with 54 to 68% amino acid identity to torovirus (ToV) papain-like protease (PLP) (ToV-PLP). Structural homology modeling predicts that this protease adopts a fold and a catalytic site characteristic of minimal PLP catalytic domains. This structure is similar to those of core catalytic domains of the foot-and-mouth disease virus leader protease and coronavirus PLPs, which act as deubiquitinating and deISGylating (interferon [IFN]-stimulated gene 15 [ISG15]-removing) enzymes on host cell substrates. Importantly, the recombinant ToV-PLP protein derived from this novel enterovirus also showed strong deubiquitination and deISGylation activities and demonstrated the ability to suppress IFN-β expression. Using reverse genetics, we generated a ToV-PLP knockout recombinant virus. Compared to the wild-type virus, the ToV-PLP knockout mutant virus showed impaired growth and induced higher expression levels of innate immune genes in infected cells. These results suggest that ToV-PLP functions as an innate immune antagonist; enterovirus G may therefore gain fitness through the acquisition of ToV-PLP from a recombination event.IMPORTANCE Enteroviruses comprise a highly diversified group of viruses. Genetic recombination has been considered a driving force for viral evolution; however, recombination between viruses from two different orders is a rare event. In this study, we identified a special case of cross-order recombination between enterovirus G (order Picornavirales) and torovirus (order Nidovirales). This naturally occurring recombination event may have broad implications for other picornaviral and/or nidoviral species. Importantly, we demonstrated that the exogenous ToV-PLP gene that was inserted into the EVG genome encodes a deubiquitinase/deISGylase and potentially suppresses host cellular innate immune responses. Our results provide insights into how a gain of function through genetic recombination, in particular cross-order recombination, may improve the ability of a virus to evade host immunity.
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22
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Knutson TP, Velayudhan BT, Marthaler DG. A porcine enterovirus G associated with enteric disease contains a novel papain-like cysteine protease. J Gen Virol 2017; 98:1305-1310. [PMID: 28590234 PMCID: PMC5656790 DOI: 10.1099/jgv.0.000799] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Identification of unknown pathogens in pigs displaying enteric illness is difficult due to the large diversity of bacterial and viral species found within faecal samples. Current methods often require bacterial or viral isolation, or testing only a limited number of known species using quantitative PCR analysis. Herein, faeces from two 25-day-old piglets with diarrhoea from Texas, USA, were analysed by metagenomic next-generation sequencing to rapidly identify possible pathogens. Our analysis included a bioinformatics pipeline of rapid short-read classification and de novo genome assembly which resulted in the identification of a porcine enterovirus G (EV-G), a complete genome with substantial nucleotide differences (>30 %) among current sequences, and a novel non-structural protein similar in sequence to the Torovirus papain-like cysteine protease (PLpro). This discovery led to the identification and circulation of an EV-G with a novel PLpro in the USA that has not been previously reported.
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Affiliation(s)
- Todd P Knutson
- Veterinary Diagnostic Laboratory, Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN 55108, USA
| | - Binu T Velayudhan
- Texas A&M Veterinary Medical Diagnostic Laboratory, Amarillo, TX 79106, USA
| | - Douglas G Marthaler
- Veterinary Diagnostic Laboratory, Department of Veterinary Population Medicine, University of Minnesota, St Paul, MN 55108, USA
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Ávila-Pérez G, Rejas MT, Rodríguez D. Ultrastructural characterization of membranous torovirus replication factories. Cell Microbiol 2016; 18:1691-1708. [PMID: 27218226 PMCID: PMC7162420 DOI: 10.1111/cmi.12620] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/27/2016] [Accepted: 05/19/2016] [Indexed: 12/24/2022]
Abstract
Plus‐stranded RNA viruses replicate in the cytosol of infected cells, in membrane‐bound replication complexes containing the replicase proteins, the viral RNA and host proteins. The formation of the replication and transcription complexes (RTCs) through the rearrangement of cellular membranes is currently being actively studied for viruses belonging to different viral families. In this work, we identified double‐membrane vesicles (DMVs) in the cytoplasm of cells infected with the equine torovirus Berne virus (BEV), the prototype member of the Torovirus genus (Coronaviridae family, Nidovirales order). Using confocal microscopy and transmission electron microscopy, we observed a close relationship between the RTCs and the DMVs of BEV. The examination of BEV‐infected cells revealed that the replicase proteins colocalize with each other and with newly synthesized RNA and are associated to the membrane rearrangement induced by BEV. However, the double‐stranded RNA, an intermediate of viral replication, is exclusively limited to the interior of DMVs. Our results with BEV resemble those obtained with other related viruses in the Nidovirales order, thus providing new evidence to support the idea that nidoviruses share a common replicative structure based on the DMV arranged clusters.
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Affiliation(s)
- Ginés Ávila-Pérez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin 3, 28049, Madrid, Spain
| | - María Teresa Rejas
- Electron Microscopy Facility, Centro de Biología Molecular Severo Ochoa, CSIC, C/Nicolás Cabrera 1, 28049, Madrid, Spain
| | - Dolores Rodríguez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, C/Darwin 3, 28049, Madrid, Spain
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24
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Ito M, Tsuchiaka S, Naoi Y, Otomaru K, Sato M, Masuda T, Haga K, Oka T, Yamasato H, Omatsu T, Sugimura S, Aoki H, Furuya T, Katayama Y, Oba M, Shirai J, Katayama K, Mizutani T, Nagai M. Whole genome analysis of Japanese bovine toroviruses reveals natural recombination between porcine and bovine toroviruses. INFECTION GENETICS AND EVOLUTION 2015; 38:90-95. [PMID: 26708248 PMCID: PMC7185535 DOI: 10.1016/j.meegid.2015.12.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 12/15/2015] [Accepted: 12/15/2015] [Indexed: 01/03/2023]
Abstract
Bovine toroviruses (BToVs), belong to the subfamily Toroviridae within the family Coronaviridae, and are pathogens, causing enteric disease in cattle. In Japan, BToVs are distributed throughout the country and cause gastrointestinal infection of calves and cows. In the present study, complete genome sequences of two Japanese BToVs and partial genome sequences of two Japanese BToVs and one porcine torovirus (PToV) from distant regions in Japan were determined and genetic analyses were performed. Pairwise nucleotide comparison and phylogenetic analyses revealed that Japanese BToVs shared high identity with each other and showed high similarities with BToV Breda1 strain in S, M, and HE coding regions. Japanese BToVs showed high similarities with porcine toroviruses in ORF1a, ORF1b, and N coding regions and the 5′ and 3′ untranslated regions, suggestive of a natural recombination event. Recombination analyses mapped the putative recombinant breakpoints to the 3′ ends of the ORF1b and HE regions. These findings suggest that the interspecies recombinant nature of Japanese BToVs resulted in a closer relationship between BToV Breda1 and PToVs. Recombination events between porcine and bovine torovirus were identified. Recombinant breakpoints were mapped at ORF1b and HE coding regions. These recombinant viruses are prevalent throughout Japan.
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Affiliation(s)
- Mika Ito
- Ishikawa Nanbu Livestock Hygiene Service Center, Saida, Kanazawa, Ishikawa 920-3101, Japan
| | - Shinobu Tsuchiaka
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Yuki Naoi
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Konosuke Otomaru
- Joint Faculty of Veterinary Medicine, Kagoshima University, Korimoto, Kagoshima 890-0065, Japan
| | - Mitsuo Sato
- Tochigi Prefectural Central District Animal Hygiene Service Center, Hiraidekougyoudanchi, Utsunomiya, Tochigi 321-0905, Japan
| | - Tsuneyuki Masuda
- Kurayoshi Livestock Hygiene Service Center, Kiyotani, Kurayoshi, Tottori 683-0017, Japan
| | - Kei Haga
- Department of Virology II, National Institute of Infectious Diseases, Musashimurayama, Tokyo 208-0011, Japan
| | - Tomoichiro Oka
- Department of Virology II, National Institute of Infectious Diseases, Musashimurayama, Tokyo 208-0011, Japan
| | - Hiroshi Yamasato
- Kurayoshi Livestock Hygiene Service Center, Kiyotani, Kurayoshi, Tottori 683-0017, Japan
| | - Tsutomu Omatsu
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Satoshi Sugimura
- Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Hiroshi Aoki
- Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-8602, Japan
| | - Tetsuya Furuya
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan; Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Yukie Katayama
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Mami Oba
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Junsuke Shirai
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan; Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Kazuhiko Katayama
- Department of Virology II, National Institute of Infectious Diseases, Musashimurayama, Tokyo 208-0011, Japan
| | - Tetsuya Mizutani
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Makoto Nagai
- Research and Education Center for Prevention of Global Infectious Disease of Animal, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan; Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan.
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25
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Tokarz R, Sameroff S, Hesse RA, Hause BM, Desai A, Jain K, Ian Lipkin W. Discovery of a novel nidovirus in cattle with respiratory disease. J Gen Virol 2015; 96:2188-2193. [PMID: 25918239 DOI: 10.1099/vir.0.000166] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The family Coronaviridae represents a diverse group of vertebrate RNA viruses, all with genomes greater than 26,000 nt. Here, we report the discovery and genetic characterization of a novel virus present in cattle with respiratory disease. Phylogenetic characterization of this virus revealed that it clusters within the subfamily Torovirinae, in the family Coronaviridae. The complete genome consists of only 20,261 nt and represents the smallest reported coronavirus genome. We identified seven ORFs, including the canonical nidovirus ORF1a and ORF1b. Analysis of polyprotein 1ab revealed that this virus, tentatively named bovine nidovirus (BoNV), shares the highest homology with the recently described python-borne nidoviruses and contains several conserved nidovirus motifs, but does not encode the NendoU or O-MT domains that are present in other viruses within the family Coronaviridae. In concert with its reduced genome, the atypical domain architecture indicates that this virus represents a unique lineage within the order Nidovirales.
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Affiliation(s)
- Rafal Tokarz
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, NY 10032, USA
| | - Stephen Sameroff
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, NY 10032, USA
| | - Richard A Hesse
- Kansas State Veterinary Diagnostic Laboratory and Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS, 66508, USA
| | - Ben M Hause
- Kansas State Veterinary Diagnostic Laboratory and Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS, 66508, USA
| | - Aaloki Desai
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, NY 10032, USA
| | - Komal Jain
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, NY 10032, USA
| | - W Ian Lipkin
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, NY 10032, USA
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26
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Parvez MK. The hepatitis E virus ORF1 'X-domain' residues form a putative macrodomain protein/Appr-1″-pase catalytic-site, critical for viral RNA replication. Gene 2015; 566:47-53. [PMID: 25870943 PMCID: PMC7127128 DOI: 10.1016/j.gene.2015.04.026] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 03/24/2015] [Accepted: 04/09/2015] [Indexed: 12/13/2022]
Abstract
The hepatitis E virus (HEV) ORF1 gene encodes the non-structural polyprotein wherein the ‘X-domain’ still remains poorly defined. Cellular X-domain associated macrodomain protein/ADP-ribose-1″-monophosphatase (Appr-1″-pase) activities are also reported in coronaviruses (CoV), including identification of its homologs in alpha and rubella viruses. The present study investigated the role(s) of X-domain residues in HEV replication cycle. In silico analysis showed a high degree of evolutionary conservation of X-domain (a.a. 785–942) a.a. positions wherein the N-terminus residues ‘Asn806, Asn809, His812, Gly815, Gly816, and Gly817’ formed a potential catalytic-site homolog of CoVAppr-1″-pase. To experimentally test this prediction, X-domain ‘active-site’ residues were subjected to mutational analysis using the HEV-SAR55 replicon (pSK-GFP). FACS analysis of mutant RNA transfected S10-3 cells showed that Gly816Ala and Gly817Ala constructs completely abrogated HEV replication, similar to their Gly816Val and Gly817Val counterparts. However, ‘Gly815Ala’ mutant replicated very poorly in contrast to ‘Gly815Val’ that completely abolished GFP synthesis. Furthermore, while ‘Asn806Ala’ mutant retained RNA replication, the ‘Asn809Ala’ and His812Leu mutants showed non-viability. Notably, in a sequential-nucleotide mutation analysis, the dispensability of X-domain in HEV replication at transcriptional level has already been demonstrated (Parvez, 2013b). Taken together, the present data strongly argue for an essential role of X-domain residues (Asn809, His812, Gly816 and Gly817) at post-translational level, indicating its involvement in viral replication. In conclusion, the speculated regulatory role of ORF1 X-domain in HEV replication cycle critically depends on the ‘Asn, Asn, His, Gly, Gly, Gly’ segment/secondary structure. Nevertheless, further biochemical or biophysical characterizations of HEV X-domain associated Appr-1″-pase activity would only confirm its biological significance in virus or host-pathogenesis. Cellular ‘X-domain’ associated Appr-1″-pase also reported in RNA viruses Appr-1″-pase active-site homolog ‘NNHGGG’ mapped in HEV X-domain Mutational analysis showed criticality of the active-site a.a. in HEV replication. Dispensability of nt. conservation suggested a putative Appr-1″-pase activity.
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Affiliation(s)
- Mohammad Khalid Parvez
- Department of Pharmacognosy, King Saud University College of Pharmacy, PO Box-2457, Riyadh 11451, Saudi Arabia.
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27
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Sun H, Lan D, Lu L, Chen M, Wang C, Hua X. Molecular characterization and phylogenetic analysis of the genome of porcine torovirus. Arch Virol 2014; 159:773-8. [PMID: 24122107 PMCID: PMC7086580 DOI: 10.1007/s00705-013-1861-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 01/22/2013] [Indexed: 11/28/2022]
Abstract
In this study, we amplified and sequenced the first genome of porcine torovirus (PToV SH1 strain). The genome was found to be 28,301 bp in length, sharing 79 % identity with Breda virus. It mainly consists of replicase (20,906 bp) and structural genes: spike (4,722 bp), membrane (702 bp), hemagglutinin-esterase (1,284 bp), and nucleocapsid (492 bp). Sequence alignments and structure prediction suggest genetic differences among toroviruses, mainly in NSP1 (papain-like cysteine proteinase domain). Rooted phylogenetic trees were constructed based on the 3C-like proteinase and RNA-dependent RNA polymerase genes. PToV, Berne virus and Breda virus were clustered together, forming a separate branch from white bream virus that was distant from that of the coronaviruses.
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Affiliation(s)
- Huan Sun
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240 China
| | - Daoliang Lan
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240 China
- Tibetan Plateau Base, Southwest University for Nationalities, Chengdu, 610041 China
| | - Lifang Lu
- Fast Track Center, GE (China) Research and Development Center, Shanghai, 210203 China
| | - Molin Chen
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240 China
| | - Changsong Wang
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240 China
| | - Xiuguo Hua
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240 China
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28
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Dhama K, Pawaiya R, Chakrabort S, Tiwari R, Verma A. Toroviruses Affecting Animals and Humans: A Review. ACTA ACUST UNITED AC 2014. [DOI: 10.3923/ajava.2014.190.201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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29
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Gülaçtı I, Işıdan H, Sözdutmaz I. Detection of bovine torovirus in fecal specimens from calves with diarrhea in Turkey. Arch Virol 2014; 159:1623-7. [PMID: 24420162 DOI: 10.1007/s00705-014-1977-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 12/31/2013] [Indexed: 12/17/2022]
Abstract
Bovine torovirus (BToV), a member of the family Coronaviridae, is an established gastrointestinal infectious agent in cattle. In this study, we performed a survey to detect BToV in Turkey between 2009 and 2011 using 235 fecal samples from neonatal calves with diarrhea that were analyzed by the nested reverse transcription (RT) PCR method using primers located in the consensus sequences of the BToV membrane (M) gene. The BToV M gene was detected in 4.7 % (11/235) of the samples using the nested RT-PCR method. The nucleotide sequences of partial M fragments from the BToV isolates, including the newly identified Turkish isolates, showed more than 96 % identity. The result indicates that BToV is one of the pathogens that contribute to neonatal calf diarrhea cases in Turkey.
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Affiliation(s)
- Irem Gülaçtı
- The Pendik Veterinary Control and Research Institute, 34890, İstanbul, Turkey
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30
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Toroviruses (Coronaviridae). REFERENCE MODULE IN BIOMEDICAL SCIENCES 2014. [PMCID: PMC7157456 DOI: 10.1016/b978-0-12-801238-3.02674-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Toroviruses are single-stranded RNA peplomer-bearing enveloped viruses producing enteric disease in animals and humans. They have a unique extracellular C-shape or open torus morphology. There are four species in the genus Torovirus (family Coronaviridae, order Nidovirales): Equine torovirus (EToV), Bovine torovirus (BToV), Human torovirus (HToV), and Porcine torovirus (PToV), which have been reported worldwide. Their genome contains six ORFs, which are transcribed as a 3’-coterminal nested set of four mRNAs. ORF1a and 1b encode the replicase, and ORFs 2–5 encode the spike (S), membrane (M), hemagglutinin-esterase (HE), and nucleocapsid (N) proteins, respectively. Only EToVs and BToV Aichi/2004 propagate in cell culture.
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31
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Aita T, Kuwabara M, Murayama K, Sasagawa Y, Yabe S, Higuchi R, Tamura T, Miyazaki A, Tsunemitsu H. Characterization of epidemic diarrhea outbreaks associated with bovine torovirus in adult cows. Arch Virol 2011; 157:423-31. [PMID: 22167249 PMCID: PMC7087103 DOI: 10.1007/s00705-011-1183-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 11/22/2011] [Indexed: 11/28/2022]
Abstract
Bovine torovirus (BToV) is recognized as an enteric pathogen of calves, but its etiological role in diarrhea and epidemiological characterization in adult cows remain unclear. In 2007-2008, three outbreaks of epidemic diarrhea occurred in adult cows at three dairy farms in Niigata Prefecture, Japan. BToV was the only enteric pathogen detected in these outbreaks, as determined by electron microscopy, reverse transcription-PCR, bacteria and parasite tests of fecal samples, and antibody tests with paired sera. The epidemiological features of the three outbreaks were similar to those of bovine coronavirus infection, except for the absence of bloody diarrhea, with diarrhea spreading among most adult cows, but not in calves, within several days and diarrhea lasting for 3-5 days with anorexia. Decreased milk production and mild respiratory symptoms were also observed in two of the outbreaks. Nucleotide sequence analysis of the BToV nucleocapsid, spike, and hemagglutinin-esterase (HE) genes revealed a close relatedness among the detected BToV strains from each outbreak and those of Japanese BToV strain Aichi/2004. Furthermore, we isolated a BToV strain, designated Niigata (TC), from a fecal sample using a human rectal tumor cell line. Sequence analysis of this isolate and Aichi/2004 indicated that both strains have truncated HE genes with deletions in the 3′ region that occurred through cell culture-adaptation. The short projections that are believed to be formed by the HE protein on virus particles were not observed in these cultured strains by electron microscopy. Taken together, these results suggest that BToV causes epidemic diarrhea in adult cows and should be included in the differential diagnosis of diarrhea in adult cows. In addition, our findings indicate that the HE protein of BToV may not be necessary for viral replication.
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Affiliation(s)
- Tsunehiko Aita
- Niigata Chuo Livestock Hygiene Service Center, Hataya 686, Nishikan, Niigata, Niigata 9590423, Japan
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32
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Kuri T, Eriksson KK, Putics A, Züst R, Snijder EJ, Davidson AD, Siddell SG, Thiel V, Ziebuhr J, Weber F. The ADP-ribose-1''-monophosphatase domains of severe acute respiratory syndrome coronavirus and human coronavirus 229E mediate resistance to antiviral interferon responses. J Gen Virol 2011; 92:1899-1905. [PMID: 21525212 DOI: 10.1099/vir.0.031856-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Several plus-strand RNA viruses encode proteins containing macrodomains. These domains possess ADP-ribose-1″-phosphatase (ADRP) activity and/or bind poly(ADP-ribose), poly(A) or poly(G). The relevance of these activities in the viral life cycle has not yet been resolved. Here, we report that genetically engineered mutants of severe acute respiratory syndrome coronavirus (SARS-CoV) and human coronavirus 229E (HCoV-229E) expressing ADRP-deficient macrodomains displayed an increased sensitivity to the antiviral effect of alpha interferon compared with their wild-type counterparts. The data suggest that macrodomain-associated ADRP activities may have a role in viral escape from the innate immune responses of the host.
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Affiliation(s)
- Thomas Kuri
- Department of Virology, University of Freiburg, D-79008 Freiburg, Germany
| | - Klara K Eriksson
- Research Department, Kantonal Hospital St Gallen, St Gallen, Switzerland
| | - Akos Putics
- Institute of Virology and Immunology, University of Würzburg, D-97078 Würzburg, Germany
| | - Roland Züst
- Research Department, Kantonal Hospital St Gallen, St Gallen, Switzerland
| | - Eric J Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew D Davidson
- Division of Virology, Department of Cellular and Molecular Medicine, School of Medical and Veterinary Sciences, University of Bristol, Bristol, UK
| | - Stuart G Siddell
- Division of Virology, Department of Cellular and Molecular Medicine, School of Medical and Veterinary Sciences, University of Bristol, Bristol, UK
| | - Volker Thiel
- Research Department, Kantonal Hospital St Gallen, St Gallen, Switzerland
| | - John Ziebuhr
- Institute of Medical Virology, Justus Liebig University Giessen, D-35392 Giessen, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.,Department of Virology, University of Freiburg, D-79008 Freiburg, Germany
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33
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Genetic and antigenic characterization of newly isolated bovine toroviruses from Japanese cattle. J Clin Microbiol 2010; 48:1795-800. [PMID: 20220164 DOI: 10.1128/jcm.02339-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Torovirus, a member of the Coronaviridae family, is a gastrointestinal infectious agent that has been identified in humans, cattle, pigs, and equines. Toroviruses, except equine torovirus, are difficult to propagate in cell culture; indeed, to date, only the Aichi/2004 strain of bovine torovirus (BToV) has been isolated among the human, bovine, and porcine toroviruses. In the present study, four cytopathogenic BToVs were isolated from diarrheal feces of the cattle using the HRT-18 cell line, and their genetic and antigenic properties were compared. The cytopathogenic features of BToV isolates in HRT-18 cells were similar to those of the Aichi/2004 strain. However, none of the isolates showed cytopathogenic effects in the HRT-18 cells of different origin, suggesting that one significant factor contributing to the cytopathogenicity of BToV depends on properties of the HRT-18 cells themselves. All BToVs isolated were able to agglutinate mouse, but not chicken, erythrocytes, while they lacked receptor-destroying enzyme activity. Analysis of the N terminus of the spike gene showed that three isolates, but not the Gifu-2007TI/E strain, were phylogenetically located in cluster 1 and its analogs and revealed high cross-reactivity with each other, as demonstrated by neutralization (NT) and hemagglutination inhibition (HI) assays. The Gifu-2007TI/E strain was classified close to cluster 2 and exhibited relatively low cross-reactivity with these viruses; however, the difference was not sufficient to classify BToVs into serotypes, suggesting that at least two subtypes distinguishable by the structure of the N terminus of the spike gene and that both NT and HI tests may be exist.
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34
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Firth AE, Atkins JF. A case for a CUG-initiated coding sequence overlapping torovirus ORF1a and encoding a novel 30 kDa product. Virol J 2009; 6:136. [PMID: 19737402 PMCID: PMC2749830 DOI: 10.1186/1743-422x-6-136] [Citation(s) in RCA: 8] [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: 08/09/2009] [Accepted: 09/08/2009] [Indexed: 11/23/2022] Open
Abstract
The genus Torovirus (order Nidovirales) includes a number of species that infect livestock. These viruses have a linear positive-sense ssRNA genome of approximately 25-30 kb, encoding a large polyprotein that is expressed from the genomic RNA, and several additional proteins expressed from a nested set of 3'-coterminal subgenomic RNAs. In this brief report, we describe the bioinformatic discovery of a new, apparently coding, ORF that overlaps the 5' end of the polyprotein coding sequence, ORF1a, in the +2 reading frame. The new ORF has a strong coding signature and, in fact, is more conserved at the amino acid level than the overlapping region of ORF1a. We propose that the new ORF utilizes a non-AUG initiation codon--namely a conserved CUG codon in a strong Kozak context--upstream of the ORF1a AUG initiation codon, resulting in a novel 258 amino acid protein, dubbed '30K'.
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Affiliation(s)
- Andrew E Firth
- BioSciences Institute, University College Cork, Cork, Ireland
| | - John F Atkins
- BioSciences Institute, University College Cork, Cork, Ireland
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112-5330, USA
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35
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Lal SK, Imbert I, Canard B, Ziebuhr J. Expression and Functions of SARS Coronavirus Replicative Proteins. MOLECULAR BIOLOGY OF THE SARS-CORONAVIRUS 2009. [PMCID: PMC7124140 DOI: 10.1007/978-3-642-03683-5_6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The discovery of a previously unknown coronavirus as the causative agent of the SARS epidemic in 2002/2003 stimulated a large number of studies into the molecular biology of SARS coronavirus (SARS-CoV) and related viruses. This research has provided significant new insight into the functions and activities of the coronavirus replicase–transcriptase complex, a multiprotein complex that directs coordinated processes of both continuous and discontinuous RNA synthesis to replicate and transcribe the large coronavirus genome, a single-stranded, positive-sense RNA of ~30 kb. In this chapter, we review our current understanding of the expression and functions of key replicative enzymes, such as RNA polymerases, helicase, ribonucleases, ribose-2′-O-methyltransferase and other replicase gene-encoded proteins involved in genome expression, virus–host interactions and other processes. Collectively, these recent studies reveal fascinating details of an enzymatic machinery that, in the RNA virus world, is unparalleled in terms of the number and nature of virally encoded activities involved in virus replication and host interactions.
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Affiliation(s)
- Sunil K. Lal
- grid.425195.e0000000404987682Engineering & Biotechnology, International Centre for Genetic, Aruna Asaf Ali Marg, New Delhi, 110067 India
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36
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The complete sequence of a human parainfluenzavirus 4 genome. Viruses 2009; 1:26-41. [PMID: 21994536 PMCID: PMC3185463 DOI: 10.3390/v1010026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 05/22/2009] [Accepted: 05/26/2009] [Indexed: 02/06/2023] Open
Abstract
Although the human parainfluenza virus 4 (HPIV4) has been known for a long time, its genome, alone among the human paramyxoviruses, has not been completely sequenced to date. In this study we obtained the first complete genomic sequence of HPIV4 from a clinical isolate named SKPIV4 obtained at the Hospital for Sick Children in Toronto (Ontario, Canada). The coding regions for the N, P/V, M, F and HN proteins show very high identities (95% to 97%) with previously available partial sequences for HPIV4B. The sequence for the L protein and the non-coding regions represent new information. A surprising feature of the genome is its length, more than 17 kb, making it the longest genome within the genus Rubulavirus, although the length is well within the known range of 15 kb to 19 kb for the subfamily Paramyxovirinae. The availability of a complete genomic sequence will facilitate investigations on a respiratory virus that is still not completely characterized.
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Organ-specific attenuation of murine hepatitis virus strain A59 by replacement of catalytic residues in the putative viral cyclic phosphodiesterase ns2. J Virol 2009; 83:3743-53. [PMID: 19176619 DOI: 10.1128/jvi.02203-08] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The Murine hepatitis virus (MHV) strain A59 ns2 protein is a 30-kDa nonstructural protein that is expressed from a subgenomic mRNA in the cytoplasm of virus-infected cells. Its homologs are also encoded in other closely related group 2a coronaviruses and more distantly related toroviruses. Together, these proteins comprise a subset of a large superfamily of 2H phosphoesterase proteins that are distinguished by a pair of conserved His-x-Thr/Ser motifs encompassing catalytically important residues. We have used a vaccinia virus-based reverse genetic system to produce recombinant viruses encoding ns2 proteins with single-amino-acid substitutions in, or adjacent to, these conserved motifs, namely, inf-ns2 H46A, inf-ns2 S48A, inf-ns2-S120A, and inf-ns2-H126R. All of the mutant viruses replicate in mouse 17 clone 1 fibroblast cells and mouse embryonic cells to the same extent as the parental wild-type recombinant virus, inf-MHV-A59. However, compared to inf-MHV-A59, the inf-ns2 H46A and inf-ns2-H126R mutants are highly attenuated for replication in mouse liver following intrahepatic inoculation. Interestingly, none of the mutant viruses were attenuated for replication in mouse brain following intracranial inoculation. These results show that the ns2 protein of MHV-A59 has an important role in virus pathogenicity and that a substitution of the histidine residues of the MHV-A59 ns2 His-x-Thr/Ser motifs is critical for virus virulence in the liver but not in the brain. This novel phenotype suggests a strategy to investigate the function of the MHV-A59 ns2 protein involving the search for organ-specific proteins or RNAs that react differentially to wild-type and mutant ns2 proteins.
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Detection and characterization of bovine torovirus from the respiratory tract in Japanese cattle. Vet Microbiol 2008; 136:366-71. [PMID: 19128894 PMCID: PMC7117103 DOI: 10.1016/j.vetmic.2008.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 11/13/2008] [Accepted: 11/24/2008] [Indexed: 12/30/2022]
Abstract
Bovine torovirus (BToV), a member of the Coronaviridae family, is a causative agent of diarrhea in cattle, but it may also possess tropism for the respiratory tract. However, no surveys concerning with the relation between respiratory symptoms and the detection of BToV have been conducted in wide range. Among 311 nasal samples, BToV gene products were detected in seven samples (rBToV-1 to -7) derived only from calves with respiratory symptoms, suggesting that BToV may be a predisposing factor and/or causative agent for bovine respiratory disease. Regarding the degree of similarity between the spike and hemagglutinin-esterase coding regions, the rBToVs showed over 90.8% similarity with one another and 73.5–99.0% similarity with fecal tract-derived BToVs. rBToV-1, -2, and -3 were identical despite their being collected during different seasons; in comparison, rBToV-4 and -5 were distinct despite the fact that they were collected from the same herd, suggesting the existence of diversity among domestic rBToVs. One animal with a BToV-positive nasal sample also shed the virus in its feces, suggesting dual tropisms for BToV.
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Sittidilokratna N, Dangtip S, Cowley JA, Walker PJ. RNA transcription analysis and completion of the genome sequence of yellow head nidovirus. Virus Res 2008; 136:157-65. [PMID: 18582978 PMCID: PMC7114370 DOI: 10.1016/j.virusres.2008.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 04/30/2008] [Accepted: 05/03/2008] [Indexed: 11/25/2022]
Abstract
Yellow head virus (YHV) is a pathogen of the black tiger shrimp (Penaeus monodon) and, with gill-associated virus (GAV), is one of two known invertebrate nidoviruses. We describe sequences of the large replicase gene (ORF1a) and 5′- and 3′-terminal UTRs, completing the 26,662 nt sequence of the YHV genome. ORF1a (12,219 nt) encodes a ∼462,662 Da polypeptide containing a putative 3C-like protease and a putative papain-like protease with the canonical C/H catalytic dyad and α + β fold. The read-through pp1ab polyprotein contains putative uridylate-specific endoribonuclease and ribose-2′-O-methyl transferase domains, and an exonuclease domain incorporating unusual dual Zn2+-binding fingers. Upstream of ORF1a, the 71 nt 5′-UTR shares 82.4% identity with the 68 nt 5′-UTR of GAV. The 677 nt 3′-terminal region contains a single 60 nt ORF, commencing 298 nt downstream of ORF3, that is identical to N-terminal coding region of the 249 nt GAV ORF4. Northern blots using RNA from YHV-infected shrimp and probes directed at ORF1a, ORF1b, ORF2 and ORF3 identified a nested set of 3′-coterminal RNAs comprising the full-length genomic RNA and two sub-genomic (sg) mRNAs. Intergenic sequences upstream of ORF2 and ORF3 share high identity with GAV, particularly in the conserved domains predicted to mediate sgmRNA transcription.
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Affiliation(s)
- Nusra Sittidilokratna
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Phathumthani 12120, Thailand
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Park SJ, Oh EH, Park SI, Kim HH, Jeong YJ, Lim GK, Hyun BH, Cho KO. Molecular epidemiology of bovine toroviruses circulating in South Korea. Vet Microbiol 2008; 126:364-71. [PMID: 17719729 PMCID: PMC7117412 DOI: 10.1016/j.vetmic.2007.07.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Revised: 07/16/2007] [Accepted: 07/17/2007] [Indexed: 10/31/2022]
Abstract
The prevalence of the bovine torovirus (BToV) and its genetic characterization have been reported in North America, Europe and Japan. Therefore, this study examined the prevalence and genetic diversity of the BToV in a total of 645 diarrheic fecal samples from 629 Korean native beef calf herds using RT-PCR and nested PCR with the primer pairs specific to a part of the BToV membrane (M) gene. Overall, 19 (2.9%) out of 645 diarrheic samples from 19 herds (6.9%) tested positive for BToVs by either RT-PCR or nested PCR. A comparison of the nucleotide (nt) and amino acid (aa) sequences of a part of the BToV M gene (409bp) among the BToVs showed the Korean BToVs to have comparatively higher sequence homology to the Japanese and Dutch BToVs than to the American and Italian BToVs. Generally, the Korean BToV strains clustered with the Japanese and Dutch BToV strains. However, the American and Italian BToV strains clustered on a separate major branch, suggesting that these are more distantly related to other known BToV strains. These results suggest that the BToV infections are sporadic in diarrheic calves in South Korea, and the Korean BToV strains are more closely related to the Japanese and Dutch BToVs than to the American and Italian BToVs.
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Affiliation(s)
- Su-Jin Park
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
| | - Eun-Hee Oh
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
| | - Sang-Ik Park
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
| | - Ha-Hyun Kim
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
| | - Young-Ju Jeong
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
| | - Guem-Ki Lim
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
| | - Bang-Hun Hyun
- National Veterinary Research and Quarantine Services, Gyonggi-do 430-824, South Korea
| | - Kyoung-Oh Cho
- Biotherapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, South Korea
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Kirisawa R, Takeyama A, Koiwa M, Iwai H. Detection of bovine torovirus in fecal specimens of calves with diarrhea in Japan. J Vet Med Sci 2008; 69:471-6. [PMID: 17551218 DOI: 10.1292/jvms.69.471] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to determine the prevalence of bovine torovirus (BoTV) in bovine fecal samples and to determine whether a relationship exists between BoTV and diarrhea in Japan. Ninety-nine diarrheic and 114 normal fecal samples from calves in Hokkaido Prefecture and 38 diarrheic fecal samples from calves in 10 other prefectures were examined by reverse transcription (RT)-PCR with primers designed in the spike (S) gene for the presence of BoTV. The specimens were also examined for the presence of other enteric pathogens, bovine rotavirus, coronavirus and Cryptosporidium spp. BoTV RNA was detected in 15 (15.2%) of the 99 diarrheic samples from Hokkaido and in 9 (23.7%) of the 38 diarrheic samples from the other prefectures. The incidence of BoTV in control specimens was 7.0%. In 11 of the 15 BoTV-positive specimens from Hokkaido, BoTV was the only pathogen detected among those examined, and 11 BoTV-positive specimens were obtained from calves less than 2 weeks of age. Rotavirus was confirmed to be associated with calf diarrhea, but coronavirus and Cryptosporidium spp. were not. Nucleotide sequences of 17 different BoTV RT-PCR products were determined. Phylogenetic analysis based on the sequences revealed that Japanese BoTVs could be classified into at least two groups. This study showed that BoTV is a common virus in fecal specimens of calves with diarrhea in Japan and may be an important pathogen of cattle, principally in young calves less than 2 weeks of age.
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Affiliation(s)
- Rikio Kirisawa
- Veterinary Microbiology, Department of Pathobiology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan
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Hoet A, Horzinek M. Torovirus. ENCYCLOPEDIA OF VIROLOGY 2008. [PMCID: PMC7148633 DOI: 10.1016/b978-012374410-4.00516-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Toroviruses are single-stranded RNA viruses with a peplomer-bearing envelope that have been associated with enteric disease in cattle and possibly humans. Toroviruses appear to occur worldwide, and torovirus-like particles in fecal preparations have been reported from Europe, the Americas, Asia, New Zealand, and South Africa. These viruses have a unique C-shape or open torus morphology in the extracellular environment. There are four recognized species in the genus Torovirus (family Coronaviridae, order Nidovirales): Equine torovirus, Bovine torovirus, Human torovirus, and Porcine torovirus. Among them there is little genetic divergence (20–40%). Antigenic cross-reactivity has revealed a relationship between equine torovirus (EToV), bovine torovirus (BToV), and human torovirus (HToV). The torovirus genome contains six open reading frames (ORFs), which are transcribed as a 3′ co-terminal nested set of four mRNAs. ORF1a and -1b encode the replicase, and ORFs 2–5 encode the spike (S), membrane (M), hemagglutinin-esterase (HE), and nucleocapsid (N) proteins, respectively. EToV is apathogenic, and the only torovirus that has been grown in vitro. All BToV strains are pathogenic, causing diarrhea in experimentally or naturally infected calves. HToVs have been associated with gastroenteritis and diarrhea in children, as well as with nosocomial infections in infants with necrotizing enterocolitis.
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Kuwabara M, Wada K, Maeda Y, Miyazaki A, Tsunemitsu H. First isolation of cytopathogenic bovine torovirus in cell culture from a calf with diarrhea. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:998-1004. [PMID: 17567770 PMCID: PMC2044491 DOI: 10.1128/cvi.00475-06] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A cytopathogenic virus (designated the Aichi/2004 strain) was isolated in a human rectal adenocarcinoma cell line (HRT-18) from the ileum contents of a calf with diarrhea. Oval and elongated particles, approximately 100 to 170 nm in diameter, with club-shaped projections were seen in the infected culture supernatant, and torovirus-like (tubular and torus nucleocapsid) structures were seen in the infected cells by electron microscopy. An antiserum against bovine torovirus (BToV) reacted with the infected cells by immunofluorescence and neutralized the isolate. However, antisera against bovine coronavirus (BCV) failed to react with the infected cells by immunofluorescence or did not neutralize the isolate. Further, the isolate was positive for BToV by reverse transcription-PCR (RT-PCR) targeting fragments of the nucleocapsid (N), membrane (M), and spike (S) genes. Comparison of the nucleotide sequences of the PCR products with those of the published N, M, and S genes (476 to 497, 672, and 687 to 690 nucleotides, respectively) of toroviruses showed high sequence identities (up to 99.4%, 98.7%, and 94.9% for the N, M, and S genes, respectively) between the isolate and BToVs. In contrast, the isolate was negative for BCV by RT-PCR. In a serological survey of serum samples from 355 calves at 33 farms, 92% of calves were positive for neutralizing antibodies to the isolate. These results indicate that the isolate in this study was BToV and that BToV infection might be common in cattle in Japan. To our knowledge, this is the first isolation of BToV in tissue culture.
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Affiliation(s)
- Masaki Kuwabara
- Nishimikawa Livestock Hygiene Service Center, Zizouno 1-306, Miai, Okazaki, Aichi 4440805, Japan
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44
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Ito T, Okada N, Fukuyama SI. Epidemiological analysis of bovine torovirus in Japan. Virus Res 2007; 126:32-7. [PMID: 17320234 PMCID: PMC7114342 DOI: 10.1016/j.virusres.2007.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 01/12/2007] [Accepted: 01/18/2007] [Indexed: 01/18/2023]
Abstract
Bovine torovirus (BToV), a member of the Coronaviridae family, is an established gastrointestinal infectious agent in cattle. No epidemiological research on BToV has been reported from Japan. In this study, we performed a survey to detect BToV in Japan in 2004 and 2005 using 231 fecal samples (167 from diarrheic cattle and 64 from asymptomatic cattle) that were analyzed by nested reverse transcription (RT) PCR using primers located in the consensus sequences of the reported BToV nucleocapsid (N), membrane (M), and spike (S) genes. BToV N, M, and S genes were detected in 6.5% (15/231), 6.1% (14/231), and 5.6% (13/231) of samples by nested-RT-PCR, respectively. In conclusion, detectability was improved compared to the results of the first round of RT-PCR. BToV was detected at a significantly higher rate in diarrheic samples than in asymptomatic samples (14/167 diarrheic samples [8.4%] and 1/64 asymptomatic samples [1.6%]), suggesting that BToV may act as a risk factor for diarrhea in Japanese cattle. The nucleotide sequence of M fragments from the BToV isolates including the newly identified Japanese isolates showed more than 97% identity. A similar degree of homology was observed in the N gene fragment among BToV isolates with the exception of BRV-1 and BRV-2. Domestic samples were classified into three clusters by phylogenetic analysis of the S gene fragment, which were considerably correlated with the geographic origin of the samples. BToV positive areas did not adjoin each other but were spread across a wide range, suggesting that BToV exists conventionally in Japan and is geographically differentiated. We also developed an RFLP method to distinguish these clusters using two restriction enzymes, HaeIII and AccI. This method should be useful for comparing newly acquired BToV-positive samples with the reported BToVs.
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Affiliation(s)
- Toshihiro Ito
- Kyoto Biken Laboratories, Inc., 24-16 Makishima-cho Uji-shi, Kyoto 611-0041, Japan.
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45
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Imbert I, Guillemot JC, Bourhis JM, Bussetta C, Coutard B, Egloff MP, Ferron F, Gorbalenya AE, Canard B. A second, non-canonical RNA-dependent RNA polymerase in SARS coronavirus. EMBO J 2006; 25:4933-42. [PMID: 17024178 PMCID: PMC1618104 DOI: 10.1038/sj.emboj.7601368] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 09/01/2006] [Indexed: 12/18/2022] Open
Abstract
In (+) RNA coronaviruses, replication and transcription of the giant ∼30 kb genome to produce genome- and subgenome-size RNAs of both polarities are mediated by a cognate membrane-bound enzymatic complex. Its RNA-dependent RNA polymerase (RdRp) activity appears to be supplied by non-structural protein 12 (nsp12) that includes an RdRp domain conserved in all RNA viruses. Using SARS coronavirus, we now show that coronaviruses uniquely encode a second RdRp residing in nsp8. This protein strongly prefers the internal 5′-(G/U)CC-3′ trinucleotides on RNA templates to initiate the synthesis of complementary oligonucleotides of <6 residues in a reaction whose fidelity is relatively low. Distant structural homology between the C-terminal domain of nsp8 and the catalytic palm subdomain of RdRps of RNA viruses suggests a common origin of the two coronavirus RdRps, which however may have evolved different sets of catalytic residues. A parallel between the nsp8 RdRp and cellular DNA-dependent RNA primases is drawn to propose that the nsp8 RdRp produces primers utilized by the primer-dependent nsp12 RdRp.
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Affiliation(s)
- Isabelle Imbert
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - Jean-Claude Guillemot
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - Jean-Marie Bourhis
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - Cécile Bussetta
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - Bruno Coutard
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - Marie-Pierre Egloff
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - François Ferron
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
| | - Alexander E Gorbalenya
- Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Bruno Canard
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, Marseille Cedex, France
- Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d'Ingénieurs de Luminy-Case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 9, France. Tel.: +33 491 82 86 44; Fax: +33 491 82 86 46; E-mail: or
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Schütze H, Ulferts R, Schelle B, Bayer S, Granzow H, Hoffmann B, Mettenleiter TC, Ziebuhr J. Characterization of White bream virus reveals a novel genetic cluster of nidoviruses. J Virol 2006; 80:11598-609. [PMID: 16987966 PMCID: PMC1642614 DOI: 10.1128/jvi.01758-06] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The order Nidovirales comprises viruses from the families Coronaviridae (genera Coronavirus and Torovirus), Roniviridae (genus Okavirus), and Arteriviridae (genus Arterivirus). In this study, we characterized White bream virus (WBV), a bacilliform plus-strand RNA virus isolated from fish. Analysis of the nucleotide sequence, organization, and expression of the 26.6-kb genome provided conclusive evidence for a phylogenetic relationship between WBV and nidoviruses. The polycistronic genome of WBV contains five open reading frames (ORFs), called ORF1a, -1b, -2, -3, and -4. In WBV-infected cells, three subgenomic RNAs expressing the structural proteins S, M, and N were identified. The subgenomic RNAs were revealed to share a 42-nucleotide, 5' leader sequence that is identical to the 5'-terminal genome sequence. The data suggest that a conserved nonanucleotide sequence, CA(G/A)CACUAC, located downstream of the leader and upstream of the structural protein genes acts as the core transcription-regulating sequence element in WBV. Like other nidoviruses with large genomes (>26 kb), WBV encodes in its ORF1b an extensive set of enzymes, including putative polymerase, helicase, ribose methyltransferase, exoribonuclease, and endoribonuclease activities. ORF1a encodes several membrane domains, a putative ADP-ribose 1"-phosphatase, and a chymotrypsin-like serine protease whose activity was established in this study. Comparative sequence analysis revealed that WBV represents a separate cluster of nidoviruses that significantly diverged from toroviruses and, even more, from coronaviruses, roniviruses, and arteriviruses. The study adds to the amazing diversity of nidoviruses and appeals for a more extensive characterization of nonmammalian nidoviruses to better understand the evolution of these largest known RNA viruses.
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Affiliation(s)
- Heike Schütze
- The Queen's University of Belfast, School of Biomedical Sciences, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom
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Smits SL, Snijder EJ, de Groot RJ. Characterization of a torovirus main proteinase. J Virol 2006; 80:4157-67. [PMID: 16571831 PMCID: PMC1440467 DOI: 10.1128/jvi.80.8.4157-4167.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 02/02/2006] [Indexed: 11/20/2022] Open
Abstract
Viruses of the order Nidovirales encode huge replicase polyproteins. These are processed primarily by the chymotrypsin-like main proteinases (M(pro)s). So far, M(pro)s have been studied only for corona-, arteri-, and roniviruses. Here, we report the characterization of the M(pro) of toroviruses, the fourth main Nidovirus branch. Comparative sequence analysis of polyprotein 1a of equine torovirus (EToV) strain Berne, identified a serine proteinase domain, flanked by hydrophobic regions. Heterologous expression of this domain resulted in autoprocessing at flanking cleavage sites. N-terminal sequence analysis of cleavage products tentatively identified FxxQ downward arrow(S, A) as the substrate consensus sequence. EToV M(pro) combines several traits of its closest relatives. It has a predicted three-domain structure, with two catalytic beta-barrel domains and an additional C-terminal domain of unknown function. With respect to substrate specificity, the EToV M(pro) resembles its coronavirus homologue in its preference for P1-Gln, but its substrate-binding subsite, S1, more closely resembles that of arteri- and ronivirus M(pro)s, which prefer P1-Glu. Surprisingly, in contrast to the M(pro)s of corona- and roniviruses, but like that of arterivirus, the torovirus M(pro) uses serine instead of cysteine as its principal nucleophile. Under the premise that the M(pro)s of corona- and toroviruses are more closely related to each other than to those of arteri- and roniviruses, the transition from serine- to cysteine-based proteolytic catalysis (or vice versa) must have happened more than once in the course of nidovirus evolution. In this respect, it is of interest that a mutant EToV M(pro) with a Ser165-->Cys substitution retained partial enzymatic activity.
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Affiliation(s)
- Saskia L Smits
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
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48
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Gorbalenya AE, Enjuanes L, Ziebuhr J, Snijder EJ. Nidovirales: evolving the largest RNA virus genome. Virus Res 2006; 117:17-37. [PMID: 16503362 PMCID: PMC7114179 DOI: 10.1016/j.virusres.2006.01.017] [Citation(s) in RCA: 646] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2005] [Revised: 01/13/2006] [Accepted: 01/18/2006] [Indexed: 11/19/2022]
Abstract
This review focuses on the monophyletic group of animal RNA viruses united in the order Nidovirales. The order includes the distantly related coronaviruses, toroviruses, and roniviruses, which possess the largest known RNA genomes (from 26 to 32kb) and will therefore be called "large" nidoviruses in this review. They are compared with their arterivirus cousins, which also belong to the Nidovirales despite having a much smaller genome (13-16kb). Common and unique features that have been identified for either large or all nidoviruses are outlined. These include the nidovirus genetic plan and genome diversity, the composition of the replicase machinery and virus particles, virus-specific accessory genes, the mechanisms of RNA and protein synthesis, and the origin and evolution of nidoviruses with small and large genomes. Nidoviruses employ single-stranded, polycistronic RNA genomes of positive polarity that direct the synthesis of the subunits of the replicative complex, including the RNA-dependent RNA polymerase and helicase. Replicase gene expression is under the principal control of a ribosomal frameshifting signal and a chymotrypsin-like protease, which is assisted by one or more papain-like proteases. A nested set of subgenomic RNAs is synthesized to express the 3'-proximal ORFs that encode most conserved structural proteins and, in some large nidoviruses, also diverse accessory proteins that may promote virus adaptation to specific hosts. The replicase machinery includes a set of RNA-processing enzymes some of which are unique for either all or large nidoviruses. The acquisition of these enzymes may have improved the low fidelity of RNA replication to allow genome expansion and give rise to the ancestors of small and, subsequently, large nidoviruses.
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Affiliation(s)
- Alexander E Gorbalenya
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, LUMC E4-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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Putics Á, Gorbalenya AE, Ziebuhr J. Identification of protease and ADP-ribose 1''-monophosphatase activities associated with transmissible gastroenteritis virus non-structural protein 3. J Gen Virol 2006; 87:651-656. [PMID: 16476987 DOI: 10.1099/vir.0.81596-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The replicase polyproteins, pp1a and pp1ab, of porcine Transmissible gastroenteritis virus (TGEV) have been predicted to be cleaved by viral proteases into 16 non-structural proteins (nsp). Here, enzymic activities residing in the amino-proximal region of nsp3, the largest TGEV replicase processing product, were characterized. It was shown, by in vitro translation experiments and protein sequencing, that the papain-like protease 1, PL1(pro), but not a mutant derivative containing a substitution of the presumed active-site nucleophile, Cys(1093), cleaves the nsp2|nsp3 site at (879)Gly|Gly(880). By using an antiserum raised against the pp1a/pp1ab residues 526-713, the upstream processing product, nsp2, was identified as an 85 kDa protein in TGEV-infected cells. Furthermore, PL1(pro) was confirmed to be flanked at its C terminus by a domain (called X) that mediates ADP-ribose 1''-phosphatase activity. Expression and characterization of a range of bacterially expressed forms of this enzyme suggest that the active X domain comprises pp1a/pp1ab residues Asp(1320)-Ser(1486).
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Affiliation(s)
- Ákos Putics
- Institute of Virology and Immunology, University of Würzburg, Versbacher Straße 7, 97078 Würzburg, Germany
| | - Alexander E Gorbalenya
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - John Ziebuhr
- Institute of Virology and Immunology, University of Würzburg, Versbacher Straße 7, 97078 Würzburg, Germany
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