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Qing E, Hantak M, Perlman S, Gallagher T. Distinct Roles for Sialoside and Protein Receptors in Coronavirus Infection. mBio 2020; 11:e02764-19. [PMID: 32047128 PMCID: PMC7018658 DOI: 10.1128/mbio.02764-19] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/21/2020] [Indexed: 12/18/2022] Open
Abstract
Coronaviruses (CoVs) are common human and animal pathogens that can transmit zoonotically and cause severe respiratory disease syndromes. CoV infection requires spike proteins, which bind viruses to host cell receptors and catalyze virus-cell membrane fusion. Several CoV strains have spike proteins with two receptor-binding domains, an S1A that engages host sialic acids and an S1B that recognizes host transmembrane proteins. As this bivalent binding may enable broad zoonotic CoV infection, we aimed to identify roles for each receptor in distinct infection stages. Focusing on two betacoronaviruses, murine JHM-CoV and human Middle East respiratory syndrome coronavirus (MERS-CoV), we found that virus particle binding to cells was mediated by sialic acids; however, the transmembrane protein receptors were required for a subsequent virus infection. These results favored a two-step process in which viruses first adhere to sialic acids and then require subsequent engagement with protein receptors during infectious cell entry. However, sialic acids sufficiently facilitated the later stages of virus spread through cell-cell membrane fusion, without requiring protein receptors. This virus spread in the absence of the prototype protein receptors was increased by adaptive S1A mutations. Overall, these findings reveal roles for sialic acids in virus-cell binding, viral spike protein-directed cell-cell fusion, and resultant spread of CoV infections.IMPORTANCE CoVs can transmit from animals to humans to cause serious disease. This zoonotic transmission uses spike proteins, which bind CoVs to cells with two receptor-binding domains. Here, we identified the roles for the two binding processes in the CoV infection process. Binding to sialic acids promoted infection and also supported the intercellular expansion of CoV infections through syncytial development. Adaptive mutations in the sialic acid-binding spike domains increased the intercellular expansion process. These findings raise the possibility that the lectin-like properties of many CoVs contribute to facile zoonotic transmission and intercellular spread within infected organisms.
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Affiliation(s)
- Enya Qing
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Michael Hantak
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Stanley Perlman
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Tom Gallagher
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
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Le Coupanec A, Desforges M, Meessen-Pinard M, Dubé M, Day R, Seidah NG, Talbot PJ. Cleavage of a Neuroinvasive Human Respiratory Virus Spike Glycoprotein by Proprotein Convertases Modulates Neurovirulence and Virus Spread within the Central Nervous System. PLoS Pathog 2015; 11:e1005261. [PMID: 26545254 PMCID: PMC4636366 DOI: 10.1371/journal.ppat.1005261] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/16/2015] [Indexed: 11/24/2022] Open
Abstract
Human coronaviruses (HCoV) are respiratory pathogens that may be associated with the development of neurological diseases, in view of their neuroinvasive and neurotropic properties. The viral spike (S) glycoprotein is a major virulence factor for several coronavirus species, including the OC43 strain of HCoV (HCoV-OC43). In an attempt to study the role of this protein in virus spread within the central nervous system (CNS) and neurovirulence, as well as to identify amino acid residues important for such functions, we compared the sequence of the S gene found in the laboratory reference strain HCoV-OC43 ATCC VR-759 to S sequences of viruses detected in clinical isolates from the human respiratory tract. We identified one predominant mutation at amino acid 758 (from RRSR↓ G758 to RRSR↓R758), which introduces a putative furin-like cleavage (↓) site. Using a molecular cDNA infectious clone to generate a corresponding recombinant virus, we show for the first time that such point mutation in the HCoV-OC43 S glycoprotein creates a functional cleavage site between the S1 and S2 portions of the S protein. While the corresponding recombinant virus retained its neuroinvasive properties, this mutation led to decreased neurovirulence while potentially modifying the mode of virus spread, likely leading to a limited dissemination within the CNS. Taken together, these results are consistent with the adaptation of HCoV-OC43 to the CNS environment, resulting from the selection of quasi-species harboring mutations that lead to amino acid changes in viral genes, like the S gene in HCoV-OC43, which may contribute to a more efficient establishment of a less pathogenic but persistent CNS infection. This adaptative mechanism could potentially be associated with human encephalitis or other neurological degenerative pathologies. Human coronaviruses (HCoV) are respiratory pathogens involved in a sizable proportion of common colds. They have over the years been associated with the development of neurological diseases, given their demonstrated neuroinvasive and neurotropic properties. The viral spike (S) glycoprotein appears to be associated with these neurologic features and is a major factor of virulence for several coronavirus species, including HCoV-OC43. To further characterize the role of this protein in neurovirulence and virus spread within the CNS, we sought to identify amino acid residues that may be important for this function. Our data revealed that one of them, G758R, introduces a functional furin-like cleavage site in the S protein (RRSR↓R758). This change in S protein mostly impacts neurovirulence, which seems associated with a modified viral dissemination, without significantly affecting its neuroinvasive capacity. This mutation, found in all characterized contemporary human clinical respiratory isolates, underlines previous findings that naturally existing field isolates of HCoV-OC43 variants still possess the capacity to invade the CNS where they could eventually adapt and establish a persistent human CNS infection, a mechanism potentially associated with human encephalitis or neurodegenerative pathologies of unknown etiologies.
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Affiliation(s)
- Alain Le Coupanec
- Laboratory of Neuroimmunovirology, INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
| | - Marc Desforges
- Laboratory of Neuroimmunovirology, INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
- * E-mail: (MDe); (PJT)
| | - Mathieu Meessen-Pinard
- Laboratory of Neuroimmunovirology, INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
| | - Mathieu Dubé
- Laboratory of Neuroimmunovirology, INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
| | - Robert Day
- Institut de Pharmacologie de Sherbrooke, Faculté de Médecine et Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Nabil G. Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montréal, Québec, Canada
| | - Pierre J. Talbot
- Laboratory of Neuroimmunovirology, INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
- * E-mail: (MDe); (PJT)
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3
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Entry of hepatitis B virus into immortalized human primary hepatocytes by clathrin-dependent endocytosis. J Virol 2012; 86:9443-53. [PMID: 22740403 DOI: 10.1128/jvi.00873-12] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The lack of a suitable in vitro hepatitis B virus (HBV) infectivity model has limited examination of the early stages of the virus-cell interaction. In this study, we used an immortalized cell line derived from human primary hepatocytes, HuS-E/2, to study the mechanism of HBV infection. HBV infection efficiency was markedly increased after dimethyl sulfoxide (DMSO)-induced differentiation of the cells. Transmission electron microscopy demonstrated the presence of intact HBV particles in DMSO-treated HBV-infected HuS-E/2 cells, which could be infected with HBV for up to at least 50 passages. The pre-S1 domain of the large HBsAg (LHBsAg) protein specifically interacted with clathrin heavy chain (CHC) and clathrin adaptor protein AP-2. Short hairpin RNA knockdown of CHC or AP-2 in HuS-E/2 cells significantly reduced their susceptibility to HBV, indicating that both are necessary for HBV infection. Furthermore, HBV entry was inhibited by chlorpromazine, an inhibitor of clathrin-mediated endocytosis. LHBsAg also interfered with the clathrin-mediated endocytosis of transferrin by human hepatocytes. This infection system using an immortalized human primary hepatocyte cell line will facilitate investigations into HBV entry and in devising therapeutic strategies for manipulating HBV-associated liver disorders.
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Upregulation of the chemokine (C-C motif) ligand 2 via a severe acute respiratory syndrome coronavirus spike-ACE2 signaling pathway. J Virol 2010; 84:7703-12. [PMID: 20484496 DOI: 10.1128/jvi.02560-09] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) was identified to be the causative agent of SARS with atypical pneumonia. Angiotensin-converting enzyme 2 (ACE2) is the major receptor for SARS-CoV. It is not clear whether ACE2 conveys signals from the cell surface to the nucleus and regulates expression of cellular genes upon SARS-CoV infection. To understand the pathogenesis of SARS-CoV, human type II pneumocyte (A549) cells were incubated with the viral spike protein or with SARS-CoV virus-like particles containing the viral spike protein to examine cytokine modulation in lung cells. Results from oligonucleotide-based microarray, real-time PCR, and enzyme-linked immunosorbent assays indicated an upregulation of the fibrosis-associated chemokine (C-C motif) ligand 2 (CCL2) by the viral spike protein and the virus-like particles. The upregulation of CCL2 by SARS-CoV spike protein was mainly mediated by extracellular signal-regulated kinase 1 and 2 (ERK1/2) and AP-1 but not the IkappaBalpha-NF-kappaB signaling pathway. In addition, Ras and Raf upstream of the ERK1/2 signaling pathway were involved in the upregulation of CCL2. Furthermore, ACE2 receptor was activated by casein kinase II-mediated phosphorylation in cells pretreated with the virus-like particles containing spike protein. These results indicate that SARS-CoV spike protein triggers ACE2 signaling and activates fibrosis-associated CCL2 expression through the Ras-ERK-AP-1 pathway.
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Yamada Y, Liu XB, Fang SG, Tay FPL, Liu DX. Acquisition of cell-cell fusion activity by amino acid substitutions in spike protein determines the infectivity of a coronavirus in cultured cells. PLoS One 2009; 4:e6130. [PMID: 19572016 PMCID: PMC2700284 DOI: 10.1371/journal.pone.0006130] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 06/03/2009] [Indexed: 12/30/2022] Open
Abstract
Coronavirus host and cell specificities are determined by specific interactions between the viral spike (S) protein and host cell receptor(s). Avian coronavirus infectious bronchitis (IBV) has been adapted to embryonated chicken eggs, primary chicken kidney (CK) cells, monkey kidney cell line Vero, and other human and animal cells. Here we report that acquisition of the cell–cell fusion activity by amino acid mutations in the S protein determines the infectivity of IBV in cultured cells. Expression of S protein derived from Vero- and CK-adapted strains showed efficient induction of membrane fusion. However, expression of S protein cloned from the third passage of IBV in chicken embryo (EP3) did not show apparent syncytia formation. By construction of chimeric S constructs and site-directed mutagenesis, a point mutation (L857-F) at amino acid position 857 in the heptad repeat 1 region of S protein was shown to be responsible for its acquisition of the cell–cell fusion activity. Furthermore, a G405-D point mutation in the S1 domain, which was acquired during further propagation of Vero-adapted IBV in Vero cells, could enhance the cell–cell fusion activity of the protein. Re-introduction of L857 back to the S gene of Vero-adapted IBV allowed recovery of variants that contain the introduced L857. However, compensatory mutations in S1 and some distant regions of S2 were required for restoration of the cell–cell fusion activity of S protein carrying L857 and for the infectivity of the recovered variants in cultured cells. This study demonstrates that acquisition of the cell–cell fusion activity in S protein determines the selection and/or adaptation of a coronavirus from chicken embryo to cultured cells of human and animal origins.
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Affiliation(s)
- Yoshiyuki Yamada
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
| | - Xiao Bo Liu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Shou Guo Fang
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
| | - Felicia P. L. Tay
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
| | - Ding Xiang Liu
- Institute of Molecular and Cell Biology, Proteos, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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6
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Hsieh PK, Chang SC, Huang CC, Lee TT, Hsiao CW, Kou YH, Chen IY, Chang CK, Huang TH, Chang MF. Assembly of severe acute respiratory syndrome coronavirus RNA packaging signal into virus-like particles is nucleocapsid dependent. J Virol 2006; 79:13848-55. [PMID: 16254320 PMCID: PMC1280188 DOI: 10.1128/jvi.79.22.13848-13855.2005] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus (SARS-CoV) was recently identified as the etiology of SARS. The virus particle consists of four structural proteins: spike (S), small envelope (E), membrane (M), and nucleocapsid (N). Recognition of a specific sequence, termed the packaging signal (PS), by a virus N protein is often the first step in the assembly of viral RNA, but the molecular mechanisms involved in the assembly of SARS-CoV RNA are not clear. In this study, Vero E6 cells were cotransfected with plasmids encoding the four structural proteins of SARS-CoV. This generated virus-like particles (VLPs) of SARS-CoV that can be partially purified on a discontinuous sucrose gradient from the culture medium. The VLPs bearing all four of the structural proteins have a density of about 1.132 g/cm(3). Western blot analysis of the culture medium from transfection experiments revealed that both E and M expressed alone could be released in sedimentable particles and that E and M proteins are likely to form VLPs when they are coexpressed. To examine the assembly of the viral genomic RNA, a plasmid representing the GFP-PS580 cDNA fragment encompassing the viral genomic RNA from nucleotides 19715 to 20294 inserted into the 3' noncoding region of the green fluorescent protein (GFP) gene was constructed and applied to the cotransfection experiments with the four structural proteins. The SARS-CoV VLPs thus produced were designated VLP(GFP-PS580). Expression of GFP was detected in Vero E6 cells infected with the VLP(GFP-PS580), indicating that GFP-PS580 RNA can be assembled into the VLPs. Nevertheless, when Vero E6 cells were infected with VLPs produced in the absence of the viral N protein, no green fluorescence was visualized. These results indicate that N protein has an essential role in the packaging of SARS-CoV RNA. A filter binding assay and competition analysis further demonstrated that the N-terminal and C-terminal regions of the SARS-CoV N protein each contain a binding activity specific to the viral RNA. Deletions that presumably disrupt the structure of the N-terminal domain diminished its RNA-binding activity. The GFP-PS-containing SARS-CoV VLPs are powerful tools for investigating the tissue tropism and pathogenesis of SARS-CoV.
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Affiliation(s)
- Ping-Kun Hsieh
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, No. 1, Jen-Ai Road, 1st Section, Taipei 100, Taiwan
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7
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Fang SG, Shen S, Tay FPL, Liu DX. Selection of and recombination between minor variants lead to the adaptation of an avian coronavirus to primate cells. Biochem Biophys Res Commun 2005; 336:417-23. [PMID: 16137658 PMCID: PMC7092901 DOI: 10.1016/j.bbrc.2005.08.105] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Accepted: 08/12/2005] [Indexed: 01/24/2023]
Abstract
An interesting question posed by the current evidence that severe acute respiratory syndrome coronavirus may be originated from an animal coronavirus is how such an animal coronavirus breaks the host species barrier and becomes zoonotic. In this report, we study the chronological order of genotypic changes in the spike protein of avian coronavirus infectious bronchitis virus (IBV) during its adaptation to a primate cell line. Adaptation of the Beaudette strain of IBV from chicken embryo to Vero cells showed the accumulation of 49 amino acid mutations. Among them, 26 (53.06%) substitutions were located in the S protein. Sequencing analysis and comparison of the S gene demonstrated that the majority of the mutations were accumulated and fixed at passage 7 on Vero cells and minor variants were isolated in several passages. Evidence present suggests that the dominant Vero cell-adapted IBV strain may be derived from the chicken embryo passages by selection of and potential recombination between the minor variants. This may explain why adaptation is a rapid process and the dominant strain, once adapted to a new host cell, becomes relatively stable.
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Affiliation(s)
- Shou Guo Fang
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
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8
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Wang YH, Chang SC, Huang C, Li YP, Lee CH, Chang MF. Novel nuclear export signal-interacting protein, NESI, critical for the assembly of hepatitis delta virus. J Virol 2005; 79:8113-20. [PMID: 15956556 PMCID: PMC1143724 DOI: 10.1128/jvi.79.13.8113-8120.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The process of host factor-mediated nucleocytoplasmic transport is critical for diverse cellular events in eukaryotes and the life cycle of viruses. We have previously identified a chromosome region maintenance 1-independent nuclear export signal (NES) at the C terminus of the large form of hepatitis delta antigen (HDAg), designated NES(HDAg-L) that is required for the assembly of hepatitis delta virus (HDV) (C.-H. Lee et al., J. Biol. Chem. 276:8142-8148, 2001). To look for interacting proteins of the NES(HDAg-L), yeast two-hybrid screening was applied using the GAL4-binding domain fused to the NES(HDAg-L) as bait. Among the positive clones, one encodes a protein, designated NESI [NES(HDAg-L) interacting protein] that specifically interacted with the wild-type NES(HDAg-L) but not with the export/package-defective HDAg-L mutant, NES*(HDAg-L), in which Pro-205 has been replaced by Ala. Northern blot analysis revealed NESI as the gene product of a 1.9-kb endogenous mRNA transcript that is present predominantly in human liver tissue. NESI consists of 467 amino acid residues and bears a putative actin-binding site and a bipartite nuclear localization signal. Specific interaction between HDAg-L and NESI was further confirmed by coimmunoprecipitation and immunofluorescence staining. Overexpression of antisense NESI RNAs inhibited the expression of NESI and abolished HDAg-L-mediated nuclear export and assembly of HDV genomic RNA. These data indicate a critical role of NESI in the assembly of HDV through interaction with HDAg-L.
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Affiliation(s)
- Yun-Hsin Wang
- Institute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, No. 1, Jen-Ai Road, First Section, Taipei 100, Taiwan
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9
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Han DP, Kim HG, Kim YB, Poon LL, Cho MW. Development of a safe neutralization assay for SARS-CoV and characterization of S-glycoprotein. Virology 2004; 326:140-9. [PMID: 15262502 PMCID: PMC7127165 DOI: 10.1016/j.virol.2004.05.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 05/14/2004] [Accepted: 05/17/2004] [Indexed: 11/28/2022]
Abstract
The etiological agent of severe acute respiratory syndrome (SARS) has been identified as a novel coronavirus SARS-CoV. Similar to other coronaviruses, spike (S)-glycoprotein of the virus interacts with a cellular receptor and mediates membrane fusion to allow viral entry into susceptible target cells. Accordingly, S-protein plays an important role in virus infection cycle and is the primary target of neutralizing antibodies. To begin to understand its biochemical and immunological properties, we expressed both full-length and ectodomain of the protein in various primate cells. Our results show that the protein has an electrophoretic mobility of about 160–170 kDa. The protein is glycosylated with high mannose and/or hybrid oligosaccharides, which account for approximately 30 kDa of the apparent protein mass. The detection of S-protein by immunoassays was difficult using human convalescent sera, suggesting that the protein may not elicit strong humoral immune response in virus-infected patients. We were able to pseudotype murine leukemia virus particles with S-protein and produce SARS pseudoviruses. Pseudoviruses infected Vero E6 cells in a pH-independent manner and the infection could be specifically inhibited by convalescent sera. Consistent with low levels of antibodies against S-protein, neutralizing activity was weak with 50% neutralization titers ranging between 1:15 to 1:25. To facilitate quantifying pseudovirus-infected cells, which are stained blue with X-Gal, we devised an automated procedure using an ELISPOT analyzer. The high-throughput capacity of this procedure and the safety of using SARS pseudoviruses should make possible large-scale analyses of neutralizing antibody responses against SARS-CoV.
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Affiliation(s)
- Dong P Han
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Hyung G Kim
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Young B Kim
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Leo L.M Poon
- Department of Microbiology, Queen Mary Hospital, University of Hong Kong, Hong Kong, China
| | - Michael W Cho
- Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Corresponding author. Department of Medicine, Division of Infectious Diseases, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4984. Fax: +1-216-844-1409.
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Shen S, Law Y, Liu D. A single amino acid mutation in the spike protein of coronavirus infectious bronchitis virus hampers its maturation and incorporation into virions at the nonpermissive temperature. Virology 2004; 326:288-98. [PMID: 15302214 PMCID: PMC7126609 DOI: 10.1016/j.virol.2004.06.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Revised: 05/25/2004] [Accepted: 06/03/2004] [Indexed: 11/22/2022]
Abstract
The spike (S) glycoprotein of coronavirus is responsible for receptor binding and membrane fusion. A number of variants with deletions and mutations in the S protein have been isolated from naturally and persistently infected animals and tissue cultures. Here, we report the emergence and isolation of two temperature sensitive (ts) mutants and a revertant in the process of cold-adaptation of coronavirus infectious bronchitis virus (IBV) to a monkey kidney cell line. The complete sequences of wild type (wt) virus, two ts mutants, and the revertant were compared and variations linked to phenotypes were mapped. A single amino acid reversion (L294-to-Q) in the S protein is sufficient to abrogate the ts phenotype. Interestingly, unlike wt virus, the revertant grows well at and below 32 degrees C, the permissive temperature, as it carries other mutations in multiple genes that might be associated with the cold-adaptation phenotype. If the two ts mutants were allowed to enter cells at 32 degrees C, the S protein was synthesized, core-glycosylated and at least partially modified at 40 degrees C. However, compared with wt virus and the revertant, no infectious particles of these ts mutants were assembled and released from the ts mutant-infected cells at 40 degrees C. Evidence presented demonstrated that the Q294-to-L294 mutation, located at a highly conserved domain of the S1 subunit, might hamper processing of the S protein to a matured 180-kDa, endo-glycosidase H-resistant glycoprotein and the translocation of the protein to the cell surface. Consequently, some essential functions of the S protein, including mediation of cell-to-cell fusion and its incorporation into virions, were completely abolished.
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Affiliation(s)
| | | | - D.X Liu
- Corresponding author. Institute of Molecular and Cell Biology, 30 Medical Drive, 117609, Singapore. Fax: +65-67791117.
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11
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de Haan CAM, Stadler K, Godeke GJ, Bosch BJ, Rottier PJM. Cleavage inhibition of the murine coronavirus spike protein by a furin-like enzyme affects cell-cell but not virus-cell fusion. J Virol 2004; 78:6048-54. [PMID: 15141003 PMCID: PMC415802 DOI: 10.1128/jvi.78.11.6048-6054.2004] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cleavage of the mouse hepatitis coronavirus strain A59 spike protein was blocked in a concentration-dependent manner by a peptide furin inhibitor, indicating that furin or a furin-like enzyme is responsible for this process. While cell-cell fusion was clearly affected by preventing spike protein cleavage, virus-cell fusion was not, indicating that these events have different requirements.
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Affiliation(s)
- Cornelis A M de Haan
- Virology Division, Department of Infectious Diseases & Immunology, Yalelaan 1, 3584CL Utrecht, The Netherlands.
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12
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Lan Y, Lu W, Xu X. Genomic instability of prawn white spot bacilliform virus (WSBV) and its association to virus virulence. Virus Res 2002; 90:269-74. [PMID: 12457981 DOI: 10.1016/s0168-1702(02)00231-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Prawn White Spot Bacilliform Virus (WSBV) is a major pathogen that causes prawn diseases. In this study, we examined the sequence of WSBV genome DNA in the shrimp Penaeus japonicus, P. vannamei, P. Monodon, P. chinensis and Metapenaeus ensis through successive PCR amplification of the DNA fragments in the whole WSBV genome. We found a sequence deletion hotspot in the WSBV genome that is 305107 bp in length. The sizes of the deleted fragments were 4.6, 4.8 or 8.1 kbp depending on the species of prawn. Since the mortality of shrimp infected by the intact WSBV was always significantly higher than that of shrimp infected by DNA fragment-deleted WSBV, we suggest that this deletion be somehow linked to the virulence of the virus itself. This result may lead to the discovery of the molecular mechanism of the pathogenicity of WSBV in shrimps.
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Affiliation(s)
- Yongsheng Lan
- School of Life Science, Xiamen University, Xiamen 361005, PR China
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13
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Matsuyama S, Taguchi F. Communication between S1N330 and a region in S2 of murine coronavirus spike protein is important for virus entry into cells expressing CEACAM1b receptor. Virology 2002; 295:160-71. [PMID: 12033774 PMCID: PMC7133742 DOI: 10.1006/viro.2002.1391] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The soluble receptor-resistant (srr) mutants, srr7 and srr11, isolated from a murine coronavirus, mouse hepatitis virus (MHV) JHMV, have an amino acid mutation at positions 1114 (Leu to Phe) and 65 (Leu to His), respectively, in the spike (S) protein. These mutants failed to efficiently infect BHK cells expressing CEACAM1b (BHK-R2), due to their low entry into this cell line, although they infected cells expressing CEACAM1a (BHK-R1) in a manner similar to that of wild-type (wt) JHMV cl-2 (Matsuyama and Taguchi, Virology 273, 80-89, 2000). Following the repeated passage of these mutants through BHK-R2 cells, viruses were no longer isolated from srr11-infected cells, while two distinct mutants, srr7A and srr7B, were obtained from srr7-infected cells. Srr7A and srr7B grew 2 log10 higher than srr7 and induced fusion in BHK-R2 cells, being similar to wt virus. In addition to the amino acid change at position 1114 that stemmed from parental srr7, srr7A and srr7B had mutations around position 280, corresponding to the third region of the S1N330 receptor-binding site (S1N330-III) common to all MHV strains examined thus far. Srr7A and srr7B S proteins showed high fusogenicity in both BHK-R1 and BHK-R2 cells, like the wt virus, while srr7Aa and srr7Ba S proteins, which had mutations in S1N330-III but not at amino acid 1114, exhibited profoundly reduced fusion activity in these cell lines. These findings suggest that communication between S1N330-III and the amino acid at position 1114 is important for efficient fusion activity in BHK-R2 cells. S1N330-III is a possible region in the S1 involved in viral entry into cells.
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Affiliation(s)
- Shutoku Matsuyama
- National Institute of Neuroscience, NCNP, 4-1-1 Ogawahigashi, Kodaira, Tokyo, 187-8502, Japan
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Hingley ST, Leparc-Goffart I, Seo SH, Tsai JC, Weiss SR. The virulence of mouse hepatitis virus strain A59 is not dependent on efficient spike protein cleavage and cell-to-cell fusion. J Neurovirol 2002; 8:400-10. [PMID: 12402166 PMCID: PMC7095328 DOI: 10.1080/13550280260422703] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The cleavage and fusion properties of recombinant murine hepatitis viruses (MHV) were examined to assess the role of the cleavage signal in determining the extent of S protein cleavage, and the correlation between cleavage and induction of cell-to-cell fusion. Targeted recombination was used to introduce amino acid substitutions into the cleavage signal of the fusion glycoprotein (spike or S protein) of MHV strain A59. The recombinants were then used to address the question of the importance of S protein cleavage and viral-mediated cell-to-cell fusion on pathogenicity. Our data indicate that cleavage of spike is not solely determined by the amino acid sequence at the cleavage site, but may also depend on sequences removed from the cleavage site. In addition, efficient cell-to-cell fusion is not necessary for virulence.
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Affiliation(s)
- Susan T Hingley
- Department of Pathology, Microbiology and Immunology, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania 19131, USA.
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15
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Morales S, Parra B, Ramakrishna C, Blau DM, Stohlman SA. B-cell-mediated lysis of cells infected with the neurotropic JHM strain of mouse hepatitis virus. Virology 2001; 286:160-7. [PMID: 11448169 PMCID: PMC7142306 DOI: 10.1006/viro.2001.0991] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cells expressing the spike (S) glycoprotein of the neurotropic JHM strain (JHMV) of mouse hepatitis virus (MHV) are susceptible to lysis by B cells derived from naïve mice, including B cells from perforin-deficient mice. Cytolysis requires interaction of the virus receptor and the viral S glycoprotein, is independent of other viral-induced components, and is not a unique property of B cells. Neutralizing anti-S-protein monoclonal antibodies (mAb) and a mAb specific for the viral receptor inhibit lysis. However, cells infected with an MHV strain unable to induce cell-cell fusion are resistant to lysis and lysis of JHMV-infected cells is inhibited by an anti-S-protein nonneutralizing mAb which prevents S-protein-mediated cell fusion. These data suggest that B cells may function as antibody-independent innate immune response during JHMV infection in vivo.
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Affiliation(s)
- S Morales
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, California 90033, USA
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Phillips JJ, Chua M, Seo SH, Weiss SR. Multiple regions of the murine coronavirus spike glycoprotein influence neurovirulence. J Neurovirol 2001; 7:421-31. [PMID: 11582514 PMCID: PMC7095106 DOI: 10.1080/135502801753170273] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The spike (S) glycoprotein of mouse hepatitis virus (MHV) is a major determinant of neurovirulence. Using targeted recombination we previously demonstrated that the S gene of the highly neurovirulent MHV-4 conferred a dramatic increase in neurovirulence to the mildly neurovirulent MHV-A59. To identify the genetic determinants of neurovirulence within the MHV-4 spike, we generated isogenic recombinant viruses containing various MHV-4/MHV-A59 chimeric spike genes, and studied their phenotypes in vivo. The MHV-4/MHV-A59 chimeric spike genes consisted of either reciprocal exchanges between the S1 and S2 spike subunits, or smaller exchanges specifically in the hypervariable region (HVR) of S1. The chimeric spike gene containing recombinants all exhibited efficient replication in vitro, yet many were severely attenuated for virulence in vivo. Furthermore, these attenuated recombinants exhibited decreased titers of infectious virus in the brain relative to the parental recombinant viruses containing the full-length MHV-4 or MHV-A59 spike genes. This is the first report that compares the neurovirulence and pathogenesis of isogenic viruses with defined alterations in the MHV spike protein. From these studies, it appears that the interactions of multiple regions of the MHV spike, including the HVR, act in concert to allow for efficient infection of and virulence in the murine central nervous system.
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Affiliation(s)
- Joanna J. Phillips
- Department of Microbiology, University of Pennsylvania School of Medicine, 203A Johnson Pavillion, 36th Street and Hamilton Walk, 19104-6076 Philadelphia, PA USA
| | - MingMing Chua
- Department of Microbiology, University of Pennsylvania School of Medicine, 203A Johnson Pavillion, 36th Street and Hamilton Walk, 19104-6076 Philadelphia, PA USA
| | - Su-hun Seo
- Department of Microbiology, University of Pennsylvania School of Medicine, 203A Johnson Pavillion, 36th Street and Hamilton Walk, 19104-6076 Philadelphia, PA USA
| | - Susan R. Weiss
- Department of Microbiology, University of Pennsylvania School of Medicine, 203A Johnson Pavillion, 36th Street and Hamilton Walk, 19104-6076 Philadelphia, PA USA
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Yoo D, Pei Y, Christie N, Cooper M. Primary structure of the sialodacryoadenitis virus genome: sequence of the structural-protein region and its application for differential diagnosis. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2000; 7:568-73. [PMID: 10882653 PMCID: PMC95915 DOI: 10.1128/cdli.7.4.568-573.2000] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2000] [Accepted: 04/04/2000] [Indexed: 11/20/2022]
Abstract
Sialodacryoadenitis virus (SDAV) is a coronavirus that is commonly found in laboratory rats and that causes sialodacryoadenitis and respiratory illness. We cloned and sequenced the 3' terminal 9.8 kb of the genomic RNA and analyzed the structure of the viral genome. As with mouse hepatitis coronaviruses (MHVs), the SDAV genome was able to code for a spike protein, a small membrane protein, a membrane-associated protein, and a nucleocapsid protein. In addition, the hemagglutinin-esterase gene capable of encoding a protein of 439 amino acids (aa) was identified. The putative functional site for acetylesterase activity was present in the HE protein as Phe-Gly-Asp-Ser (FGDS), suggesting that the SDAV HE protein might have retained the esterase activity. Immediately upstream of the HE gene and downstream of the polymerase 1b gene, the NS2 nonstructural-protein gene was identified with a coding capacity of 274 aa. A motif of UCUAAAC was identified as a potential transcription signal for subgenomic mRNA synthesis. Large insertions of 172, 127, and 44 aa were detected in the N-terminal half of the predicted S protein of SDAV when its sequence was compared to the sequences of MHV 2, MHV JHM, and MHV A59, respectively. The sequence information on the SDAV S-protein gene was applied to a differential diagnostic PCR to detect and distinguish the rat coronavirus from mouse coronaviruses. This is the first report on the comprehensive genetic information of any rat coronavirus.
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Affiliation(s)
- D Yoo
- Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1 Canada.
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