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Weiss SR, Navas-Martin S. Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus. Microbiol Mol Biol Rev 2005. [PMID: 16339739 DOI: 10.1128/mmbr.69.4.635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023] Open
Abstract
Coronaviruses are a family of enveloped, single-stranded, positive-strand RNA viruses classified within the Nidovirales order. This coronavirus family consists of pathogens of many animal species and of humans, including the recently isolated severe acute respiratory syndrome coronavirus (SARS-CoV). This review is divided into two main parts; the first concerns the animal coronaviruses and their pathogenesis, with an emphasis on the functions of individual viral genes, and the second discusses the newly described human emerging pathogen, SARS-CoV. The coronavirus part covers (i) a description of a group of coronaviruses and the diseases they cause, including the prototype coronavirus, murine hepatitis virus, which is one of the recognized animal models for multiple sclerosis, as well as viruses of veterinary importance that infect the pig, chicken, and cat and a summary of the human viruses; (ii) a short summary of the replication cycle of coronaviruses in cell culture; (iii) the development and application of reverse genetics systems; and (iv) the roles of individual coronavirus proteins in replication and pathogenesis. The SARS-CoV part covers the pathogenesis of SARS, the developing animal models for infection, and the progress in vaccine development and antiviral therapies. The data gathered on the animal coronaviruses continue to be helpful in understanding SARS-CoV.
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Affiliation(s)
- Susan R Weiss
- Department of Microbiology, University of Pennsylvania School of Medicine, 36th Street and Hamilton Walk, Philadelphia, Pennsylvania 19104-6076, USA.
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102
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Novoa RR, Calderita G, Cabezas P, Elliott RM, Risco C. Key Golgi factors for structural and functional maturation of bunyamwera virus. J Virol 2005; 79:10852-63. [PMID: 16103138 PMCID: PMC1193595 DOI: 10.1128/jvi.79.17.10852-10863.2005] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Several complex enveloped viruses assemble in the membranes of the secretory pathway, such as the Golgi apparatus. Among them, bunyaviruses form immature viral particles that change their structure in a trans-Golgi-dependent manner. To identify key Golgi factors for viral structural maturation, we have purified and characterized the three viral forms assembled in infected cells, two intracellular intermediates and the extracellular mature virion. The first viral form is a pleomorphic structure with fully endo-beta-N-acetylglucosaminidase H (Endo-H)-sensitive, nonsialylated glycoproteins. The second viral intermediate is a structure with hexagonal and pentagonal contours and partially Endo-H-resistant glycoproteins. Sialic acid is incorporated into the small glycoprotein of this second viral form. Growing the virus in glycosylation-deficient cells confirmed that acquisition of Endo-H resistance but not sialylation is critical for the trans-Golgi-dependent structural maturation and release of mature viruses. Conformational changes in viral glycoproteins triggered by changes in sugar composition would then induce the assembly of a compact viral particle of angular contours. These structures would be competent for the second maturation step, taking place during exit from cells, that originates fully infectious virions.
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Affiliation(s)
- Reyes R Novoa
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología, CSIC, Cantoblanco, Madrid, Spain
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103
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Navas-Martin S, Hingley ST, Weiss SR. Murine coronavirus evolution in vivo: functional compensation of a detrimental amino acid substitution in the receptor binding domain of the spike glycoprotein. J Virol 2005; 79:7629-40. [PMID: 15919915 PMCID: PMC1143675 DOI: 10.1128/jvi.79.12.7629-7640.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Murine coronavirus A59 strain causes mild to moderate hepatitis in mice. We have previously shown that mutants of A59, unable to induce hepatitis, may be selected by persistent infection of primary glial cells in vitro. These in vitro isolated mutants encoded two amino acids substitutions in the spike (S) gene: Q159L lies in the putative receptor binding domain of S, and H716D, within the cleavage signal of S. Here, we show that hepatotropic revertant variants may be selected from these in vitro isolated mutants (Q159L-H716D) by multiple passages in the mouse liver. One of these mutants, hr2, was chosen for more in-depth study based on a more hepatovirulent phenotype. The S gene of hr2 (Q159L-R654H-H716D-E1035D) differed from the in vitro isolates (Q159L-H716D) in only 2 amino acids (R654H and E1035D). Using targeted RNA recombination, we have constructed isogenic recombinant MHV-A59 viruses differing only in these specific amino acids in S (Q159L-R654H-H716D-E1035D). We demonstrate that specific amino acid substitutions within the spike gene of the hr2 isolate determine the ability of the virus to cause lethal hepatitis and replicate to significantly higher titers in the liver compared to wild-type A59. Our results provide compelling evidence of the ability of coronaviruses to rapidly evolve in vivo to highly virulent phenotypes by functional compensation of a detrimental amino acid substitution in the receptor binding domain of the spike glycoprotein.
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MESH Headings
- Amino Acid Substitution
- Animals
- Coronavirus Infections/pathology
- Coronavirus Infections/physiopathology
- Coronavirus Infections/virology
- Evolution, Molecular
- Hepatitis, Viral, Animal/pathology
- Hepatitis, Viral, Animal/physiopathology
- Hepatitis, Viral, Animal/virology
- Liver/pathology
- Liver/virology
- Male
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred C57BL
- Murine hepatitis virus/genetics
- Murine hepatitis virus/pathogenicity
- Receptors, Virus/metabolism
- Recombination, Genetic
- Specific Pathogen-Free Organisms
- Spike Glycoprotein, Coronavirus
- Viral Envelope Proteins/chemistry
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/metabolism
- Virulence
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Affiliation(s)
- Sonia Navas-Martin
- Department of Microbiology, University of Pennsylvania, School of Medicine, 36th Street and Hamilton Walk, Philadelphia, PA 19104-6076, USA.
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104
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Sainz B, Rausch JM, Gallaher WR, Garry RF, Wimley WC. Identification and characterization of the putative fusion peptide of the severe acute respiratory syndrome-associated coronavirus spike protein. J Virol 2005; 79:7195-206. [PMID: 15890958 PMCID: PMC1112137 DOI: 10.1128/jvi.79.11.7195-7206.2005] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) is a newly identified member of the family Coronaviridae and poses a serious public health threat. Recent studies indicated that the SARS-CoV viral spike glycoprotein is a class I viral fusion protein. A fusion peptide present at the N-terminal region of class I viral fusion proteins is believed to initiate viral and cell membrane interactions and subsequent fusion. Although the SARS-CoV fusion protein heptad repeats have been well characterized, the fusion peptide has yet to be identified. Based on the conserved features of known viral fusion peptides and using Wimley and White interfacial hydrophobicity plots, we have identified two putative fusion peptides (SARS(WW-I) and SARS(WW-II)) at the N terminus of the SARS-CoV S2 subunit. Both peptides are hydrophobic and rich in alanine, glycine, and/or phenylalanine residues and contain a canonical fusion tripeptide along with a central proline residue. Only the SARS(WW-I) peptide strongly partitioned into the membranes of large unilamellar vesicles (LUV), adopting a beta-sheet structure. Likewise, only SARS(WW-I) induced the fusion of LUV and caused membrane leakage of vesicle contents at peptide/lipid ratios of 1:50 and 1:100, respectively. The activity of this synthetic peptide appeared to be dependent on its amino acid (aa) sequence, as scrambling the peptide rendered it unable to partition into LUV, assume a defined secondary structure, or induce both fusion and leakage of LUV. Based on the activity of SARS(WW-I), we propose that the hydrophobic stretch of 19 aa corresponding to residues 770 to 788 is a fusion peptide of the SARS-CoV S2 subunit.
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Affiliation(s)
- Bruno Sainz
- Department of Microbiology and Immunology, Tulane University Health Sciences Center, 1430 Tulane Avenue, SL-43, New Orleans, LA 70112, USA
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105
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Nal B, Chan C, Kien F, Siu L, Tse J, Chu K, Kam J, Staropoli I, Crescenzo-Chaigne B, Escriou N, van der Werf S, Yuen KY, Altmeyer R. Differential maturation and subcellular localization of severe acute respiratory syndrome coronavirus surface proteins S, M and E. J Gen Virol 2005; 86:1423-1434. [PMID: 15831954 DOI: 10.1099/vir.0.80671-0] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Post-translational modifications and correct subcellular localization of viral structural proteins are prerequisites for assembly and budding of enveloped viruses. Coronaviruses, like the severe acute respiratory syndrome-associated virus (SARS-CoV), bud from the endoplasmic reticulum-Golgi intermediate compartment. In this study, the subcellular distribution and maturation of SARS-CoV surface proteins S, M and E were analysed by using C-terminally tagged proteins. As early as 30 min post-entry into the endoplasmic reticulum, high-mannosylated S assembles into trimers prior to acquisition of complex N-glycans in the Golgi. Like S, M acquires high-mannose N-glycans that are subsequently modified into complex N-glycans in the Golgi. The N-glycosylation profile and the absence of O-glycosylation on M protein relate SARS-CoV to the previously described group 1 and 3 coronaviruses. Immunofluorescence analysis shows that S is detected in several compartments along the secretory pathway from the endoplasmic reticulum to the plasma membrane while M predominantly localizes in the Golgi, where it accumulates, and in trafficking vesicles. The E protein is not glycosylated. Pulse-chase labelling and confocal microscopy in the presence of protein translation inhibitor cycloheximide revealed that the E protein has a short half-life of 30 min. E protein is found in bright perinuclear patches colocalizing with endoplasmic reticulum markers. In conclusion, SARS-CoV surface proteins S, M and E show differential subcellular localizations when expressed alone suggesting that additional cellular or viral factors might be required for coordinated trafficking to the virus assembly site in the endoplasmic reticulum-Golgi intermediate compartment.
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Affiliation(s)
- Béatrice Nal
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Cheman Chan
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Francois Kien
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Lewis Siu
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Jane Tse
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Kid Chu
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Jason Kam
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
| | - Isabelle Staropoli
- Unité d'Immunologie Virale, Institut Pasteur, 25 rue du Dr Roux, Paris, France
| | | | - Nicolas Escriou
- Unité de Génétique Moléculaire des Virus Respiratoires, Institut Pasteur, 25 rue du Dr Roux, Paris, France
| | - Sylvie van der Werf
- Unité de Génétique Moléculaire des Virus Respiratoires, Institut Pasteur, 25 rue du Dr Roux, Paris, France
| | - Kwok-Yung Yuen
- Department of Microbiology, The University of Hong Kong, Hong Kong, China
| | - Ralf Altmeyer
- HKU-Pasteur Research Centre, 8 Sassoon Road, Hong Kong, China
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106
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Guillén J, Pérez-Berná AJ, Moreno MR, Villalaín J. Identification of the membrane-active regions of the severe acute respiratory syndrome coronavirus spike membrane glycoprotein using a 16/18-mer peptide scan: implications for the viral fusion mechanism. J Virol 2005; 79:1743-52. [PMID: 15650199 PMCID: PMC544113 DOI: 10.1128/jvi.79.3.1743-1752.2005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2004] [Accepted: 09/16/2004] [Indexed: 02/07/2023] Open
Abstract
We have identified the membrane-active regions of the severe acute respiratory syndrome coronavirus (SARS CoV) spike glycoprotein by determining the effect on model membrane integrity of a 16/18-mer SARS CoV spike glycoprotein peptide library. By monitoring the effect of this peptide library on membrane leakage in model membranes, we have identified three regions on the SARS CoV spike glycoprotein with membrane-interacting capabilities: region 1, located immediately upstream of heptad repeat 1 (HR1) and suggested to be the fusion peptide; region 2, located between HR1 and HR2, which would be analogous to the loop domain of human immunodeficiency virus type 1; and region 3, which would correspond to the pretransmembrane region. The identification of these membrane-active regions, which are capable of modifying the biophysical properties of phospholipid membranes, supports their direct role in SARS CoV-mediated membrane fusion, as well as facilitating the future development of SARS CoV entry inhibitors.
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Affiliation(s)
- Jaime Guillén
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, E-03202 Elche-Alicante, Spain
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107
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Bergeron E, Vincent MJ, Wickham L, Hamelin J, Basak A, Nichol ST, Chrétien M, Seidah NG. Implication of proprotein convertases in the processing and spread of severe acute respiratory syndrome coronavirus. Biochem Biophys Res Commun 2005; 326:554-63. [PMID: 15596135 PMCID: PMC7092861 DOI: 10.1016/j.bbrc.2004.11.063] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Indexed: 11/24/2022]
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) is the etiological agent of SARS. Analysis of SARS-CoV spike glycoprotein (S) using recombinant plasmid and virus infections demonstrated that the S-precursor (proS) exists as a ∼190 kDa endoplasmic reticulum form and a ∼210 kDa Golgi-modified form. ProS is subsequently processed into two C-terminal proteins of ∼110 and ∼80 kDa. The membrane-bound proprotein convertases (PCs) furin, PC7 or PC5B enhanced the production of the ∼80 kDa protein. In agreement, proS processing, cytopathic effects, and viral titers were enhanced in recombinant Vero E6 cells overexpressing furin, PC7 or PC5B. The convertase inhibitor dec-RVKR-cmk significantly reduced proS cleavage and viral titers of SARS-CoV infected cells. In addition, inhibition of processing by dec-RVKR-cmk completely abrogated the virus-induced cellular cytopathicity. A fluorogenically quenched synthetic peptide encompassing Arg761 of the spike glycoprotein was efficiently cleaved by furin and the cleavage was inhibited by EDTA and dec-RVKR-cmk. Taken together, our data indicate that furin or PC-mediated processing plays a critical role in SARS-CoV spread and cytopathicity, and inhibitors of the PCs represent potential therapeutic anti-SARS-CoV agents.
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Affiliation(s)
- Eric Bergeron
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Que., Canada H2W 1R7
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108
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Abstract
This chapter describes the interactions between the different structural components of the viruses and discusses their relevance for the process of virion formation. Two key factors determine the efficiency of the assembly process: intracellular transport and molecular interactions. Many viruses have evolved elaborate strategies to ensure the swift and accurate delivery of the virion components to the cellular compartment(s) where they must meet and form (sub) structures. Assembly of viruses starts in the nucleus by the encapsidation of viral DNA, using cytoplasmically synthesized capsid proteins; nucleocapsids then migrate to the cytosol, by budding at the inner nuclear membrane followed by deenvelopment, to pick up the tegument proteins.
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Affiliation(s)
- Cornelis A M de Haan
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
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109
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Abstract
Enveloped viruses have evolved membrane glycoproteins (GPs) that mediate entry into host cells. These proteins are important targets for antiviral therapies and vaccines. Several efforts to understand and combat infection by severe acute respiratory syndrome coronavirus (SARS-CoV) have therefore focused on the viral GP, known as spike (S). In a short period of time, important aspects of SARS-CoV S-protein function were unraveled. The identification of angiotensin-converting enzyme 2 (ACE2) as a receptor for SARS-CoV provided an insight into viral tropism and pathogenesis, whereas mapping of functional domains in the S-protein enabled inhibitors to be generated. Vaccines designed on the basis of SARS-CoV S-protein were shown to be effective in animals and consequently are attractive candidates for vaccine trials in humans. Here, we discuss how SARS-CoV S facilitates viral entry into target cells and illustrate current approaches that are used to inhibit this process.
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110
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Bosch BJ, Martina BEE, Van Der Zee R, Lepault J, Haijema BJ, Versluis C, Heck AJR, De Groot R, Osterhaus ADME, Rottier PJM. Severe acute respiratory syndrome coronavirus (SARS-CoV) infection inhibition using spike protein heptad repeat-derived peptides. Proc Natl Acad Sci U S A 2004; 101:8455-60. [PMID: 15150417 PMCID: PMC420415 DOI: 10.1073/pnas.0400576101] [Citation(s) in RCA: 298] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The coronavirus SARS-CoV is the primary cause of the life-threatening severe acute respiratory syndrome (SARS). With the aim of developing therapeutic agents, we have tested peptides derived from the membrane-proximal (HR2) and membrane-distal (HR1) heptad repeat region of the spike protein as inhibitors of SARS-CoV infection of Vero cells. It appeared that HR2 peptides, but not HR1 peptides, were inhibitory. Their efficacy was, however, significantly lower than that of corresponding HR2 peptides of the murine coronavirus mouse hepatitis virus (MHV) in inhibiting MHV infection. Biochemical and electron microscopical analyses showed that, when mixed, SARS-CoV HR1 and HR2 peptides assemble into a six-helix bundle consisting of HR1 as a central triple-stranded coiled coil in association with three HR2 alpha-helices oriented in an antiparallel manner. The stability of this complex, as measured by its resistance to heat dissociation, appeared to be much lower than that of the corresponding MHV complex, which may explain the different inhibitory potencies of the HR2 peptides. Analogous to other class I viral fusion proteins, the six-helix complex supposedly represents a postfusion conformation that is formed after insertion of the fusion peptide, proposed here for coronaviruses to be located immediately upstream of HR1, into the target membrane. The resulting close apposition of fusion peptide and spike transmembrane domain facilitates membrane fusion. The inhibitory potency of the SARS-CoV HR2-peptides provides an attractive basis for the development of a therapeutic drug for SARS.
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Affiliation(s)
- Berend Jan Bosch
- Division of Virology, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, and Institute of Biomembranes, Utrecht University, 3584 CL Utrecht, The Netherlands
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