Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1175175 (SARS)
 19,188 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antibodies to SARS-Coronavirus (SARS-CoV)-specific B cell epitopes might recognize the pathogen and interrupt its adherence to and penetration of host cells. Hence, these epitopes could be useful for diagnosis and as vaccine constituents. Using the phage-displayed peptide library screening method and purified Fab fragments of immunoglobulin G (IgG Fab) from normal human sera and convalescent sera from SARS-CoV-infected patients as targets, 11 B cell epitopes of SARS-CoV spike glycoprotein (S protein) and membrane protein (M protein) were screened. After a bioinformatics tool was used to analyze these epitopes, four epitope-based S protein dodecapeptides corresponding to the predominant epitopes were chosen for synthesis. Their antigenic specificities and immunogenicities were studied in vitro and in vivo. Flow cytometry and ELISPOT analysis of lymphocytes as well as a serologic analysis of antibody showed that these peptides could trigger a rapid, highly effective, and relatively safe immune response in BALB/c mice. These findings might aid development of SARS diagnostics and vaccines. Moreover, the role of S and M proteins as important surface antigens is confirmed.
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PMID:Selection of SARS-coronavirus-specific B cell epitopes by phage peptide library screening and evaluation of the immunological effect of epitope-based peptides on mice. 1705 22

The SARS-coronavirus (SARS-CoV) is the etiological agent of the severe acute respiratory syndrome (SARS). The SARS-CoV spike (S) glycoprotein mediates membrane fusion events during virus entry and virus-induced cell-to-cell fusion. The cytoplasmic portion of the S glycoprotein contains four cysteine-rich amino acid clusters. Individual cysteine clusters were altered via cysteine-to-alanine amino acid replacement and the modified S glycoproteins were tested for their transport to cell-surfaces and ability to cause cell fusion in transient transfection assays. Mutagenesis of the cysteine cluster I, located immediately proximal to the predicted transmembrane, domain did not appreciably reduce cell-surface expression, although S-mediated cell fusion was reduced by more than 50% in comparison to the wild-type S. Similarly, mutagenesis of the cysteine cluster II located adjacent to cluster I reduced S-mediated cell fusion by more than 60% compared to the wild-type S, while cell-surface expression was reduced by less than 20%. Mutagenesis of cysteine clusters III and IV did not appreciably affect S cell-surface expression or S-mediated cell fusion. The wild-type S was palmitoylated as evidenced by the efficient incorporation of (3)H-palmitic acid in wild-type S molecules. S glycoprotein palmitoylation was significantly reduced for mutant glycoproteins having cluster I and II cysteine changes, but was largely unaffected for cysteine cluster III and IV mutants. These results show that the S cytoplasmic domain is palmitoylated and that palmitoylation of the membrane proximal cysteine clusters I and II may be important for S-mediated cell fusion.
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PMID:Palmitoylation of the cysteine-rich endodomain of the SARS-coronavirus spike glycoprotein is important for spike-mediated cell fusion. 1713 30

Both innate and adaptative immune responses contribute to the control of infectious diseases, including by limiting the spreading of zoonotic diseases from animal reservoirs to humans. Pigs represent an important animal reservoir for influenza virus infection of human populations and are also naturally infected by coronaviruses, an important group of viruses, which includes the recently emerged severe acute respiratory syndrome (SARS) virus. Studies on both innate and adaptative immune responses of pigs to influenza virus and coronaviruses contribute, therefore, to a better control of these infections in their natural hosts and will be briefly reviewed in this article. Pro-inflammatory cytokines, including type I interferon (IFN), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), were found in lung secretions of influenza virus infected pigs, and correlated with the intensity of clinical signs, whereas prior vaccination against influenza strongly reduced the production of infectious virus and cytokines in the lungs upon challenge, which was associated with clinical protection. An early type I IFN production was also found in coronavirus infected pigs, including at mucosal sites. IFN induction by coronavirus is shown to involve interaction between a viral glycoprotein and a leukocyte subset, likely equivalent to plasmacytoid dendritic cells, present in the mucosae and associated lymphoid tissues. Given the IFN mediated antiviral and immunomodulatory effects, the use of IFN or IFN inducers may prove an efficient strategy for a better control of influenza virus and coronavirus infections in pigs. Because influenza and coronaviruses target mucosal surfaces, adaptative immune responses have to be characterized at mucosal sites. Thus, nasal and pulmonary antibody responses were analyzed in influenza virus infected or vaccinated pigs showing short-lived, but potentially protective local IgA and IgG antibody (Ab) responses. Interestingly, primary influenza virus infection induced long-lived increase of lung CD8(+) T cells and local lymphoproliferative responses. Pigs infected by a respiratory coronavirus (PRCV) showed virus-specific IgG Ab-secreting cells in the bronchial lymph nodes, whereas the transmissible gastroenteritis coronavirus (TGEV) induced more IgA Ab-secreting cells in gut tissues, which illustrates the importance of the route of antigen administration for inducing local immune effector mechanisms. Porcine viral infections provide, therefore, valuable models for evaluating the immune parameters that are important for controlling transmission of important viral zoonotic infections.
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PMID:Porcine innate and adaptative immune responses to influenza and coronavirus infections. 1713 2

We generated a recombinant vesicular stomatitis virus (VSV) pseudotype (VSV Delta G*SG) by replacing the envelope G gene with the GFP gene and complementing with spike glycoprotein (S) of SARS-CoV in trans. The neutralization and infection blocking tests showed that the VSV Delta G*SG and SARS-CoV reacted similarly to SARS-CoV specific antiserum, suggesting the VSVDelta G*SG can be a safe replacement of the live SARS-CoV for neutralization test and cell-entry assay.
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PMID:Generating vesicular stomatitis virus pseudotype bearing the severe acute respiratory syndrome coronavirus spike envelope glycoprotein for rapid and safe neutralization test or cell-entry assay. 1713 19

Human coronavirus NL63 (HCoV-NL63) has recently been identified as a causative agent of acute respiratory tract illnesses in infants and young children. The HCoV-NL63 spike (S) protein mediates virion attachment to cells and subsequent fusion of the viral and cellular membranes. This viral entry process is a primary target for vaccine and drug development. HCoV-NL63 S is expressed as a single-chain glycoprotein and consists of an N-terminal receptor-binding domain (S1) and a C-terminal transmembrane fusion domain (S2). The latter contains two highly conserved heptad-repeat (HR) sequences that are each extended by 14 amino acids relative to those of the SARS coronavirus or the prototypic murine coronavirus, mouse hepatitis virus. Limited proteolysis studies of the HCoV-NL63 S2 fusion core identify an alpha-helical domain composed of a trimer of the HR segments N57 and C42. The crystal structure of this complex reveals three C42 helices entwined in an oblique and antiparallel manner around a central triple-stranded coiled coil formed by three N57 helices. The overall geometry comprises distinctive high-affinity conformations of interacting cross-sectional layers of the six helices. As a result, this structure is unusually stable, with an apparent melting temperature of 78 degrees C in the presence of the denaturant guanidine hydrochloride at 5 M concentration. The extended HR regions may therefore be required to prime the group 1 S glycoproteins for their fusion-activating conformational changes during viral entry. Our results provide an initial basis for understanding an intriguing interplay between the presence or absence of proteolytic maturation among the coronavirus groups and the membrane fusion activity of their S glycoproteins. This study also suggests a potential strategy for the development of improved HCoV-NL63 fusion inhibitors.
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PMID:Core structure of S2 from the human coronavirus NL63 spike glycoprotein. 1717 42

The severe acute respiratory syndrome (SARS) outbreak of 2002 and 2003 occurred as a result of zoonotic transmission. Coronavirus (CoV) found in naturally infected palm civet (civet-CoV) represents the closest genetic relative to SARS-CoV, but the degree and the determinants of cross-neutralization among these viruses remain to be investigated. Studies indicate that the receptor binding domain (RBD) of the SARS-CoV spike (S) glycoprotein contains major determinants for viral entry and neutralization. We aim to characterize the impact of natural mutations within the RBDs of civet-CoVs on viral entry and cross-neutralization. In this study, the S glycoprotein genes were recovered from naturally infected civets in central China (Hubei province), extending the geographic distribution of civet-CoV beyond the southeastern province of Guangdong. Moreover, pseudoviruses generated in our laboratory with four civet S genes, each with a distinct RBD, infected cells expressing human receptor angiotensin-converting enzyme 2, but with 90 to 95% less efficiency compared to that of SARS-CoV. These four civet S genes were also constructed as DNA vaccines to immunize mice. Immunized sera elicited against most civet S glycoproteins displayed potent neutralizing activities against autologous viruses but were much less efficient (50% inhibitory concentration, 20- to 40-fold) at neutralizing SARS-CoV and vice versa. Convalescence-phase sera from humans were similarly ineffective against the dominant civet pseudovirus. Our findings suggest that the design of SARS vaccine should consider not only preventing the reemergence of SARS-CoV but also providing cross-protection, thus interrupting zoonotic transmission of a group of genetically divergent civet CoVs of broad geographic origin.
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PMID:Natural mutations in the receptor binding domain of spike glycoprotein determine the reactivity of cross-neutralization between palm civet coronavirus and severe acute respiratory syndrome coronavirus. 1731 67

The SARS-CoV spike glycoprotein (S) is the main target of the protective immune response in humans and animal models of SARS. Here, we demonstrated that efficient expression of S from the wild-type spike gene in cultured cells required the use of improved plasmid vectors containing donor and acceptor splice sites, as well as heterologous viral RNA export elements, such as the CTE of Mazon-Pfizer monkey virus or the PRE of Woodchuck hepatitis virus (WPRE). The presence of both splice sites and WPRE markedly improved the immunogenicity of S-based DNA vaccines against SARS. Upon immunization of mice with low doses (2 microg) of naked DNA, only intron and WPRE-containing vectors could induce neutralizing anti-S antibodies and provide protection against challenge with SARS-CoV. Our observations are likely to be useful for the construction of plasmid and viral vectors designed for optimal expression of intronless genes derived from cytoplasmic RNA viruses.
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PMID:Heterologous viral RNA export elements improve expression of severe acute respiratory syndrome (SARS) coronavirus spike protein and protective efficacy of DNA vaccines against SARS. 1733 58

Human severe acute respiratory syndrome coronavirus (hSARS-CoV) is the causative agent for SARS infection. Its surface glycoprotein (spike protein) is considered to be one of the prime targets for SARS therapeutics and intervention because its proteolytic maturation by a host protease is crucial for host-virus fusion. Using intramolecularly quenched fluorogenic (IQF) peptides based on hSARS-CoV spike protein (Abz-(755)Glu-Gln-Asp-Arg-Asn-Thr-Arg-Glu-Val-Phe-Ala-Gln(766)-Tyx-NH(2)) and in vitro studies, we show that besides furin, other PCs, like PC5 and PC7, might also be involved in this cleavage event. Through kinetic measurements with recombinant PCs, we observed that the peptide was cleaved efficiently by both furin and PC5, but very poorly by PC7. The cleavage could be blocked by a PC-inhibitor, alpha1-PDX, in a dose-dependent manner. Circular dichroism spectra indicated that this peptide possesses a high degree of sheet structure. Following cleavage by furin, the sheet content increased, possibly at the expense of turn and random structures. (1)H NMR spectra from 2D COSY and ROESY experiments under physiological buffer and pH conditions indicated that this peptide possesses a structure with a turn at its C-terminal segment, close to the cleavage site. The data suggest that the cleavable peptide bond is located within the most exposed domain; this is supported by the nearby turn structure. Several strong to weak NMR ROESY correlations were detected, and a 3D structure of the spike IQF peptide that contains the crucial cleavage site R(761) E has been proposed.
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PMID:A fluorogenic peptide containing the processing site of human SARS corona virus S-protein: kinetic evaluation and NMR structure elucidation. 1747 79

The spike (S) glycoprotein of coronaviruses is known to be essential in the binding of the virus to the host cell at the advent of the infection process. To study the maturation pathway of the S glycoprotein of the severe acute respiratory syndrome (SARS)-coronavirus (CoV) within the host cell, a T7/vaccinia virus-based expression system coupled to immunoprecipitation with anti-S antibodies was used to test and analyze different forms of the S glycoprotein. The state of maturity of the S glycoprotein can be deduced from its sensitivity to hydrolysis by endoglycosidase H (EndoH) or N-glycosidase F (N-Gly F). A fully matured S glycoprotein will be modified with complex oligosaccharides which makes it resistant to cleavage by EndoH but not by N-Gly F. By exploiting this characteristic, it is then possible to determine which forms of the immunoprecipitated S protein are properly processed by the host cell. With this system, many different constructs of the S glycoprotein can be analyzed in parallel thus providing another method by which to study the functional domains of S involved in membrane fusion event that occurs during viral infection.
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PMID:Expression, glycosylation, and modification of the spike (S) glycoprotein of SARS CoV. 1750 75

The international outbreak of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) in 2002-2003 highlighted the need to develop pretested human vaccine vectors that can be used in a rapid response against newly emerging pathogens. We evaluated Newcastle disease virus (NDV), an avian paramyxovirus that is highly attenuated in primates, as a topical respiratory vaccine vector with SARS-CoV as a test pathogen. Complete recombinant NDV was engineered to express the SARS-CoV spike S glycoprotein, the viral neutralization and major protective antigen, from an added transcriptional unit. African green monkeys immunized through the respiratory tract with two doses of the vaccine developed a titer of SARS-CoV-neutralizing antibodies comparable with the robust secondary response observed in animals that have been immunized with a different experimental SARS-CoV vaccine and challenged with SARS-CoV. When animals immunized with NDV expressing S were challenged with a high dose of SARS-CoV, direct viral assay of lung tissues taken by necropsy at the peak of viral replication demonstrated a 236- or 1,102-fold (depending on the NDV vector construct) mean reduction in pulmonary SARS-CoV titer compared with control animals. NDV has the potential for further development as a pretested, highly attenuated, intranasal vector to be available for expedited vaccine development for humans, who generally lack preexisting immunity against NDV.
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PMID:Newcastle disease virus, a host range-restricted virus, as a vaccine vector for intranasal immunization against emerging pathogens. 1753 26


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