National Center for
3I6G: Newly Identified Epitope Mn2 From Sars-Cov M Protein Complexed Withhla-A0201
The membrane protein of severe acute respiratory syndrome coronavirus acts as a dominant immunogen revealed by a clustering region of novel functionally and structurally defined cytotoxic T-lymphocyte epitopes
J. Infect. Dis. (2010) 202 p.1171-1180
BACKGROUND: Severe acute respiratory syndrome coronavirus (SARS-CoV), which emerged with highly contagious and life-threatening characteristics in 2002, remains a potential risk for future outbreaks. Membrane (M) and envelope (E) proteins are major structural proteins of the SARS-CoV. The M protein has been determined as a protective antigen in humoral responses. However, its potential roles in stimulating cellular immunity remain elusive. METHODS: In this study, a panel of peptides derived from M and E proteins were tested by in vitro refolding, T2 cell-binding assays, and responses stimulated by cytotoxic T-lymphocyte (CTL) epitopes in HLA-A2.1/K(b) transgenic mice and human peripheral blood mononuclear cells (PBMCs). RESULTS: A nonameric epitope Mn2 and a decameric epitope Md3 derived from the M protein were identified and used for the evaluation of M protein-specific immunity. Responses stimulated by M protein-specific CTL epitopes have been found in the PBMCs of donors who had recovered from SARS infection. Additionally, the transmembrane domain of the M protein may contain a T cell epitope cluster revealed by the immunogenic and structural analysis of a panel of truncated peptides overlapping with Mn2 and Md3. CONCLUSIONS: The M protein of SARS-CoV holds dominant cellular immunogenicity. This, together with previous reports of a strong humoral response against the M protein, may help to further explain the immunogenicity of SARS and serves as potential targets for SARS-CoV vaccine design.