Received on December 1, 2003
Accepted on February 24, 2004

Clinical Immunology

Synthetic Peptide Studies on the Severe Acute Respiratory Syndrome (SARS) Coronavirus Spike Glycoprotein: Perspective for SARS Vaccine Development

¹ Departments of Molecular Biotechnology Program, Biology, and Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong
² Research Center of Medical Sciences, Guangdong Provincial People's Hospital, Guangdong, China
³ Microbiology, The Chinese University of Hong Kong, Shatin, Hong Kong
⁴ Chemical Pathology, The Chinese University of Hong Kong, Shatin, Hong Kong
⁵ Biology, The Chinese University of Hong Kong, Shatin, Hong Kong
⁶ Biochemistry, The Chinese University of Hong Kong, Shatin, Hong Kong
⁷ Departments of Molecular Biotechnology Program, Biology, Biochemistry, and Biology, The Chinese University of Hong Kong, Shatin, Hong Kong

^* To whom correspondence should be addressed. E-mail: smngai{at}cuhk.edu.hk.

Background: The S (spike) protein of the etiologic coronavirus (CoV) agent of severe acute respiratory syndrome (SARS) plays a central role in mediating viral infection via receptor binding and membrane fusion between the virion and the host cell. We focused on using synthetic peptides for developing antibodies against SARS-CoV, which aimed to block viral invasion by eliciting an immune response specific to the native SARS-CoV S protein.

Methods: Six peptide sequences corresponding to the surface regions of SARS-CoV S protein were designed and investigated by use of combined bioinformatics and structural analysis. These synthetic peptides were used to immunize both rabbits and monkeys. Antisera collected 1 week after the second immunization were analyzed by ELISA and tested for antibody specificity against SARS-CoV by immunofluorescent confocal microscopy.

Results: Four of our six synthetic peptides (S2, S3, S5, and S6) elicited SARS-CoV-specific antibodies, of which S5 (residues 788-820) and S6 (residues 1002-1030) exhibited similar immunogenic responses compared with a parallel investigation using truncated recombinant protein analogs of the SARS-CoV S protein. This suggested that our S5 and S6 peptides may represent two minimum biologically active sequences of the immunogenic regions of the SARS-CoV S protein.

Conclusions: Synthetic peptides can elicit specific antibodies to SARS-CoV. The study provides insights for the future development of SARS vaccine via the synthetic-peptide-based approach.