The serological properties of the cell surface proteins of Vibrio cholerae

The serological properties of cell surface proteins of Vibrio cholerae belonging to both the biotypes (classical and El Tor) and the serotypes (Ogawa and Inaba) were investigated. Proteins were isolated by extracting V. cholerae with EDTA in the presence of sodium chloride. The surface localization of these proteins was confirmed with (a) radioiodinated protein A as an immunoprobe and (b) antiserum absorption studies with whole bacteria. There were similarities among the polypeptides of cell surface proteins isolated from various V. cholerae types. Antisera to these proteins agglutinated several V. cholerae strains, irrespective of biotype, serotype and antibiotic sensitivity. The antisera did not agglutinate pathogenic enteric bacteria such as enterotoxigenic Escherichia coli, Salmonella typhi, Shigella spp., Aeromonas hydrophila and Yersinia enterocolitica. The cell surface proteins of V. cholerae were immunogenic in rabbits as high titres of anti-protein specific antibodies were detected by the ELISA technique in the immune sera. These results suggest that the cell surface proteins are common antigens of V. cholerae and can be developed as a potential vaccine candidate against cholera.