ELECTROPHORETIC MOBILITY AND IMMUNE-RESPONSE OF OUTER-MEMBRANE PROTEINS OF VIBRIO-CHOLERAE O139

The outer membrane (OM) protein components of a Vibrio cholerae O1 and four V. cholerae O139 strains, collected from cholera patients, were analysed by SDS-PAGE. A protein of 69 kDa molecular mass was observed only when the OMPs were prepared from strains grown in synthetic broth . As a result of passage in the rabbit ileal loop (RIL), virulence was enhanced, and a protein component around 18 kDa of the V. cholerae O1 39 OM became the major protein component. On immunoblot analysis with rabbit antiserum against V. cholerae O139 OM, it was shown that, apart from the major protein component of V. cholerae O1 OM of around 45 kD a and that of V. cholerae O139 OM of around 38 kDa, all other minor pr otein components were cross-reactive between the two serogroups. In im munoblot assays with convalescent sera obtained from V. cholerae O139- infected patients, it was observed that in addition to the lipopolysac charide (LPS)-induced antibody, only the 38 kDa major protein componen t elicited considerable levels of antibody in the patient. Minor OM co mponents of 18 kDa were detected in the immunoblot analysis by LPS-dir ected antibody, however, as the OM proteins are known to be associated with LPS.