SCREENING OF TNPHOA MUTANTS OF VIBRIO-CHOLERAE O139 FOR IDENTIFICATION OF ANTIGENS INVOLVED IN COLONIZATION

A new serogroup of Vibrio cholerae non-01, designated as 0139, has eme rged causing cholera-like disease among adults. Laboratory and field s tudies clearly show that there is no cross-protection between 01 and 0 139 pathogenic strains. Since colonisation of the intestine is a most important step in the pathogenesis of cholera caused by 01 strains and colonising antigens are known to be protective, investigation of the colonising antigens of 0139 strain was initiated. By TnphoA mutagenesi s, mutants were generated with insertions in the genome encoding membr ane spanning or secretory proteins. Screening of the mutants for adher ence to rabbit intestinal surface and colonisation in 5-day-old mice r esulted in the identification of mutant clones, which were less adhesi ve than was the wild-type parent strain and which could not efficientl y colonise the gut. Such non-colonising strains were attenuated in vir ulence. Analysis of the proteins by SDS-PAGE revealed that the non-col onising mutants did not express a 40-kDa outer-membrane protein.