Immunochemical characterisation of Vibrio cholerae O139 O antigens and production of a diagnostic antiserum without absorption

Rabbits and mice immunised with chemically extracted O-antigens (O-Ags) of Vibrio cholerae O139 (O-AgB and O-AgD) developed antibodies (Abs) which appeared to be highly specific in ELISA for the relevant antigens and V. cholerae O139 strains without absorption, in contrast to the Abs against the heated O-Ag (O-AgH). An ELISA test based on the use of these Abs was shown to detect V. cholerae O139 strains down to concentrations of (9.4 × 104)–(7.5 × 105) vibrios/ml and demonstrated no cross-reaction with other vibrios including representatives of serogroup O22. Native and proteinase K-treated O-AgB, O-AgD, O-AgH, as well as whole-cell lysates of V. cholerae O139 strains of different origin were used in immunoblotting with these Abs. Clear differences in the patterns of zones of specific reaction between chemically extracted and heated O-Ags and between lipopolysaccharide profiles of the V. cholerae O139 strains of different origin were observed. Serogroup-specific protein bands in the native O-AgB and O-AgD preparations were defined. The approach described for obtaining serogroup-specific Abs against vibrios and other bacteria seems to be promising for the development of specific diagnostic tests and further investigation of bacterial antigenic structure.