Comparison of immunochemical specificities of Vibrio parahaemolyticus O10 and O12 antigens using monoclonal antibodies.

The monoclonal antibodies against Vibrio parahaemolyticus O10 and O12 antigens (lipopolysaccharide, LPS) were prepared and specificities of the antibodies were examined. Five of six anti-O10 antibodies reacted with O10 antigen, but none of them reacted with O12 antigen. On the contrary all of the five anti-O12 antibodies reacted with O10 antigen as well as homologous O12 antigen. O10 and O12 antigens were subjected to alkali treatment or periodate oxidation, and reactivities of these chemically modified preparations with the monoclonal antibodies were examined. Reactivities of O10 with anti-O10 and anti-O12 antibodies were reduced by the above two chemical treatments, but that of O12 with anti-O12 was not. O-Deacetylation of O10 LPS by the alkaline treatment was confirmed by NMR spectroscopy. These results suggest contributions to O10-specificity of O-acetyl group and periodate sensitive sugar residue. Inhibition experiments of O10 and O12 homologous precipitations were also carried out with various sugars. From the results we concluded that O10 and O12 antigenic determinants were distinct entities, although O10 and O12 antigens have been reported to be similar and cross-reactive.