Monoclonal antibodies against the common polysaccharide of Streptococcus agalactiae.

A monoclonal antibody giving a dominant reaction with the group-specific polysaccharide of streptococcus group B in an ELISA test has been developed. The purified polysaccharide exhibited a high positivity with reference anti B streptococcal antiserum in the ELISA test. Cross-tests of antibodies with other groups of streptococci provided a minimum cross-reaction only in the case of G streptococci. Monoclonal antibodies were prepared usingStreptococcus agalactiœ S 589 MT strain isolated from a case of bovine mastitis which does not express Ia, Ib, II, III, IV and V type antigens, nor C, R and X protein antigens.