Affinity Constants of Anti-Leptospira Monoclonal Antibodies, Numbers of Antigenic Determinants on Leptospiras, and Their Influence on the Microscopic Agglutination Test and ELISA

The affinity constants of anti-canicola and anti-hebdomadis monoclonal antibodies and the numbers of antigenic determinants per organism of each serovar of leptospira were determined, and their influence on the results of microscopic agglutination test (MAT) and ELISA were examined. In the combinations of a monoclonal antibody and some serovar which showed higher affinity constants at levels of 107S to 108/m order, both MAT and ELISA were positive except for one combination, while in the combinations which gave lower affinity constants at levels of 106/m order, MAT was positive but ELISA was negative. The number of antigenic determinants seemed to have no significant influence on the results. The disagreement due to the difference in the threshold affinities of MAT and ELISA should be considered in the use of monoclonal antibodies in the taxonomy of leptospira.