Immunoglobulin M and G antibody response in rabbits after experimental Haemophilus ducreyi infection.

The enzyme-linked immunosorbent assay and immunoblot technique were used to investigate the humoral immune response following intradermal infection of rabbits with Haemophilus ducreyi. Basically, the kinetics of IgM and IgG antibody synthesis was the same as in other bacterial infections. However, antibody titres in the enzyme-linked immunosorbent assay were remarkably low. In the immunoblot experiments, antibodies of both immunoglobulin classes were mainly directed against Haemophilus ducreyi antigens with relative molecular masses of 79,000, 62,000, 55,000, 49,000, and 26,000, suggesting that these antigens may play a dominant role in the humoral immune response after infection.