Immunologic analysis of Mycoplasma arthritidis surface proteins

LEW rats experimentally infected with Mycoplasma arthritidis failed to express metabolism inhibition (MI) antibodies. Our hypothesis was that rats failed to immunologically recognize the antigens responsible for eliciting those antibodies. LEW rats, injected i.v. with M. arthritidis, recognized only two low-MW surface antigens by radioimmunoprecipitation by 1 week after injection. However, by 6 weeks these rats recognized most of the same M. arthritidis surface antigens by Western blot and radioimmunoprecipitation as were recognized by immunized rabbits. The most important exception was a 47-to 50-kDa (kilodalton) surface protein that was antigenic only for rabbits. We had previously produced two monoclonal antibodies with MI activity that recognized two distinct M. arthritidis epitopes. However, neither of these corresponded to the antigen that rats failed to recognize, and LEW rats produced IgG antibodies against both monoclonal antibody-defined "MI antigens." Therefore, the failure of rats to express MI activity against M. arthritidis remains unexplained.