Effects of active and passive immunization in the Mycoplasma arthritidis infection of rats.

Viable, heat-inactivated, formalin-inactivated and sonicated Mycoplasma (M.) arthritidis antigens as well as immune sera against M. arthritidis and spleen cells from Lewis rats recovered from M. arthritidis infection were injected into naive Lewis rats prior to a challenge infection with 10(7) cfu of M. arthritidis and tested for their protective effects. Viable mycoplasmas induced arthritis combined with the production of high titers of antibodies against M. arthritidis and resistance to a second infection. The application of the inactivated M. arthritidis-antigens in emulsion of incomplete Freund's Adjuvant (ICFA) to naive rats, which also induced a strong antibody production, as well as the inoculation of reconvalescent serum from rats infected with M. arthritidis and hyperimmune serum against M. arthritidis from rabbits and mice protected rats also from an outbreak of arthritis after challenge. The injection of sonicated M. arthritidis antigen without ICFA which failed to induce the production of antibodies and the transfer of spleen cells from rats recovered from M. arthritidis infection had no protective function. The investigations showed, that antibodies play an important role in the prevention of M. arthritidis infections in Lewis rats.