Studies of polyarthritis caused by Mycoplasma arthritidis in rats. II. Serological investigation of rats experimentally infected with M. arthritidis ISR 1.

In sera of rats which developed severe polyarthritis after infection with 10(9) CFU of Mycoplasma arthritidis ISR 1, antibodies against M. arthritidis could be detected by the complement fixation test (CFT), enzyme immune assay (EIA), indirect hemagglutination (IHA), and metabolic inhibition test (MIT). Peak titers (CFT - 1:4096, EIA - 1:2560, IHA - 1:640 and MIT - 1:64) were reached between 2 and 12 weeks after infection. The antibodies persisted for at least 9 months, but started to decrease gradually 5 to 7 months after infection. No antibodies against M. arthritidis could be detected in the growth inhibition test. Immune complexes were found 4 days after infection. They decreased rapidly during the first two months after infection after which they increased again. At no time, rheumatoid factors could be detected. Rats which had recovered from the polyarthritis induced by intravenous injection of M. arthritidis ISR 1 were resistant to a subsequent infection.