Transferred humoral immunity in chickens to Mycoplasma gallisepticum.

Progeny chicks of Mycoplasma gallisepticum (MG)-infected and MG-free white leghorns were used to evaluate the protective effects of maternal antibodies against aerosol challenge with the virulent R strain of MG at 3, 7, or 14 days of age. Interference by maternal antibodies with day-1 vaccination with the F strain of MG was also studied. In another trial, 8, 4, or 2 ml of high- or low-titered antiserum was given to 20-day-old commercial white leghorn chicks. Protection was measured in terms of air-sac lesions post-challenge with the R strain of MG as above. Maternal antibody in the chicks conferred very little protection against challenge and did not interfere with day-1 vaccination with the F strain of MG. Low-titered antibody gave no protection against growth of MG in the tracheas, but the high-titered MG antiserum did confer some protection against airsacculitis. This protection might be due to growth-inhibition antibody in the transferred serum.