| Abstract: | Newly hatched chickens were inoculated intranasally with either the S6 or TS 100 strain of Mycoplasma gallisepticum (MG) or they were left uninoculated. The three groups of chickens did not differ discernibly in body, spleen, or bursa weight during the 27-day sampling period. However, the S6-inoculated chickens showed a more pronounced cellular response in the nasal passages and had nearly complete lymphoid depletion in the spleens. The TS 100-inoculated birds expressed only a mild cellular reaction, which was localized in the nasal passages. Uninoculated chickens appeared normal histologically. Serologic tests such as rapid serum plate agglutination, hemagglutination-inhibition, and radioimmunoassay were able to detect antibody responses of chickens to MG inoculations yet could not differentiate the response to TS 100 from the response to S6. Tracheal secretions in intact TS 100-inoculated chickens contained antibodies to MG, yet only one-half of the bursectomized inoculated chickens contained detectable antibody, which appeared to be IgG. This led to the conclusion that bursectomy suppresses the appearance of locally synthesized IgG antibodies to MG in tracheal washings. The locally produced antibody was considered important in the development of resistance induced by intranasal inoculation of TS mutants. |
