Abstract
Four cows were inoculated via the udder with the 1836 strain ofMycoplasma bovigenitalium. The serological response was investigated using the complement-fixation and serum plate agglutination tests. A heterologous response toM. mycoideswas observed, associated with an increase in the anti-γ-globulin titres in the cow's serum. The heterologous response persisted in one cow for 6 weeks after infection. The nature of the immunoglobulin response was characterized by density gradient centrifugation, and by mercaptoethanol and rivanol treatment of the serum and was found to consist entirely of 19 S γ-globulins.TheMycoplasmapersisted in the udder for the 18 weeks duration of the experiment. TheMycoplasmawas not isolated from the blood. One of the cows became lame with swollen joints;Bacillus cereuswas isolated from the joints and blood.