A field trial with an experimental vaccine against Staphylococcus aureus mastitis in cattle. 2. Antibody response.

A Staphylococcus aureus vaccine containing whole, inactivated bacteria with pseudocapsule and alpha and beta toxoids with a mineral oil as adjuvant, was used in a field trial. Heifers were injected in the area of the supramammary lymph nodes with vaccine or placebo twice before calving and observed and sampled throughout their first lactation. Antibody response toward the pseudocapsule and the alpha toxin was significant in serum from the vaccinated cows. These antibody concentrations were significantly higher in serum and milk during the entire lactation compared with that of the controls. The antibody response to the beta toxin was moderate in serum from vaccinated cows; no differences in antibody concentrations in milk were significant between groups. The antibody response to the pseudocapsule consisted of the IgG1 and IgG2 isotypes, but, in milk, only the concentration of IgG1 was significantly increased in the vaccinated cows during the lactation compared with the control cows.