EFFECT OF A STAPHYLOCOCCUS-AUREUS BACTERIN ON SERUM ANTIBODY, NEW INFECTION, AND MAMMARY HISTOLOGY IN NONLACTATING DAIRY-COWS

The influence of a Staphylococcus aureus mastitis vaccine on immunolog ic status and rate of new IMI was evaluated. At drying off, cows were vaccinated, either intramuscularly or subcutaneously in the area of th e supramammary lymph node, or were left as unvaccinated controls; vacc inates received booster injections at 6 wk. Serum antibody concentrati ons, bacteriologic status, and SCC of quarter milk samples were determ ined. Four weeks after revaccination, cows were challenged by intramam mary infusion of S. aureus and then killed 24 to 72 h later. Mean seru m antistaphylococcal antibody titer of vaccinated cows during the tria l was 4.7-fold that of controls, Challenge resulted in IMI rates of 92 , 36, and 60% for control cows, cows vaccinated intramuscularly, and c ows vaccinated in the area of the supramammary lymph node. Vaccination by either route had no influence on mammary parenchymal tissue compon ents compared with controls; however, leukocyte infiltration was great er in quarters from cows vaccinated in the area of the supramammary ly mph node than in quarters from unvaccinated controls. Plasma cell popu lations producing IgG1, IgG2, IgA, and IgM were greatest in quarters o f cows vaccinated in the area of the supramammary lymph node followed by those in quarters of cows vaccinated intramuscularly and control co ws.