DIFFERENCES IN BOVINE LYMPHOCYTE ANTIGEN ASSOCIATIONS BETWEEN IMMUNE RESPONSIVENESS AND RISK OF DISEASE FOLLOWING INTRAMAMMARY INFECTION WITH STAPHYLOCOCCUS-AUREUS

This study evaluated the relationships between immune response, diseas e resistance, and bovine leukocyte antigens, BoLA, in Holstein cows fo llowing in tramammary challenge with Staphylococcus aureus. This inves tigation was to determine whether immune responsiveness differed betwe en these cows and whether differences were related to expression of cl ass I BoLA antigens, which might explain the increased resistance or s usceptibility to S. aureus mastitis. Antibody responses to S. aureus i n milk and serum, total IgG(1) in milk, and blastogenic responses with and without concanavalin A were evaluated. The CA42 allele, previousl y associated with increased risk of infection, was relatively uninform ative for the immune response parameters examined. Other alleles, such as W3, were associated with higher milk antibody responses to S. aure us and higher milk IgG(1) postchallenge. Alleles W7, W4, and W26 were associated with lower milk IgG(1) and lower antibody titers in serum p ostchallenge. The Association reported between allele CA42 and increas ed risk of S. aureus mastitis did not relate to lower antibody or blas togenic responses by these cows; however, indicators of innate resista nce were not examined. In addition, the different associations detecte d between milk and serum emphasize the importance of considering mucos al immunity and unique immunological compartments when searching for r elevant genetic markers of disease resistance.