Tick resistance and the major histocompatibility system.

199 3/4 Brahman 1/4 Shorthorn cattle, whose resistance to the cattle tick Boophilus microplus had been determined by clinical trial, were tested for 19 bovine lymphocyte antigens. Of eleven antigens detected at a frequency greater than 5%, two were found to be associated with tick resistance and a third was associated with susceptibility to ticks. However, none of these antigens accounts for more than 2.1% of the variance, indicating that these associations are not strong.