Caprine major histocompatibility complex : definition of sera recognizing Class I and II lymphocyte antigens and evaluation of these sera for identifying individuals susceptible to caseous lymphadenitis and caprine arthritis encephalitis

Abstract

Sera from 297 primiparous goats were screened for the presence of both Class I and Class II antibodies in a 2-stage microcytoxicity assay. Eleven Class I antigens were defined; both statistical as well as family studies indicated that these 11 antigens were controlled by 2 loci. Antigens TX 1-7 located a t 1 locus account for 85% of the gene products at that locus and antigens Tx 8-11 account for 86% of the gene products a t the other locus. In addition 47 of the 297 sera were observed to possess antibodies to Class II lymphocyte antigens found mainly on B cells. Of these 47 sera 13 sera were observed to detect 5 different antigenic determinants. Family studies indicated a single locus model; however, frequency data were indicative of polyspecific sera with these 5 antigens accounting for 91% of the gene products. Once established, the Class I and Class II antigen systems were used to examine the possibility of disease association with 2 diseases of considerable economic importance to the goat industry, CAE and CLA. Although the results are preliminary, they do seem promising. One hundred positive and 100 negative animals tested for antibody to CAEY, as defined by the agarose gel immunodiffusion assay, were tested against both Class I and Class II antigens using Chi square and relative risk calculations for disease associations. There was a significant association between CaLA cluster Tx9 and the individual serum Tx18 and the presence of antibody to CAEV. In the CLA study, in which CLA was found to have an incidence rate of 15.7% in a mature goat population, there appears to be a significant association of Class I antigen Tx6 and a unique antigen detected by the single serum Tx104 with predisposition to CLA. Further refinement of both antigen systems will be needed in the future. However, if the initial studies prove valid, these antigens may prove useful in improving herd health through selective breeding regimens.