PORCINE MAJOR HISTOCOMPATIBILITY COMPLEX

The major histocompatibility complex in swine (swine leucocyte antigen : SLA) is located on chromosome 7 with the class I and class III regio ns separated by the centromere from the class II region. The overall m olecular organisation of the class I and III regions is well known, bu t further research is needed to establish that of the class ii region. Approximately sixty genes have been characterised to date, including ten tightly packed SLA class I sequences. The exact number of function al polymorphic class I genes, as defined by serology, probably Varies from one to four, depending on the haplotype. At least two other dista ntly class I-related gene families exist. The numerous and significant associations reported between SLA haplotypes and physiological traits are described. These traits include immune responsiveness to a variet y of microbes and metazoan parasites, and male and female production a nd reproduction performance. The results obtained suggest that selecti on for specific SLA haplotypes may assist in the improvement of porcin e production.