ALLO‐AGGRESSION IN CHICKENS

Simonsen, M. Allo-aggression in chicken. Serological identification of the major genetic locus. Acta path, microbiol. scand. Sect. C, 83: 1–14, 1975. The B-group is the conventional name for the major histocompatibility system (MHS) of the chicken and was first described as a blood group locus. It actually comprises an unknown number of linked loci, at least one of which (AA) governs allo-aggression as manifested, and studied here by the GVH reaction. The gene product(s) of the AA locus would appear to be expressed not only in T cells but also for example in the nucleated erythrocytes, which fact would then in principle permit their detection by haemagglutination. In practice such detection requires that a number of other haemagglutinating antibodies, directed against other antigens of the same B haplotype be first removed, because the unabsorbed antiserum against one given haplotype seems to agglutinate the RBC of almost any unrelated chicken in the world. A strategy is described which allows a planned absorption of the irrelevant specificities from sera against entire haplotypes; hence lead to successful typing for the AA locus. Some observations suggest an extreme degree of linkage disequilibrium in White Leghorns with respect to the genes determining the Bl haplotype, which appears to be a common haplotype in that particular race.