Tests of association of lymphocyte alloantigen genotypes with resistance to viral oncogenesis in chickens. 1. Marek's disease in F7 progeny derived from 6(3) X 15(1) crosses.

Marek's disease (MD)-susceptible progeny of the B5B5 genotype from the F7 generation derived from crosses of Regional Poultry Research Laboratory inbred lines 6(3) and 15(1) were tested for variation in MD resistance associated with the T lymphocyte antigen loci Ly-4 and Th-1. The four double homozygous genotypic classes of Ly-4 and Th-1 were tested in a 2 X 2 design. The Ly-4bb/Th-1aa chickens were significantly more resistant to MD oncogenesis than the other three genotypes. Thus, resistance within B5B5 genotypes appears to be associated with genetic interaction between two T cell antigen loci, which are not linked with the B complex.