Genetic analysis of four differing traits (MHC haplotype, tumor response, CD4:CD8 ratio, ev 17) in CB and CC congenic chickens.

Two closely related inbred lines of chickens, CB and CC, were compared for major histocompatibility complex (MHC) haplotype, response to tumors induced by Rous sarcoma virus and CD4:CD8 ratio. Genetic analysis showed that all the above traits were associated with the MHC. In all CB chickens, we found an additional endogenous virus, ev 17, a proviral sequence lacking in all tested CC animals. From our analysis and data from the literature, we presume that the presence of ev 17 in CB chickens is probably caused by gene duplication of ev 1 with extensive nucleotide alterations. Our analysis with (CB x CC) x CC backcrosses demonstrate that ev 17 is not linked to the chicken B complex. From our experiments, we conclude that inbred CB and CC chickens differ in MHC and ev 17, and we established additional congenic inbred lines with and without the proviral locus ev 17.