Response of major histocompatibility (B) complex haplotypes B22, B26, and B30 to Rous sarcomas

The response to Rous sarcoma virus-induced tumors was measured over a 2-yr period using Line UNH 105 New Hampshire chickens segregating for three major histocompatibility (B) complex haplotypes, B22, B26, and B30. Twelve sires and 49 dams were used to produce 489 pedigreed progeny consisting of six B genotypes B22/B22, B22/B26, B22/B30, B26/B26, B26/B30, and B30/B30. Six-wk-old chicks were inoculated in the wingweb with a pseudotype of Bryan high-titer Rous sarcoma virus designated as BH RSV (RAV-1). Resultant tumors were scored six times during a 10-wk period, which served as a basis for a tumor profile index (TPI) assigned to each chick. The B22/B26 chickens (means TPI = 2.6) had the greatest antitumor response, which was significantly different from that of B26/B26 (means TPI = 3.0) and B30/B30 chickens (means TPI = 3.4), the lowest responders. Lower mean TPI of two heterozygotes, B22/B26 (2.6) and B26/B30 (2.9), compared with those of appropriate homozygotes, suggested complementation between B22 and B26 as well as B26 and B30. Chi-square analysis revealed an additional beneficial effect of the B22 haplotype in tumor-bearing chickens, as B22-containing genotypes had a significantly higher survival rate than genotypes not containing B22.