Host age and major histocompatibility genotype influence on Rous sarcoma regression in chickens.

The influence of host age and B (major histocompatibility complex) genotype on the fate of Rous sarcoma virus (RSV)-induced tumors was investigated. White Leghorn lines 61 and 151, developed at the Regional Poultry Research Laboratory (RPRL) at East Lansing, MI, and their crosses (F3 to F5) segregating for the B genotype were used. Preliminary experiments with noninbred White Leghorns showed that chickens RSV-inoculated at 4 weeks of age had a significantly lower incidence of tumor regression than chickens RSV-inoculated at 6, 8, 10, 12, and 14 weeks of age. The (61 X 151) F5B2/B2 and B5/B5 chickens inoculated at 6 weeks of age had a lower incidence of tumor regression than (61 X 151)F3 and F4, B2/B2 and B5/B5 chickens RSV-inoculated between 58 and 88 weeks of age, respectively. Some (61 X 151) B2/B2 chickens inoculated between 58 and 88 weeks of age regressed their tumors while all chickens of corresponding genotype inoculated at 6 weeks of age died with tumors. the (61 X 151) B2/B2 chickens had a higher incidence of tumor regression than B5/B5 chickens regardless of age. The genetic RSV-inoculation on the fate of RSV-induced tumors.