Date of Award

Fall 1982

Project Type


Program or Major

Genetics (Animal Sciences)

Degree Name

Doctor of Philosophy


The MHC of the chicken (B complex) has been shown to exert a decisive influence on the fate of Rous sarcoma virus (RSV)-induced tumors. However, noninbred chickens with identical B genotypes and inbred lines indistinguishable at the MHC have demonstrated considerable variation in response to RSV challenge. The major objective of this research was to determine the cause of variation in anti-Rous sarcoma response observed among chickens with "identical" B genotypes.

Chickens were evaluated for anti-tumor response following wingweb inoculation with RSV at six weeks of age. A comparison of anti-sarcoma responses of (15I-5 x 6-1)F1 versus (15I-5 x 7-2)F1 chickens revealed rapid regression among the (15I-5 x 6-1)F1's and tumor progression among the (15I-5 x 7-2)F1's. A three way cross between (15I-5 x 6-3)F1's and line 7-2 produced B2/B2 and B2/B15 progeny. B2/B15 chickens from this cross, identical at the B complex to the (15I-5 x 7-2)F1 progressors, were characterized by tumor regression. Therefore a non-MHC influence associated with the line 7-2 background appeared to suppress anti-sarcoma response.

Similar findings were obtained using F2 and backcross progeny of lines 100 and UNH 105, low response being associated with the line 100 background. Both lines 7-2 and 100 are susceptible to Marek's disease (MD). Histological evidence for MD involvement was obtained from bursal sections of chickens that had died of progressive sarcoma growth. It is postulated that low anti-sarcoma response associated with MD susceptible lines may result from environmental exposure to MD and subsequent immunosuppression in spite of vaccination for MD at hatching. If low anti-sarcoma response associated with lines 100 and 7-2 is a result of immunosuppression by MD virus, then non-MHC genetic background would appear to be a strong factor influencing relative susceptibility to MD.