Role of immunocompetence, immunosuppression and social stress in susceptibility of chickens to Rous sarcoma

Abstract

A series of six experiments involving a total of 1627 birds from four genetic lines known to differ in their resistance to Rous sarcoma virus (RSV) were conducted. In experiment one, the relationship between transplantation and tumor immunity was studied. Five day-old male chicks of the RSV-susceptible incross line (IC) were given random skin allografts which were scored for survival and feather growth at weekly intervals. Birds which showed either rapid graft rejection by four weeks postgrafting or profusely feathered accepted grafts by seven weeks postgrafting, were challenged with RSV when they reached eight weeks of age. Resulting tumors were scored at weekly intervals through 12 weeks postchallenge and a daily record of mortality was maintained. Mortality and mean survival time (MST) in birds accepting skin allografts were 94.92% and 41.58 ± 8.08 days compared to 66.67% and 24.49 ± 4.415 days for birds rejecting skin allografts, respectively. These differences in mortality and MST were highly significant (P (less than or equal to sign) 0.01). Also, mean tumor scores were consistently higher in birds accepting skin allografts than those rejecting their grafts. This similarity in the pattern of response of birds to skin allografting and to subsequent RSV challenge strongly suggests a relationship between transplantation and tumor immunity. Additionally, these results indicate that the response of birds to skin allografting may provide an useful measure of bird's immunocompetence to Rous sarcoma..