Role of the B complex in the genetic control of the Rous sarcoma virus induced tumors in chickens

Abstract

Recent studies suggest that the gene locus controlling the fate of tumors induced by Rous sarcoma virus (RSV) is linked to the B histo­ compatibility complex. Birds carrying the dominant allele regress the tumor; homozygous recessives being unable to do so, develop large tumors and die. These are called progressors. The Bryan strain of RSV was inoculated into 220 6 week old Leghorns 1 1 2 2 1 9 1 9 homozygous for B B > B B , or B B of which the percentages of progres­ sors were 79, 22 and 56, respectively. The balance of each were regressors and survived. The B^B^ test birds were derived from special matings, i.e., high and low immune responders to the amino acid polymer, GAT. Of 67 tests progeny of the B^B^ GAT-low mating, 63 or 94% proved to be progressors, and 6% were regressors. Of 84 test progeny of the B^B^ GAT-high matings, 67% were progressors, and 33% were regressors. The difference between the high and low GAT responders is highly significant and indicates that the locus controlling the fate of RSV-induced tumors is closely linked to the locus controlling immune response to GAT. The latter maps within the Ir region of the B histocompatibility complex. 60 INTRODUCTION Previous studies have reported evidence for genetic control of resis­ tance and susceptibility to infection frou Rous sarcoma virus (RSV) inoculation in young chickens (Waters and Burmester 1961, Crittenden et al. 1964, Gyles et al. 1968). More recently Collins and co-workers (1977) and Schierman and co-workers (1977) demonstrated that genetic control of the fate of RSV tumors is closely linked to, or within, the B major histo­ compatibility complex. In addition, the Schierman group found that regression of RSV tumors, induced by the Schraidt-Ruppin strain of subgroup B, is determined by a dominant gene designated R-Rs-1^. The recessive allele, designated r-Rs-1^, permits uncontrolled (progressive) tumor growth in homozygous birds. Our study, reported herein, indicates that the RSV genes map within the Ir region of the B complex. In particular, we have found close linkage between the RSV genes, which control tumor regression to subgroup A RSV, and the immune response locus (Ir-GAT), which controls antibody production to the amino acid polymer, GAT^^ (Pevzner et