Immunological Determinants of Avian Sarcoma Viruses: Presence of Group-Specific Antibodies in Fowl Sera Demonstrated by Complement-Fixation Inhibition Test

A complement-fixation inhibition test revealed antibodies in the sera of fowls immunized with Rous sarcoma virus (RSV). These antibodies were specific for antigen preparations of representative members of the avian leukosis complex and cross reacted with all antigens tested with the characteristics of group-specific antibodies. The antigens studied included: 1) chick-embryo tissue-cultured cells infected with the following strains of RSV—Bryan high-titer (BH-RSV), Schmidt-Ruppin (SR-RSV), Harris (H-RSV), and a strain of avian lymphomatosis RPL12; 2) tumors induced in chickens, turkeys, and Japanese quail with BH-RSV and SR-RSV; and 3) hamster tumors induced by SR-RSV. The RSV group-specific antibodies in fowl sera had no neutralizing activity.