Reactivity of antisera to endogenous tumor virus for splenic B lymphocytes of immunized 15I(5) x 7(2) and 15I(5) x 7(1) chickens.

Immunofluorescence was employed to assay the spleens from several strains of chicken for the presence of antigen reactive with rabbit antisera elicited to the endogenous oncornavirus RAV-O. Antigen was detected in numerous islands or clusters of B lymphocytes that were localized to splenic red pulp of 15I(5) x 7(2) and 15I(5) x 7(1) chickens that had been sensitized to sheep red blood cells. Competition experiments provided evidence for cross-reactivity with structural antigen of RAV-0. Islands of antigen-positive cells were not detected in the spleens of nonsensitized 15I(5) x 7(2) or 15I(5) x 7(1) chickens although several of these spleens exhibited small numbers of scattered antigen-positive B cells. Spleens of sensitized or nonsensitized Spafas MR53 chickens did not react to detectable levels with the anti-RAV-O sera.