Studies on the Nature and Genetic Control of an Antigen in Normal Chick Embryos which Reacts in the COFAL Test

Summary Chick embryos from the inbred Reaseheath I line of chickens contained a complement-fixing antigen which reacted in the COFAL test, whereas embryos from the inbred Reaseheath C line lacked the antigen. In cross-bred embryos between the I and C lines the antigen segregated in accordance with the hypothesis that the presence of the antigen was controlled by a single autosomal dominant gene. The antigen appeared to be identical to the group-specific antigen of the avian leukosis-sarcoma group of viruses. No infectious virus was detected in I-line embryos, and the presence of the antigen was not correlated with response to the A and B subgroups of avian leukosis-sarcoma viruses. The possible relationship between the I-line antigen and viral group-specific antigen is discussed.