Association of Marek's disease with Ea-B and immune response genes in subline and F2 populations of the Iowa State S1 Leghorn line.

Chickens from the Iowa State S1 White Leghorn line, selected for characteristics of Ea-B serotype, humoral immune response to glutamic acid-alanine-tyrosine (Ir-GAT), and response to Rous sarcoma virus (RSV)-induced tumors, were evaluated for genetic resistance to Marek's disease (MD). In the first two trials, sublines that were triple homozygous for the three traits were challenged with MD virus. Birds of the B1B1 blood type were significantly (P less than .001) more resistant to MD than chickens of the B19B19 blood type. High responders to GAT were significantly (P less than .001) more resistant to MD virus than low responders. The RSV classification had no detectable association with MD resistance. Chickens challenged with MD virus in the third trial were an F2 population produced from inter se matings of S1 chickens heterozygous for the three traits under selection. Data from this trial confirmed increased MD resistance of chickens possessing the B1B1 blood type when associated with genes encoding high immune response to GAT.