ASSOCIATION OF ENDOGENOUS VIRAL GENES WITH QUANTITATIVE TRAITS IN CHICKENS SELECTED FOR HIGH EGG-PRODUCTION AND SUSCEPTIBILITY OR RESISTANCE TO MAREKS-DISEASE

1. The association of endogenous viral (ev) genes with quantitative tr aits in 2 genetically distinct sets of White Leghorn strains were inve stigated. Strain S had been selected for susceptibility to Marek's dis ease (MD) whereas strain K had been selected for resistance to MD and high egg production and egg weight. 2. In all, 8 ev genes were typed. Ev10, ev19 and 'newB' occurred exclusively in strain S, 'newA' occurre d only in strain K, and ev1, ev3, ev6 and ev8 occurred in both strains . 3. Whereas ev6 and ev8 were associated with reduction in egg product ion rate in strain S, in strain K, the presence of ev3 was associated with increased group specific antigen. 4. The genetic background of th e chicken strain may play a role in the way certain a genes affect tra its. 5. It was thought that the position of ev genes on the chromosome may be important and their association with traits of economic import ance make them potential genetic markers for uncovering quantitive tra it loci.