Genetic control of susceptibility to an a subgroup sarcoma virus in commercial chickens.

Sykes Line A White Leghorn and Line B Rhode Island Red embryos had differences in the average pock counts on the chorio-allantoic membrane (CAM) after infection with the Bryan strain of Rous sarcoma Virus (BS-RSV). By crossing the two lines 2610 embryos comprising 38 sire families were obtained. After challenge of their CAMs with BS-RSV analysis of the number of resulting pocks was made to determine whether or not the CAM response, a numerical trait, was controlled by simple Mendelian inheritance in commercial fowl. It was shown by appropriate statistical models that the trait was mainly controlled by a single pair of genes. However evidence in favour of other genes having a minor influence was also present in these lines of chicken.