Plumage colour gene (i (+)), a possible modifier on cellular susceptibility to RSV (RAV 49) in White Leghorn Fowl.

Seventy-six embryos from three isozygous Reaseheath lines I, C and W and 336 embryos derived from W X R line inbred parents, of White Leghorn fowl, segregating for plumage colour genes and tumour virus genes controlling susceptibility to an avian tumour virus of subgroup C, RSV(RAV49), were studied to examine whether the epistatic dominant white (I gene) and its recessive allele (i (+) gene) in the host genome modified susceptibility to RNA tumour viruses.It was observed that the recessive allele of the dominant white gene modified the incidence of tumour pocks on the chorioallantoic membranes of embryos inoculated with RSV(RAV49). In the segregating W X R population, susceptible black embryos had on average 46 pocks fewer than the white susceptible embryos which had about 119 pocks.It was further shown in this stock of birds that the tumour virus genes and the plumage colour genes for dominant white are located on different chromosomes.