Resistance to Marek’s Disease Virus in White Leghorn Chickens: Effects of Avian Leukosis Virus Infection Genotype, Reciprocal

ABSTRACT Genetic improvement for resistance to Marek’s Disease (MD) in chickens continues to be of inter-est to the poultry industry. The aims of this study were to identify effects of the MHC on the molecular level and of avian leukosis virus (ALV) resistance status on MD mortality in two noninbred White Leghorn chicken lines that differ in B blood group type. Previously, within each of the chicken lines, sublines had been selected for resis-tance or susceptibility to ALV infection with Subgroups A and B. In this study, F2 offspring, obtained by crossing the two ALV-resistant or the two ALV-susceptible sub-lines, were tested for MD mortality after contact exposure at 1 d of age. Reciprocal matings were made in the grand-(Key words: chicken, Marek’s disease, major histocompatibility complex, restriction fragment length polymorphism, survival analysis