INFLUENCE OF B-HAPLOTYPE ON THE RELATIVE EFFICACY OF MAREKS-DISEASE VACCINES OF DIFFERENT SEROTYPES

To determine if B-haplotype differentially influences vaccinal immunity to very virulent Marek's disease (MD) virus challenge, chickens of five 15.B-congenic lines were vaccinated with vaccines representing serotypes 1, 2, and 3. B-haplotype differentially influenced vaccinal immunity to very virulent MD virus challenge using vaccines of all three serotypes, and different MD vaccines were optimal for some B-haplotypes. Regarding specific haplotypes, the 15.B-congenic chickens with B2 and B-13 developed less protection against MD than chickens with B-15 following vaccination with all three serotypes of MD vaccine, whereas the chickens with B-5 and B21 developed variable protection with different MD vaccines. Thus, for induction of maximum MD resistance, it may be necessary to select a vaccine appropriate for the predominant B-haplotypes of the chicken flock.