EFFICACY OF MAREKS-DISEASE VACCINES IN MHC HETEROZYGOUS CHICKENS - MHC CONGENIC X INBRED LINE F1 MATINGS

The goal of this study is to demonstrate that Mhc (B) heterozygous chickens differ in efficacy of response to several Marek's disease (MD) vaccines. Four types of B-2 heterozygotes, in addition to (BB2)-B-2 homozygotes, were developed by crossing 15.B congenic males to inbred line 7(1) ((BB2)-B-2) hens. The five types of F-1 chicks were intermingled in isolators and vaccinated with one of four types of MD vaccine before inoculation with the very virulent Md5 strain of MD herpesvirus. The F-1 chickens differ in development of protective immunity following MD vaccination from two perspectives. First, chickens of a particular Mhc genotype were protected better by some vaccines than others, Second, individual vaccine preparations protected some Mhc genotypes more effectively. We conclude that some MD vaccines are more appropriate than others for certain B-haplotypes when chickens are heterozygous for the Mhc. The value of using Mhc-congenic x inbred line F-1 animals for studies concerning the influence of the Mhc on vaccinal immunity is discussed.