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Title: EFFICACY OF MAREK'S DISEASE VACCINES IN MHC HETEROZYGOUS CHICKENS: MHC CONGENIC X INBRED LINE F1 MATINGS

Author
item Bacon, Larry
item Witter, Richard

Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Previous experiments established that special laboratory strains of chickens differing for a marker (B blood type) on blood cells were equally susceptible to a tumor condition called Marek's disease (MD). However, following vaccination the chickens in some strains were better protected against MD than those in other strains. In this experiment, males of five of the special lines were mated to females of another inbred line, i.e. a line in which all chickens are virtually genetically identical. The offspring chicks from the strain-cross mating contained various B types, obtaining the B2 marker from the hen and either B2, B5, B13, B15, or B21 from the male. Following vaccination against MD with one of four vaccines, and infection with the MD virus causing the tumor condition, some of the B types were shown to differ in protection against MD, and some B types responded better to one or more of the four vaccines tested. Commercial chickens are developed by strain-cross matings and are known to contain two B markers similar to those identified in this study. Therefore, these results indicate that commercial poultry producers can improve the vaccinal response against MD by using vaccines most appropriate for the B markers in the chicken strains they utilize.

Technical Abstract: 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 B2 heterozygotes, in addition to B**2B**2 homozygotes, were developed by crossing 15.B congenic males to inbred line 71 (B**2B**2) hens. The five types of F1 chicks were intermingled in isolators and vaccinated with one of four types of MD vaccine prior to inoculation with the very virulent Md5 strain of MD herpesvirus. The F1 chickens differ in development of protective immunity following MD vaccination from two perspectives. First, F1 chickens of a given B-genotype are protected better by some MD vaccines than others, and the best vaccine is dependent upon the B-haplotypes possessed by the F1 chicken. Alternatively, three of the four vaccines given to F1 chickens of several B-genotypes were shown to protect some B-genotypes better than others. 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 F1 animals for studies concerning the influence of the Mhc on vaccinal immunity is discussed.