Non - MHC alloantigen effects on resistance and susceptibility to Eimeria tenella

s of papers 39 167 Non-MHC alloantigen effects on resistance and susceptibility to Eimeria tenella . R. L. Taylor, Jr.*1 and W. E. Briles2, 1Dept. of Animal and Nutritional Sciences, University of New Hampshire, Durham, NH 03824, 2Dept. of Biological Sciences, Northern Illinois University, DeKalb, IL 60115. Major histocompatibility (B) complex (MHC) genes and non-MHC genes have a role in host responses to the protozoan parasite, Eimeria tenella. The current study was performed to examine the effect of non-MHC alloantigens on resistance and susceptibility to E. tenella in a cross between a modified Wisconsin Line 3 and White Leghorns. Pedigree matings between B2B5 sires and 5 or 6 B2B2 dams/sire, which segregated for at least two alleles of 8 additional alloantigen systems (A, C, D, E, H, I, L, P), produced B2B2 and B2B5 progeny which possessed various combinations of other alloantigen genes. Alloantigens were typed in agglutination assays at 3 wk of age using specific antisera raised against each haplotype transmitted by the parental stocks. Chicks were weighed at 5 wk of age and challenged with 30,000 E. tenella oocysts. Six days after challenge, the birds were weighed and cecal lesion scores were assessed. Two trials having a total of 258 chicks were used. Data were analyzed by least squares analysis of variance with trial, sex, sire, and alloantigen system as main effects. Significant means were separated using Fishers protected LSD. Initial analysis for B system effects revealed that weight gain differed significantly between B2B2 and B2B5 chicks (P < 0.004). Neither initial body weight or cecal lesion scores were affected by B genotype. Subsequent analysis for other alloantigen systems was performed separately on the B2B2 and B2B5 genotypes. Among the 8 alloantigen systems, only the L system had a significant effect. The L1L2 and L2L2 genotypes had significantly lower lesion scores than the L1L1 genotype in B2B2 chicks but not in B2B5 chicks. These data indicate that the L alloantigen alters the susceptibility to E. tenella in the context of the most susceptible B2B2 genotype.