Immunocompetences in Two Pairs of B Congenic Chicken Lines

Abstract

Influences of chicken major histocompatibility complex (B) on immunoglobulin M (IgM) and G (IgG) production, cell mediated immune response, and immunity against different disease agents were examined in two pairs of B congenic chicken lines. Inbred line CB (B¹² B¹²) and line HA (B¹¹ B¹¹), selected for graft-vs-host reaction (GVHR) high, were served as the genetic background for the experiment. Heterozygous genotype birds from these lines (B¹¹ B¹²) were backcrossed to the CB and HA ones, respectively, upto eight generations for the production of CBH (B¹¹ B¹²) and HCB (B¹¹ B¹²) lines. At 10 wk of age, IgM and IgG levels were measured. A significant difference was found between the pairs of congenic lines for the production of serum IgM and IgG, and the heterozygous genotype was involved for higher IgM and IgG production than the homozygous genotypes. Cell mediated immune response, measured by splenomegaly index at 12 wk of age, was significantly higher in the CBH line than the CB line. The HA line showed significantly lower immunity against Mycoplasma gallisepticum, Mycoplasma synoviae, and Coryza type C than the HCB line. On the other hand, the HCB line was associated with lower immunity to Coryza type A. These results demonstrated that genes of the MHC had a significant effect on serum IgM and IgG production. Splenomegaly index and immunity to disease agents were also influenced by the genes of the MHC. A heterozygotic advantage of B haplotypes on IgM and IgG production, splenomegaly index, and immunity to MG, MS, and CC were observed.