Associations of six candidate genes with antibody response kinetics in hens

The chicken B-cell marker (ChB6), caspase-1, inhibitor of apoptosis protein-1 (IAP-1), interleukin-15 receptor alpha-chain (IL-15Ralpha), interleukin-2 receptor gamma-chain (IL-2Rgamma), and immunoglobulin supfamily gene (ZOV3), as physiological candidate genes for chicken immune response, were selected to investigate associations with antibody kinetics to SRBC and killed B. abortus. An F2 population was derived from mating highly inbred (>99%) males of two MHC-congenic Fayoumi lines (named M5.1 and M15.2) with G-B1 Leghorn hens. Antibody response to SRBC and B. abortus after immunization at 19 and 22 wk were measured. Secondary phase parameters of maximum titers (Ymax) and time required to achieve Ymax (Tmax) were estimated from postsecondary titers by using a nonlinear regression model. The DNA polymorphisms of six genes were identified, and associations of single nucleotide polymorphisms (SNP) in the six genes with antibody response parameters were analyzed. Significant main effects of the gene polymorphisms were mostly found in the lineage of the M5.1 grandsire and primarily on antibody response to B. abortus. There was general agreement of allelic effect within antibody parameters among genes. These results suggest that the SNP characterized in the study may serve as markers for genetic enhancement of humoral immune capacity in the chicken.