RESUMEN
To understand the role of interferon (IFN)-γ gene (IFNG) single-nucleotide polymorphisms (SNPs) in the resistance to H5N1 highly pathogenic avian influenza (HPAI), we determined the SNPs, the log2-transformed specific antibody titers, and ex vivo recall antigen-specific IFN-γ production by peripheral blood mononuclear cells (PBMCs) in 62 red junglefowls (Gallus gallus) immunized twice with inactivated H5N1 HPAI vaccine. Consequently, 52 SNPs were detected in the amplified 1137-bp length covering the promoter region and all exons, with +2133A/T SNP in the coding DNA sequence that caused a missense mutation and was identified in G. gallus for the first time. For -316A/G SNP genotypes, the chi-squared test showed that the bird sample was in the Hardy-Weinberg equilibrium (P=0.369>0.05), and the least squares analysis revealed an increasing tendency in the antibody titers with G to A substitution so that a significant difference occurred between the AA genotype (8.031±0.247) and the GG genotype (6.571±0.528) (P=0.015<0.05, 95% confidence interval [CI]: 0.0004-0.0866), as basically consistent with the antigen-induced IFN-γ protein expression, which indicated possible association of the -316A/G SNP with a secondary humoral immune response to the HPAI vaccine in the bird population. These findings may help to improve genetic resistance using cross-breeding and enhance HPAI vaccine-induced immunity in chicken production.