Association Analysis of Single Nucleotide Polymorphisms in the 5′ Regulatory Region of the IL-6 Gene with Eimeria tenella Resistance in Jinghai Yellow Chickens

摘要

Interleukin 6 ( ) is an immunoregulatory cytokine involved in various inflammatory and immune responses. To investigate the effects of single nucleotide polymorphisms (SNPs) and haplotypes of -6 on resistance to ( ), SNPs in the 5′ regulatory region of -6 were detected with direct sequencing, and the effects of SNPs and haplotypes on resistance to were analyzed by the least square model in Jinghai yellow chickens. Nineteen SNPs were identified in the 5′ regulation region of , among which three SNPs were newly discovered. The SNP association analysis results showed that nine of the SNPs were significantly associated with resistance indexes; the A-483G locus was significantly associated with the GSH-Px, IL-2, and IL-17 indexes ( < 0.05); the C-447G locus was significantly associated with the SOD, GSH-Px, IL-17, and IL-2 indexes ( < 0.05); and the G-357A locus had significant effects on the CAT and IL-16 indexes ( < 0.05). Haplotype analysis showed that H2H3 and H2H5 were favorable haplotype combinations with good coccidium resistance. Furthermore, we used qRT-PCR and observed that the expression of in the infection group was higher than that in the control group in the liver, proventriculus, small intestine, thymus, kidney, and bursa of Fabricius and extremely significantly different than that in the cecum especially ( < 0.01). In summary, SNPs and haplotypes in the 5′ regulatory region of have important effects on resistance, and the results will provide a reference for molecular marker selection of resistance in Jinghai yellow chickens.