Genetic Diversity of TLR4 and IL2 Loci Involved In Immune System in Some Iranian Indigenous Chicken Breeds

In this study, allelic polymorphism in candidate genes of TLR and IL involved in the immune system in four Iranian indigenous chickens were examined using PCR-RFLP technique. A total of birds including common, West Azerbaijan, Marandi, Mazandarani indigenous chicken breeds were selected. For detection of mutation in TLR ( bp) and IL ( bp) genes the PCR products were digested by Sau I and HphI restriction enzymes, respectively. Two alleles of C ( and bp) and G ( , and bp) and three genotypes of CC, CG and GG were identified in TLR marker site. Following the enzymatic digestion of the IL gene, two alleles of A ( , , and bp) and B ( , , , and bp) and three genotypes of AA, AB and BB were identified. The whole populations was in HardyWeinberg equilibrium for TLR and IL marker sites. The calculated Shannon information index and fixation index values for TLR and IL marker sites was estimated to be ( and ) and (and ), respectively. The highest observed heterozygosity value for TLR and IL loci was estimated to be ( and ), respectively. Regarding to the existence of polymorphism in the studied loci and reduction of heterozygosity in these populations, the occurrence of non-random crosses can be prevented. This leads to an increase in heterozygosity and thus prevents the loss of genetic diversity in the populations would be. In the populations also, by studying the immune responses associated with these two loci, these sites can be used as suitable markers in breeding programs for increase of resistance to diseases in indigenous chickens.