Study of Single Nucleotide Polymorphisms of Major Histocompatibility Complex Region Related to the Immune System in Commercial Broiler and Layer Chickens

Chicken major histocompatibility complex region (MHC) is important in the productive traits, immune responses, resistance to infectious diseases and phylogenetic relationships.

This study was investigated for single nucleotide polymorphisms of MHC region related to the immune system in commercial broiler and layer chickens.

One hundred blood samples were taken from commercial broiler and layer chickens and genomic DNA was extracted by salting out method. The allelic polymorphisms were investigated in B-L, B-F and B-G loci using PCR-RFLP and MspI enzyme.

For two commercial broiler and laying populations, in the 374 bp locus of B-L, only BB genotype was detected but in the 1048 bp locus of B-F, two genotypes of CG and GG were identified in broiler chickens. The C allele contained four bands of 515, 410, 75 and 47 bp, and the G allele with five bands of 410, 302, 213, 75 and 47 bp. In B-G (401 bp) locus, three genotypes of MM, MN and NN and two alleles of M with one band (401 bp) and N with two bands (350 and 51 bp) were identified. In total populations, the Shannon information index was calculated to be 0.45 and 0.73 in markers loci of B-F and B-G, and the fixation index values were -0.20 and 0.34, respectively. The highest observed heterozygosity index for B-F and B-G loci was 0.34 and 0.23, respectively.

Considering the confirmation of the presence of polymorphism in two loci of the B-F (in commercial broiler population) and B-G (in commercial broiler and layer populations), these sites can be used as genetic marker in breeding programs to increase resistance to diseases.