Single Nucleotide Polymorphism Of MHC B-F And B-L Genes Associated With Anticoccidiosis Traits In Jinghai Yellow Chicken

Major Histocompatibility Complex(MHC)is a heredity domain on chromosome 16, composed of close linkaged and high polymorphic loci, related to several diseases'resistance and susceptibility. 100 Chisese local Jinghai Yellow chicken, bred under the same condition, were used in this experiment. After inoculated with coccidian, we determined the experimental animal by various kinds of anti-disease index, used PCR-SSCP typing tech to analyze the polymorphism of MHC B-F gene extron3 and B-LBⅡgene extron2. Association analysis identified SNPs in significant relationship with different anti-disease character. The results were as follows :1. MHC B-F gene extron3 genetic polymorphism:Sequencing primer P1 amplification product, we found that it was the part sequence of extron3 of MHC B-F gene, had high homology, 205 basic radicals, encoding 68 animo-acid residues. PCR product direct sequencing procured 13 individuals'DNA sequences, discovered 30 nucleotide diversity sites. The mutations were all basi-substitution, no basi-insertion or basi-deletion. All mutations contained heterozygosis site, 43,44 and 169 site showed a third basic radical type, contributed to genotype and gene recombination rate. In all 68 encoding amino-acid sequences, 19 residues changed, the homology of DNA sequence (175/205)higher than amino-acid sequence(52/68),indecated that its sequence polymorphism mostly reflected on its amino-acids level.2. MHC B-LBⅡgene extron2 genetic polymorphsim:Sequencing primer P2 amplification product, it was the part sequence of extron2 of MHC B-LBⅡgene, had high homology, 270 basic radicals were found, encoding 90 animo-acid residues. PCR product direct sequencing procured 16 individuals'DNA sequences, discovered 60 nucleotide diversity sites. The mutations were all basi-substitution, no basi-insertion or basi-deletion, some had two above basic change, contributed to genotype and gene recombination rate. In all 90 encoding amino-acid sequences, 32 residues changed, the homology of DNA sequence (210/270)higher than amino-acid sequence(58/90),indecated that its sequence polymorphism mostly reflected on its amino-acids level also.3. Association analysis between MHC B-F gene extron3 SNPs and anti-coccidiosis character:We analyzed 100 Jinghai Yellow chicken MHC B-F gene extron3 SNPs and their anti-disease characters, found 9 SNPs sites of plus sense mutation were significantly related with several detected anti-disease characters in different degree. The results were: SNP on 29 and 89 sites were in significant correlation withβ- carotine conten(tp<0.05); SNP on 28,50,92,95,155,158,175,177 site were in significant correlation with nitrate content(p<0.05).4. Association analysis between MHC B-LBⅡgene extron2 SNPs and anti-coccidiosis character:Analysis between 100 Jinghai Yellow chicken MHC B-LBⅡgene extron2 SNPs and anti-coccidiosis character showed that 15 SNPs sites of plus sense mutation in significant correlation with different anti-disease characters: 9,10,11,14,16,20,22,70,78,126,141,219,241 site SNPs were significantly related with increase of BW(p<0.05); 70,206 site SNPs were significantly related with coccidian egg content(p<0.05);24 site SNP were significantly related with nitrate content(p<0.05).