Association Of PCR-RFLP Polymorphisms Of NRAMP1 Genes With Immune Traits And Production Traits

Disease resistance is becoming a main target trait in breeding for livestocks at present. NRAMP1 (Natural resistance associated macrophage protein) plays a key role in innate immune defencing infection with intracellular pathogen such as Mycobacterium and Salmonella. In this research we studied the association of Polymorphisms of NRAMP1 gene with some immune traits and some production traits in order to analyse whether the gene could be a candidate gene for disease resistance.1. PCR-RFLP analysis was used to detect the variations within intron 6 of the porcine NRAMP1 gene on 165 Large White (LW) pigs and 109 Zhongxu Black (ZB) pigs population which were reared in the same conditions. Both Polymorphonuclear Leukocytes (PMN) by Nitroblue Tetrazolium (NBT) Reduction (PN) and Cytotoxicity of Monocyte (MT) were measured. The results showed that there was one Ndel restriction locus with three genotypes (AA, BB and AB, respectively) in both LW and ZB breeds. The frequency of gene and genotype were similar in two breeds. The frequency of genotype of AA was 0.006, AB was 0.667 and BB was 0.327 in LW, and in ZB breed the frequency of AA was 0.009, AB was 0.725 and BB was 0.266, respectively. The frequency of allele A was 0.34 and B was 0.66 in LW, and in ZB breed the frequency of allele A was 0.372 and B was 0.628.2. Association of NRAMP1 gene polymorphisms with some immune traits were analysed done by SAS software and the results showed that the effect of interaction between breeds and genotypes had very significant on PN (P<0.01).The value of PN of BB genotype was higher than AB genotype (P<0.01) in LW breed, however, in Zhongxu Black the value of PN of AB genotype was higher than BB genotype (P<0.05). Cytotoxicity of Monocyte (MT) was measured only in LW, the value of MT of BB genotype was higher than AB genotype (P<0.05).3. Association analysis between NRAMP1 gene polymorphisms and immune and production traits showed that the breed had significant effect on the weight of 180 days (P<0.05). The 180 days weight of LW was higher than ZB breed. The individuals weights of 180 days with different genotypes in same breed were significant different, BB genotype was higher than AB genotype (P<0.05) in LW, but in ZB the 180 days weights of different genotypes were not significant different (P>0.05).4. Analysis of the death rate showed that there were no significant differences between the two breeds and different genotypes as well as the death rate of different genotypes in same breed. But the death rate of BB genotype was lower than AB genotype in LW, while in Zhongxu Black the death rate of AB genotype was lower than BB genotype.All those results indicated that polymorphisms of NRAMP1 gene had significant effect on the immune traits and the production traits and could be treat as a candidate gene of disease resistance.