Identification of porcine CTLA4 gene polymorphism and their association with piglet diarrhea and performance traits.

The objective of this study was to evaluate the association between the cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) gene and piglet diarrhea. In this study, the mRNA expression of the CTLA4 gene increased significantly in IPEC-J2 cells after Escherichia coli K88 infection. Single nucleotide polymorphisms (SNPs) located in the 5' flanking region (SNPs g.107281989C>T) and 3'-untranslated region (3'-UTR; SNPs g.107288753C>A) were identified, and they were in linkage disequilibrium in both Min pigs and the Landrace population. Association analysis showed that Landrace piglets with a TT or AA genotype had a lower diarrhea index, and AA animals had higher average daily gain when compared to CC pigs, respectively (p < 0.05). However, the relationship between SNPs and diarrhea and performance traits in the Min population was not significant. Haplotype analysis indicated that the TC haplotype had the lowest diarrhea index. The 5' flanking deletion assay suggested that SNP g.107281989C>T was a molecular marker instead of the functional marker. This research demonstrated that genetic variances in the CTLA4 gene had significant effects on Landrace piglet diarrhea resistance.