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Firstly, our research group identified Sutai pigs’ phenotypes that exhibited extreme resistance and susceptibility to the Escherichia coli F18 respectively, and then eight ETEC (Enterotoxigenic Escherichia coli) F18-resistant piglets and eight ETEC F18-sensitive piglets were selected. Then, the TAP1 (Transporter associated with antigen processing) mRNA relative expression levels were analyzed in 11 tissues of the resistant and susceptible phenotypes. Simultaneously, we detected the genetic variations in exon 3 of the TAP1 gene and evaluated the TAP1 mRNA expression levels among the different genotype pigs to study the effects of the genetic variation on gene expression, and the E. coli F18 resistance. The results revealed higher expression levels in the resistant genotypes than that in the susceptible genotypes in 11 tissues, with significant differences in the spleen, lymph node, lung, thymus, duodenum and jejunum. Furthermore, a G729A mutation was identified in the TAP1 gene exon 3, and this mutation deviates from Hardy-Weinberg equilibrium (p < 0.01). The TAP1 mRNA levels in GG genotype were significantly higher than that in the other two genotypes, with significant differences in the liver, lung, kidney, thymus, lymph node, duodenum and jejunum tissues. We speculated that high expression of the TAP1 gene might confer resistance against the E. coli F18, the G729A mutation had a significant effect on the mRNA expression, and individuals with the GG genotype possessed a stronger ability to resist the E. coli F18 infection.

ABSTRACT. The bactericidal/permeability-increasing protein (BPI) gene has been identified as a candidate gene for disease-resistance breeding. We evaluated whether polymorphisms in exons 4 and 10 of the BPI gene are associated with immune indices [interleukin-2 (IL-2), IL-4, IL-6, interferon-b (IFN-b), . In this study, we identified one mutation (C522T) in the BPI exon 4 site and two mutations (A1060G and T1151G) in the BPI exon 10 site. Correlation analysis revealed that in the Sutai pig population, the effect of genotypes at the BPI exon 4 site on the level of IL-6 was significant (P < 0.05), with an effective genotype of CD; moreover, the effect of genotypes at the BPI exon 10 site on the level of IL-12 was significant (P < 0.05), and the effective genotype was AB. The optimal combined genotype was CD-AB, which was more effective regarding the IL-6 and IL-12 6049 BPI gene mutations affect immune indices ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (2): 6048-6058 (2015) levels compared to the other combined genotypes (P < 0.05). These results indicate that single nucleotide polymorphisms and the combined genotypes of BPI exons 4 and 10 affect immune indices in Sutai pigs. Therefore, these genotypes should be further examined as effective markers for disease-resistant breeding of pigs.