Polymorphisms of three gene-derived STS on pig chromosome 13q41 are associated with susceptibility to enterotoxigenic Escherichia coli F4ab/ac in pigs

Neonatal diarrhea caused by enterotoxigenic Escherichia coli (ETEC) F4 is a common and serious disease, resulting in significant economical loss in the pig industry. The locus encoding ETEC F4 receptor has been mapped to pig chromosome (SSC) 13q41, and one of the most significantly linked markers is S0075. In this study, we selected three genes including SLC12A8, MYLK and KPNA1 from a chromosomal region flanking S0075 on SSC13 to develop pig specific sequence tagged sites (STS). Seven single nucleotide polymorphisms were identified in the three pig STS using DNA of four full-sib susceptible and resistant animals in a White Duroc x Erhualian intercross. All grandparents, parents and 755 offspring in the intercross were genotyped for three polymorphisms, including SLC12A8 g.159A > G, MYLK g.1673A > G and KPNA1 g.306A > G. Family-based transmission disequilibrium test (TDT) revealed that all polymorphisms and the corresponding haplotypes are significantly associated with ETEC F4ab/ac (especially F4ac) brush border adhesion phenotypes, indicating that these polymorphism are in linkage disequlibrium with causal mutation(s) of the gene encoding ETEC F4ab/ac receptor. Our results strengthen the evidence for the involvement of SSC13q41 in high acquiring risk of ETEC F4ab/ac infection, and provide novel polymorphic markers for fine mapping of the ETEC F4ab/ac receptor locus.