Analysis of polymorphism in the porcine TLR4 gene and its expression related to Escherichia coli F18 infection

摘要

The genetic variation in exon 1 of the TLR4 gene was detected among a total of 893 animals, including Asian wild boars, 3 imported commercial and 10 Chinese indigenous pig breeds. The expression of TLR4 was assayed by RT-PCR and different expression between resistant and sensitive resource populations to ETEC F18 was analysed to discuss the role that the TLR4 gene plays in resistance. In this study, new alleles were detected in exon 1 of the TLR4 gene. These polymorphisms are significantly different between Chinese indigenous breeds and imported breeds. Based on the published TLR4 gene sequence (AB232527) in GenBank, a 93G > C mutation was found in 5’UTR and only a 194G > A synonymous mutation was found in the coding sequence of exon 1. In addition, TLR4 gene was broadly expressed in 11 tissues with the highest level in lung. The expression was relatively high in the lymph nodes, kidney and spleen. Generally, the expression of TLR4 gene in sensitive individuals was higher than that in resistant individuals. The results indicated that the downregulation of the mRNA expression of TLR4 gene had reduced the transmembrane signal transduction of LPS and then led to the responsive ability of the host to ETEC F18 in piglets.