Genetic variation in exon 10 of the BPI gene is associated with Escherichia coli F18 susceptibility in Sutai piglets.

Our aim was to investigate the effect of the porcine bactericidal/permeability-increasing protein (BPI) on the susceptibility to enterotoxigenic Escherichia coli F18 (ETEC F18). Specifically, we wanted to determine whether the HpaII restriction polymorphism in exon 10 of BPI mediates susceptibility to ETEC F18. Thirty verified ETEC F18-resistant and thirty susceptible Sutai (Duroc×Taihu) piglets were identified using the receptor binding assay. Exon 10 of the BPI gene produced the AA, BB, and AB genotypes after HpaII digestion. The genotype distribution among ETEC F18-resistant piglets was significantly different from that among susceptible piglets. Among piglets with the AA genotype, 90% were ETEC F18-resistant; this percentage of resistant piglets was significantly higher than the percentage of resistant piglets with the AB (57.1%) and BB genotypes (17.4%). There was high expression only in the tissues of the duodenum and jejunum, wherein the expression levels in the ETEC F18-resistant group were significantly higher than those in the susceptible group (P<0.05). The average expression levels in individuals with the AA genotype were significantly higher than those in individuals with the AB or BB genotype (P<0.05), while the results of Western blot show the same evidences as real time PCR. These results indicate that the upregulation of porcine BPI gene expression in the small intestines plays a direct role in resistance to ETEC F18 infection. The AA genotype for the HpaII site in exon 10 of the porcine BPI gene was demonstrated to be an anti-ETEC F18 marker and could be used for selective breeding to enhance ETEC F18 resistance.

Analysis of differential miRNA expression in the duodenum of Escherichia coli F18-sensitive and -resistant weaned piglets.

Small RNA duodenal libraries were constructed for Escherichia coli F18-sensitive and -resistant weaned piglets in full-sib pair groups and sequenced using Illumina Solexa high-throughput sequencing technology. The identification of differentially expressed miRNAs provides the basis for improved database information on pig miRNAs, understanding the genetic basics of differences in resistance to E. coli F18 between local Chinese and exotic pig breeds, and finding new resistance markers for E. coli F18 infection. The duodenum of all individuals contained more than 90% of known swine miRNAs. A total of 58 differentially expressing miRNAs were identified, of which 46 were increased and 12 were decreased in E. coli F18-sensitive pigs. Of miRNAs with increased expression, ssc-miR-143 was most highly expressed, followed by ssc-let-7f, ssc-miR-192, and ssc-miR-21. We identified a total of 2036 intersection target genes by comparing TargetScan data and previous gene expression profile results. Gene ontology and pathway analysis of intersection genes showed that differentially expressed miRNAs were mainly involved in the immune response and transcriptional regulation. Combining information on differential miRNA expression and their regulatory relationships with transcription factors, identified 12 candidate miRNA disease markers, including 11 miRNAs with increased expression, ssc-miR-143, ssc-let-7f, ssc-miR-30e, ssc-miR-148a, ssc-miR-148b, ssc-miR-181a, ssc-miR-192, ssc-miR-27b, ssc-miR-15b, ssc-miR-21, and ssc-miR-215, and one with decreased expression, ssc-miR-152. Quantitative real-time PCR analysis of candidate miRNA expression in a larger cohort of E coli F18-sensitive and -resistant animals confirmed the high-throughput sequencing results.

Study on the age-dependent tissue expression of FUT1 gene in porcine and its relationship to E. coli F18 receptor.

Escherichia coli (E. coli) that produces adhesin F18 is the main pathogen responsible for porcine post-weaning diarrhea and edema disease. The receptor for E. coli F18 has not been described in pigs, however the alpha (1,2)-fucosyltransferase (FUT1) gene on chromosome 6 has been proposed as a candidate. The objective of this study, therefore, was to investigate the relationship between FUT1 gene expression and E. coli F18 receptor in Sutai pigs of different ages (8-, 18-, 30- and 35-day-old). FUT1 gene expression was detected in 11 pig tissues with the highest level in lung, and expressed consistently at the four time points. In most tissues, FUT1 gene expression levels decreased from days 8 to 18, then continually increased on days 30 and 35, with expression around weaning time higher than that on day 8. Gene ontology and pathway analysis showed that FUT1 was involved in 32 biological processes, mainly those integral to the membrane, or involved in glycosylation, as well as regulation of binding, interestingly participating in three pathways related to glycosphingolipid biosynthesis. From this analysis and the high linkage disequilibrium between the FUT1 gene and the E. coli F18 receptor locus, we can speculate that higher expression of the FUT1 gene in small intestine is beneficial to the formation of receptors to the E. coli F18 strain and is related to the sensitivity to the pathogen.