Differential expression of genes BPI, TAP1, SLA-1 and SLA-3 in Escherichia coli F18-resistant and sensitive Meishan post-weaning piglets

The genetic basis and mechanism of sensitivity or resistance to the significant pathogen Escherichia coli F18 is not clear in native Chinese pig breeds and may differ from that in non-native breeds. Our previous research showed that the genes BPI, TAP1, SLA-1 and SLA-3 may play important roles in resistance to E. coli F18 in post-weaning piglets. This study was based on success in selecting and identifying full sib Chinese native Meishan breed post-weaning E. coli F18-resistant and sensitive piglets. Real-time PCR was used to detect expression levels of the genes BPI, TAP1, SLA-1 and SLA-3 in liver, spleen, thymus, lymph node, duodenum, and jejunum tissues between E. coli F18-resistant and -sensitive Meishan piglets. Only the BPI gene was obviously tissue specific; it was highly expressed in the duodenum and jejunum, but expressed at a low level in other tissues. The other three genes were expressed in all the studied tissues, and particularly highly in immune organs and intestinal tissues. The expression level of BPI in the duodenum of the resistant group was significantly higher than that in the sensitive group (P < 0.01). The SLA-3 expression level in the thymus of the resistant group was significantly higher than that in the sensitive group (P < 0.05). TAP1 and SLA-1 gene expression levels were generally higher in the resistant group than the sensitive group, but there were no significant differences. Genes BPI and SLA-3 play an important role in the processes of resistance to E. coli F18 in Meishan weaned piglets. We speculate that BPI protein may have a direct killing effect on Gram-negative bacteria such as E. coli strain F18 in the intestine; the resistance of Meishan weaned piglets to E. coli F18 is likely to be related to the upregulation of intestinal BPI. The upregulation of SLA-3 may increase the resistance of weaned piglets to E. coli F18 by regulation of the immune response.