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Based on the established resource populations of Sutai pig, the expression of BPI gene was assayed by Real-time PCR to detect the tissue expression and analyze the differential expression between Escherichia coli F18-resistant and sensitive piglets. This study aimed at providing a theoretical foundation for further research on the role BPI gene in host immunity and resistance to E. coli F18. The results showed that the expression of BPI gene was extremely low or undetectable in tissues including heart, liver, spleen, lung, kidney, stomach, muscle, thymus, and lymph nodes, which was in a stark contrast to the significantly high levels in duodenum and jejunum. In the tissues of both jejunum and duodenum, the mRNA expression of BPI gene in resistant individuals was significant higher than that in the sensitive individuals (Pamp;0.05). The results suggested that BPI gene was likely to be related to the intestinal infection caused by E. coli F18. It is possible that the increased expression of BPI gene in intestinal is in connection with the resistance to E. coli F18.

ABSTRACT. We compared and analyzed expression of the BPI gene of Sutai piglets ranging from newborn to post-weaning days 8, 18, 30, and 35 by the real-time PCR method, in order to determine if it is involved in protection against disease caused by ETEC F18. There was a significant difference between 18-and 35-day expression in the jejunum. There were also significant differences between 35-day expression and expression at the other development stages in the duodenum. There were no significant differences in expression at 8, 18, and 30 days in the jejunum. We conclude that the porcine BPI gene may be the direct factor that caused resistance to ETEC F18 in weaning piglets, and that the resistance to ETEC F18 in weaning piglets is related to upregulation of mRNA expression of the BPI gene to a certain extent.

ABSTRACT. TLR4 is the main recognition receptor of bacterial lipopolysaccharides, which play an important role in innate and adaptive immunity. We used real-time PCR to analyze the tissue expression profile and differential expression of TLR4 in 4 pig populations (Escherichia coli F18-resistant Sutai, E. coli F18-sensitive Sutai, Large White, Meishan), in order to determine the role that the TLR4 gene plays in resistance to E. coli F18. We found that TLR4 expressed consistently in the 4 populations, with relatively high levels in immune tissues and the highest level in the lung. Generally, the expression of TLR4 in E. coli F18-sensitive individuals was the highest, followed by that in E. coli F18-resistant, Large White and Meishan. In the spleen, lung, kidney, lymph nodes, and thymus gland, TLR4 expression is significantly higher in the E. coli F18-sensitive than in the other 3 populations; there were no significant differences among E. coli F18-resistant Sutai, Large White, and Meishan. In addition, Gene Ontology and pathway analysis showed that TLR4 takes part in the inflammatory response. We found that porcine TLR4 has consistent tissue specificity in each breed, and downregulation of expression of the TLR4 gene is related to resistance to E. coli F18 in weaning piglets.