Expression pattern of porcine antimicrobial peptide PR-39 and its induction by enterotoxigenic Escherichia coli (ETEC) F4ac

PR-39 is a gene-encoded, proline-arginine-rich porcine antimicrobial peptide with multiple biological functions. In the current study, the tissue-specific mRNA expression of PR-39 was investigated in Chinese Jinhua pigs, and the effect of enterotoxigenic Escherichia coli (ETEC) expressing F4ac (K88ac) fimbriae challenge on the mRNA expression of PR-39 in various tissues was compared between Jinhua and Landrace pigs. The three most stable expressed housekeeping genes were validated before evaluating PR-39 expression. PR-39 mRNA was predominantly expressed in the bone marrow compared with the spleen, thymus, MLN, liver and ileum. The ETEC F4ac challenge could up-regulate PR-39 mRNA expression in both Jinhua and Landrace pigs, but the changes were different between the two breeds. Jinhua pigs responded more strongly to ETEC F4ac challenge than did Landrace pigs, because the interaction between the breed and challenge significantly impact PR-39 mRNA in the thymus, liver and ileum. The PR-39 mRNA expression levels of challenged Jinhua pigs were significantly higher in the spleen, thymus, liver, ileum and MLN compared with challenged Landrace pigs. These differences in the mRNA expression of PR-39 could be a result of genetic differences in the resistance to ETEC F4ac infection between the two breeds, but this speculation requires further investigation.