Effects of orally administering the antimicrobial peptide buforin II on small intestinal mucosal membrane integrity, the expression of tight junction proteins and protective factors in weaned piglets challenged by enterotoxigenic Escherichia coli

The antimicrobial peptide buforin II contains residues Thr16 to Lys36 of buforin I and exhibits antimicrobial activity that is twice as potent as that of its parent peptide. Buforin II was expressed in Pichia pastoris FZM2009 as a fusion peptide linked to porcine interferon-α and tested as an alternative to antimicrobial growth-promoters in pig production. Fifteen Landrace × Yorkshire barrows (5.55 ± 0.49 kg), weaned at 21 days of age, were challenged with three enterotoxigenic Escherichia coli strains. The animals were randomly divided into 3 groups with 5 barrows in each, fed a maize-soybean meal diet, and orally dosed with 5 mL sterile water (CON), 5 mL buforin II (BF; 0.05 mg/mL in sterile water), or 5 mL colistin sulphate (CS; 0.5 mg/mL in sterile water) twice daily for 21 days. Compared with CS and CON, oral administration of BF increased (P<0.05) daily weight gain, feed intake gain, and feed conversion. The expression of tight junction proteins and protective factors in the small intestine also increased in BF-treated piglets. Compared with the CON group, oral administration of BF and CS decreased (P<0.05) for the abundance of hemolytic E. coli in rectal swabs. Collectively, our results indicate that oral administration of buforin II protects small intestinal mucosal membrane integrity by increasing the abundance of tight junction proteins and enhancing the expression of protective factors, and can reduce hemolytic E. coli concentrations in the intestines of piglets.