Induction of maggot antimicrobial peptides and treatment effect in Salmonella pullorum-infected chickens

SUMMARY Antimicrobial peptides (AMP) are important components of the host innate immune response, as they exert broad-spectrum antimicrobial activities against pathogenic microbes. The AMP allow housefly larva (maggots) to live in harsh environments filled with pathogenic bacteria. In this study, maggot AMP were induced by incubation with inactivated Salmonella pullorum and crudely extracted. The concentration and antimicrobial activity of the maggot AMP were then measured. In bird experiments, chickens were artificially infected with S. pullorum, and the maggot AMP extracts were used to treat the infected chickens. The expression level of AMP was significantly enhanced by S. pullorum stimulation, and the antibiotic activity of the S. pullorum-induced AMP was significantly stronger than that of the noninduced AMP, especially against S. pullorum. In the bird experiments, based on survival rate, blood indicators, and intestinal bacterial changes, maggot AMP and antibiotics were successful in treating the S. pullorum-infected chickens. In conclusion, AMP have the potential for further development as a convenient, alternative antibiotic strategy to reduce the use of antibiotics and disease resistance.