About 70% of all antibiotics produced in the world are used in the farm animal industry. The massive usage of antibiotics during farm animal production has caused rapid development of antibiotic resistance in bacteria, which poses a serious risk to human and livestock health when treating bacterial infections. Protegrin-1 (PG-1) is a potent antimicrobial peptide (AMP), initially identified in pig leukocytes with a broad-spectrum antibacterial and antiviral activity, and a low rate of inducing bacterial resistance.
To develop genetic approaches for reducing the use of antibiotics in farm animal production, we produced transgenic mice carrying a bovine tracheal AMP gene promoter-controlled PG-1 transgene. The PG-1 transgene was specifically expressed in the respiratory tract of transgenic mice upon induction by bacterial infection. These PG-1 transgenic mice exhibited enhanced resistance to nasal bacterial infection as the infected transgenic mice showed a higher survival rate, lower bacterial load and milder histological severity than the infected wild-type control littermates.
The present study provides a promising genetic strategy to prevent airway bacterial infections in animals by bacteria-inducible tissue-specific expression of PG-1 transgene, an approach which may also be helpful for reducing the possibility of inducing bacterial resistance.