Evaluation of therapeutic efficacy of antimicrobial peptide JH-3 in Salmonella infection

Abstract:

[Objective] Salmonella is an important zoonotic pathogen and the main cause of gastrointestinal disease worldwide, causing about 21 million cases of typhoid fever in the world each year, poses a serious threat to the world public health. The current serious problem of antibiotic abuse urges to find a substitute for antibiotics. The antimicrobial peptide JH-3 gains broad-spectrum bactericidal activity after being separated and artificial transformed by our group. In this study, we studied the therapeutic efficacy of antimicrobial peptide JH-3 to treat Chinese multi-drug resistant Salmonella CVCC541 infection in a mouse model. [Methods] In the prevention group, BALB/c mice were continuously intraperitoneally injected with antimicrobial peptide JH-3 or ciprofloxacin (CPFX) for 3 days before (B3d, total 40 mg/kg) Salmonella CVCC541 infection; while the drugs were continuously intraperitoneally injected for 3 days after (P3d, total 40 mg/kg) Salmonella infection in the therapy group. [Results] The ciprofloxacin in prevention group showed the best preventive effect, antimicrobial peptide JH-3 (B3d) also showed effective prevention against Salmonella infection, significantly protected mice from the lethal doses of CVCC541 infection as survival rates was 100% in this group. The clinical score, pathological changes of small intestine and the bacterial burdens in spleen and in other organs were decreased to that of the ciprofloxacin prevention group, suggesting JH-3 has the similar preventive function with ciprofloxacin. The therapeutic effect of JH-3 was poor, though the clinical score, pathological changes of small intestine and the bacterial burden were significantly higher in JH-3 treatment group (P3d) when compared to JH-3 prevention group (B3d), the survival was 70%, which was significantly higher than that of the untreated infection group. [Conclusion] This study systematically evaluated the therapeutic effect of antimicrobial peptide JH-3 on Salmonella infection. Our results showed prophylactic administration of JH-3 gains the best antibacterial effect, which is equivalent to ciprofloxacin treatment, providing a reference for the research and development of novel antibiotics.