Evaluation of the efficacy of the antimicrobial peptide HJH-3 in chickens infected with Salmonella Pullorum

Abstract

As a promising substitute for antibiotics, increasing attention has been given to the clinical application of antimicrobial peptides (AMPs). In this study, the mode of action of the HJH-3 against Salmonella Pullorum was investigated. The structure and properties of HJH-3 were examined in silico, and minimum inhibitory concentrations (MICs) were determined to evaluate its antimicrobial spectrum. The time-kill kinetics of HJH-3 was determined. The hemolytic activity of HJH-3 was determined by measuring the hemoglobin ultraviolet absorption value, and the cytotoxicity was determined using a CCK-8 kit. The protective effect of HJH-3 on chickens infected with S. Pullorum was evaluated in vivo. The results demonstrated that HJH-3 exhibited strong antibacterial activity against Gram-negative pathogens at MIC values of 1.5625–25 μg/mL and against Gram-positive pathogens at MIC values of 25–50 μg/mL. HJH-3 also showed activity against the Candida albicans (100 μg/mL) and Bacillus subtilis (6.25–12.5 μg/mL). HJH-3 at 100 μg/mL completely killed S. Pullorum after co-incubation for 6 h. Likewise, the hemolysis rate of CRBCs treated with 100 μg/mL HJH-3 (7.31%) was lower than that of CRBCs treated with 100 μg/mL pexiganan (40.43%). Although the hemolysis rate of CRBCs treated with 400 μg/mL HJH-3 was increased to 13.37%, it was much lower than that of 400 μg/mL pexiganan (57.27%). In regards to cytotoxicity, HJH-3 had almost no-effect on the CEF proliferation, pexiganan decreased CEFs proliferation from 56.93 to 31.00% when increasing the concentration from 50 to 200 μg/mL. In a chicken infection model, the results showed that the antibiotic prevention and HJH-3 prevention groups exhibited the best treatment effect, with the chickens being protected from the lethal dose of S. Pullorum, a decreased number of bacteria in the blood and spleen, and less pathological changes in intestinal segments. The prevention of infection by HJH-3 was similar to that by Ampicillin; the effect of treatment after infection was lower than that of treatment before infection, and the survival rate of infected chicks treated with HJH-3 was 70%, which was still higher than that of the infected chickens. These results suggest that HJH-3 has good clinical application potential and can be used as a substitute for antibiotics for the prevention and treatment of S. Pullorum infection.

Bithionol Restores Sensitivity of Multidrug-Resistant Gram-Negative Bacteria to Colistin with Antimicrobial and Anti-biofilm Effects

“…To evaluate the application security of BT, we tested the toxic effects of BT on the RAW 264.7 cells by using the CCK-8 method . Based on the results of the checkerboard assays, DMSO was used as the control group, while different concentrations of BT and BT/COL combinations were used as the experimental group.…”

Gallnut tannic acid alleviates gut damage induced by Salmonella pullorum in broilers by enhancing barrier function and modulating microbiota

“…The composition of intestinal flora is closely linked to the function of the intestinal barrier and plays a crucial role in the host's defense against pathogenic microorganisms and energy provision ( 45 , 46 ). Previous studies have indicated that S. pullorum invasion disrupts gut flora, although the exact effects remain to be elucidated ( 33 , 47 , 48 ). Our study confirms these findings, demonstrating a significant decrease in gut microbial diversity in chicks infected with S. pullorum .…”

Innate immune response of host cells infected with Salmonella

“…Subsequent analysis using flow cytometry demonstrated a significant increase in the mortality rate of Salmonella pullorum following exposure to the antimicrobial peptide HJH-3 [24]. Notably, after 6 hours of co-culture with the Salmonella pullorum, a concentration of 100 μg/mL of HJH-3 proved sufficient to entirely eradicate the strain [25]. AMPs have broad-spectrum antibacterial activity, and using artificially extracted maggot AMPs has shown antibacterial activity against various bacteria.…”