Controlling the Colonization of Clostridium perfringens in Broiler Chickens by an Electron-Beam-Killed Vaccine

SIMPLE SUMMARY: Clostridium perfringens (Cp) is a bacterium that causes necrotic enteritis in chickens and is responsible for an economic loss of about 6 billion U.S. dollars in the poultry industry worldwide. Consumption of Cp contaminated chicken meat causes foodborne illnesses in humans. Although Cp can be controlled in chickens by administering antibiotics through feed and water, the ban on the antibiotics owing to concerns on antibiotic resistance has created the need to identify alternative control approaches. As vaccination could be used as an alternative, we used electron beam irradiation (eBeam) to kill the bacterium and use the killed cells as vaccine to control the colonization of Cp in broiler chickens. In this study, we exposed three different strains of Cp to eBeam irradiation and used them as a vaccine to day-18 embryos. After the embryos hatched, the birds in each treatment were segregated into two groups for live Cp challenge at two time points. The results indicate that the vaccine effectively controlled the colonization of all three strains of Cp when challenged with live Cp, indicating that the vaccinated birds had acquired immunity. The current approach can reduce Cp colonization in chickens, thereby reducing economic loss. ABSTRACT: Clostridium perfringens (Cp) is a Gram-positive anaerobe that is one of the causative agents of necrotic enteritis (NE) in chickens, which leads to high mortality. Owing to the ban of administering antibiotics in feed to chickens, there has been an increase in the number of NE outbreaks all over the world, and the estimated loss is approximately 6 billion U.S. dollars. The best alternative method to control NE without antibiotics could be vaccination. In this study, we exposed three different strains of Cp to electron beam (eBeam) irradiation to inactivate them and then used them as a killed vaccine to control the colonization of Cp in broiler chickens. The vaccine was delivered to 18-day old embryos in ovo and the chickens were challenged with the respective vaccine strain at two different time points (early and late) to test the protective efficacy of the vaccine. The results indicate that an effective eBeam dose of 10 kGy inactivated all three strains of Cp, did not affect the cell membrane or epitopes, induced significant levels of IgY in the vaccinated birds, and further reduced the colonization of Cp strains significantly (p < 0.0001) in late challenge (JGS4064: 4 out of 10; JGS1473: 0 out of 10; JGS4104: 3 out of 10). Further studies are necessary to enhance the efficacy of the vaccine and to understand the mechanism of vaccine protection.