Abstract
Necrotic enteritis is an economically important poultry disease caused by the bacterium Clostridium perfringens. There are currently no necrotic enteritis vaccines commercially available for use in broiler birds, the most important target population. Salmonella-vectored vaccines represent a convenient and effective option for controlling this disease. We used a single attenuated Salmonella vaccine strain, engineered to lyse within the host, to deliver up to three C. perfringens antigens. Two of the antigens were toxoids, based on C. perfringens α-toxin and NetB toxin. The third antigen was fructose-1,6-bisphosphate aldolase (Fba), a metabolic enzyme with an unknown role in virulence. Oral immunization with a single Salmonella vaccine strain producing either Fba, α-toxoid and NetB toxoid, or all three antigens, was immunogenic, inducing serum, cellular and mucosal responses against Salmonella and the vectored C. perfringens antigens. All three vaccine strains were partially protective against virulent C. perfringens challenge. The strains delivering Fba only or all three antigens provided the best protection. We also demonstrate that both toxins and Fba are present on the C. perfringens cell surface. The presence of Fba on the cell surface suggests that Fba may function as an adhesin.
Highlights
Keeping our food supply safe is one of many challenges facing the agriculture industry
Typhimurium vaccine strains required arabinose for growth and had similar growth characteristics in Luria Broth (LB) broth (0.1% arabinose, 0.1% mannose) (S1 Fig)
Fba is an enzyme of the Embden-Meyerhof-Parnas glycolytic pathway that converts D-fructose-1,6-bisphosphate into D-glyceraldehyde-3-phosphate and dihydroxyacetone phosphate [26]
Summary
Keeping our food supply safe is one of many challenges facing the agriculture industry. Maintenance of a healthy flock requires a multi-faceted strategy that includes good husbandry, strong biosecurity practices, proper feed formulation, vaccination, and veterinary care. One element of poultry rearing has been the inclusion of antibiotics in the feed to promote growth.
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