Immunization with a subunit of housekeeping proteins provide partial protection against experimental necrotic enteritis in broiler chickens

Abstract

Abstract Necrotic enteritis (NE) due to Clostridium perfringens (CP) infections is a prevalent enteric infectious disease accounting for $6 billion economical loss in global poultry industry. The increasing incidence of NE has been associated with the reduction and withdrawal of antibiotic growth promoters from animal feed during recent years. Therefore, the development of effective vaccines specific for NE assumes a priority for poultry industry. By far, no any effective vaccines are commercially available in broiler chickens. Our aim was to identify the potential CP proteins as vaccine targets for NE. We expressed 4 different recombinant CP proteins targeting 6 antigens: 3 major virulence-related toxins (alpha-toxin, NetB and TpeL), and 3 pilus subunit or enzymes (Collagen adhesion protein (Cna), Fructose-1,6-bisphosphate aldolase (FBA) and a Hypothetic protein (HP)), and their protection efficacies were evaluated with a severe Coccidiosis/NE challenge model using netB+tpeL+ CP strain. Young chicks were immunized twice subcutaneously with adjuvanted CP proteins on days 4, and 15. Prior to challenge, the chickens immunized with related antigens had much higher serum antibody titers for Cna and FBA/HP antigens than those with any of 3 toxin antigen-immunized groups. Following the challenge, the Cna-immunized group showed the least mortality and lowest lesion score among the individual antigen-vaccinated groups, while the pooled antigens-immunized group demonstrated no mortality against virulent challenges. The results indicate that the immunization with CP housekeeping protein, Cna, conferred better protection than other conventional virulence-related toxin proteins. Mucosal delivery system is being investigated next.