Immunization with novel vaccine candidate recombinant antigens from virulent Clostridium perfringens field strains confers partial protection against necrotic enteritis in broiler chickens

Necrotic enteritis (NE) is one of the top enteric infectious diseases in commercial broiler chickens that is caused primarily by Clostridium perfringens (CP) A/G strains and responsible for around $6 billion economical loss worldwide.  Coccidiosis is the major predisposing factor for NE. With gradual reduction and eventual withdrawal of antibiotic growth promoters from animal feed due to public and regulatory pressures, alternatives to antibiotic approaches assume top- priority for global poultry industry. Vaccination should be an ideal approach for mass prevention. However, there is no effective vaccine commercially available for NE. In this study, the recombinant proteins: chimeric NetB and alpha-toxin (NA), chimeric Fructose-1,6-bisphosphate aldolase and a hypothetic protein (FBA/HP), truncated TpeL, and Collage adhesion protein (Cna) were evaluated for their vaccine efficacy against severe NE challenge with netB+tpeL+ CP strain using two different NE challenge models which were developed at ARS. Young broiler chicks were immunized twice subcutaneously with adjuvanted CP proteins on days 4, and 15 and various disease parameters were evaluated. Optimum protection was seen when CP proteins mixed with MONTANIDE™ ISA 71 VG (Seppic Inc., France) were given twice intramuscularly using a dual infection NE model (E. maxima/CP) and a CP alone NE model. Immunization with all pooled antigens provided better protection against virulent challenges in both models.  Immunization with these immunogens merits further investigation in the future, especially in mucosal delivery route.  
 
Keywords: Necrotic enteritis, vaccine, Clostridium perfringens, ii recombinant proteins.