Vaccination with a novel quadrivalent fusion protein protects chickens against necrotic enteritis lesions caused by Clostridium perfringens

Necrotic enteritis (NE), caused by Clostridium perfringens, is a debilitating disease that results in significant production losses in the poultry industry. Traditionally, antibiotics have been used to control NE in flocks; however, due to concerns about the potential for selection of antibiotic resistance, antibiotic residues in meat, and restrictions on antibiotic use in some regions, alternative methods to control this disease are needed. In previous studies, proteins such as NetB, the key virulence factor, and alpha toxin have been used individually as subunit vaccines, but only partial protection was induced. It appears that a single subunit antigen is insufficient to produce high levels of protection. Here, an experimental vaccine, incorporating fragments from four antigens, was designed and tested. To simplify the production and delivery of multiple recombinant antigens, a novel quadrivalent (QV) fusion protein was designed. The QV-protein vaccine and each of the individual proteins were tested as vaccine candidates in a necrotic enteritis challenge model. The birds were vaccinated subcutaneously twice and then challenged with a pathogenic strain of C. perfringens. The development of necrotic lesions was scored, and serum IgY antibody responses were assessed. Compared with unvaccinated birds, birds vaccinated with QV-protein had significantly lower lesion scores (p < 0.05). Western blot and ELISA analyses demonstrated that vaccination with the QV-protein induced antibodies specific for all four target protein fragments within the QV-protein. In conclusion, the QV-protein provides the basis for ongoing NE vaccine development.