Vaccination of broilers with recombinant alpha-toxin protected broilers against an experimental challenge with Clostridium perfringens, suggesting that alpha-toxin plays a role in the pathogenesis of necrotic enteritis (NE).

In the study, broiler chicks were vaccinated subcutaneously with recombinant alpha-toxin at 5 and 15 days of age, then 10 days later were challenged with C. perfringens, the cause of necrotic enteritis. The challenge was administered twice daily for 4 consecutive days by mixing C. perfringens cultures with feed.

Non-vaccinated birds challenged with C. perfringens developed NE at the rate of 87.8%, but only 54.9% of vaccinated birds developed lesions. In addition, non-vaccinated birds had lesion scores averaging 2.37, compared to 1.35 in vaccinated birds, write K. K. Cooper and colleagues at the University of Arizona, Tucson, in the June 2008 issue of Veterinary Microbiology.

Vaccination also produced an antibody response — post-vaccination anti-alpha-toxin titers in vaccinated birds were more than 5-fold greater than in non-vaccinated birds. After challenge, vaccinated birds had average IgG (IgY) titers >15-fold higher compared to those of non-vaccinated birds, the investigators say.

NE in poultry has re-emerged as a concern for poultry producers due in part to the ban on in-feed antimicrobial growth promoters, but the results of this study, say the investigators, suggest that alpha-toxin may serve as an effective immunogen and, as such, may play a role in the pathogenesis of necrotic enteritis.

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