US Study Suggests Alpha-toxin Plays Role in Cause of NE
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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