Alpha-toxin a ‘primary player’
Dr. Scott: Classic virulence
In a discussion on the mechanisms of
protection conferred by the Clostridium
perfringens type A toxoid vaccine,
Broussard confirmed that there is more
to be discovered about why and how the
vaccine triggers immunity.
Dr. John F. Prescott, University of Guelph, Ontario, who gave a presentation on NE and alpha-toxin during another session at the poultry conference (see
article, page 10), expressed surprise that Australian researchers, whose work was widely publicized, were able to induce
NE using C. perfringens that lacked the alpha-toxin gene.
“When we vaccinate with just alpha-
toxoid — not just secreted protein —
we can get excellent protection, so the alpha-toxin has to be involved,”
he reported.
Dr. Joan Schrader, the Intervet/
Schering-Plough Animal Health researcher involved in the development
of the C. perfringens type A toxoid
vaccine, said she had no difficulty “giving other proteins their due,” but emphasized that she and many other researchers
had identified alpha-toxin as a primary player. “I think C. perfringens type A
toxoid vaccine is efficacious because of that,” she added.
Prescott reminded the audience that alpha-toxin is “the classic clostridial
toxin — the First World War gas
gangrene toxin. It’s how C. perfringens
is recognized.”
A lot of secreted proteins have been
discovered that are virulence-associated, but “certainly alpha-toxin is the classic
virulence factor of C. perfringens,”
he added.
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