Virulence of Clostridium perfringens in an experimental model of poultry necrotic enteritis

Department of Veterinary Science and Microbiology, University of Arizona, Tucson, AZ 85721, USA.
Veterinary Microbiology (Impact Factor: 2.73). 10/2009; 142(3-4):323-8. DOI: 10.1016/j.vetmic.2009.09.065
Source: PubMed

ABSTRACT Poultry necrotic enteritis (NE) has, over recent decades, been prevented and treated by addition of antimicrobials to poultry feed. Recent bans of antimicrobial growth promoters in feed, as well as other factors, have led to a slow, worldwide re-emergence of NE. Understanding of pathogenesis of NE has been hampered by lack of a consistent and effective experimental model in which virulence of strains can be reliably evaluated, with an endpoint yielding lesions comparable to those seen in acute NE in the field. The overall objective of this work was to develop an experimental approach that would allow consistent production of a full range of clinical signs and lesions of the disease, and to do so without use of coccidia as inciting agents. In addition, we assessed the virulence of strains of Clostridium perfringens from field cases of NE. Broiler chicks fed a commercial chick starter for 7 days post-hatch were switched to a high protein feed mixed 50:50 with fishmeal for an additional 7 days. On day 14, feed was withheld for 20 h, and birds were then offered feed mixed with C. perfringens (3 parts culture to 4 parts feed) twice daily on 4 consecutive days. On average, >75% of challenged birds developed typical gross lesions when inoculated with type A strains from field cases of NE. In addition, in vivo passage apparently increases strain virulence. Virulence varies from strain-to-strain; NetB-producing strains were virulent, as were some NetB non-producing strains.

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    ABSTRACT: NetB (necrotic enteritis toxin B) is a recently identified β-pore-forming toxin produced by Clostridium perfringens. This toxin has been shown to play a major role in avian necrotic enteritis. In recent years, a dramatic increase in necrotic enteritis has been observed, especially in countries where the use of antimicrobial growth promoters in animal feedstuffs has been banned. The aim of this work was to determine whether immunisation with a NetB toxoid would provide protection against necrotic enteritis. The immunisation of poultry with a formaldehyde NetB toxoid or with a NetB genetic toxoid (W262A) resulted in the induction of antibody responses against NetB and provided partial protection against disease.
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