The successful experimental induction of necrotic enteritis in chickens by Clostridium perfringens: a critical review

Abstract

Necrotic enteritis (NE) is one of the most important enteric diseases in poultry and is a high cost to the industry worldwide. It is caused by avian-specific, Necrotic Enteritis Beta toxin (NetB)-producing, strains of Clostridium perfringens that also possess in common other virulence-associated genes. In Europe the disease incidence has increased since the ban on in-feed “growth promoting” antibiotics. Because of this, many recent studies of NE have focused on finding different ways to control the disease, and on understanding its pathogenesis. Frustratingly, reproduction of the disease has proven impossible for some researchers. This review describes and discusses factors known to be important in reproducing the disease experimentally, as well as other considerations in reproducing the disease. The critical bacterial factor is the use of virulent, netB-positive, strains; virulence can be enhanced by using tpeL- positive strains and by the use of young rather than old broth cultures to increase toxin expression. Intestinal damaging factors, notably the use of concurrent or preceding coccidial infection, or administration of coccidial vaccines, combined with netB-positive C. perfringens administration, can also be used to induce NE. Nutritional factors, particularly feeding high percentage of cereals containing non-starch polysaccharides (NSP) (wheat, rye, and barley) enhance disease by increasing digesta viscosity, mucus production and bacterial growth. Animal proteins, especially fish meal, enhance C. perfringens proliferation and toxin production. Other factors are discussed that may affect outcome but for which evidence of their importance is lacking. The review compares the different challenge approaches; depending on the aim of particular studies, the different critical factors can be adjusted to affect the severity of the lesions induced. A standardized scoring system is proposed for international adoption based on gross rather than histopathological lesions; if universally adopted this will allow better comparison between studies done by different researchers. Also a scoring system is provided to assist decisions on humane euthanasia of sick birds.

Progress and problems in vaccination against necrotic enteritis in broiler chickens

“…It is observed that the severity of the challenge, the infection model, feed and housing conditions of the birds, the strain used for infection, and many more factors affect the protection conferred by a vaccine that is under development. In this regard, a universal infection model that can be used to test the efficacy of vaccines could be of value, as suggested by Shojadoost et al (2012), but this will be difficult to establish. The ideal vaccine strain would be one that, apart from inducing immunity and protection, can be added to the feed or drinking water, or sprayed on the 1-day- CFU, colony-forming units; DEAE-dextran, diethylaminoethanol; EF-Tu, elongation factor Tu; GDP, glyceraldehyde-3-phosphate dehydrogenase; i.m., intramuscular; rPLC, recombinant alpha toxin C-terminal domain-encoding sequence; s.c., subcutaneous; TCP, total combining power; tPFOR, truncated pyruvate:ferredoxin oxidoreductase.…”

The CpAL Quorum Sensing System Regulates Production of Hemolysins CPA and PFO To Build Clostridium perfringens Biofilms

“…A similar EN disease produced by type A and type C strains affects chickens and other domestic birds. Chicken EN globally costs the poultry industry $2 billion per year (35).…”

Pathologic Study on the Enterohepatic Affections in Chickens at Alexandria Province, Egypt

“…Such epithelial damage is permitting the infection by Clostridium perfringens to replicate and produce toxin. Moreover, plasma proteins in the lumen of the gut escaped during coccidiosis are considered favorable nutrient substrates for Clostridium perfringens proliferation and production of toxins (Shojadoost et al, 2012). Finally, it could be concluded that colibacillosis is the most prevalent disease affect different chicken breeds at Alexandria province.…”