Title

The importance of the strain of Clostridium perfringens in the development of necrotic enteritis of poultry

Date of Completion

January 2010

Keywords

Biology, Microbiology|Agriculture, Animal Pathology

Degree

Ph.D.

Abstract

Necrotic enteritis (NE) is an important economic disease of the poultry industry. Despite, being first described almost 50 years ago, the pathogenesis of NE is currently poorly understood. The present study describes a reproducible disease model for NE that was further developed and refined to investigate various factors that were thought to be important in the development of disease. Using the disease model, it was shown that under the conditions tested, factors such as co-infection with Eimeria species, genotype of chicken and the strain of C. perfringens were the most critical factors involved in disease development, while other factors such as age of chickens, contact with litter and protein content of the diet played a lesser role. ^ The importance of the strain of C. perfringens in the development of NE was further investigated, by examining the role of the recently discovered NetB toxin in the pathogenesis of NE. The work described here was the first demonstration that netB was present in C. perfringens isolates outside of Australia, and, could be found in healthy chickens and in other animal species (bovine). It also confirmed that the majority (58%) of chickens with NE, were caused by C. perfringens isolates that were netB positive. The ability of these strains to produce disease was evaluated in the NE model and it was determined that only strains that possess netB were capable of producing NE regardless of the source of the isolate. netB negative strains including those isolated from cases of NE were unable to produce NE in the disease model. ^ Finally, this work demonstrated for the first time, that C. perfringens strains, regardless of disease producing capability were capable of binding to extracellular matrix molecules (ECMM) and in some cases to Caco-2 cells. The finding that C. perfringens strains that are capable of producing severe disease in the NE model were also capable of binding to collagen type III, IV, fibrinogen, laminin and vitronectin better than less severe disease producing strains, suggests that the ability to adhere to ECMMs might be an important virulence factor for C. perfringens in producing NE. ^