Experimental model for the reproduction of necrotic enteritis in turkeys using differentstrains.

Abstract

Necrotic enteritis (NE) is a disease affecting poultry caused by virulence factors, primarily toxins, produced by(Cp). Although NE is well documented in turkey flocks, only one study describes its pathogenesis suggesting a protocol for the induction of the disease. The aim of this study was to set up a challenge model for the experimental reproduction of NE in turkeys, in line with clinical signs currently observed in the field. To this purpose, the disease was induced based on the administration of some well-known predisposing factors for chicken (sudden switch to a high protein diet, coccidia) and challenging the birds with Cp strains with different genetic virulence factors isolated from chicken and turkey affected by NE. The predisposing factors were administered to three experimental groups (T02, T03, T04). In addition, groups T03 and T04 were challenged with Cp isolated from chicken or turkey, respectively. Group T01 served as the negative control. Clinical signs, gross pathology and histopathological lesions were scored and compared between groups. The challenge with the chicken Cp strain induced clinical manifestations of NE (80% mortality) and reproduced lesions both macroscopically and microscopically. In groups challenged with Cp, gross pathology revealed more severe lesions (&#x2009;<&#x2009;0.001) when compared to the group challenged with the predisposing factors only. Histopathologically, those findings were confirmed only in group T03 in the jejunum (&#x2009;<&#x2009;0.001). This experimental model will be useful to test the efficacy of control/preventive measures and to better understand the virulence factors involved in the pathogenesis of NE in turkeys.Not all(Cp) strains can reproduce severe necrotic enteritis (NE) in turkeys.The developed NE reproduction model caused 80% mortality.A reliable NE reproduction model is crucial to investigate pathogenic Cp strains.