Intracloacal Inoculation of Broiler Chickens with Clostridium perfringens Strains: Evaluation of Necrotic Enteritis Disease Development and Lymphoid Immune Responses

Necrotic enteritis (NE) is an economically important disease of chickens. We have recently shown that inflammatory responses in chickens inoculated orally with virulent Clostridium perfringens were spatially regulated. Here, we used previously virulence-characterized netB(+) C. perfringens strains, avirulent CP5 and virulent CP18 and CP26, to assess the severity of NE and immune responses in broiler chickens when inoculated intracloacally. The results showed that CP18- and CP26-infected birds had a reduced weight gain and developed milder/less severe NE lesions, as determined by the gross lesions scores, suggesting a subclinical-grade infection. Gene expression analysis in infected birds revealed three statistically significant observations compared to uninfected-control: (1) Increased expression of anti-inflammatory/immunoregulatory interleukin (IL)-10/transforming growth factor (TGF)beta in cecal tonsil (CT) and bursa of Fabricius in the CP18/CP26-infected groups. (2) Increased CT transcription of pro-inflammatory IL-1 beta, IL-6 and interferon (IFN)gamma and decreased Harderian gland (HG) expression of IFN gamma in the CP18/CP26-infected birds. (3) Increased HG or bursal expression of IL-4 and IL-13 in CP5-infected birds. Collectively, intracloacal C. perfringens inoculation seems to induce a highly regulated inflammatory response in the CT and other mucosal lymphoid organs and an intracloacal infection model may be useful in evaluating immune responses in chickens with subclinical NE.

Automated summary

Necrotic enteritis (NE) is a significant disease of chickens, causing economic losses. In this study, chickens were inoculated intracloacally with different strains of C. perfringens to evaluate the severity of NE and immune responses. The results showed that chickens infected with CP18 and CP26 had reduced weight gain and milder NE lesions. Gene expression analysis revealed increased expression of anti-inflammatory/immunoregulatory factors in certain lymphoid organs, suggesting a highly regulated immune response.