Mucosal and systemic lymphoid immune responses against Clostridium perfringens strains with variable virulence in the production of necrotic enteritis in broiler chickens

ABSTRACT

Necrotic enteritis (NE), caused by Clostridium perfringens, is an economically important disease of chickens. Although NE pathogenesis is moderately well studied, the host immune responses against C. perfringens are poorly understood. The present study used an experimental NE model to characterize lymphoid immune responses in the caecal tonsils (CT), bursa of Fabricius, Harderian gland (HG) and spleen tissues of broiler chickens infected with four netB+ C. perfringens strains (CP1, CP5, CP18, and CP26), of which CP18 and CP26 strains also carried the tpeL gene. The gross and histopathological lesions in chickens revealed CP5 to be avirulent, while CP1, CP18, and CP26 strains were virulent with CP26 being “very virulent”. Gene expression analysis showed that, while the virulent strains induced a significantly upregulated expression of pro-inflammatory IL-1β gene in CT, the CP26-infected birds had significantly higher CT transcription of IFNγ and IL-6 pro-inflammatory genes compared to CP5-infected or uninfected chickens. Furthermore, CP26 infection also led to significantly increased bursal and HG expression of the anti-inflammatory/regulatory genes, IL-10 or TGFβ, compared to control, CP5 and CP1 groups. Additionally, the splenic pro- and anti-inflammatory transcriptional changes were observed only in the CP26-infected chickens. An antibody-mediated response, as characterized by increased IL-4 and/or IL-13 transcription and elevated IgM levels in birds infected with virulent strains, particularly in the CP26-infected group compared to uninfected controls, was also evident. Collectively, our findings suggest that lymphoid immune responses during NE in chickens are spatially regulated such that the inflammatory responses against C. perfringens depend on the virulence of the strain.

KEYWORDS:

• Necrotic enteritis
• Clostridium perfringens
• chickens
• immune response
• virulence
• cytokines
• pathogenesis

Acknowledgements

The authors immensely thank Dr. John F Prescott, University of Guelph, Canada, for reviewing the manuscript and providing useful edits and critical comments. We acknowledge Perdue Farms Kenly Hatchery for providing chicks and the Laboratory Animal Research facility at the North Carolina State University for their help during the conduct of this study. We also thank Taylor Boyett and Lauren Stokes for their help with the chicken trials of this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded in part by the U.S. Poultry and Egg Association Foundation.