Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 1996
Publication Date: N/A
Interpretive Summary: Coccidiosis is an intestinal disease causd by several species of Eimeria. Infection of chicken coccidia causes significant economic loss due to mortality, morbidity and nutrient malabsorption. Development of an immunological control strategy requires comprehensive understanding of protective host immune responses. In this paper ARS scientists report that a factor produced by macrophages is responsible for weight loss following coccidiosis. Identification of immunological events responsible for intestinal damage should help lead to the development of effective control strategy for coccidiosis.
The effect of tumor necrosis-like factor (TNLF) on the pathogenesis of coccidiosis was investigated. Injection of crude chicken TNLF enhanced the weight loss caused by Eimeria tenella infection. Rabbit polyclonal antibody against recombinant human tumor necrosis factor-a (rhTNF) partially restored E. tenella-induced weight loss in SC chickens, but not in TK chickens. However, injection of chickens with chicken TNLF, rhTNF, and rabbit serum against rhTNF had no significant effect on cecal lesion. Both SC and TK chickens produced circulating TNLF following primary, but not secondary infection, and SC chickens showed higher level of TNLF production than TK chickens. Peripheral blood leukocyte-derived macrophages from SC and TK chickens produced significant amount of TNLF comapred to preinfection condition when co-cultered with sporozoites. In general, macrophages from SC chickens produced higher levels of TNLF than from TK chickens. No significant difference was observed between primary and secondary infection. These results suggest that the excessive TNF production may be involved in weight loss caused by E. tenella infection in SC chickens.