Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 26, 1997
Publication Date: N/A
Interpretive Summary: Coccidiosis, an economically important disease of chickens, turkeys, and game birds, costs the U.S. poultry industry approximately $300 million annually. The primary means of control of the disease, anticoccidial drugs, are becoming less effective than before as the parasites show increasing resistance to the drugs. As a result, alternative measures against coccidiosis, including immunological and biological control, are gaining in importance. One strategy for controlling coccidiosis by biological means is to prevent invasion of the host bird by the coccidia, thereby preventing subsequent disease. Each species of coccidia invades only a limited, defined area of the intestine, suggesting that specific characteristics of the cells in each area regulate cellular invasion. The current study showed that these factors are different for turkeys and chickens. Growth medium from cultures of intestinal cells (containing cell metabolic products) of both chickens and turkeys cells enhanced invasion by turkey coccidia but not by chicken coccidia. Examination of this phenomenon should allow clarification of cellular invasion at the molecular level. An understanding of the mechanisms of invasion will provide the basis for the development of strategies to markedly reduce parasite without lowering the productivity of the host bird.
Cells from different areas of the intestines of turkeys and chickens were cultured in vitro. Media, conditioned by the growth of these cells was tested for the ability to influence invasion of baby hamster kidney cells by sporozoites of the avian coccidia. Conditioned medium from cultures of both turkey cecal cells and yolk stalk diverticulum cells significantly enhanced invasion by the turkey cecal and mid-intestine coccidia, Eimeria adenoeides and E. meleagrimitis, respectively, as compared with invasion in the presence of control medium. The enhancement (2.1-2.4 fold) occurred with conditioned media from early (1) as well as later (11) passages of cells. Additionally, conditioned media from cultures of chicken cecal and duodenal loop cell cultures significantly enhanced invasion by E. adenoeides, the turkey cecal coccidium, but to a lesser degree (1.6--1.7 fold) than the turkey cell conditioned media. However, neither the chicken ncecal cell medium nor conditioned media from any other chicken intestinal cell cultures enhanced invasion by E. tenella, the chicken cecal coccidium. Apparently, under these experimental conditions, the conditioned media influenced invasion by the turkey coccidia to a greater extent than the chicken coccidia. Although morphologically dissimilar when first plated, the gross appearance and growth of the turkey and chicken cells when conditioned media was collected was comparable.