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United States Department of Agriculture

Agricultural Research Service

Title: Analysis of Eimeria Tenella Expressed Sequence Tags Enriched for Genes Expression by Oocysts Using Subtractive Hybridization.

Authors
item Miska, Kate
item Fetterer, Raymond
item Barfield, Ruth

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 12, 2004
Publication Date: June 3, 2004
Citation: Miska, K.B., Fetterer, R.H., Barfield, R.C. 2004. Analysis of Eimeria tenella expressed sequence tags enriched for genes expression by oocysts using subtractive hybridization. Journal of Parasitology. 90:1245-1252.

Interpretive Summary: Eimeria tenella is one of several species of coccidia that infect poultry causing intestinal infections (coccidiosis) resulting in significant economic losses to the poultry industry worldwide. While the life cycle of this parasite is well described, little is known about the genetic mechanisms that control its progression. This research concentrates on two stages of the E. tenella life-cycle: the unsporulated and sporulated oocysts. The aim of this study was to determine which genes are expressed by sporulated and unsporulated oocysts, and to determine whether these genes are also expressed by sporozoites and/or merozoites (which are the intracellular stages of the parasite). Studying gene expression is very important since it enables us to determine which genes are important for parasite development and survival. We evaluated 499 DNA sequences representing genes expressed by either unsporulated or sporulated oocysts. Of these, 224 sequences were isolated from sporulated oocysts and 275 from unsporulated oocysts. When compared with each other for areas of overlap, 163 non-redundant sequences were found. 35.6 % of the non-redundant sequences encode known proteins, while 64.4% encode unknown proteins. 11 non-redundant sequences were isolated from both sporulated and unsporulated oocysts, while 95 were isolated only from sporulated oocysts and 57 from only sporulated oocysts. 53.7% of non-redundant sequences isolated from sporulated oocysts and 79.0% of sequences isolated from unsporulated oocysts represented genes that may not be expressed by sporozoites or merozoites. This indicates that approximately half the genes expressed by sporulated oocysts are also expressed by sporozoites and/or merozoites, however most of genes expressed by unsporulated oocysts are not expressed by either sporozoites or merozoites.

Technical Abstract: Eimeria tenella is one of several species of coccidia that infect poultry causing avian coccidiosis, resulting in significant economic losses to the poultry industry. To study gene expression during E. tenella oocyst development 499 expressed sequence tags (ESTs) were isolated and sequenced from cDNA enriched for transcripts expressed by unsporulated or sporulated oocysts. Of these, 224 clones were isolated from cDNA of sporulated oocysts and 275 from unsporulated oocysts. When compared with each other 163 non-redundant sequences were found, and 35.6 % of these share significant homology to proteins in Genbank, while 64.4% represent novel genes. Eleven of the non-redundant sequences were isolated from cDNA of both sporulated and unsporulated oocysts, while 95 were isolated only from sporulated oocysts and 57 from sporulated oocysts. 53.7% of non-redundant sequences isolated from sporulated oocysts and 79% of the sequences isolated from unsporulated oocysts represented transcripts not previously isolated from sporozoites or merozoites. These values indicate that approximately half of genes expressed by sporulated oocysts are also expressed by sporozoites and/or merozoites however gene expression profiles of unsporulated oocysts differ highly from expression profiles of sporozoites and merozoites.

Last Modified: 4/23/2014