Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2007
Publication Date: 4/1/2008
Citation: Miska, K.B., Fetterer, R.H., Rosenberg, G.H. 2008. Analysis of transcripts expressed by intracellular stages of Eimeria acervulina using expressed sequence tags (ESTs). Journal of Parasitology. 94:462-466. Interpretive Summary: Eimeria acervulina is one of several species of coccidia that infect poultry causing intestinal infections (coccidiosis) resulting in significant economic losses to the poultry industry worldwide. Although E. acervulina is present in abundance in poultry facilities and is responsible for clinical outbreaks of coccidiosis there is very little molecular data concerning this parasite. This research concentrates on determining which genes are expressed by the intracellular stages of this parasite. The intracellular stages are responsible for much of the symptoms of coccidiosis therefore it is important that these are studies in multiple species of Eimeria. Over 2000 DNA sequences representing genes expressed by either merozoites or schizonts were analyzed. Of these, 1,026 represent unique sequences. Approximately half the sequences represent genes that code for unknown proteins. Additionally, it is apparent that genes expressed by E. acervulina merozoites are very different than those expressed by similar stages of E. tenella. For example, genes that encode proteins that are important in parasite invasion, called microneme proteins, are highly expressed in E. tenella however, only 2 sequences encoding these proteins were found in E. acervulina. This study represents the first comparative analysis of genes expressed by two species of chicken coccidia, revealing that at the molecular level these species may be very different. This may have an impact on future strategies in designing coccidiosis control
Technical Abstract: Coccidiosis in chickens is caused by seven species belonging to the genus Eimeria. Even though coccidiosis is a complex disease that can be caused by any combination of these species most of the molecular research concerning chicken Eimeria has been limited to Eimeria tenella. This study describes the first large-scale analysis of ESTs generated from second stage merozoites and schizonts of E. acervulina. Over 2000 ESTs were sequenced and these represent 1,026 unique sequences. About half of the ESTs encode proteins of unknown function or hypothetical proteins. Surprisingly, only 30% of the E. cervulina ESTs share significant sequence identity with sequences in the E. tenella genome. Additionally, expression profiles appear to be much different compared to those of E. tenella. One of the differences is the very low number of transcripts that encode putative microneme proteins. This study underlines the differences in the molecular aspects of two Eimeria species that in the past have thought to be highly similar in nature.