Genome sequence of the avian coccidiosis-causing agent, Eimeria tenella

Bart Barrell1, Matt Berriman1, Arthur Gruber2, Al Ivens1, Marie-Adèle Rajandream1, Pierre Rivailler3, Martin Shirley3, Fiona Tomley3.
1Wellcome Trust Sanger Institute, Genome Campus, Hinxton, CB10 1SA, UK
2 University of Sao Paulo, Faculty of Vet.Medicine and Zootechny, Av. Prof. Orlando Marques de Paiva 87, Sao Paulo - SP - Brazil - 05508-000
3 Institute for Animal Health, Compton, Newbury, Berkshire, RG20 7NN, UK

Eimeria spp are major pathogens of intensely reared livestock. Drug resistance in the parasite is increasing and no new drugs have been introduced for more than 10 years. Live vaccination is effective but difficult to implement due to the large number of chicken required in the manufacture. Recombinant vaccines are desirable but their discovery will be preceded by a detailed molecular knowledge of the parasite.

Against this backdrop, a project to sequence the entire genome of Eimeria tenella was started in 2002. Whole genome shotgun sequencing has produced contiguous sequences totalling 58 Mb in length. Predicting the genes is the next challenge. Although distantly related to other Apicomplexan parasites that have been subjected to genome sequencing, Eimeria is the most complex yet. The base composition of the genome is unusual and the gene structures are complex. Gene predictions can be browsed, searched or downloaded via the GeneDB database (http://www.genedb.org/Eimeria), allowing scientists working on Eimeria to quickly access genes of interest to their own research, such as enzymes, ligands, transporters or surface proteins. Detailed annotation of the genes will allow aspects of the organism’s biology to be reconstructed in silico, for instance to gain insights into pathways that would take years to characterise in vitro or in vivo.

The genome sequence provides a framework to underpin scientific research, not only accelerating hypothesis driven research but also generating hypotheses for further investigation.

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