The Eimeria tenella genome project at The Sanger Institute, a joint collaboration with Drs. Martin Shirley and Fiona Tomley (Institute of Animal Health, Compton, UK), has been funded by the BBSRC.
The Sanger-based project is part of the Eimeria Genome Consortium.
Brief overview
Coccidiosis, caused by species of intracellular protozoan parasites belonging to the genus Eimeria (phylum Apicomplexa), remains one of the economically most important diseases in modern poultry production. The disease is caused by the replication within the intestine of the asexual and/or sexual stages of seven species of Eimeria (usually several species occur concurrently) and although clinical disease in intensively reared poultry is now relatively uncommon, sub clinical infections are the norm. The total cost of coccidial infections in the UK (circa 780 million broilers) has been estimated to be at least 42 million pounds per year in the UK, with a global cost estimated in the hundreds of millions. At least a quarter of this cost derives from prophylatics and therapy, the remainder attributable to "failure to thrive".
The genome
The Houghton strain of Eimeria tenella was been selected by the research community for the genome project. The genome is approximately 60 MB in size, with a GC content of approximately 53%. There are 14 chromosomes that range in size from 1Mb to > 6Mb. Two major ribosomal DNA clusters, that account for some 2.5% of the genome size, have been mapped as tandem arrays on chromosome 12 (140 copies of an 8 Kb 18S-5.8S-28S unit) and chromosome 10 (500 copies of a 730bp 5S unit).
Data access
A >8x coverage of the genome has been produced by whole genome shotgun
sequencing plus about 25,000 re-sequencing reads from selected clones.
Sequence reads and assemblies are available on the Sanger
Institute Eimeria ftp site and sequence similarity search
facilities via a dedicated
blast server.
Preliminary bioinformatic analyses are being
performed; gene predictions, and their associated annotation, are
made publically available via the GeneDB database.
Related projects
Eimeria maxima sequencing
In collaboration with Dr. Damer Blake at the Institute of Animal Health, a 136kb BAC (EMAX7A2) from the related parasite E. maxima has been sequenced and finished (barring a repetitive region from base position 9,131-17,752). The consensus sequence is available for download from the Sanger Institute E.maxima ftp site.
E. tenella EST projects at WTSI
A number of E. tenella EST libraries have been sequenced. Data will be available for download from here shortly.
Other Eimeria projects
- ~28.5k EST sequences, mostly generated at Wash U
- a genetic linkage map
- ~30k Eimeria spp. ORESTES sequences at USP, Brasil
