For 70% of these genes, we could identify

clear orthologs in other organisms, whereas the remaining 30% are most probably Echinococcus- or cestode-specific genes or gene families. Mostly for comparative studies with the Echinococcus multilocularis reference genome, NGS has very recently also been used for a first characterization of the genome of E. granulosus. This project is being carried out by the parasite genomics group of the WTSI led by Matt Berriman in collaboration with Cecilia Fernandez (University of Montevideo). Because of its importance in human infections, the G1 (sheep) strain was chosen for sequencing and, like in the case of E. multilocularis, protoscoleces after treatment

with low pH/pepsin were used Gefitinib supplier as a source for genomic DNA to minimize host contamination (C. Fernandez, pers. comm.). After a first round of Illumina sequencing, SB203580 ic50 the genome has been assembled into 5200 contigs that, using the E. multilocularis genome as a reference framework, have been further assembled into ∼2000 scaffolds that are available via http://www.sanger.ac.uk/resources/downloads/helminths/echinococcus-granulosus.html. As expected, the genomes of E. granulosus and E. multilocularis are highly homologous with overall 96% identity at the nucleotide sequence level within the coding regions of predicted genes, and still around 91% identity in promoter regions. Because the E. granulosus

contigs have been assembled into supercontigs using E. multilocularis as a reference, no valid conclusions concerning genomic rearrangements between the species can been made at present. Direct comparisons of longer contigs of the E. granulosus genome assembly with the E. multilocularis sequence, however, indicate that there is also a high level of synteny between both species. Differences Phosphatidylinositol diacylglycerol-lyase in gene structure and sequence can mostly be observed in the case of expanded gene families, such as the recently described hsp70 family (42) that contains a significant number of pseudogenes. The E. granulosus genome assembly is currently awaiting additional Illumina data, and thus, substantial improvement is expected soon. A third important project on a taeniid cestode addresses the whole genome of T. solium (43) and is being carried out by a Mexican consortium directed by Juan-Pedro Laclette (http://bioinformatica.biomedicas.unam.mx/taenia/) located at the Universidad National Autonoma de Mexico. As in the case of the E. multilocularis genome, this project has followed a hybrid strategy in which classical capillary sequencing of cloned genome fragments has been combined with NGS. In a first phase of the project, ∼20 000 ESTs from adult worms and cysticerci were generated, followed by estimation of the parasite’s genome size.