The Echinococcus canadensis (G7) genome: a key knowledge of parasitic platyhelminth human diseases

MALDONADO, L.; ASSIS J.; GOMES ARAÚJO, FLAVIO; SALIM, A.; MACCHIAROLI, N.; CUCHER, M.; CAMICIA, F.; FOX, A.; ROSENZVIT, M. C.; OLIVEIRA, G.; KAMENETZKY, L.

BMC GENOMICS

BIOMED CENTRAL LTD

Lugar: Londres; Año: 2017

1471-2164

Background:The parasite Echinococcus canadensis (G7) (phylum Platyhelminthes, class Cestoda) is one of the causative agents ofechinococcosis. Echinococcosis is a worldwide chronic zoonosis affecting humansas well as domestic and wild mammals, which has been reported as a prioritizedneglected disease by the World Health Organisation. Nogenomic data, comparative genomic analyses, or efficient therapeutic and diagnostictools are available for this severe disease. The information presented in this study it will help understanding thepeculiar biological characters and designing species-specific control tools.Results: We sequenced, assembled andannotated the 115-Mb genome of E.canadensis (G7). Comparative genomic analyses using whole genome data fromthree Echinococcus species not only confirmed the status of E.canadensis (G7) as a separate species but also demonstrated a high nucleotidesequences divergence in relation to  E.granulosus (G1). The E. canadensis(G7) genome contains 11,449 genes with acore set of 881 orthologs shared among five cestode species. Comparative genomicsrevealed that there are more single nucleotide polymorphisms (SNPs) between E. canadensis (G7) and E. granulosus (G1) than between E. canadensis (G7) and E.multilocularis. This result was surprising since E. canadensis (G7)and E. granulosus (G1) were considered to belong to the complex species E.granulosus sensu lato. We described SNPs in known drug targets andmetabolism genes in the E. canadensis(G7) genome. Regarding gene regulation, we analysed three particular features:CpG island distribution along the three Echinococcus genomes, DNAmethylation system and small RNA pathway. The results suggest the occurrence ofyet unknown gene regulation mechanisms in Echinococcus.Conclusions: This is the first work that addresses Echinococcus comparativegenomics. The resources presented here will promote the study of mechanisms ofparasite development as well as new tools for drug discovery. The availabilityof a high-quality genome assembly is critical for fully exploring the biologyof pathogenic organism. The E. canadensis (G7) genome presented in thisstudy provides a unique opportunity to address the genetic diversity among the genusEchinococcus and its particular developmental features. At present,there is no unequivocal taxonomic classification of Echinococcus species. Additional cestode genomes need to be sequencedto unequivocally resolve  their phylogeny