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

BACKGROUND: The parasite Echinococcus canadensis (G7) (phylum Platyhelminthes, class Cestoda) is one of the causative agents of echinococcosis. Echinococcosis is a worldwide chronic zoonosis affecting humans as well as domestic and wild mammals, which has been reported as a prioritized neglected disease by the World Health Organisation. No genomic data, comparative genomic analyses or efficient therapeutic and diagnostic tools are available for this severe disease. The information presented in this study will help to understand the peculiar biological characters and to design species-specific control tools. RESULTS: We sequenced, assembled and annotated the 115-Mb genome of E. canadensis (G7). Comparative genomic analyses using whole genome data of three Echinococcus species not only confirmed the status of E. canadensis (G7) as a separate species but also demonstrated a high nucleotide sequences divergence in relation to E. granulosus (G1). The E. canadensis (G7) genome contains 11,449 genes with a core set of 881 orthologs shared among five cestode species. Comparative genomics revealed 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 unexpected since E. canadensis (G7) and E. granulosus (G1) were considered to belong to the species complex E. granulosus sensu lato. We described SNPs in known drug targets and metabolism genes in the E. canadensis (G7) genome. Regarding gene regulation, we analysed three particular features: CpG island distribution along the three Echinococcus genomes, DNA methylation system and small RNA pathway. The results suggest the occurrence of yet unknown gene regulation mechanisms in Echinococcus. CONCLUSIONS: This is the first work that addresses Echinococcus comparative genomics. The resources presented here will promote the study of mechanisms of parasite development as well as new tools for drug discovery. The availability of a high-quality genome assembly is critical for fully exploring the biology of a pathogenic organism. The E. canadensis (G7) genome presented in this study provides a unique opportunity to address the genetic diversity among the genus Echinococcus and its particular developmental features. At present, there is no unequivocal taxonomic classification of Echinococcus species; however, the genome-wide SNPs analysis performed here revealed the phylogenetic distance among these three Echinococcus species. Additional cestode genomes need to be sequenced to be able to resolve their phylogeny.

Small molecule inhibitors of Ago2 decrease Venezuelan equine encephalitis virus replication.

Venezuelan equine encephalitis virus (VEEV) is classified as a Category B Select Agent and potential bioterror weapon for its severe disease course in humans and equines and its potential for aerosol transmission. There are no current FDA licensed vaccines or specific therapies against VEEV, making identification of potential therapeutic targets a priority. With this aim, our research focuses on the interactions of VEEV with host microRNA (miRNA) machinery. miRNAs are small non-coding RNAs that act as master regulators of gene expression by downregulating or degrading messenger RNA, thus suppressing production of the resultant proteins. Recent publications implicate miRNA interactions in the pathogenesis of various viral diseases. To test the importance of miRNA processing for VEEV replication, cells deficient in Ago2, an important component of the RNA-induced silencing complex (RISC), and cells treated with known Ago2 inhibitors, notably acriflavine (ACF), were utilized. Both conditions caused decreased viral replication and capsid expression. ACF treatment promoted increased survival of neuronal cells over a non-treated, infected control and reduced viral titers of fully virulent VEEV as well as Eastern and Western Equine Encephalitis Viruses and West Nile Virus, but not Vesicular Stomatitis Virus. ACF treatment of VEEV TC-83 infected mice resulted in increased in vivo survival, but did not affect survival or viral loads when mice were challenged with fully virulent VEEV TrD. These results suggest that inhibition of Ago2 results in decreased replication of encephalitic alphaviruses in vitro and this pathway may be an avenue to explore for future therapeutic development.