A Portrait of the Transcriptome of the Neglected Trematode, Fasciola gigantica—Biological and Biotechnological Implications

Neil D Young,Terence W Spithill,Sirikachorn Tangkawattana,Cinzia Cantacessi,Thewarach Laha,Robin B Gasser,Ross S Hall,Aaron R Jex,Bronwyn E Campbell,Prasarn Tangkawattana

doi:10.1371/journal.pntd.0001004

Abstract

Fasciola gigantica (Digenea) is an important foodborne trematode that causes liver fluke disease (fascioliasis) in mammals, including ungulates and humans, mainly in tropical climatic zones of the world. Despite its socioeconomic impact, almost nothing is known about the molecular biology of this parasite, its interplay with its hosts, and the pathogenesis of fascioliasis. Modern genomic technologies now provide unique opportunities to rapidly tackle these exciting areas. The present study reports the first transcriptome representing the adult stage of F. gigantica (of bovid origin), defined using a massively parallel sequencing-coupled bioinformatic approach. From >20 million raw sequence reads, >30,000 contiguous sequences were assembled, of which most were novel. Relative levels of transcription were determined for individual molecules, which were also characterized (at the inferred amino acid level) based on homology, gene ontology, and/or pathway mapping. Comparisons of the transcriptome of F. gigantica with those of other trematodes, including F. hepatica, revealed similarities in transcription for molecules inferred to have key roles in parasite-host interactions. Overall, the present dataset should provide a solid foundation for future fundamental genomic, proteomic, and metabolomic explorations of F. gigantica, as well as a basis for applied outcomes such as the development of novel methods of intervention against this neglected parasite.

Highlights

Liver flukes are socio-economically important parasitic flatworms (Platyhelminthes: Trematoda: Digenea) affecting humans and livestock in a wide range of countries
Fasciola gigantica (Digenea) is a socioeconomically important liver fluke of humans and other mammals. It is the predominant cause of fascioliasis in the tropics and has a serious impact on the lives of tens of millions of people and other animals; yet, very little is known about this parasite and its relationship with its hosts at the molecular level
Advanced sequencing and bioinformatic technologies were employed to explore the genes transcribed in the adult stage of F. gigantica

Summary

Introduction

Liver flukes are socio-economically important parasitic flatworms (Platyhelminthes: Trematoda: Digenea) affecting humans and livestock in a wide range of countries. Two key representatives are Fasciola gigantica and F. hepatica These parasites are the main cause of fascioliasis, a significant disease in ungulates [1,2,3] and humans, which is usually contracted via the ingestion of contaminated aquatic plants [4]. The pathogenesis of fascioliasis in the definitive host is characterized by two main phases: (i) the acute/subacute phase begins with the ingestion of the metacercarial stage on herbage and is characterized by tissue damage, caused by the migration of immature worms through the duodenal wall, and the liver capsule and parenchyma (usually 2–6 weeks) [1]. Clinical signs can include abdominal pain, fever, anaemia, hepatomegaly and weight loss; (ii) the chronic phase commences when adult worms have established in the biliary ducts (,7–8 weeks after infection) [1]. Fascioliasis can sometimes be associated with complications, such as co-infections with anaerobic bacteria [1,10]

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Results

Discussion

Conclusion