Analysis of an expressed sequence tag library from Dicrocoelium dentriticum

Dicrocoeliidae Family: Major Species Causing Veterinary Diseases

This chapter analyses the taxonomic position of the Dicrocoeliidae family and several of its genera and species. The chapter reviews the biology of major veterinary disease-causing species, including Dicrocoelium dendriticum, Dicrocoelium hospes, Dicrocoelium chinensis, Eurytrema pancreaticum and Platynosomum fastosum. All these species have indirect life cycles with two intermediate hosts: molluscs as the first host and ants, grasshoppers and lizards as the second host. Dicrocoelium dendriticum is a widespread liver fluke found in ruminants across Europe, Asia, North Africa and North America. It can also infect humans. Dicrocoelium hospes is widely distributed in the savanna areas of Africa south of the Sahara, while D. chinensis is mainly found in ruminants in East Asia and some European countries (probably imported from Asia). Eurytrema pancreaticum is a common parasite that lives in the bile ducts, gall bladder, pancreatic ducts and intestines of ruminants. It is found in Europe, Madagascar, Asia and South America. Adults of P. fastosum live in the liver, gall bladder and pancreas of birds and mammals in Europe, Africa, Asia, North, Central and South America. Information on the epidemiology, pathology, clinical aspects, diagnosis, treatment, control, prevention and economic impact of Dicrocoeliosis caused by D. dendriticum, Eurytrematodosis and Platynosomiosis have been included.

Dicrocoeliidae Family: Major Species Causing Veterinary Diseases

This chapter analyses the taxonomic position of Dicrocoeliidae family and several of its genus and species. The biology of the major species causing veterinary diseases such Dicrocoelium dendriticum, Dicrocoelium hospes, Dicrocoelium chinensis, Eurytrema pancreaticum and Platynosomum fastosum, has been reviewed. All these species have an indirect life cycle, involving two intermediate hosts (molluscs as first and ants, grasshoppers and lizards as second). Dicrocoelium dendriticum is a very widespread hepatic trematode in the ruminants of many countries in Europe, Asia, North Africa and North America, even affecting humans. Dicrocoelium hospes is widely distributed in the savanna areas of Africa south of the Sahara, whilst D. chinensis has mainly been found in ruminants in East Asia and some European countries (probably imported from Asia). Eurytrema pancreaticum is a common parasite whose adults live in ruminant bile ducts, gall bladder, pancreatic ducts and intestines in Europe, Madagascar, Asia and South America. Adult P. fastosum live in the liver, gall bladder and pancreas of birds and mammals in Europe, Africa, Asia, North, Central and South America. Information about the epidemiology, pathology, clinical aspect, diagnosis, treatment, control, prevention and economic impact mainly of Dicrocoeliosis produced by D. dendriticum, as well as of Eurytrematodosis and Platynosomiosis, has been included.

The omic approach to parasitic trematode research-a review of techniques and developments within the past 5 years

The evolution of technologies to explore parasite biology at a detailed level has made significant advances in recent years, particularly with the development of omic-based strategies. Whilst extensive efforts have been made in the past to develop therapeutic and prophylactic control strategies for trematode parasites, only the therapeutic anthelmintic approach can be regarded as usable in clinical practice. Currently, there is no commercialised prophylactic strategy (such as vaccination) for protection of the definitive host against any trematode parasite. Since 2010 in particular, the integration of omic technologies, including liquid chromatography-mass spectrometry (LC-MS) and next-generation sequencing (NGS), has been increasingly reported in trematode-related studies. Both LC-MS and NGS facilitate a better understanding of the biology of trematodes and provide a promising route to identifying clinically important biological characteristics of parasitic trematodes. In this review, we focus on the application, advantages, and disadvantages of omic technologies (LC-MS and NGS) in trematode research within the past 5 years and explore the use and translation of the omic-based research results into practical tools to deal with infection.

Surface analysis of Dicrocoelium dendriticum. The molecular characterization of exosomes reveals the presence of miRNAs

With the aim of characterizing the molecules involved in the interaction of Dicrocoelium dendriticum adults and the host, we have performed proteomic analyses of the external surface of the parasite using the currently available datasets including the transcriptome of the related species Echinostoma caproni. We have identified 182 parasite proteins on the outermost surface of D. dendriticum. The presence of exosome-like vesicles in the ESP of D. dendriticum and their components has also been characterized. Using proteomic approaches, we have characterized 84 proteins in these vesicles. Interestingly, we have detected miRNA in D. dendriticum exosomes, thus representing the first report of miRNA in helminth exosomes.

BIOLOGICAL SIGNIFICANCE

In order to identify potential targets for intervention against parasitic helminths, we have analyzed the surface of the parasitic helminth Dicrocoelium dendriticum. Along with the proteomic analyses of the outermost layer of the parasite, our work describes the molecular characterization of the exosomes of D. dendriticum. Our proteomic data confirm the improvement of protein identification from "non-model organisms" like helminths, when using different search engines against a combination of available databases. In addition, this work represents the first report of miRNAs in parasitic helminth exosomes. These vesicles can pack specific proteins and RNAs providing stability and resistance to RNAse digestion in body fluids, and provide a way to regulate host-parasite interplay. The present data should provide a solid foundation for the development of novel methods to control this non-model organism and related parasites. This article is part of a Special Issue entitled: Proteomics of non-model organisms.

The MF6p/FhHDM-1 major antigen secreted by the trematode parasite Fasciola hepatica is a heme-binding protein

Blood-feeding parasites have developed biochemical mechanisms to control heme intake and detoxification. Here we show that a major antigen secreted by Fasciola hepatica, previously reported as MF6p, of unknown function (gb|CCA61804.1), and as FhHDM-1, considered to be a helminth defense molecule belonging to the family of cathelicidin-like proteins (gb|ADZ24001.1), is in fact a heme-binding protein. The heme-binding nature of the MF6p/FhHDM-1 protein was revealed in two independent experiments: (i) immunopurification of the secreted protein·heme complexes with mAb MF6 and subsequent analysis by C8 reversed-phase HPLC and MS/MS spectrometry and (ii) analysis of the binding ability of the synthetic protein to hemin in vitro. By immunohistochemistry analysis, we have observed that MF6p/FhHDM-1 is produced by parenchymal cells and transported to other tissues (e.g. vitellaria and testis). Interestingly, MF6p/FhHDM-1 is absent both in the intestinal cells and in the lumen of cecum, but it can be released through the tegumental surface to the external medium, where it binds to free heme molecules regurgitated by the parasite after hemoglobin digestion. Proteins that are close analogs of the Fasciola MF6p/FhHDM-1 are present in other trematodes, including Clonorchis, Opistorchis, Paragonimus, Schistosoma, and Dicrocoelium. Using UV-visible spectroscopy and immunoprecipitation techniques, we observed that synthetic MF6p/FhHDM-1 binds to hemin with 1:1 stoichiometry and an apparent Kd of 1.14 × 10(-6) M(-1). We also demonstrated that formation of synthetic MF6p/FhHDM-1·hemin complexes inhibited hemin degradation by hydrogen peroxide and hemin peroxidase-like activity in vitro. Our results suggest that MF6p/FhHDM-1 may be involved in heme homeostasis in trematodes.