Cestode genomics – progress and prospects for advancing basic and applied aspects of flatworm biology

Olson, Peter D.; Zarowiecki, Magdalena; Kiss, Ferenc; Brehm, Klaus

doi:10.1111/j.1365-3024.2011.01319.x

Cited by 81 publications

(96 citation statements)

References 158 publications

(252 reference statements)

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“…E. granulosusspecific EgAgB is likely to be a key factor in the process of immune evasion, as the antigen is secreted and variable 34 . Encoded by a gene family, we found seven EgAgB genes in the genome, similar to in a previous report 13 .…”

Section: Evading Immune Recognition and Regulation Of Host Immunologisupporting

confidence: 75%

“…The E. granulosus genome had 48 DLC members (compared to 35 in Schistosoma japonicum and 29 in Schistosoma mansoni), whereas 4-7 were found in the 4 nematodes. We identified 49 cadherins in the E. granulosus genome, similar to the numbers found in schistosomes (51-65) but more than in nematodes (12)(13)(14)(15)(16)(17)(18) (Supplementary Table 22b). Cadherins belong to a class of type 1 transmembrane proteins that have important roles in cell recognition and adhesion.…”

Section: Domain Families Gained In E Granulosusmentioning

confidence: 49%

“…Expanded domain families in E. granulosus included the heat shock protein 70 (Hsp70), universal stress protein (USP), poly-(ADP-ribose) polymerase (PARP) and prothymosin families (Supplementary Table 22a). Hsp70 proteins have important roles in protein folding and in protecting cells from stress, and expansion of this family in E. granulosus has been reported 13 . Expression of Hsp70 genes was substantially different in the four life-cycle stages; for example, EG_09650 was only expressed in adult worms, and EG_10561 was highly expressed in the hydatid cyst membrane (Supplementary Table 23).…”

Section: Domain Families Gained In E Granulosusmentioning

confidence: 99%

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The genome of the hydatid tapeworm Echinococcus granulosus

et al. 2013

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A r t i c l e sThe dog tapeworm E. granulosus is one of a group of medically important parasitic helminths of the family Taeniidae (Platyhelminthes; Cestoda; Cyclophyllidea) that infect at least 50 million people globally 1 . Its life cycle involves two mammals, including an intermediate host, usually a domestic or wild ungulate (humans are accidental intermediate hosts) and a canine-definitive host, such as the domestic dog. The larval (metacestode) stage causes hydatidosis (cystic hydatid disease; cystic echinococcosis), a chronic cyst-forming disease in the intermediate (human) host. Currently, up to 3 million people are infected with E. granulosus 2,3 , and, in some areas, 10% of the population has detectable hydatid cysts by abdominal ultrasound and chest X-ray 4,5 .E. granulosus has no gut, circulatory or respiratory organs. It is monoecious, producing diploid eggs that give rise to ovoid embryos, the oncospheres. Strobilization is a notable feature of cestode biology, whereby proglottids bud distally from the anterior scolex, resulting in the production of tandem reproductive units exhibiting increasing degrees of development. A unique characteristic of the larvae (protoscoleces, PSCs) within the hydatid cyst is an ability to develop bidirectionally into an adult worm in the dog gastrointestinal tract or into a secondary hydatid cyst in the intermediate (human) host, a process triggered by bile acids 6 . Another distinct feature of E. granulosus is its capacity to infect and adapt to a large number of mammalian species as intermediate hosts, which has contributed to its cosmopolitan global distribution.Here we report the sequence and analysis of the E. granulosus genome. Comprising nine pairs of chromosomes 7 , it is one of the first cestode genomes to be sequenced and complements the recent publication by Tsai et al. 8 of a high-quality genome for Echinococcus multilocularis (the cause of alveolar echinococcosis), together with draft genomes of three other tapeworm species including E. granulosus. Our study provides insights into the biology, development, differentiation, evolution and host interaction of E. granulosus and has identified a range of drug and vaccine targets that can facilitate the development of new intervention tools for hydatid treatment and control. Cystic echinococcosis (hydatid disease), caused by the tapeworm E. granulosus, is responsible for considerable human morbidity and mortality. This cosmopolitan disease is difficult to diagnose, treat and control. We present a draft genomic sequence for the worm comprising 151.6 Mb encoding 11,325 genes. Comparisons with the genome sequences from other taxa show that E. granulosus has acquired a spectrum of genes, including the EgAgB family, whose products are secreted by the parasite to interact and redirect host immune responses. We also find that genes in bile salt pathways may control the bidirectional development of E. granulosus, and sequence differences in the calcium channel subunit EgCa v b 1 may be associated with praziquantel sens...

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Section: Evading Immune Recognition and Regulation Of Host Immunologisupporting

confidence: 75%

Section: Domain Families Gained In E Granulosusmentioning

confidence: 49%

Section: Domain Families Gained In E Granulosusmentioning

confidence: 99%

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The genome of the hydatid tapeworm Echinococcus granulosus

et al. 2013

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“…The recovered hidden orthologs have an immediate impact on our understanding of gene complement evolution in Platyhelminthes, particularly those lineages that are the subject of intense research, such as the regenerative model Schmidtea mediterranea and parasitic flatworms (Berriman et al 2009;Wang et al 2011;Olson et al 2012;. The identification of fast-evolving orthologs for important centrosomal proteins in S. mediterranea and other flatworms lineages (Fig.…”

Section: Wwwgenomeorgmentioning

confidence: 99%

Increased taxon sampling reveals thousands of hidden orthologs in flatworms

et al. 2017

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Gains and losses shape the gene complement of animal lineages and are a fundamental aspect of genomic evolution. Acquiring a comprehensive view of the evolution of gene repertoires is limited by the intrinsic limitations of common sequence similarity searches and available databases. Thus, a subset of the gene complement of an organism consists of hidden orthologs, i.e., those with no apparent homology to sequenced animal lineages-mistakenly considered new genes-but actually representing rapidly evolving orthologs or undetected paralogs. Here, we describe Leapfrog, a simple automated BLAST pipeline that leverages increased taxon sampling to overcome long evolutionary distances and identify putative hidden orthologs in large transcriptomic databases by transitive homology. As a case study, we used 35 transcriptomes of 29 flatworm lineages to recover 3427 putative hidden orthologs, some unidentified by OrthoFinder and HaMStR, two common orthogroup inference algorithms. Unexpectedly, we do not observe a correlation between the number of putative hidden orthologs in a lineage and its "average" evolutionary rate. Hidden orthologs do not show unusual sequence composition biases that might account for systematic errors in sequence similarity searches. Instead, gene duplication with divergence of one paralog and weak positive selection appear to underlie hidden orthology in Platyhelminthes. By using Leapfrog, we identify key centrosome-related genes and homeodomain classes previously reported as absent in free-living flatworms, e.g., planarians. Altogether, our findings demonstrate that hidden orthologs comprise a significant proportion of the gene repertoire in flatworms, qualifying the impact of gene losses and gains in gene complement evolution.

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“…In 80-95% of cases echinococcosis is located in the liver and lungs, more rarely in the brain. There are no typical symptoms characteristic for uncomplicated echinococcosis (3,4). Diagnosis is based on additional examinations.…”

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confidence: 99%