SCP/TAPS proteins of parasitic helminths have been proposed to play key roles in fundamental biological processes linked to the invasion of and establishment in their mammalian host animals, such as the transition from free-living to parasitic stages and the modulation of host immune responses. Despite the evidence that SCP/TAPS proteins of parasitic nematodes are involved in host-parasite interactions, there is a paucity of information on this protein family for parasitic trematodes of socio-economic importance.
We conducted the first large-scale study of SCP/TAPS proteins of a range of parasitic trematodes of both human and veterinary importance (including the liver flukes Clonorchis sinensis, Opisthorchis viverrini, Fasciola hepatica and F. gigantica as well as the blood flukes Schistosoma mansoni, S. japonicum and S. haematobium). We mined all current transcriptomic and/or genomic sequence datasets from public databases, predicted secondary structures of full-length protein sequences, undertook systematic phylogenetic analyses and investigated the differential transcription of SCP/TAPS genes in O. viverrini and F. hepatica, with an emphasis on those that are up-regulated in the developmental stages infecting the mammalian host.
This work, which sheds new light on SCP/TAPS proteins, guides future structural and functional explorations of key SCP/TAPS molecules associated with diseases caused by flatworms. Future fundamental investigations of these molecules in parasites and the integration of structural and functional data could lead to new approaches for the control of parasitic diseases.
Citation: Cantacessi C, Hofmann A, Young ND, Broder U, Hall RS, Loukas A, et al. (2012) Insights into SCP/TAPS Proteins of Liver Flukes Based on Large-Scale Bioinformatic Analyses of Sequence Datasets. PLoS ONE 7(2): e31164. https://doi.org/10.1371/journal.pone.0031164
Editor: Jeong-Sun Seo, Seoul National University College of Medicine, Republic of Korea
Received: November 8, 2011; Accepted: January 3, 2012; Published: February 22, 2012
Copyright: © 2012 Cantacessi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The Gasser Lab is presently supported by funding from the Australian Research Council, Melbourne Water Corporation and the National Health and Medical Research Council (RBG). Support from the Victorian Life Sciences Computation Initiative and IBM Collaboratory is also acknowledged (RBG). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The Gasser Lab is presently supported by funding from the Australian Research Council, Melbourne Water Corporation and the National Health and Medical Research Council (RBG). This does not alter the authors' adherence to all the PLoS One policies on sharing data and materials.
The SCP/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS) protein family (Pfam accession number no. PF00188; InterPro accession number IPR014044) includes a range of structurally related proteins found in a wide range of eukaryotes  and characterized by the presence of SCP-extracellular domains (a single- or double-domain SCP/TAPS) which act as Ca2+-chelators in various signalling processes . SCP/TAPS proteins include rodent sperm-coating glycoproteins (or acidic glycoproteins, proposed to be involved in sperm maturation during passage through the epididymis) , mammalian testis-specific protein (Tpx-1) , glioma pathogenesis-related protein –, venom allergen 5 from vespid wasps and the venom allergen 3 from fire ants, which mediate allergic reactions to the bites by some insects of the order Hymenoptera  as well as plant pathogenesis proteins (PRPs) of the PR-1 “subfamily” which are synthesized in response to infections with pathogens or other stress-inducing factors . For parasitic helminths, SCP/TAPS proteins are common in nematodes of the orders Spirurida, Ascaridida, Tylenchida, Rhabditida and Strongylida . Within the latter order, members of the SCP/TAPS protein family have been well studied in the canine hookworm, Ancylostoma caninum. Based on the observation that these proteins are abundant in the excretory/secretory (ES) products of the serum-activated third-stage larvae (L3s), they have been designated as ‘Ancylostoma-secreted proteins’ or ‘activation-associated secreted proteins’ ( = ASPs; , ). In hookworms, SCP/TAPS proteins are thought to play an important role in the transition from the free-living to the parasitic stage of the L3s during the invasion of and the migration through the host's tissues –, as well as key role/s in the modulation of the host's immune response , . In addition, because of its immunogenic properties, one SCP/TAPS protein (called Na-ASP-2) is currently under investigation as a vaccine candidate against the disease ( = necatoriasis) caused by the human hookworm Necator americanus –.
Despite the fundamental roles that nematode SCP/TAPS proteins are proposed to play in the host-parasite interplay , –, knowledge of SCP/TAPS homologues/orthologues in parasitic trematodes ( = flukes) is scant. In a single study, Chalmers et al.  identified genes encoding SCP/TAPS proteins (designated SmVALs) of Schistosoma mansoni (a blood fluke of humans) by mining of available expressed sequence tag (EST) datasets , investigated levels of transcription of corresponding mRNAs in different developmental stages of this parasite, performed extensive analyses of the predicted amino acid sequences by homology modelling, and inferred phylogenetic relationships . Based on the results from this study, the authors proposed a role for SmVALs in processes linked to the invasion of the human host by S. mansoni . This hypothesis requires testing. In addition, elucidating the structure/s and function/s of these molecules in S. mansoni and other socioeconomically important parasitic trematodes could provide an avenue for the design of new approaches for their control.
Recently, advances in next-generation sequencing (NGS) and bioinformatics – have allowed large-scale explorations of the transcriptomes and/or genomes of a range of parasitic trematodes, including the carcinogenic opisthorchiids Clonorchis sinensis and Opisthorchis viverrini , the fasciolids Fasciola hepatica  and F. gigantica  (liver flukes) as well as Schistosoma mansoni and S. japonicum ,  (blood flukes). The sequence data generated in these studies, available for download from public databases (e.g., http://www.gasserlab.org/ and http://www.genedb.org/), represent an excellent resource for studies of SCP/TAPS proteins in parasitic trematodes. Utilizing current datasets, we conduct herein the first large-scale analysis of SCP/TAPS proteins in a range of parasitic trematodes of both human and veterinary health importance; infer relationships between/among trematode SCP/TAPS based on predictions of secondary structures of protein sequences; and investigate differences in the transcription of genes encoding SCP/TAPS between the juvenile and adult stages of O. viverrini and F. hepatica.
Materials and Methods
Sequence datasets, and identification and analyses of SCP/TAPS homologues/orthologues
The sequence data obtained from public sequence databases (i.e. http://www.gasserlab.org/ and http://www.genedb.org/) – and analysed herein included predicted peptide inferred from (i) the transcriptome [generated by 454 sequencing of normalized complementary DNA (cDNA) libraries] of the adult stage of C. sinensis (n = 50,769 predicted peptides) [Sequence Read Archive (SRA) accession number: SRA012272]; (ii) the transcriptomes [generated by Illumina sequencing of non-normalized cDNA libraries] of adult F. gigantica (n = 30,525) (SRA024257) and of both adult and juvenile stages of O. viverrini (n = 25,172) and F. hepatica (n = 19,669) (http://www.gasserlab.org/); (iii) the genome sequences of S. mansoni (n = 13,174 peptides), S. japonicum (n = 13,469) and S. haematobium (n = 13,073). The algorithms BLASTp  and InterProScan  were used to identify single- and double-domain SCP/TAPS (predicted) in each of the transcriptomic and genomic datasets based on sequence homology (e-value cut-off: 10−5) with known eukaryotic SCP/TAPS proteins (cf. ), and on the presence of one or more SCP-extracellular domains (Pfam: PF00188; InterPro: IPR014044), respectively. Signal peptides were also predicted using the program SignalP 3.0, employing both the neural network and hidden Markov Models . Putative excreted/secreted SCP/TAPS proteins were identified based on the presence of a signal peptide and sequence homology to one or more known ES proteins listed in the Secreted Protein (http://spd.cbi.pku.edu.cn/; ) and the Signal Peptide (http://proline.bic.nus.edu.sg/spdb/index.html; ) databases.
Prediction of the secondary structures of trematode SCP/TAPS and homology modelling
Structure-based sequence alignments of both single- and double-domain SCP/TAPS were generated manually, guided by secondary structure elements predicted using PSIPRED software . Individual structure-based alignments of amino acid sequences (>120 amino acids in length) were subjected to analysis by Bayesian inference (BI) using the program MrBayes v.3.1.2  and verified by Neighbour Joining (NJ) analysis using the MEGA software . Each BI analysis was conducted for 1,000,000 generations (ngen = 1,000,000), with every 100-th tree being saved, using the following parameters: rates = gamma, aamodelpr = mixed, and the other parameters left at the default settings. Tree and branch lengths were measured employing the parameter ‘sumt burnin = 1000’; an unrooted, consensus tree was constructed, with ‘contype = halfcompat’ nodal support being determined using consensus posterior probabilities and displayed employing the program TreeView v.1.6.6 . For selected single-domain SCP/TAPS proteins, homologues with known three-dimensional structures were identified using the protein-fold recognition software pGenTHREADER  and selected as templates for comparative modelling using MODELLER . Twenty independent models were generated, and the model with the lowest energy was selected, its geometry analysed using PROCHECK  and then inspected visually with PyMOL .
Assessment of levels of transcription of genes encoding SCP/TAPS in selected liver flukes
The raw sequence reads derived from each of the non-normalized cDNA libraries from adult and juvenile O. viverrini and F. hepatica were mapped to the longest contigs representing individual SCP/TAPS proteins using the program SOAP2 . Briefly, raw sequence reads were aligned to the non-redundant transcriptomic data, such that each raw sequence read was uniquely mapped (i.e. to a unique transcript). Reads that mapped to more than one transcript (designated ‘multi-reads’) were randomly assigned to a unique transcript, such that they were recorded only once. To provide a relative assessment of transcript abundance, the number of raw reads that mapped to each sequence was normalized for length (i.e. reads per kilobase per million reads, RPKM) .
An established method  was used for probabilistic functional genetic networking among Mus musculus gene homologues/orthologues of molecules encoding SCP/TAPS proteins of parasitic trematodes using the recommended, stringent cut-off value of 4.6. The predicted networks resulting from the analyses were saved in a graphic display file (gdf) format, examined using the graph exploration system available at http://graphexploration.cond.org/ (http://www.geneorienteer.org/; ).
Results and Discussion
SCP/TAPS proteins of parasitic trematodes
A total number of 151 peptides with high homology (e-value cut-off: 10−5) to known eukaryotic SCP/TAPS were predicted from all of the genomic and/or transcriptomic sequence datasets available for trematodes (Tables S1 and S2). These datasets provide a solid resource for future structural and functional investigations of the SCP/TAPS protein family of trematodes and other parasitic helminths. Of the sequence data included here, the complement of protein-coding genes of S. mansoni comprises the largest number of predicted SCP/TAPS proteins reported to date (n = 39 and 2 single- and double-domain SCP/TAPS, respectively) (Tables S1 and S2). One of these amino acid sequences (i.e. Smp_131370) had not been predicted from the S. mansoni EST datasets analysed previously , thus representing a novel record. The large number of transcripts encoding distinct SCP/TAPS proteins in S. mansoni is in contrast to the number of SCP/TAPS-encoding genes inferred from the genomic sequence data from the other two Schistosoma species analysed herein (n = 17 and 25 for S. japonicum and S. haematobium, respectively; cf. Tables S1 and S2). The likely explanation for this result is technical and appears to relate to the fact that, in the assemblies of the S. japonicum and S. haematobium genomes, smaller proportions of genome sequence are contained within large, contiguous sequences (‘scaffolds’) , , thus leading to the fragmentation of predicted open reading frames (ORFs) and, in turn, to an underestimation of the number of protein-coding genes. In the future, bridging the gaps between scaffolds representing these draft genomes (by, for instance, performing re-assembly of Illumina reads to close gaps between adjacent contigs within scaffolds; ) should allow the unequivocal identification of the complete sets of SCP/TAPS protein-coding genes in these blood flukes and will pave the way for comparative studies. In addition, it will provide a basis for in-depth analyses of amino acid sequence features, such as patterns of cysteine residues and presence/absence of signal peptides, thus assisting future structural and functional analyses of members of the SCP/TAPS protein family in parasitic helminths.
In the present study, a total number of 42 (27%) SCP/TAPS amino acid sequences were predicted to contain an N-terminal signal peptide (Tables S1 and S2); in particular, amongst the sequence data analysed herein, the S. mansoni set of predicted proteins included the largest number of SCP/TAPS with a signal peptide indicative of secretion (n = 17; Tables S1 and S2). Conversely, none of the SCP/TAPS amino acid sequences predicted from the transcriptome of F. gigantica contained a secretory signal peptide (Tables S1 and S2), despite unpublished evidence of one SCP/TAPS containing a signal peptide in this trematode (GenBank accession number FN379399). These findings support the existence of two types of eukaryotic SCP/TAPS proteins, one of which lacks a signal peptide and is localized within the cellular compartment, in association with the Golgi endoplasmic reticulum (e.g., the Golgi-associated PR-1-related protein [GAPR-1] of vertebrates; –), and the other which contains a signal peptide and is localized in the extracellular compartment (e.g., Ac-ASP-2 of A. caninum; ). The detection of SCP/TAPS amino acid sequences that lack a predicted signal peptide in all of the trematode sequence datasets contrasts the situation for parasitic nematodes (including hookworms and filarioids) whose SCP/TAPS proteins usually possess a signal peptide and are abundant in the ES products (e.g., , , , –). To date, SCP/TAPS proteins have been identified in the ES products of various species and different developmental stages of parasitic trematodes, including S. mansoni and S. japonicum eggs ,  and O. viverrini adults . In particular, protein Sj-VAL-1 was isolated from the ES products of eggs of S. japonicum and shown to evoke a specific Th2-type immune response when inoculated into naïve mice , whereas other SCP/TAPS members have been isolated from ES products from S. mansoni miracidia and cercariae during their transition to sporocysts  and schistosomules , , respectively. These findings raise questions as to the roles that SCP/TAPS play in the infection process in both the vertebrate and molluscan hosts. In another study, SCP/TAPS proteins were not detected in ES products from juvenile or adult F. hepatica . The structural and functional differences between secreted and non-secreted SCP/TAPS proteins remain unclear  and warrant detailed investigations. Both secreted and non-secreted SCP/TAPS are characterized by the presence of a highly conserved SCP-domain . Although conserved domains are known to play key roles in determining protein function, protein-protein interactions, DNA binding and enzyme activity , structural analyses of the complete amino acid sequence of proteins are essential to assist in-depth investigations of function .
Structural classification of trematode SCP/TAPS
In the present study, a key criterion for the classification of trematode SCP/TAPS proteins was the presence of cysteine residues at particular sequence positions. Three conserved disulphide bonds, which stabilize the fold of the core, were defined as a hallmark-feature of the SCP domain. For single-domain SCP/TAPS proteins, amino acid sequence alignments, guided by predictions of their secondary structures and sequence similarity, allowed the definition of (at least) four individual groups (Table S1; Figures 1 and 2a–d; Figure S1), characterized by: (i) the presence of all conserved secondary structure elements of the SCP domain, an N-terminal α-helix in most sequences and eight conserved cysteine residues (group 1); (ii) presence of all conserved secondary structure elements of the SCP domain, an N-terminal α-helix in many sequences, a cysteine-rich N-terminal region and the absence of conserved cysteine residues after α1 and β3 (group 2); (iii) presence of all conserved secondary structure elements of the SCP domain and of one conserved cysteine residue after α1, and the absence of an N-terminal α-helix (group 3); or (iv) distribution of secondary structure elements, similar to those of groups 1–3, and the absence of conserved cysteine residues (group 4). Within group 3, F. gigantica c4654, F. gigantica c12544, O. viverrini c3766, C. sinensis c8455 and O. viverrini c2349 did not possess the cysteine residue at α1, characteristic for this group; however, the similarity between their predicted secondary structures and those of other proteins within group 3 led to their inclusion within this group. The SCP/TAPS groups differ markedly in the conservation of cysteine residues; while the conserved intra-molecular disulphide bonds are present in proteins of groups 1 and 2, they are absent from those of groups 3 and 4. Thus far, the only known example of a non-disulphide-stabilised SCP-fold is GAPR-1 . Of the 148 SCP/TAPS amino acid sequences predicted, eleven represented double-domain SCP/TAPS proteins. However, the structure-based amino acid sequence alignment revealed that the C-terminal moiety of two of these proteins, namely S. haematobium cA00818 and cA08278, possessed a non-SCP/TAPS fold. Of the remaining nine sequences, S. haematobium cA07851 represented group 1, and the other eight sequences were classified as group 2, based on the conservation of cysteine residues (Table S2; Figure 1; Figure S2). Previously, structure-based sequence alignments of SCP/TAPS proteins of nematodes had led to their categorization into three (structural) groups . Based on comparisons of the positions of the conserved cysteine residues between nematode and trematode SCP/TAPS proteins, disulphide bridges can be inferred that are crucial for the fold-stability (α2-β2 and β2-β3) and for the tolerability of variations of the molecular constituents of the SCP-fold. In particular, up to four conserved cysteine residues, including those linking α2-β2 and β2- β3, in the amino acid sequences of single-domain SCP/TAPS belonging to group 3 and 4, are mutated.
The proposed classification of groups of trematode SCP/TAPS proteins is supported by the occurrence of conserved cysteine residues. The grouping of hookworm SCP/TAPS proteins has been reported recently . For the hookworm SCP/TAPS proteins, the cysteine connectivity in the intra-molecular disulphide bonds is known from experimental three-dimensional structures and shown by colour-mapping. The likely cysteine connectivity for trematode SCP/TAPS is hypothetical and based on the modelling in this study.
Group 1 (a); group 2 (b); group 3 (c); group 4 (d). The posterior probability supporting each clade is indicated. The corresponding phylogenetic reconstructions conducted using Neighbour Joining analyses of single-domain SCP/TAPS proteins are available from the primary author upon request.
At the molecular level, SCP/TAPS proteins adopt the fold of an α-β-α sandwich, similar to the plant PR-1 protein P14a  and the hookworm protein Na-ASP-2 . Variable extensions are linked to the C-terminus of the SCP-extracellular domain and include the LCCL ( = Limulus clotting factor C, Coch-5b2, and Lgl1), the C-type lectin, the ion channel regulator  and an additional SCP-extracellular domain. The abundance of the SCP/TAPS fold and its extension, by means of a variable set of protein domains with distinct functions, suggest a “vehicle-payload” model for these proteins , whereby the C-terminally linked domain is delivered by the SCP-domain to sites of action. The SCP-fold could also be hypothesized to be involved in binding, recognition or enzymatic activities; however, further studies are required to support this hypothesis. In the future, experimental studies aimed at defining the structure-function relationships of the SCP-fold will provide a solid basis for determining its precise molecular activities. Indeed, given the magnitude of variation in the atomic structure of the SCP-fold, three-dimensional models obtained by comparative modelling need to be treated with caution. To illustrate this point, we generated and critically appraised the homology model for a group 1, single-domain SCP/TAPS protein (designated c962) from O. viverrini. For this target, the structure of Na-ASP-2 (PDB code 1u53) was identified as the best template for comparative modelling. An analysis of the predicted structure revealed that the cysteine residues that are conserved between the trematode group 1 and the hookworm group 1 SCP/TAPS proteins are engaged in disulphide bonds, due to the restraints provided by the chosen template. The remaining, even number of cysteine residues may also engage in intra-molecular disulphide bonds, and their positioning within the primary structure promotes this hypothesis. Due to the restraints by the chosen template, the homology model for the group 1 proteins of trematodes shows that these additional cysteine residues are freely surface-accessible. However, a different conformation of the connecting loops, which would bring the remaining cysteine residues into spatial vicinity, can also be proposed (Figure 3). When applying two disulphide bonds as special restraints in the comparative modelling calculation, a structure with four intra-molecular disulphide bonds was inferred. Importantly, for O. viverrini c962, an N-terminal peptide of 94 amino acids, including two cysteine residues, was excluded from comparative modelling, due to the restrictions resulting from the template structure. Indeed, a limitation of the homology modelling approach for the de novo-determination of protein structures is the fact that, since homology models only extend to the boundaries of overlap between the template and the target protein in the alignment, the effects of N- or C-terminal peptides of the target on the fold are not considered. Experimental studies of the tertiary structures of different groups of SCP/TAPS will assist substantially in enhancing our knowledge of the structure-function relationships of these proteins.
Top row: the models are rendered in cartoon representation with cysteine side chains shown as bars in grey. The colour mapping ramps from blue (N-terminal end) to red (C-terminal end). Bottom row: surface representation of the models is in the same orientation as in the top row. The electrostatic surface potential is mapped by colour (blue: positive charge; red: negative charge). The left panel shows a homology model using Na-ASP-2 (PDB code: 1u53) as a template without restraint. For the model shown in the right panel, two restraints were applied to force disulphide bonds between the remaining cysteine residues. The comparison of both models highlights the significant differences in conformation and shape resulting from different template restraints applied. The images were generated using PyMOL [http://www.pymol.org/].
Developmental regulation of SCP/TAPS transcription
Levels of transcription of molecules encoding SCP/TAPS proteins were investigated in the juvenile and adult stages of both O. viverrini and F. hepatica, two key representatives of the Trematoda. In O. viverrini, significant (p<0.001) differences in transcription were recorded for eight distinct molecules encoding SCP/TAPS (seven single- and one double-domain SCP/TAPS) (Tables S1 and S2), of which four were up-regulated in the adult stage (Table S1). Conversely, in F. hepatica, transcripts encoding six distinct (i.e. four single- and two double-domain) SCP/TAPS were significantly up-regulated in the juvenile stage (p<0.001) (Tables S1 and S2), thus suggesting that SCP/TAPS proteins might play distinct roles during the infection of and/or the establishment in the mammalian hosts of trematode species with distinct biologies. For example, excysted juveniles of O. viverrini migrate from the duodenum through the ampulla of Vater and the common bile duct to the intra-hepatic bile ducts, where they develop into adult flukes , , whereas F. hepatica juveniles burrow through the intestinal wall and migrate through the peritoneal cavity and the liver capsule to then mature to adult flukes in the bile ducts . Based on this knowledge, it is tempting to speculate that, in F. hepatica, the up-regulation of SCP/TAPS transcripts shown in the juvenile stages may favour the successful migration of the parasites through the host tissues, as hypothesized previously for the larval stages of the hookworms A. caninum and N. americanus , , , , whereas nothing is known about the molecular mechanisms that determine the up-regulation of such transcripts in the juvenile and adult stages of O. viverrini. Similar profiles of developmental regulation of genes encoding SCP/TAPS were observed previously in S. mansoni . In this blood fluke, real-time PCR analysis of molecules encoding SmVALs revealed variable profiles, which included transcripts up-regulated in the developmental stage involved in the invasion of the intermediate (i.e. miracidium) or definitive (i.e. schistosomule) hosts and other transcripts ubiquitously expressed in all of the developmental stages studied (i.e. eggs, cercariae, miracidia, schistosomules, and adult males and females) . In another study , an SCP/TAPS-encoding transcript was shown to be up-regulated in the vitelline tissues of S. japonicum, suggesting an involvement in reproductive pathways within the female worm. The developmental regulation of genes encoding SCP/TAPS throughout the life cycle of both O. viverrini and S. mansoni suggests that these molecules play diverse, but critical roles in the fundamental biology of these organisms. In the future, knowledge of the levels of transcription of genes encoding SCP/TAPS in other developmental stages of O. viverrini, as well as the localisation of SCP/TAPS proteins in the tissues of different developmental stages of parasitic trematodes, will assist in improving our understanding of the function of these molecules in these and other parasitic helminths.
Genetic interactions of SCP/TAPS homologues
Networking predicted that 16 mouse homologues/orthologues of trematode SCP/TAPS genes/transcripts, including those encoding the glioma pathogenesis-related protein GLIPR-1, Golgi-associated pathogenesis protein GLIPR-2 and cysteine-rich secretory proteins CRISP-1 and CRISP-2, interact with a total number of 391 other genes (Table S3). While little is known about these interactions at this point, interestingly, previous studies ,  have shown that the transcription of a glipr-1 orthologue is high in human glioblastoma multiforme/astrocytoma and glioma cell lines, but not detectable in other neuronal cancer cell lines or in normal brain tissue. Although this link between up-regulated transcription and glioblastoma multiforme/astrocytoma remains to be proven, it is tempting to propose that some SCP/TAPS proteins from O. viverrini (a carcinogen; , ) are involved in the pathogenesis of cholangiocarcinoma in chronically infected humans. This hypothesis warrants testing. In the first instance, studies could explore, for instance, the morphological and molecular alterations in human bile duct cell lines exposed to various SCP/TAPS proteins derived from the parasite.
Supported by the availability of the entire genome sequence of schistosomes , , recent advances in functional genomics provide unprecedented opportunities for fundamental investigations of SCP/TAPS proteins in different species and developmental stages of parasitic trematodes. Given that the life cycle of a range of parasitic trematodes (including Schistosoma spp.) can be maintained under laboratory conditions , , gene manipulation and/or silencing approaches, including transgenesis and RNA interference (RNAi) –, could be employed for investigations of functional aspects of genes encoding SCP/TAPS proteins in parasitic trematodes. Such fundamental insights will enhance the understanding of key aspects of the biology of parasitic trematodes of socio-economic importance, such as pathways linked to the infection in the host and host-parasite interactions, and could provide the basis for important biotechnological outcomes, such as the development of novel strategies for the control of trematodiases.
Structure-based alignment of full-length amino acid sequences of putative single-domain SCP/TAPS proteins predicted from the transcriptomes of Clonorchis sinensis , Opisthorchis viverrini , Fasciola hepatica and Fasciola gigantica (liver flukes), and the genomes of Schistosoma mansoni , S. japonicum and S. haematobium (blood flukes).
Structure-based alignment of full-length amino acid sequences of putative double-domain SCP/TAPS proteins predicted from the transcriptomes of Clonorchis sinensis , Opisthorchis viverrini , Fasciola hepatica and Fasciola gigantica (liver flukes), and the genomes of Schistosoma mansoni , S. japonicum and S. haematobium (blood flukes).
A summary of the characteristics of putative single-domain SCP/TAPS predicted from the transcriptomic datasets from Clonorchis sinensis , Opisthorchis viverrini , Fasciola hepatica and F. gigantica (sequence data is available for download from http://www.gasserlab.org/ ) and from the genomic datasets from Schistosoma mansoni , S. japonicum and S. haematobium .
A summary of the characteristics of putative double(SCP-extracellular)-domain SCP/TAPS predicted from the transcriptomic datasets from Clonorchis sinensis , Opisthorchis viverrini , Fasciola hepatica and F. gigantica (sequence data is available for download from http://www.gasserlab.org/ ) and from the genomic datasets from Schistosoma mansoni , S. japonicum and S. haematobium .
The authors thank Raechel Littman for some assistance with the bioinformatic analysis of sequence data.
Conceived and designed the experiments: CC NDY RBG. Performed the experiments: CC AH RSH. Analyzed the data: CC AH UB RSH. Contributed reagents/materials/analysis tools: AH RBG. Wrote the paper: CC AH RBG AL.
- 1. Cantacessi C, Campbell BE, Visser A, Geldhof P, Nolan MJ, et al. (2009) A portrait of the “SCP/TAPS” proteins of eukaryotes – developing a framework for fundamental research and biotechnological outcomes. Biotechnol Adv 27: 376–388.C. CantacessiBE CampbellA. VisserP. GeldhofMJ Nolan2009A portrait of the “SCP/TAPS” proteins of eukaryotes – developing a framework for fundamental research and biotechnological outcomes.Biotechnol Adv27376388
- 2. Fernández C, Szyperski T, Bruyère T, Ramage P, Mösinger E, et al. (1997) NMR solution structure of the pathogenesis-related protein P14a. J Mol Biol 266: 576–593.C. FernándezT. SzyperskiT. BruyèreP. RamageE. Mösinger1997NMR solution structure of the pathogenesis-related protein P14a.J Mol Biol266576593
- 3. Jalkanen J, Huhtaniemi I, Poutanen M (2005) Mouse cysteine-rich secretory protein 4 (CRISP4): a member of the Crisp family exclusively expressed in the epididymis in an androgen-dependent manner. Biol Reprod 72: 1268–1274.J. JalkanenI. HuhtaniemiM. Poutanen2005Mouse cysteine-rich secretory protein 4 (CRISP4): a member of the Crisp family exclusively expressed in the epididymis in an androgen-dependent manner.Biol Reprod7212681274
- 4. Kasahara M, Gutknecht J, Brew K, Spurr N, Goodfellow PN (1989) Cloning and mapping of a testis-specific gene with sequence similarity to a sperm-coating glycoprotein gene. Genomics 5: 527–534.M. KasaharaJ. GutknechtK. BrewN. SpurrPN Goodfellow1989Cloning and mapping of a testis-specific gene with sequence similarity to a sperm-coating glycoprotein gene.Genomics5527534
- 5. Murphy EV, Zhang Y, Zhu W, Biggs J (1995) The human glioma pathogenesis-related protein is structurally related to plant pathogenesis-related proteins and its gene is expressed specifically in brain tumors. Gene 159: 131–135.EV MurphyY. ZhangW. ZhuJ. Biggs1995The human glioma pathogenesis-related protein is structurally related to plant pathogenesis-related proteins and its gene is expressed specifically in brain tumors.Gene159131135
- 6. Yamakawa T, Miyata S, Ogawa N, Koshikawa N, Yasumitsu H, et al. (1998) cDNA cloning of a novel trypsin inhibitor with similarity to pathogenesis-related proteins, and its frequent expression in human brain cancer cells. Biochim Biophys Acta 1395: 202–208.T. YamakawaS. MiyataN. OgawaN. KoshikawaH. Yasumitsu1998cDNA cloning of a novel trypsin inhibitor with similarity to pathogenesis-related proteins, and its frequent expression in human brain cancer cells.Biochim Biophys Acta1395202208
- 7. Rosenzweig T, Ziv-Av A, Xiang C, Lu W, Cazacu S, et al. (2006) Related to testes-specific, vespid, and pathogenesis protein-1 (RTVP-1) is overexpressed in gliomas and regulates the growth, survival, and invasion of glioma cells. Cancer Res 66: 4139–4148.T. RosenzweigA. Ziv-AvC. XiangW. LuS. Cazacu2006Related to testes-specific, vespid, and pathogenesis protein-1 (RTVP-1) is overexpressed in gliomas and regulates the growth, survival, and invasion of glioma cells.Cancer Res6641394148
- 8. Lu G, Villalba M, Coscia MR, Hoffman DR, King TP (1993) Sequence analysis and antigenic cross-reactivity of a venom allergen, antigen 5, from hornets, wasps, and yellow jackets. J Immunol 150: 2823–2830.G. LuM. VillalbaMR CosciaDR HoffmanTP King1993Sequence analysis and antigenic cross-reactivity of a venom allergen, antigen 5, from hornets, wasps, and yellow jackets.J Immunol15028232830
- 9. van Loon LC, Rep M, Pieterse CM (2006) Significance of inducible defense-related proteins in infected plants. Annu Rev Phytopathol 44: 135–162.LC van LoonM. RepCM Pieterse2006Significance of inducible defense-related proteins in infected plants.Annu Rev Phytopathol44135162
- 10. Skrjabin KI, Shikhobalova NP, Schulz RS, Popova TI, Boev SN, et al. (1991) Strongylata. In: Skrjabin KI, editor. Keys to Parasitic Nematodes. [English Translation of Opredelitel' Paraziticheskikh Nematod. Izdatel'stvo Akademii Nauk SSSR, Moscow]. Vol. 3, Amerind Publishing Co. Pvt. Ltd.. pp. 230–247.KI SkrjabinNP ShikhobalovaRS SchulzTI PopovaSN Boev1991Strongylata.KI SkrjabinKeys to Parasitic Nematodes. [English Translation of Opredelitel' Paraziticheskikh Nematod. Izdatel'stvo Akademii Nauk SSSR, Moscow]Vol. 3, Amerind Publishing Co. Pvt. Ltd.230247
- 11. Hawdon JM, Jones BF, Hoffman DR, Hotez PJ (1996) Cloning and characterization of Ancylostoma-secreted protein. A novel protein associated with the transition to parasitism by infective hookworm larvae. J Biol Chem 271: 6672–6678.JM HawdonBF JonesDR HoffmanPJ Hotez1996Cloning and characterization of Ancylostoma-secreted protein. A novel protein associated with the transition to parasitism by infective hookworm larvae.J Biol Chem27166726678
- 12. Hawdon JM, Narasimhan S, Hotez PJ (1999) Ancylostoma secreted protein 2: cloning and characterization of a second member of a family of nematode secreted proteins from Ancylostoma caninum. Mol Biochem Parasitol 99: 149–165.JM HawdonS. NarasimhanPJ Hotez1999Ancylostoma secreted protein 2: cloning and characterization of a second member of a family of nematode secreted proteins from Ancylostoma caninum.Mol Biochem Parasitol99149165
- 13. Moser JM, Freitas T, Arasu P, Gibson G (2005) Gene expression profiles associated with the transition to parasitism in Ancylostoma caninum larvae. Mol Biochem Parasitol 143: 39–48.JM MoserT. FreitasP. ArasuG. Gibson2005Gene expression profiles associated with the transition to parasitism in Ancylostoma caninum larvae.Mol Biochem Parasitol1433948
- 14. Bower MA, Constant SL, Mendez S (2008) Necator americanus: the Na-ASP-2 protein secreted by the infective larvae induces neutrophil recruitment in vivo and in vitro. Exp Parasitol 118: 569–575.MA BowerSL ConstantS. Mendez2008Necator americanus: the Na-ASP-2 protein secreted by the infective larvae induces neutrophil recruitment in vivo and in vitro.Exp Parasitol118569575
- 15. Datu BJ, Gasser RB, Nagaraj SH, Ong EK, O'Donoghue P, et al. (2008) Transcriptional changes in the hookworm, Ancylostoma caninum, during the transition from a free-living to a parasitic larva. PLoS Negl Trop Dis 2: e130.BJ DatuRB GasserSH NagarajEK OngP. O'Donoghue2008Transcriptional changes in the hookworm, Ancylostoma caninum, during the transition from a free-living to a parasitic larva.PLoS Negl Trop Dis2e130
- 16. Asojo OA, Loukas A, Inan M, Barent R, Huang J, et al. (2005) Crystallization and preliminary X-ray analysis of Na-ASP-1, a multi-domain pathogenesis-related-1 protein from the human hookworm parasite Necator americanus. Acta Crystallogr Sect F Struct Biol Cryst Commun 61: 391–394.OA AsojoA. LoukasM. InanR. BarentJ. Huang2005Crystallization and preliminary X-ray analysis of Na-ASP-1, a multi-domain pathogenesis-related-1 protein from the human hookworm parasite Necator americanus.Acta Crystallogr Sect F Struct Biol Cryst Commun61391394
- 17. Bethony J, Loukas A, Smout MJ, Brooker S, Mendez S, et al. (2005) Antibodies against a secreted protein from hookworm larvae reduce the intensity of hookworm infection in humans and vaccinated laboratory animals. FASEB J 19: 1743–1745.J. BethonyA. LoukasMJ SmoutS. BrookerS. Mendez2005Antibodies against a secreted protein from hookworm larvae reduce the intensity of hookworm infection in humans and vaccinated laboratory animals.FASEB J1917431745
- 18. Loukas A, Bethony J, Brooker S, Hotez P (2006) Hookworm vaccines: past, present, and future. Lancet Infect Dis 6: 733–741.A. LoukasJ. BethonyS. BrookerP. Hotez2006Hookworm vaccines: past, present, and future.Lancet Infect Dis6733741
- 19. Mendez S, D'Samuel A, Antoine AD, Ahn S, Hotez P (2008) Use of the air pouch model to investigate immune responses to a hookworm vaccine containing the Na-ASP-2 protein in rats. Parasite Immunol 30: 53–56.S. MendezA. D'SamuelAD AntoineS. AhnP. Hotez2008Use of the air pouch model to investigate immune responses to a hookworm vaccine containing the Na-ASP-2 protein in rats.Parasite Immunol305356
- 20. Xiao S, Zhan B, Xue J, Goud GN, Loukas A, et al. (2008) The evaluation of recombinant hookworm antigens as vaccines in hamsters (Mesocricetus auratus) challenged with human hookworm, Necator americanus. Exp Parasitol 118: 32–40.S. XiaoB. ZhanJ. XueGN GoudA. Loukas2008The evaluation of recombinant hookworm antigens as vaccines in hamsters (Mesocricetus auratus) challenged with human hookworm, Necator americanus.Exp Parasitol1183240
- 21. Chalmers IW, McArdle AJ, Coulson RM, Wagner MA, Schmid R, et al. (2008) Developmentally regulated expression, alternative splicing and distinct sub-groupings in members of the Schistosoma mansoni venom allergen-like (SmVAL) gene family. BMC Genomics 9: 89.IW ChalmersAJ McArdleRM CoulsonMA WagnerR. Schmid2008Developmentally regulated expression, alternative splicing and distinct sub-groupings in members of the Schistosoma mansoni venom allergen-like (SmVAL) gene family.BMC Genomics989
- 22. Margulies M, Egholm M, Altman WE, et al. (2005) Genome sequencing in microfabricated high-density picolitre reactors. Nature 437: 376–380.M. MarguliesM. EgholmWE Altman2005Genome sequencing in microfabricated high-density picolitre reactors.Nature437376380
- 23. Bentley DR, Balasubramanian S, Swerdlow HP, Smith GP, Milton J, et al. (2008) Accurate whole human genome sequencing using reversible terminator chemistry. Nature 456: 53–59.DR BentleyS. BalasubramanianHP SwerdlowGP SmithJ. Milton2008Accurate whole human genome sequencing using reversible terminator chemistry.Nature4565359
- 24. Harris TD, Buzby PR, Babcock H, Beer E, Bowers J, et al. (2008) Single-molecule DNA sequencing of a viral genome. Science 320: 106–109.TD HarrisPR BuzbyH. BabcockE. BeerJ. Bowers2008Single-molecule DNA sequencing of a viral genome.Science320106109
- 25. Cantacessi C, Campbell BE, Gasser RB (2011) Key strongylid nematodes of animals – impact of next-generation transcriptomics on systems biology and biotechnology. Biotechnol Adv. C. CantacessiBE CampbellRB Gasser2011Key strongylid nematodes of animals – impact of next-generation transcriptomics on systems biology and biotechnology.Biotechnol Advin press. in press.
- 26. Young ND, Campbell BE, Hall RS, Jex AR, Cantacessi C, et al. (2010) Unlocking the transcriptomes of two carcinogenic parasites, Clonorchis sinensis and Opisthorchis viverrini. PLoS Negl Trop Dis 4: e719.ND YoungBE CampbellRS HallAR JexC. Cantacessi2010Unlocking the transcriptomes of two carcinogenic parasites, Clonorchis sinensis and Opisthorchis viverrini.PLoS Negl Trop Dis4e719
- 27. Young ND, Hall RS, Jex AR, Cantacessi C, Gasser RB (2010) Elucidating the transcriptome of Fasciola hepatica – a key to fundamental and biotechnological discoveries for a neglected parasite. Biotechnol Adv 28: 222–231.ND YoungRS HallAR JexC. CantacessiRB Gasser2010Elucidating the transcriptome of Fasciola hepatica – a key to fundamental and biotechnological discoveries for a neglected parasite.Biotechnol Adv28222231
- 28. Young ND, Jex AR, Cantacessi C, Hall RS, Campbell BE, et al. (2011) A portrait of the transcriptome of the neglected trematode, Fasciola gigantica – biological and biotechnological implications. PLoS Negl Trop Dis 5: e1004.ND YoungAR JexC. CantacessiRS HallBE Campbell2011A portrait of the transcriptome of the neglected trematode, Fasciola gigantica – biological and biotechnological implications.PLoS Negl Trop Dis5e1004
- 29. Berriman M, Haas BJ, LoVerde PT, Wilson RA, Dillon GP, et al. (2009) The genome of the blood fluke Schistosoma mansoni. Nature 460: 352–358.M. BerrimanBJ HaasPT LoVerdeRA WilsonGP Dillon2009The genome of the blood fluke Schistosoma mansoni.Nature460352358
- 30. The Schistosoma japonicum Genome Sequencing and Functional Analysis Consortium (2009) The Schistosoma japonicum genome reveals features of host-parasite interplay. Nature 460: 345–351.The Schistosoma japonicum Genome Sequencing and Functional Analysis Consortium2009The Schistosoma japonicum genome reveals features of host-parasite interplay.Nature460345351
- 31. Young ND, Jex AR, Li B, Liu S, Yang L, et al. (2011) Whole genome sequence of Schistosoma haematobium. Nat Genet accepted 301011. ND YoungAR JexB. LiS. LiuL. Yang2011Whole genome sequence of Schistosoma haematobium.Nat Genet accepted 301011
- 32. Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ (1990) Basic Local Alignment Search Tool. J Mol Biol 215: 403–410.SF AltschulW. GishW. MillerEW MyersDJ Lipman1990Basic Local Alignment Search Tool.J Mol Biol215403410
- 33. Hunter S, Apweiler R, Attwood TK, Bairoch A, Bateman A, et al. (2009) InterPro: the integrative protein signature database. Nucleic Acids Res 37: D211–D215.S. HunterR. ApweilerTK AttwoodA. BairochA. Bateman2009InterPro: the integrative protein signature database.Nucleic Acids Res37D211D215
- 34. Bendtsen JD, Nielsen H, von Heijne G, Brunak S (2004) Improved prediction of signal peptides: SignalP 3.0. J Mol Biol 340: 783–795.JD BendtsenH. NielsenG. von HeijneS. Brunak2004Improved prediction of signal peptides: SignalP 3.0.J Mol Biol340783795
- 35. Chen Y, Zhang Y, Yin Y, Gao G, Li S, et al. (2005) SPD—a web based secreted protein database. Nucleic Acids Res 33: D169–D173.Y. ChenY. ZhangY. YinG. GaoS. Li2005SPD—a web based secreted protein database.Nucleic Acids Res33D169D173
- 36. Choo KH, Tan TW, Ranganathan S (2005) SPdb – a signal peptide database. BMC Bioinformatics 6: 249.KH ChooTW TanS. Ranganathan2005SPdb – a signal peptide database.BMC Bioinformatics6249
- 37. McGuffin LJ, Bryson K, Jones DT (2000) The PSIPRED protein structure prediction server. Bioinformatics 16: 404–405.LJ McGuffinK. BrysonDT Jones2000The PSIPRED protein structure prediction server.Bioinformatics16404405
- 38. Ronquist F, Huelsenbeck J (2003) MRBAYES 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19: 1572–1574.F. RonquistJ. Huelsenbeck2003MRBAYES 3: Bayesian phylogenetic inference under mixed models.Bioinformatics1915721574
- 39. Kumar S, Nei M, Dudley J, Tamura K (2008) MEGA: a biologist-centric software for evolutionary analysis of DNA and protein sequences. Brief Bioinform 9: 299–306.S. KumarM. NeiJ. DudleyK. Tamura2008MEGA: a biologist-centric software for evolutionary analysis of DNA and protein sequences.Brief Bioinform9299306
- 40. Page RD (2002) Visualizing phylogenetic trees using TreeView. Curr Protoc Bioinformatics 6: 6.2.RD Page2002Visualizing phylogenetic trees using TreeView.Curr Protoc Bioinformatics66.2
- 41. Lobley A, Sadowski MI, Jones DT (2009) pGenTHREADER and pDomTHREADER: new methods for improved protein fold recognition and superfamily discrimination. Bioinformatics 25: 1761–1767.A. LobleyMI SadowskiDT Jones2009pGenTHREADER and pDomTHREADER: new methods for improved protein fold recognition and superfamily discrimination.Bioinformatics2517611767
- 42. Sali A, Blundell T (1993) Comparative protein modelling by satisfaction of spatial restraints. J Mol Biol 234: 779–815.A. SaliT. Blundell1993Comparative protein modelling by satisfaction of spatial restraints.J Mol Biol234779815
- 43. Laskowski R, MacArthur M, Moss D, Thornton J (1993) PROCHECK: A program to check the stereochemical quality of protein structures. J Appl Cryst 26: 283–291.R. LaskowskiM. MacArthurD. MossJ. Thornton1993PROCHECK: A program to check the stereochemical quality of protein structures.J Appl Cryst26283291
- 44. DeLano W (2002) W. DeLano2002The PyMOL Molecular Graphics System (http://www.pymol.org/). The PyMOL Molecular Graphics System (http://www.pymol.org/).
- 45. Li R, Yu C, Li Y, Lam TW, Yiu SM, et al. (2009) SOAP2: an improved ultrafast tool for short read alignment. Bioinformatics 25: 1966–1967.R. LiC. YuY. LiTW LamSM Yiu2009SOAP2: an improved ultrafast tool for short read alignment.Bioinformatics2519661967
- 46. Mortazavi A, Williams BA, McCue K, Schaeffer L, Wold B (2008) Mapping and quantifying mammalian transcriptomes by RNA-seq. Nat Methods 5: 621–628.A. MortazaviBA WilliamsK. McCueL. SchaefferB. Wold2008Mapping and quantifying mammalian transcriptomes by RNA-seq.Nat Methods5621628
- 47. Zhong W, Sternberg PW (2006) Genome-wide prediction of C. elegans genetic interactions. Science 311: 1481–1484.W. ZhongPW Sternberg2006Genome-wide prediction of C. elegans genetic interactions.Science31114811484
- 48. Tsai IJ, Otto TD, Berriman M (2010) Improving draft assemblies by iterative mapping and assemblies of short reads to eliminate gaps. Genome Biol 11: R41.IJ TsaiTD OttoM. Berriman2010Improving draft assemblies by iterative mapping and assemblies of short reads to eliminate gaps.Genome Biol11R41
- 49. Eberle HB, Serrano RL, Fullekrug J, Schlosser A, Lehmann WD, et al. (2002) Identification and characterisation of a novel human plant pathogenesis-related protein that localizes to lipid-enriched microdomains in the Golgi complex. J Cell Sci 115: 827–838.HB EberleRL SerranoJ. FullekrugA. SchlosserWD Lehmann2002Identification and characterisation of a novel human plant pathogenesis-related protein that localizes to lipid-enriched microdomains in the Golgi complex.J Cell Sci115827838
- 50. Eisenberg I, Barash M, Kahan T, Mitrano-Rosenbaum S (2002) Cloning and characterization of a human novel gene C9orf19 encoding a conserved putative protein with a SCP-like extracellular protein domain. Gene 293: 141–148.I. EisenbergM. BarashT. KahanS. Mitrano-Rosenbaum2002Cloning and characterization of a human novel gene C9orf19 encoding a conserved putative protein with a SCP-like extracellular protein domain.Gene293141148
- 51. van Galen J, van Balkom BWM, Serrano RL, Kaloyanova D, Eerland R, et al. (2010) Binding of GAPR-1 to negatively charged phospholipid membranes: unusual binding characteristics to phosphatidylinositol. Mol Membrane Biol 27: 81–91.J. van GalenBWM van BalkomRL SerranoD. KaloyanovaR. Eerland2010Binding of GAPR-1 to negatively charged phospholipid membranes: unusual binding characteristics to phosphatidylinositol.Mol Membrane Biol278191
- 52. Zhan B, Liu Y, Badamchian M, Williamson A, Feng J, et al. (2003) Molecular characterisation of the Ancylostoma-secreted protein family from the adult stage of Ancylostoma caninum. Int J Parasitol 33: 897–907.B. ZhanY. LiuM. BadamchianA. WilliamsonJ. Feng2003Molecular characterisation of the Ancylostoma-secreted protein family from the adult stage of Ancylostoma caninum.Int J Parasitol33897907
- 53. Moreno Y, Geary TG (2008) Stage- and gender-specific proteomic analysis of Brugia malayi excretory-secretory products. PLoS Negl Trop Dis 2: e326.Y. MorenoTG Geary2008Stage- and gender-specific proteomic analysis of Brugia malayi excretory-secretory products.PLoS Negl Trop Dis2e326
- 54. Mulvenna J, Hamilton B, Nagaraj SH, Smyth D, Loukas A, et al. (2009) Proteomics analysis of the excretory/secretory component of the blood-feeding stage of the hookworm, Ancylostoma caninum. Mol Cell Proteomics 8: 109–121.J. MulvennaB. HamiltonSH NagarajD. SmythA. Loukas2009Proteomics analysis of the excretory/secretory component of the blood-feeding stage of the hookworm, Ancylostoma caninum.Mol Cell Proteomics8109121
- 55. Hewitson JP, Harcus Y, Murray J, van Agtmaal M, Filbey KJ, et al. (2011) Proteomic analysis of secretory products from the model gastrointestinal nematode Heligmosomoides polygyrus reveals dominance of Venom Allergen-Like (VAL). J Proteomics 74: 1573–1594.JP HewitsonY. HarcusJ. MurrayM. van AgtmaalKJ Filbey2011Proteomic analysis of secretory products from the model gastrointestinal nematode Heligmosomoides polygyrus reveals dominance of Venom Allergen-Like (VAL).J Proteomics7415731594
- 56. Chen J, Hu X, He S, Wang L, Hu D, et al. (2010) Expression and immune response analysis of Schistosoma japonicum VAL-1, a homologue of vespid venom allergens. Parasitol Res 106: 1413–1418.J. ChenX. HuS. HeL. WangD. Hu2010Expression and immune response analysis of Schistosoma japonicum VAL-1, a homologue of vespid venom allergens.Parasitol Res10614131418
- 57. Cass CL, Johnson JR, Califf LL, Xu T, Hernandez HJ, et al. (2007) Proteomic analysis of Schisosoma mansoni egg secretions. Mol Biochem Parasitol 155: 84–93.CL CassJR JohnsonLL CaliffT. XuHJ Hernandez2007Proteomic analysis of Schisosoma mansoni egg secretions.Mol Biochem Parasitol1558493
- 58. Mulvenna J, Sripa B, Brindley PJ, Gorman J, Jones MK, et al. (2010) The secreted and surface proteomes of the adult stage of the carcinogenic human liver fluke Opisthorchis viverrini. Proteomics 10: 1063–1078.J. MulvennaB. SripaPJ BrindleyJ. GormanMK Jones2010The secreted and surface proteomes of the adult stage of the carcinogenic human liver fluke Opisthorchis viverrini.Proteomics1010631078
- 59. Wu XJ, Sabat G, Brown JF, Zhang M, Taft A, et al. (2009) Proteomic analysis of Schistosoma mansoni proteins released during in vitro miracidium-to-sporocyst transformation. Mol Biochem Parasitol 164: 32–44.XJ WuG. SabatJF BrownM. ZhangA. Taft2009Proteomic analysis of Schistosoma mansoni proteins released during in vitro miracidium-to-sporocyst transformation.Mol Biochem Parasitol1643244
- 60. Curwen RS, Ashton PD, Sundaralingam S, Wilson RA (2006) Identification of novel proteases and immunomodulators in the secretions of schistosome cercariae that facilitate host entry. Mol Cell Proteomics 5: 835–844.RS CurwenPD AshtonS. SundaralingamRA Wilson2006Identification of novel proteases and immunomodulators in the secretions of schistosome cercariae that facilitate host entry.Mol Cell Proteomics5835844
- 61. Hansell E, Braschi S, Medzihradszky KF, Sajid M, Debnath M, et al. (2008) Proteomic analysis of skin invasion by blood fluke larvae. PLoS Negl Trop Dis 2: e262.E. HansellS. BraschiKF MedzihradszkyM. SajidM. Debnath2008Proteomic analysis of skin invasion by blood fluke larvae.PLoS Negl Trop Dis2e262
- 62. Robinson MW, Menon R, Donnelly SM, Dalton JP, Ranganathan S (2009) An integrated transcriptomics and proteomics analysis of the secretome of the helminth pathogen Fasciola hepatica: proteins associated with invasion and infection of the mammalian host. Mol Cell Proteomics 8: 1891–1907.MW RobinsonR. MenonSM DonnellyJP DaltonS. Ranganathan2009An integrated transcriptomics and proteomics analysis of the secretome of the helminth pathogen Fasciola hepatica: proteins associated with invasion and infection of the mammalian host.Mol Cell Proteomics818911907
- 63. Osman A, Wang CK, Winter A, Loukas A, Tribolet L, et al. (2011) Distinct sub-groupings in hookworm SCP/TAPS proteins are confirmed by the crystal structure of a novel group 2 member and suggest implications for exploring host-pathogen interactions. Biotechnol Adv. A. OsmanCK WangA. WinterA. LoukasL. Tribolet2011Distinct sub-groupings in hookworm SCP/TAPS proteins are confirmed by the crystal structure of a novel group 2 member and suggest implications for exploring host-pathogen interactions.Biotechnol Advin press. in press.
- 64. Venter JC, Adams MD, Myers EW, Li PW, Mural RJ, et al. (2001) The sequence of the human genome. Science 291: 1304–1351.JC VenterMD AdamsEW MyersPW LiRJ Mural2001The sequence of the human genome.Science29113041351
- 65. Qian W, He X, Chan E, Xu H, Zhang J (2011) Measuring the evolutionary rate of protein-protein interaction. Proc Natl Acad Sci U S A 108: 8725–8730.W. QianX. HeE. ChanH. XuJ. Zhang2011Measuring the evolutionary rate of protein-protein interaction.Proc Natl Acad Sci U S A10887258730
- 66. Gibbs GM, Roelants K, O'Bryan MK (2008) The CAP Superfamily: Cysteine-Rich Secretory Proteins, Antigen 5, and Pathogenesis-Related 1 Proteins – Roles in Reproduction, Cancer, and Immune Defence. Endocr Rev 29: 865–897.GM GibbsK. RoelantsMK O'Bryan2008The CAP Superfamily: Cysteine-Rich Secretory Proteins, Antigen 5, and Pathogenesis-Related 1 Proteins – Roles in Reproduction, Cancer, and Immune Defence.Endocr Rev29865897
- 67. Asojo OA, Goud G, Dhar K, Loukas A, Zhan B, et al. (2005) X-ray structure of Na-ASP-2, a pathogenesis-related-1 protein from the nematode parasite, Necator americanus, and a vaccine antigen for human hookworm infection. J Mol Biol 346: 801–814.OA AsojoG. GoudK. DharA. LoukasB. Zhan2005X-ray structure of Na-ASP-2, a pathogenesis-related-1 protein from the nematode parasite, Necator americanus, and a vaccine antigen for human hookworm infection.J Mol Biol346801814
- 68. Kaewkes S (2003) Taxonomy and biology of liver flukes. Acta Trop 88: 177–186.S. Kaewkes2003Taxonomy and biology of liver flukes.Acta Trop88177186
- 69. Nithikathkul C, Tesana S, Sithithaworn P, Balakanich S (2007) Early stage biliary and intrahepatic migration of Opisthorchis viverrini in the golden hamster. J Helminthol 81: 39–41.C. NithikathkulS. TesanaP. SithithawornS. Balakanich2007Early stage biliary and intrahepatic migration of Opisthorchis viverrini in the golden hamster.J Helminthol813941
- 70. Dalton JP, editor. (1999) Fasciolosis. JP Dalton1999Fasciolosis.CAB International Publishing, Wallingford, Oxon. CAB International Publishing, Wallingford, Oxon.
- 71. Hotez PJ, Zhan B, Bethony JM, Loukas A, Williamson A, et al. (2003) Progress in the development of a recombinant vaccine for human hookworm disease: the Human Hookworm Vaccine Initiative. Int J Parasitol 33: 1245–1258.PJ HotezB. ZhanJM BethonyA. LoukasA. Williamson2003Progress in the development of a recombinant vaccine for human hookworm disease: the Human Hookworm Vaccine Initiative.Int J Parasitol3312451258
- 72. Gobert GN, McManus DP, Nawaratna S, Moertel L, Mulvenna J, et al. (2009) Tissue specific profiling of females of Schistosoma japonicum by integrated laser microdissection microscopy and microarray analysis. PLoS Negl Trop Dis 3: e469.GN GobertDP McManusS. NawaratnaL. MoertelJ. Mulvenna2009Tissue specific profiling of females of Schistosoma japonicum by integrated laser microdissection microscopy and microarray analysis.PLoS Negl Trop Dis3e469
- 73. Rich T, Chen P, Furman F, Huynh N, Israel MA (1996) RTVP-1, a novel human gene with sequence similarity to genes of diverse species, is expressed in tumor cell lines of glial but not neuronal origin. Gene 180: 125–130.T. RichP. ChenF. FurmanN. HuynhMA Israel1996RTVP-1, a novel human gene with sequence similarity to genes of diverse species, is expressed in tumor cell lines of glial but not neuronal origin.Gene180125130
- 74. WHO (1995) Control of foodborne trematode infections. Report of a WHO Study Group. World Health Organization Technical Report Series 849: 1–157.WHO1995Control of foodborne trematode infections. Report of a WHO Study Group.World Health Organization Technical Report Series8491157
- 75. Bouvard V, Baan R, Straif K, Grosse Y, Secretan B, et al. (2009) A review of human carcinogens-Part B: biological agents. Lancet Oncol 10: 321–322.V. BouvardR. BaanK. StraifY. GrosseB. Secretan2009A review of human carcinogens-Part B: biological agents.Lancet Oncol10321322
- 76. Lewis F, Coligan JE, Kruisbeek AM, Margulies DH, Shevach EM, Strober W, editors. (1998) Current Protocols in Immunology. Suppl 28. Schistosomiasis. F. LewisJE ColiganAM KruisbeekDH MarguliesEM ShevachW. Strober1998Current Protocols in Immunology. Suppl 28. SchistosomiasisAnimal Models for Infectious Diseases. Wiley; New York. Animal Models for Infectious Diseases. Wiley; New York.
- 77. Mann VH, Morales ME, Rinaldi G, Brindley PJ (2010) Culture for genetic manipulation of developmental stages of Schistosoma mansoni. Parasitology 137: 451–462.VH MannME MoralesG. RinaldiPJ Brindley2010Culture for genetic manipulation of developmental stages of Schistosoma mansoni.Parasitology137451462
- 78. Kalinna B, Brindley PJ (2007) Manipulating the manipulators: advances in parasitic helminth transgenesis and RNAi. Trends Parasitol 23: 197–204.B. KalinnaPJ Brindley2007Manipulating the manipulators: advances in parasitic helminth transgenesis and RNAi.Trends Parasitol23197204
- 79. Tchoubrieva E, Kalinna B (2010) Advances in mRNA silencing and transgene expression: a gateway to functional genomics in schistosomes. Biotechnol Genet Eng Rev 26: 261–280.E. TchoubrievaB. Kalinna2010Advances in mRNA silencing and transgene expression: a gateway to functional genomics in schistosomes.Biotechnol Genet Eng Rev26261280
- 80. Hagen J, Lee EF, Fairlie WD, Kalinna BH (2011) Functional genomics approaches in parasitic helminths. Parasite Immunol. J. HagenEF LeeWD FairlieBH Kalinna2011Functional genomics approaches in parasitic helminths.Parasite Immunolin press. in press.