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Schistosoma mansoni venom allergen-like proteins (SmVALs) are part of a diverse protein superfamily partitioned into two groups (group 1 and group 2). Phylogenetic analyses of group 1 SmVALs revealed that members could be segregated into subclades (A-D); these subclades share similar gene expression patterns across the parasite lifecycle and immunological cross-reactivity. Furthermore, whole-mount in situ hybridization demonstrated that the phylogenetically, transcriptionally and immunologically-related SmVAL4, 10, 18 and 19 (subclade C) were all localized to the pre-acetabular glands of immature cercariae. Our results suggest that SmVAL group 1 phylogenetic relationships, stage-specific transcriptional profiles and tissue localization are predictive of immunological cross-reactivity., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

There is currently no vaccine against schistosomiasis. With few Schistosoma vaccine candidates in clinical trials, unexplored antigens from the vulnerable schistosomulum should be considered as possible vaccine candidates. In addition, we suggest developing synthetic vesicles as a new delivery vehicle and adjuvant for immunoprophylactic schistosomula vaccine candidates., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Upon infection with Schistosoma, antibody responses are mounted that are largely directed against glycans. Over the last few years significant progress has been made in characterising the antigenic properties of N-glycans of Schistosoma mansoni. Despite also being abundantly expressed by schistosomes, much less is understood about O-glycans and antibody responses to these have not yet been systematically analysed. Antibody binding to schistosome glycans can be analysed efficiently and quantitatively using glycan microarrays, but O-glycan array construction and exploration is lagging behind because no universal O-glycanase is available, and release of O-glycans has been dependent on chemical methods. Recently, a modified hydrazinolysis method has been developed that allows the release of O-glycans with free reducing termini and limited degradation, and we applied this method to obtain O-glycans from different S. mansoni life stages. Two-dimensional HPLC separation of 2-aminobenzoic acid-labelled O-glycans generated 362 O-glycan-containing fractions that were printed on an epoxide-modified glass slide, thereby generating the first shotgun O-glycan microarray containing naturally occurring schistosome O-glycans. Monoclonal antibodies and mass spectrometry showed that the O-glycan microarray contains well-known antigenic glycan motifs as well as numerous other, potentially novel, antibody targets. Incubations of the microarrays with sera from Schistosoma-infected humans showed substantial antibody responses to O-glycans in addition to those observed to the previously investigated N- and glycosphingolipid glycans. This underlines the importance of the inclusion of these often schistosome-specific O-glycans in glycan antigen studies and indicates that O-glycans contain novel antigenic motifs that have potential for use in diagnostic methods and studies aiming at the discovery of vaccine targets., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The Schistosoma mansoni venom allergen-like (SmVAL) protein family consists of 29 members, each possessing a conserved α-β-α sandwich tertiary feature called the Sperm-coating protein/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS) domain. While the SmVALs have been found in both excretory/secretory (E/S) products and in intra/sub-tegumental (non-E/S) fractions, the role(s) of this family in host/parasite relationships or schistosome developmental processes remains poorly resolved. In order to begin quantifying SmVAL functional diversity or redundancy, dissecting the specific activity (ies) of individual family members is necessary. Towards this end, we present the characterisation of SmVAL9; a protein previously found enriched in both miracidia/sporocyst larval transformation proteins and in egg secretions. While our study confirms that SmVAL9 is indeed found in soluble egg products and miracidia/sporocyst larval transformation proteins, we find it to be maximally transcribed/translated in miracidia and subsequently down-regulated during in vitro sporocyst development. SmVAL9 localisation within sporocysts appears concentrated in parenchymal cells/vesicles as well as associated with larval germinal cells. Furthermore, we demonstrate that egg-derived SmVAL9 carries an N-linked glycan containing a schistosome-specific difucosyl element and is an immunogenic target during chronic murine schistosomiasis. Finally, we demonstrate that recombinant SmVAL9 affects the expression of extracellular matrix, remodelling matrix metalloproteinase (MMP) and tissue inhibitors of metalloproteinase (TIMP) gene products in both Biomphalaria glabrata embryonic cell (BgMMP1) and Mus musculus bone marrow-derived macrophage (MmMMP2, MmMMP9, MmMMP12, MmMMP13, MmMMP14, MmMMP28, TIMP1 and TIMP2) in vitro cultures. These findings importantly suggest that excreted/secreted SmVAL9 participates in tissue reorganisation/extracellular matrix remodelling during intra-mammalian egg translocation, miracidia infection and intra-molluscan sporocyst development/migration., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Schistosoma mansoni eggs have to cross the endothelium and intestinal wall to leave the host and continue the life cycle. Mechanisms involved in this essential step are largely unknown. Here we describe direct binding to the S. mansoni eggshell of von Willebrand factor and other plasma proteins involved in haemostasis. Using deletion-mutants, we demonstrated that it is the A1 domain of von Willebrand factor that binds to the eggshell. Our results suggest that binding of plasma proteins to the eggshell promotes binding to the endothelium, initiating the passage of the egg through the blood-vessel wall to be excreted in the end., (Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

During infection with the blood fluke Schistosoma mansoni, glycan motifs present on glycoproteins of the parasite’s eggs mediate immunomodulatory effects on the host. The recognition of these glycan motifs is primarily mediated by C-type lectin receptors on dendritic cells and other cells of the immune system. However, it is not yet known which individual glycoproteins interact with the different C-type lectin receptors, and which structural components are involved. Here we investigated the structural basis of the binding of two abundant egg antigens, kappa-5 and IPSE/a1, by the C-type lectin receptor dendritic cell-specific ICAM3-grabbing non-integrin, macrophage galactose-type lectin and mannose receptor. In the natural soluble form, the secretory egg glycoprotein IPSE/a1 interacts with dendritic cells mainly via mannose receptors. Surprisingly, in plate-based assays mannose receptors preferentially bound to mannose conjugates, while in cell-based assays, IPSE/a1 is bound via the fucosylated Galb1-4(Fuca1-3)GlcNAc (LeX) motif on diantennary N-glycans. Kappa-5, in contrast, is bound by dendritic cells viaall three C-type lectin receptors studied and for a minor part also via other, non-C-type lectin receptors.Kappa-5 interacts with macrophage galactose-type lectins via the GalNAcb1-4GlcNAc antenna present on its triantennary N-glycans, as well as the GalNAcb1-4(Fuca1-3) GlcNAc antennae present on a minor N-glycan subset. Dendritic cell-specific ICAM3-grabbing non-integrin binding of kappa-5 was mediated via the GalNAcb1-4(Fuca1-3)GlcNAc antennae, whereas binding of mannose receptors may involve either GalNAcb1-4(Fuca1-3)GlcNAc antennae or the fucosylated and xylosylated chitobiose core. This study provides a molecular and structural basis for future studies of the interaction between C-type lectin receptors and other soluble egg antigen glycoproteins and their effects on the host immune response., (2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

In schistosomiasis, the majority of symptoms of the disease is caused by the eggs that are trapped in the liver. These eggs elicit an immune reaction that leads to the formation of granulomas. The eggshell, which is a rigid insoluble structure built from cross-linked proteins, is the site of direct interaction between the egg and the immune system. However, the exact protein composition of the insoluble eggshell was previously unknown. To identify the proteins of the eggshell of Schistosoma mansoni we performed LC-MS/MS analysis, immunostaining and amino acid analysis on eggshell fragments. For this, eggshell protein skeleton was prepared by thoroughly cleaning eggshells in a four-step stripping procedure of increasing strength including urea and SDS to remove all material that is not covalently linked to the eggshell itself, but is part of the inside of the egg, such as Reynold's layer, von Lichtenberg's envelope and the miracidium. We identified 45 proteins of which the majority are non-structural proteins and non-specific for eggs, but are house-keeping proteins that are present in large quantities in worms and miracidia. Some of these proteins are known to be immunogenic, such as HSP70, GST and enolase. In addition, a number of schistosome-specific proteins with unknown function and no homology to any known annotated protein were found to be incorporated in the eggshell. Schistosome-specific glycoconjugates were also shown to be present on the eggshell protein skeleton. This study also confirmed that the putative eggshell protein p14 contributes largely to the eggshell. Together, these results give new insights into eggshell composition as well as eggshell formation. Those proteins that are present at the site and time of eggshell formation are incorporated in the cross-linked eggshell and this cross-linking does no longer occur when the miracidium starts secreting proteins., (Copyright © 2011 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

Fucosylated carbohydrate epitopes (glycotopes) expressed by larval and adult schistosomes are thought to modulate the host immune response and possibly mediate parasite evasion in intermediate and definitive hosts. While previous studies showed glycotope expression is developmentally and stage-specifically regulated, relatively little is known regarding their occurrence in miracidia and primary sporocysts. In this study, previously defined monoclonal antibodies were used in confocal laser scanning microscopy, standard epifluorescence microscopy and Western blot analyses to investigate the developmental expression of the following glycotopes in miracidia and primary sporocysts of Schistosoma mansoni: GalNAcbeta1-4GlcNAc (LDN), GalNAcbeta1-4(Fucalpha1-3)GlcNAc (LDN-F), Fucalpha1-3GalNAcbeta1-4GlcNAc (F-LDN), Fucalpha1-3GalNAcbeta1-4(Fucalpha1-3)GlcNAc (F-LDN-F), GalNAcbeta1-4(Fucalpha1-2Fucalpha1-3)GlcNAc (LDN-DF), Fucalpha1-2Fucalpha1-3GalNAcbeta1-4(Fucalpha1-2Fucalpha1-3)GlcNAc (DF-LDN-DF), Galbeta1-4(Fucalpha1-3)GlcNAc (Lewis X) and the truncated trimannosyl N-glycan Manalpha1-3(Manalpha1-6)Manbeta1-4GlcNAcbeta1-4GlcNAcbeta1-Asn (TriMan). All but Lewis X were variously expressed by miracidia and sporocysts of S. mansoni. Most notably, alpha3-fucosylated LDN (F-LDN, F-LDN-F, LDN-F) was prominently expressed on the larval surface and amongst glycoproteins released during larval transformation and early sporocyst development, possibly implying a role for these glycotopes in snail-schistosome interactions. Interestingly, Fucalpha2Fucalpha3-subsituted LDN (LDN-DF, DF-LDN-DF) and LDN-F were heterogeneously surface-expressed on individuals of a given larval population, particularly amongst miracidia. In contrast, LDN and TriMan primarily localised in internal somatic tissues and exhibited only minor surface expression. Immunoblots indicate that glycotopes occur on overlapping but distinct protein sets in both larval stages, further demonstrating the underlying complexity of schistosome glycosylation. Additionally, sharing of specific larval glycotopes with Biomphalaria glabrata suggests an evolutionary convergence of carbohydrate expression between schistosomes and their snail host.

Publication of the transcriptomes of Schistosoma mansoni and Schistosoma japonicum, in conjunction with the sequencing and assembly of their genomes, has generated a comprehensive picture of Schistosoma transcriptional and genomic diversity. Subsequently, researchers who study conjugal and developmental biology, tegumental composition and larval or egg, secretory and excretory products have used these data, in combination with the latest '-omics' technologies, to extend large-scale screens of the schistosome transcriptome, proteome and glycome. In this article, we review these postgenomic investigations and contend that the generated datasets provide a plethora of novel drug, vaccine and immunomodulatory targets that might be useful for developing new antischistosome agents.

Complex multifucosylated oligosaccharides are structural elements of glycoprotein and glycolipid subsets of larval, egg, and adult stages of Schistosoma, the parasitic worms that cause schistosomiasis, a serious disease affecting more than 200 million people in the tropics. The fucosylated structures are thought to play an important role in the immunology of schistosomiasis. Defined schistosomal oligosaccharides that enable immunological studies are difficult to obtain from natural sources. Therefore, we have chemically synthesized spacer-linked GlcNAc, Fucalpha1-3GlcNAc, Fucalpha1-2Fucalpha1-3GlcNAc, and Fucalpha1-2Fucalpha1-2Fucalpha1-3GlcNAc. This series of linear oligosaccharides was used to screen a library of anti-schistosome monoclonal antibodies by surface plasmon resonance spectroscopy. Interestingly, the reactive antibodies could be grouped according to their specificity for the different oligosaccharides tested, showing that these oligosaccharides form different immunological entities based on the number and linkage of the fucose residues. Subsequently, the thus defined monoclonal antibodies were used to visualize the expression of the corresponding oligosaccharide epitopes by adult Schistosoma mansoni worms.

Schistosoma mansoni eggs trapped in the liver of an infected host cause the major pathological manifestations of schistosomiasis. Miracidia within the deposited eggs secrete soluble egg antigens (SEA) that induce periovular granuloma formation, which may lead to severe hepatic fibrosis. Several reports have highlighted the immunomodulatory capacities of carbohydrate determinants present in the glycoproteins of SEA. These glycans contain among others the immunogenic Galbeta1-4(Fucalpha1-3)GlcNAc (LewisX) and GalNAcbeta1-4(Fucalpha1-2Fucalpha1-3)GlcNAc (LDN-DF) elements. Due to cross-reactivity with schistosomal glycan antigens, keyhole limpet haemocyanin (KLH) has been used extensively for diagnostic and therapeutic studies on schistosomiasis. In the present study, a granulomatous response with numerous eosinophils towards SEA- and KLH-coated beads implanted in the liver by mesenteric injection was observed. Immunophenotyping of these experimentally induced granulomas for cellular recruitment, chemokines, adhesion and extracellular matrix proteins revealed very close resemblance with hepatic lesions evoked by native schistosome eggs, hence demonstrating the usefulness of the bead model, in general, as well as of KLH as a model antigen to study the immunopathological mechanisms of schistosome infections. While trypsin digestion of KLH did not alter its antigenic characteristics, beads coated with SEA or KLH treated with sodium periodate to destroy the immunological properties of their carbohydrate chains, yielded only a monolayer of macrophages similar to negative control beads. Up-regulation of ICAM-1, LFA-1 and fibronectin in SEA-induced granulomas and in native and trypsinised KLH-induced granulomas indicates a major role of the carbohydrate elements of SEA and KLH in the initiation and homeostasis of the inflammatory response. These data provide new insights in the complex and multifactorial carbohydrate-dependent host-parasite immunological interactions.