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Abstract: Inspection of the nucleotide sequence of bacterial artificial chromosome number 49_J_14 [Le Paslier, M.C., Pierce, R.J., Merlin, F., Hirai, H., Wu, W., Williams, D.L., Johnston, D., LoVerde, P.T., Le Paslier, D., 2000. Construction and characterization of a Schistosoma mansoni bacterial artificial chromosome library. Genomics 65, 87–94] from chromosome 1 of the genome of Schistosoma mansoni (GenBank AC093105) revealed the likely presence of a proviral form of a novel schistosome retrotransposon. The novel element, which we named the fugitive, belonged to the mag-like family of the gypsy-Ty3 clade of long terminal repeat retrotransposons. It was closely related to the mag-like retrotransposon Gulliver from Schistosoma japonicum, but was dissimilar to several other long terminal repeat retrotransposons known from S. mansoni including Boudicca, Saci-1, Saci-2 and Saci-3. The full length fugitive element was 4811bp constituted of a single read-through open reading frame of 4134bp flanked at both ends by identical long terminal repeat sequences of 273bp. The open reading frame encoded retroviral-like gag, with a distinctive double Cys–His motif, and pol polyprotein, with a pol domain order of protease, reverse transcriptase, RNaseH and integrase. Examination of schistosome transcriptome sequences in the public domain revealed that the fugitive was transcribed in at least six developmental stages of S. mansoni, while bioinformatics approaches and Southern hybridisation analysis indicated that as many as 2000 copies of the fugitive were interspersed throughout the schistosome genome. [Copyright &y& Elsevier]

• Schistosoma mansoni secreted extracellular vesicles (EVs) are internalised by human endothelial and monocyte cell lines. • Internalisation of EVs induces differential gene expression in vascular endothelial cells. • Differentially expressed genes are involved in intravascular parasitism pathways including coagulation and inflammation. • Antibodies raised to S. mansoni EV tetraspanins block the uptake of vesicles by host endothelial and monocyte cell lines. The ability of the parasitic blood fluke Schistosoma mansoni and other parasitic helminths to manipulate host biology is well recognised, but the mechanisms that underpin these phenomena are not well understood. An emerging paradigm is that helminths transfer their biological cargo to host cells by secretion of extracellular vesicles (EVs). Herein, we show that two populations of S. mansoni secreted EVs – exosome-like vesicles (ELVs) and microvesicles (MVs) – are actively internalised in two distinct human cell lines that reflect the resident cell types encountered by the parasite in vivo: human umbilical vein endothelial cells (HUVECs) and THP-1 monocytes. RNA-sequencing of HUVECs co-cultured with S. mansoni ELVs compared with untreated HUVECs revealed differential expression of genes associated with intravascular parasitism, including vascular endothelial contraction, coagulation, arachidonic acid metabolism and immune cell trafficking and signalling. Finally, we show that antibodies raised against recombinant tetraspanin (TSP) proteins from the surface of S. mansoni EVs significantly blocked EV uptake by both HUVECs and THP-1 monocytes whereas pre-immunisation antibodies did not. To our knowledge, this is the first evidence demonstrating the internalisation of secreted EVs from any helminth into vascular endothelial cells, providing novel insight into the potential mechanisms underlying host-schistosome interactions. The ability of anti-TSP antibodies to block vesicle uptake by host target cells further supports the potential of TSPs as promising antigens for an anti-fluke vaccine. It also suggests a potential mechanism whereby the current candidate human schistosomiasis vaccine, Sm -TSP-2, exerts its protective effect in animal models. [ABSTRACT FROM AUTHOR]

A proteome microarray consisting of 992 Schistosoma mansoni proteins was produced and screened with sera to determine antibody signatures indicative of the clinical stages of schistosomiasis and the identification of subunit vaccine candidates. Herein, we describe the methods used to derive the gene list for this array (representing approximately 10% of the predicted S. mansoni proteome). We also probed a pilot version of the microarray with sera from individuals either acutely or chronically infected with S. mansoni from endemic areas in Brazil and sera from individuals resident outside the endemic area (USA) to determine if the array is functional and informative. [ABSTRACT FROM AUTHOR]

Herein we show for the first time that Schistosoma mansoni adult worms secrete exosome-like extracellular vesicles ranging from 50 to 130 nm in size. Extracellular vesicles were collected from the excretory/secretory products of cultured adult flukes and purified by Optiprep density gradient, resulting in highly pure extracellular vesicle preparations as confirmed by transmission electron microscopy and Nanosight tracking analysis. Extracellular vesicle proteomic analysis showed numerous known vaccine candidates, potential virulence factors and molecules implicated in feeding. These findings provide new avenues for the exploration of host–schistosome interactions and offer a potential mechanism by which some vaccine antigens exert their protective efficacy. [ABSTRACT FROM AUTHOR]

The tegument of Schistosoma mansoni plays an integral role in host–parasite interactions, particularly during the transition from the free-living cercariae to the intra-mammalian schistosomula stages. This developmental period is characterised by the transition from a trilaminate surface to a heptalaminate tegument that plays key roles in immune evasion, nutrition and excretion. Proteins exposed at the surface membranes of newly transformed schistosomula are therefore thought to be prime targets for the development of new vaccines and drugs for schistosomiasis. Using a combination of tegumental labelling and high-throughput quantitative proteomics, more than 450 proteins were identified on the apical membrane of S. mansoni schistosomula, of which 200 had significantly regulated expression profiles at different stages of schistosomula development in vitro, including glucose transporters, sterols, heat shock proteins, antioxidant enzymes and peptidases. Current vaccine antigens were identified on the apical membrane ( Sm -TSP-1, calpain) or sub-tegumental ( Sm -TSP-2, Sm 29) fractions of the schistosomula, displaying localisation patterns that, in some cases, differ from that in the adult stage fluke. This work provides the first known in-depth proteomic analysis of the surface-exposed proteins in the schistosomula tegument, and some of the proteins identified are clear targets for the generation of new vaccines and drugs against schistosomiasis. [ABSTRACT FROM AUTHOR]

Highlights: [•] Schistosome septins assemble into complexes and higher-order structures, including filaments and rings. [•] Polymerization of schistosome septins hastened in forchlorfenuron (FCF), a phenylurea cytokinin. [•] FCF led to a striking paralysis phenotype in cercariae and adult schistosomes. [•] The paralysis was reversible, but FCF dose- and time-dependent. [ABSTRACT FROM AUTHOR]