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Extracellular vesicles (EVs) are protein-loaded nano-scaled particles that are extracellularly released by eukaryotes and prokaryotes. Parasite’s EVs manipulate the immune system, making them probable next-generation vaccines. Schistosomal EVs carry different proteins of promising immunizing potentials. For evaluating the immune-protective role of Schistosoma mansoni (S. mansoni) egg-derived EVs against murine schistosomiasis, EVs were isolated from cultured S. mansoni eggs by progressive sequential cooling ultra-centrifugation technique. Isolated EVs were structurally identified using transmission electron microscope and their protein was quantified by Lowry’s technique. Experimental mice were subcutaneously immunized with three doses of 20 μg EVs (with or without alum adjuvant); every two weeks, then were challenged with S. mansoni cercariae two weeks after the last immunizing dose. Six weeks post infection, mice were sacrificed for vaccine candidate assessment. EVs protective efficacy was evaluated through parasitological, histopathological, and immunological parameters. Results showed significant reduction of tegumentally deranged adult worms, hepatic and intestinal egg counts reduction by 46.58%, 93.14% and 93.17% respectively, accompanied by remarkable amelioration of sizes, numbers and histopathology of hepatic granulomata mediated by high interferon gamma (IFN γ) and antibody level. Using sera from vaccinated mice, the molecular weight of EVs’ protein components targeted by the antibody produced was recognized by western immunoblot. Results revealed two bands of ~ 14 KDa and ~ 21 KDa, proving that EVs are able to stimulate specific antibodies response. In conclusion, the present study highlighted the role of S. mansoni-egg derived EVs as a potential vaccine candidate against murine schistosomiasis mansoni.

Background: Depending mainly on Praziquantel (PZQ) for treatment of schistosomiasis poses a great challenge in terms of effectiveness and resistance. Nanoscale particles formed by metals as iron nanoparticles (INPs) have recently gained approval from the Food and Drug Administration for use as therapeutic agents. Therefore, INPs application as potential therapeutic agents against schistosomiasis may give promising results. Objective: The present study aimed at assessing the efficacy of INPs; iron oxide or magnetite INPs (MNPs) and zero-valent INPs (ZV-INPs) on S. mansoni using parasitological and histopathological parameters. Material and Methods: In the current study, MNPs and ZV-INPs were prepared by biogenic synthesis and were given to mice orally on the 42 nd day post infection (dpi) with S. mansoni in a dose of 10 mg/kg for four consecutive doses. The therapeutic efficacy was assessed using parasitological (mortality rate, adult worm load as well as female fecundity) and histopathological parameters (tissue egg count in both liver and intestine) in comparison to untreated and PZQ treated control groups. Results: Results revealed that ZV-INPs have a significant effect in decreasing both tissue egg count and hepatic granulomata size. While the MNPs have a significant effect against the total and female worms burden, tissue egg counts, female fecundity, and number of liver granuloma. Conclusion: Herein, it was concluded that both types of INPs used in the study are potentially effective anti-schistosomal agents.

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