Fasciola gigantica enolase is a major component of worm tegumental fraction protective against sheep fasciolosis

A Comparative Analysis of the Protein Cargo of Extracellular Vesicles from Helminth Parasites

Helminth parasites cause debilitating-sometimes fatal-diseases in humans and animals. Despite their impact on global health, mechanisms underlying host-parasite interactions are still poorly understood. One such mechanism involves the exchange of extracellular vesicles (EVs), which are membrane-enclosed subcellular nanoparticles. To date, EV secretion has been studied in helminth parasites, including EV protein content. However, information is highly heterogeneous, since it was generated in multiple species, using varied protocols for EV isolation and data analysis. Here, we compared the protein cargo of helminth EVs to identify common markers for each taxon. For this, we integrated published proteomic data and performed a comparative analysis through an orthology approach. Overall, only three proteins were common in the EVs of the seven analyzed species. Additionally, varied repertoires of proteins with moonlighting activity, vaccine antigens, canonical and non-canonical proteins related to EV biogenesis, taxon-specific proteins of unknown function and RNA-binding proteins were observed in platyhelminth and nematode EVs. Despite the lack of consensus on EV isolation protocols and protein annotation, several proteins were shown to be consistently detected in EV preparations from organisms at different taxa levels, providing a starting point for a selective biochemical characterization.

Cloning and expression of Fasciola hepatica enolase gene and efficacy of recombinant protein in the serodiagnosis of sheep fasciolosis

Fasciolosis caused by Fasciola hepatica is a disease of zoonotic importance that is common worldwide and can cause serious problems in farm animals, some wild animals and humans. The development of diagnostic kits for the correct diagnosis of fasciolosis in sheep is important in terms of preventing yield losses. With this study, it is aimed to clone and express the enolase gene to be isolated from adult F. hepatica and to determine the effectiveness of the recombinant antigen in the serodiagnosis of sheep fasciolosis. For this aim, primers were designed to amplify the enolase gene from the F. hepatica enolase sequence, mRNA was isolated from F. hepatica adult fluke obtained from an infected sheep followed by cDNA was obtained. Enolase gene was amplified by PCR and the product was cloned and then expressed. The efficiency of the purified recombinant protein was displayed by Western blot (WB) and ELISA using positive and negative sheep sera. As a result, the sensitivity and specificity rates of the recombinant FhENO antigen were 85% and %82.8 by WB while the rates were 90% and 97.14% by ELISA, respectively. At the same time, in sheep blood sera samples collected from the Elazig and Siirt provinces of Turkey, 100 (50%) of 200 sera were found to be positive by WB and 46 (23%) were found to be positive by ELISA. The most important problem in ELISA was the high cross-reaction rate of the recombinant antigen used, as in WB. In order to prevent the cross-reactions, it will be useful to compare the genes encoding the enolase protein of parasites from the closely related parasite family, and select the regions where there are no common epitopes, and clone them and test the purified protein.

Extracellular vesicles from Fasciola gigantica induce cellular response to stress of host cells

Extracellular vesicles (EVs) from parasitic helminths play an important role in immunomodulation. However, EVs are little studied in the important parasite Fasciola gigantica. Here the ability of EVs from F. gigantica to induce cellular response to stress (reactive oxygen species generation, autophage and DNA damage response) in human intrahepatic biliary epithelial cells (HIBEC) was investigated. F. gigantica-derived EVs were isolated by ultracentrifugation, and identified with transmission electron microscopy, nanoparticle size analysis and parasite-derived EV markers. Internalization of EVs by HIBEC was determined by confocal immunofluorescence microscopy and flow cytometry. ROS levels in HIBEC were detected by molecular probing. EVs-induced autophagy and DNA-damaging effects were determined by evaluating expression levels of light chain 3B protein (LC3B), phosphor- H2A.X and phosphor-Chk1, respectively. Results revealed that EVs with sizes predominately ranging from 39 to 110 nm in diameter were abundant in adult F. gigantica and contained the parasite-derived marker proteins enolase and 14-3-3, and EVs were internalized by HIBEC. Further, uptake of EVs into HIBEC was associated with increased levels of reactive oxygen species, LC3Ⅱ, phosphor-H2A.X and phosphor-Chk1, suggesting EVs are likely to induce autophagy and DNA damage & repair processes. These results indicate F. gigantica EVs are associated with modulations of host cell responses and have a potential important role in the host-parasite interactions.

Complete Molecular and Immunoprotective Characterization of Babesia microti Enolase

The apicomplexan Babesia microti is the primary causative agent of human babesiosis, one of the most broadly distributed tick-borne diseases worldwide. B. microti undergoes a complex lifecycle within both the mammalian host and the tick vector, and employs several different specific molecular mechanisms to enter host cells. Enolase, the key glycolytic enzyme in intracellular glucose metabolism, can also be expressed on the parasite’s outer surface, binds to human plasminogen, and coordinates apicomplexan parasite invasion of host cells, however, it lacks sorting sequences or lipoprotein anchor sites. In the present study, we isolated the coding gene of B. microti enolase (BmEno), expressed it within E. coli and purified the recombinant BmEno protein (rBmEno). Consequently, we confirmed cytoplasmic and surface localization of BmEno via immunofluorescence, and demonstrated that rBmEno catalyzes the dehydration of 2-phospho-D-glycerate to phosphoenolpyruvate. Moreover, our results showed that rBmEno binds to human plasminogen, and that the lysine analog ε-aminocaproic acid significantly inhibited this binding. Furthermore plasminogen bound to rBmEno converts to active plasmin. Additionally, actively immunizing mice with rBmEno could evoke a partial protective immunity against B. microti infection following challenge. In conclusion, B. microti enolase is a multifunctional cytoplasmic protein which is also expressed at the parasitic outer surface, facilitates binding to host plasminogen, and could partially protect hosts against parasite infection.

Regulatory effects of Echinococcus multilocularis extracellular vesicles on RAW264.7 macrophages

Extracellular vesicles (EVs) play a role in intercellular communications via exchanging biological molecules, being involved in host-parasite interplay. Little is to date known about E. multilocularis EVs and their biological activities. Here spherical EVs secreted by E. multilocularis metacestodes were shown to range predominately from 34nm to 95nm in diameter. A total of 433 proteins were identified in the EVs, and the proteins involved in binding (42%) and catalytic activity (41%) were most frequently represented. Moreover, the proteins associated with EV biogenesis and trafficking, including annexin, 14-3-3, tetraspanin and heat shock protein 70kDa, were highly enriched. It was shown that the EVs remarkably suppressed NO produced by activated RAW macrophages via downregulation of inducible nitric oxide synthase expression (p <0.01). Suppression of pro-inflammatory cytokines, especially IL-1α and IL-1β, was also observed post treatment with the EVs. Conversely, increased expression of the majority (10/11) of key components involved in the LPS/TLR4 pathway was induced by the EVs. These results demonstrate a regulatory effect of E. multilocularis EVs on macrophages, suggesting a role in parasite-host interactions.