Abstract
The S. mansoni adult worm n-butanol extract (Sm-AWBE) has been previously shown to contain specific S. mansoni antigens that have been used for immunodiagnosis of schistosomiasis in solid phase alkaline phosphatase immunoassay (APIA) and western blot (WB) analyses. Sm-AWBE was also used in immunoprotection studies against a fatal live-cercariae challenge in experimental mouse vaccination (~43% protection). The Sm-AWBE fraction was prepared by mixing adult worm membranous suspensions with aqueous-saturated n-butanol, centrifuging and recovering n-butanol-resistant proteins in the aqueous phase. Here we report a preliminary identification of Sm-AWBE protein components as revealed from a qualitative proteomic study after processing Sm-AWBE by 1D-gel electrophoresis, in-gel and in-solution tryptic digestions, and mass spectrometry analyses. We identified 33 proteins in Sm-AWBE, all previously known S. mansoni proteins and antigens; among them, immunomodulatory proteins and proteins mostly involved in host–parasite interactions. About 81.8% of the identified Sm-AWBE proteins are antigenic. STRING analysis showed a set of Sm-AWBE proteins configuring a small network of interactive proteins and a group of proteins without interactions. Functional groups of proteins included muscle contraction, antioxidant, GPI-anchored phosphoesterases, regulatory 14-3-3, various enzymes and stress proteins. The results widen the possibilities to design novel antigen combinations for better diagnostic and immunoprotective strategies for schistosomiasis control.
Highlights
The S. mansoni tegument, gut and extracellular vesicles are host–parasite interfaces where key parasite proteins can be targets for drug and immunological attacks [1], as well as representing candidates for S. mansoni diagnostic and vaccination [2]
Electrophoretic, and western blot (WB) studies [3,4], we know that Sm-AWBE contains a mixture of enzymes, proteins and glycoproteins that have for long served as a source of very specific S. mansoni antigens for use in solid-phase alkaline phosphatase enzyme immunoassay (APIA) [3] and WB (4) diagnostic surveys in low endemic schistosomiasis regions of South America and the Caribbean [3,4,5,6]
Sm-AWBE Proteins Identified from the In-Gel and In-Solution Digestions
Summary
The S. mansoni tegument, gut and extracellular vesicles are host–parasite interfaces where key parasite proteins can be targets for drug and immunological attacks [1], as well as representing candidates for S. mansoni diagnostic and vaccination [2]. Electrophoretic, and western blot (WB) studies [3,4], we know that Sm-AWBE contains a mixture of enzymes, proteins and glycoproteins that have for long served as a source of very specific S. mansoni antigens for use in solid-phase alkaline phosphatase enzyme immunoassay (APIA) [3] and WB (4) diagnostic surveys in low endemic schistosomiasis regions of South America and the Caribbean [3,4,5,6]. Proteins resisting denaturation to organic solvents or detergents have particular molecular structures, 3D-conformations, or both, which make them insensitive to the action of those chemicals [8], such as proteins harboring long coil stretches (chaperones and stress proteins, etc.), highly glycosylated proteins (glycoproteins and proteoglycans) and GPI-anchored membrane proteins, etc. Typical n-butanol extracted proteins include GPI-anchored membrane parasite enzymes such as alkaline phosphatase (SmAP) [10,11,12]
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