What’s in SWAP? Abundance of the principal constituents in a soluble extract of Schistosoma mansoni revealed by shotgun proteomics

Abstract

BackgroundThe soluble antigen preparation of adult schistosomes (SWAP) has often been used to probe host responses against these blood-dwelling parasites. Despite its long-established use there is limited knowledge about its composition. The information we provide here on the molecular composition of SWAP may contribute as a guide for a rational selection of antigenic targets.MethodsLabel-free quantitative shotgun proteomics was employed to determine the composition and abundance of SWAP constituents. Briefly, paired adult Schistosoma mansoni worms were sonicated in PBS pH 7.2 and ultracentrifuged for recovery of the soluble supernatant. An aliquot was subjected to trypsin digestion. Resulting peptides were separated under ultra-high performance liquid chromatography and analysed using an orbitrap mass spectrometer. Spectral data were interrogated using SequestHT against an in-house S. mansoni database. Proteins were quantified by recording the mean area under curve obtained for up to three most intense detected peptides. Proteins within the 90th percentile of the total SWAP mass were categorized according to their sub-cellular/tissue location.ResultsIn this work we expanded significantly the list of known SWAP constituents. Through application of stringent criteria, a total of 633 proteins were quantitatively identified. Only 18 proteins account to 50 % of the total SWAP mass as revealed by their cumulative abundance. Among them, none is predicted as a secreted molecule reinforcing the point that SWAP is dominated by cytosolic and cytoskeletal proteins. In contrast, only 3 % of the mass comprised proteins proposed to function at the host-parasite interfaces (tegument and gut), which could conceivably represent vulnerable targets of a protective immune response. Paradoxically, at least 11 SWAP proteins, comprising ~25 % of its mass, have been tested as vaccine candidates.ConclusionsOur data suggest that use of SWAP to probe host responses has greatest value for diagnostic purposes or assessing intensity of infection. However, the preparation is of limited utility as an antigen source for investigating host responses to proteins expressed at or secreted from worm-host interfaces. The data also pose the question as to why vaccination with SWAP, containing so many proposed vaccine candidates, has no additive or even synergistic effects on the induction of protection.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0943-x) contains supplementary material, which is available to authorized users.

A potential prophylactic strategy of anti-schistosomal immunization using nanotechnology in murine models

“…Proteomic study of the adult SWAP revealed the intracellular nature of 80% of its recognized molecules, the gastrodermis and tegument which represent the major host-parasite interfaces contribute only 3% of signature proteins. This analysis supports SWAP as a good enhancer of the humoral and cell-mediated host immune responses [13] . Abdel-Zaher et al, (14) used a polyvalent vaccine including SWAP and they noticed severe changes in the adult worm tegument in the form of distortion, erosion, sloughing, and atrophy of tubercles.…”

“…In our study, we used a SWAP preparation that is used by immunologists to probe host responses to schistosome infections (13) . It has been reported to induce antibodies capable of killing the schistosomulum in vitro (41) , and to convey partial protection in vivo (42) .…”

“…SEM of S. mansoni adult worms (49 days postchallenged by schistosomiasis) are shown in figures (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Normal male and female worms and in copula were obtained from subgroup (2`) ( Figs.…”

Schistosomes Enhance Plasminogen Activation: The Role of Tegumental Enolase

“…Our inability to detect enolase activity in medium in which schistosomes were cultured for up to 48 hours demonstrates that the parasites did not secrete the enzyme nor was it released as a result of damage to the parasites in culture. This is an important point since enolase has recently been shown to be among the most abundant proteins in the schistosome cytosol [ 39 ], any damage to the worms could lead to the leakage of the enzyme from internal tissues and confound our results. No such leakage was detected.…”

Imunoproteômica aplicada ao aprimoramento do diagnóstico sorológico da estrongiloidíase humana

“…As contribuições da proteômica no estudo de parasitoses são amplas e estão relacionadas principalmente com biologia parasitária e a identificação de alvos para o aprimoramento do diagnóstico, sobretudo com o auxílio da imunoproteômica, que visa a identificação de proteínas imunogênicas principalmente por Western-blotting. Estudos proteômicos e imunoproteômicos de diversos parasitos que acometem o homem podem ser encontrados na literatura como com Leishmania spp (Matrangolo et al, 2013;Braga et al, 2014), Angiostrongylus spp (Rebello et al, 2011), Schistosoma mansoni (Castro-Borges et al, 2007;Neves et al, 2015) e Taenia solium (Victor et al, 2012;Diaz-Masmela et al, 2013).…”