Strongyloides stercoralis proteome: A reverse approach to the identification of potential immunogenic candidates
Introduction
Strongyloidiasis is an infection by Strongyloides stercoralis, an earthworm that is found in tropical and subtropical areas. Human strongyloidiasis is caused by two species of the parasitic nematode. Strongyloides, S. stercoralis being the most frequent pathogen in humans; S. Fuelleborni, found sporadically in Africa and Papua New Guinea, and S. stercoralis are affecting around 370 million people worldwide, particularly in remote rural areas [1]. It is a neglected tropical disease that can lead to severe symptoms and even death in immunosuppressed people [2].
The parasite has a complex life cycle due to the possibility of a direct and indirect development or to produce internally and externally, parasitological techniques are the common tool for the diagnosis of strongyloidiasis; the coprological testing is the normal methodology, however, the sensitivity of traditional parasitological tests is low [[3], [4], [5], [6]]. With the purpose of improving the sensitivity of the diagnostic, another alternative technique has been tested, for example, molecular methods have proved to be highly sensitive and specific for detection of parasitic agents in fecal matter; however, there are discrepancies in the reported accuracy of PCR [7]. Other tests are serological and some of them are commercially available [1]. Nevertheless, for these tests, possible cross-reactions with other parasites have been proven and crude larval antigen require some special conditions and, for that reason, the process is laborious, slow and expensive [8]. Nonetheless, purified recombinant antigens or using synthetic peptides as antigens for immunodiagnostic increase the accuracy [9,10]. In the case of detection of S. stercoralis, the incorporation of other recombinants could increase the accuracy of this method. Some authors have identified proteins from excretory/secretory (E/S) products with potential as a possible immunogen for the production of antibodies in order to detect this parasite, for example [11]; describe fatty acid binding (FAB) and fatty acid and retinol-binding (FAR) as possible new immunogen that could be considered as an alternative diagnostic tool in ELISA.
Reverse vaccinology is a methodology that uses bioinformatic tools. Studies have shown many advantages: to reduce time, to refine the number of proteins to be studied facilitating the selection process, to decrease the number of validation experiments and the possibility to synthesize peptides for immunodiagnosis leading to the development of several high sensitivity and specificity tests in recent years. For this field, different sources have been used: the genomic, proteomic, and transcriptomic datasets of pathogens [12,13,14,15]. Considering that secreted/excreted proteins could be a good target in the detection of parasites or as possible immunological compounds. Bioinformatics tools become a fast and inexpensive alternative to identify these possible immunoreactive proteins of S. stercoralis. Bearing this in mind, the selection of the target molecules was based on the analysis of their, specificity, the duration of the immune response and their ability to create immunological memory.
A pipeline of algorithms was utilized for the prediction of novel antigenic peptides from the entire proteome of S. stercoralis. From the set of 12.858 proteins, 34 proteins were predicted to be the top candidate for the design of the novel vaccines or diagnostic tests.
Section snippets
Methods
Reverse vaccinology module (RVM) incorporates sub-filters which are comprised of various efficient tools and updated databases to achieve optimal output. Each database and tool are downloaded and installed locally. BLAST searches are enabled for all the databases with defined threshold values.
Results
S. stercoralis data base in Uniprot reported 12,851 proteins which were analyzed to identify the best epitope as a possible vaccine of diagnosis protein. The first activity was to detect the location of each protein by CELLO2GO. The secreted and plasma membrane proteins were considered as a possible target; in total, the software identified 909 as extracellular and 3487 plasma membrane proteins as possible candidates. The rest, 1513 cytoplasmic proteins and proteins located inside the cell were
Discussion
Currently, a diagnosis of Strongylodiasis sp is still lacking, and the treatment presents many adverse effects. For diagnosis, the microscopic examination of stools has insufficient sensitivity; however, many molecular strategies have been implemented to increase the specificity of serological tests. Synthetic peptides and recombinant antigens (NIE) have been used to increase the specificity of serological methods such as ELISA and luciferase immunoprecipitation system (Hajighahramani et al.,
Conclusion
Reverse vaccinology modules were used to predict diagnostic or vaccinology approaches. 12.851 proteins of proteomic from Uniprot were analyzed. 34 immunogenic candidates were identified, with higher antigenic activity, less than 2 α-helices, and non-allergen and without having homology with host proteins. It is important to clarify that all of them had ortholog protein with Strongyloides ratti. Some of them presented a good binding with immunological cell (T and B cell). The methodology
Declaration of competing interest
The author declares that they have no conflict of interest.
Acknowledgement
This study was supported by a Grant from swiss government excellence scholarship for salary for postdoctoral reseracher, State Secretariat for Education, Research and Innovation SERI, Federal Commission for Scholarships for Foreign Students FCS [2017.0821, 2017].
References (53)
- et al.
Novel approaches to the diagnosis of Strongyloides stercoralis infection
Clin. Microbiol. Infect.
(2015) - et al.
Strongyloidiasis—the most neglected of the neglected tropical diseases?
Trans. R. Soc. Trop. Med. Hyg.
(2009) - et al.
Comparison between PCR and larvae visualization methods for diagnosis of Strongyloides stercoralis out of endemic area: a proposed algorithm
Acta Trop.
(2016) - et al.
Identification of universal diagnostic peptide candidates for neglected tropical diseases caused by cestodes through the integration of multi-genome-wide analyses and immunoinformatic predictions
Infect. Genet. Evol.
(2017) - et al.
Predicting transmembrane protein topology with a hiden Markov model: application to complete genomes
J. Mol. Biol.
(2001) - et al.
The mammalian pannexin family is homologous to the Invertebrate innexin gap junction proteins
Genomics
(2004) - et al.
Characterization of an Onchocerca Volvulus cDNA clone encoding a genus specific antigen present in infective larvae and adult worms
Mol. Biochem. Parasitol.
(1991) - et al.
Evaluation of a synthetic peptide from the Taenia saginata 18kDa surface/secreted oncospheral adhesion protein for serological diagnosis of bovine cysticercosis
Acta Trop.
(2016) - et al.
Structural analysis of B-cell epitopes in antibody:protein complexes
Mol. Immunol.
(2013) - et al.
Characterization of a recombinant immunodiagnostic antigen (NIE) from Strongyloides stercoralis L3-stage larvae
Mol. Biochem. Parasitol.
(2002)
Strongyloidiasis: a disease of socioeconomic disadvantage
Int. J. Environ. Res. Publ. Health
Identification and preliminary evaluation of a novel recombinant protein for serodiagnosis of strongyloidiasis
Am. J. Trop. Med. Hyg.
Prospective evaluation of enzyme-linked immunosorbent assay and immunoblot methods for the diagnosis of endemic Strongyloides stercoralis infection
Am. J. Trop. Med. Hyg.
The universal protein knowledgebase
Nucleic Acids Res.
Serology and eosinophil count in the diagnosis and management of strongyloidiasis in a non-endemic area
Am. J. Trop. Med. Hyg.
Improved diagnosis of Strongyloides stercoralis using recombinant antigen-based serologies in a community-wide study in northern Argentina
Clin. Vaccine Immunol.
A luciferase immunoprecipitation systems assay enhances the sensitivity and specificity of diagnosis of Strongyloides stercoralis infection
J. Infect. Dis.
Production of recombinant 14-3-3 protein and determination of its immunogenicity for application in serodiagnosis of strongyloidiasis
Trans. R. Soc. Trop. Med. Hyg.
Current progress of immunoinformatics approach harnessed for cellular- and antibody-dependent vaccine design
Pathog. Glob. Health
T-cell epitope vaccine design by immunoinformatics
Open Biol
Identifying novel B cell epitopes within Toxoplasma gondii GRA6
Kor. J. Parasitol.
SignalP 4.0: discriminating signal peptides from transmembrane regions
Nat. Methods
CELLO2GO: a web server for protein subCELlular LOcalization prediction with functional gene ontology annotation
PLoS One
VaxiJen: a server for prediction of protective antigens, tumour antigens and subunit vaccines
BMC Bioinf.
High-throughput prediction of protein antigenicity using protein microarray data
Bioinformatics
The HMMTOP transmembrane topology prediction server
Bioinformatics
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