Angiostrongilus cantonensis aspartyl protease: Epitope mapping, characterization and development of an ELISA peptide assay for specific diagnostic of angiostrongyliasis

Background: Angiostrongyliasis, the main cause universal of eosinophilic meningitis, is an emergent disease due to Angiostrongylus cantonensis (rat lungworm) larvae, transmitted accidentally to human. Actual diagnosis of human angiostrongyliasis is based on epidemiologic characteristics, clinical symptoms, medical history, and laboratory findings, in particular, hyper eosinophilia in blood and cerebrospinal fluid. Thus, the diagnosis is difficult and can be often confused with those produced by other parasitic diseases. Therefore, the development of a fast and specific diagnostic test for the angiostrongyliasis continuous a challenge mainly due to the lack of specificity of the described tests. Material and Methods: In this work, we have used a peptide microarray approach to identify single and specific epitopes of an aspartyl protease (C7BVX5-1) of the worm and synthesized octameric bi-specific epitope peptides to evaluate its performance in an ELISA-peptide assay. In addition, the protein was characterized structurally and phylogenetically using bioinformatics tools. Results: Twelve B-linear epitopes were identified, validated by ELISA and the diagnostics performance of two of them demonstrated by an ELISA-peptide. The date showed that the A. cantonensis presenilin-like presents nine transmembrane domains but is not an aspartyl protease from the A22 family and is localized in a separate subgroup along with the Haemogonchus contornus enzyme and detached from other worms subclasses. Conclusions: Our data indicate that putatively two epitopes (PsAg3 and PsAg9) cross-react with A. costaricensis and the other eight epitopes are apparently unique for A. cantonensis and could be used to develop specific immunological assay for the diagnostic of angiostrongyliasis caused by A. cantonensis.