Identification of cross-reactive markers to strengthen the development of immunodiagnostic methods for angiostrongyliasis and other parasitic infections.

Angiostrongylus cantonensis is the main causative agent of eosinophilic meningoencephalitis (EoM) in humans. Molecular diagnostic methods are essential since the identification of larvae in cerebrospinal fluid (CSF) is extremely rare. To date, the detection of a 31 kDa antigen by Western blotting has been the primary immunodiagnostic method for EoM caused by A. cantonensis. However, cross-reactivity with other parasites has been observed. Therefore, we conducted a comparative analysis using sera from individuals with angiostrongyliasis. We also characterized proteins isolated from different cellular sources of A. cantonensis, Toxocara canis, Schistosoma mansoni, and Strongyloides stercoralis with mass spectrometry. A total of 115 cross-reactive proteins were identified. Three of these proteins, heat shock protein, an intermediate filament protein, and galectin 1, represent potential markers for cross-reactivity. In addition, synthetic peptides were generated from previously identified diagnostic targets and tested against sera from individuals infected with several other parasites. As a result, two other markers of cross-reactivity were identified: peptide #4 derived from the 14-3-3 protein and peptide #12 derived from the Lec-5 protein. In contrast, 34 proteins were exclusively present in the Angiostrongylus extracts and represent promising diagnostic molecules for specific identification of A. cantonensis infection. In particular, cytochrome oxidase subunit I is of great interest as a possible immunodiagnostic target for angiostrongyliasis.