Screening of antigenic vesicular fluid proteins of Echinococcus multilocularis as potential viability biomarkers to monitor drug response in alveolar echinococcosis patients

Purpose: The only drugs available to treat alveolar echinococcosis (AE) are mostly parasitostatic and in many cases prescribed for life. Decision criteria for discontinuation rely on the absence of parasitic viability. The aim of the present study is to search for candidate proteins that may exhibit good potential as biomarkers for viability. Experimental design: Sixteen serum samples (five healthy controls, 11 patients with AE), are used. AE-patients are classified into three groups ``Cured'' (n = 2), ``ABZ-responders'' (n = 4) and ``ABZ-nonresponders'' (n = 5). Immunoreactive proteins from vesicular fluid (VF) are identified and quantified by LC-MS/MS analysis after immunoprecipitation (IP) using all 16 serum samples. Results: Shotgun analysis of VF lead to the identification of 107 E. multilocularis proteins. Comparative proteomics reveal nine proteins more abundant in IP eluates from ABZ-nonresponder patients (cathepsin b, prosaposin a preprotein, actin modulator protein, fucosidase alpha L1 tissue, gluthatione-S-tranferase, beta galactosidase, elongation factor 2, H17g protein tegumental antigen, and NiemannPick C2 protein). Conclusions and clinical relevance: Detection of antibodies against these proteins by ELISA could be helpful to monitor the course of alveolar echinococcosis under albendazole (ABZ) treatment.