In-depth Proteomic and Glycomic Analysis of the Adult-Stage Cooperia oncophora Excretome/Secretome

Cooperia oncophora is one of the most common intestinal parasitic nematodes in cattle worldwide. To date, C. oncophora infections are treated using broad-spectrum anthelmintics. However, during the last decade reports of anthelmintic resistance in this parasite species have emerged worldwide, necessitating new avenues for its control, possibly through vaccination. In this frame we analyzed the adult-stage C. oncophora excretome/secretome (ES), covering both the protein and glycan components, since this fraction constitutes the primary interface between parasite and host and may hold potential vaccine candidates. Two-dimensional gel electrophoretic separation of the ES material enabled the MALDI-TOF mass spectrometry (MS)-directed identification of twelve distinct proteins, grouped in three separate molecular weight fractions: i) a high molecular weight fraction consisting of a double-domain activation-associated secreted protein (ASP), ii) a mid-molecular weight fraction predominantly containing a single-domain ASP, a thioredoxin peroxidase and innexin, and iii) a low molecular weight protein pool essentially holding two distinct low molecular weight antigens. Further MS-driven glycan analysis mapped a variety of N-glycans to the mid-molecular weight single-domain ASP, with Man6GlcNAc2 oligomannosyl glycans as the major species. The predominance of the non-glycosylated double-domain ASP in the high-molecular weight fraction renders it ideal for advancement towards vaccine trials and development.