Characterisation of protective vaccine antigens from the thiol-containing components of excretory/secretory material ofOstertagia ostertagi

Abstract

AbstractPrevious vaccination trials have demonstrated that thiol proteins affinity purified fromOstertagia ostertagiexcretory-secretory products (O. ostertagiES-thiol) are protective against homologous challenge. Here we have shown that protection induced by this vaccine was consistent across four independent vaccine-challenge experiments. Protection is associated with reduced cumulative faecal egg counts across the duration of the trials, relative to control animals. To better understand the diversity of antigens inO. ostertagiES-thiol we used high-resolution shotgun proteomics to identify 490 unique proteins in the vaccine preparation. The most numerous ES-thiol proteins, with 91 proteins identified, belong to the sperm-coating protein/Tpx/antigen 5/pathogenesis-related protein 1 (SCP/TAPS) family. This family includes previously identifiedO. ostertagivaccine antigensO. ostertagiASP-1 and ASP-2. The ES-thiol fraction also has numerous proteinases, representing three distinct classes, including: metallo-; aspartyl– and cysteine proteinases. In terms of number of family members, the M12 astacin-like metalloproteinases, with 33 proteins, are the most abundant family inO. ostertagiES-thiol. TheO. ostertagiES-thiol proteome provides a comprehensive database of proteins present in this vaccine preparation and will guide future vaccine antigen discovery projects.