Identification of potential protective antigens of Ostertagia ostertagi with local antibody probes

Abstract

The identification of protective helminth antigens remains the most important challenge in the development of parasitic vaccines. To identify protective antigens of Ostertagia ostertagi, an important abomasal parasite of cattle, parasite-specific local antibodies from the abomasal mucus and from the draining lymph nodes were collected from calves immunized with multiple infections and from 'primary infected' animals. With these probes, Western blots of extracts and excretion/ secretion (E/S) material from L3, L4 and adult life-stages as well as cDNA expression libraries were screened to identify antigens that were exclusively recognized by antibodies from 'immunized' calves. In the adult stage, a protein of 32 kDa was specifically detected on Western blot by mucus antibodies from 'immunized' animals. In the L3 and L4 larval stages, proteins situated in the regions of 28-29 kDa were recognized by mucus antibodies and a 59 kDa antigen was specifically recognized by lymph node antibodies from 'immunized' animals. Screening E/S material revealed no specific difference in recognition pattern between 'immunized' and 'primary infected' animals. Screening of the cDNA libraries revealed 26 relevant clones, coding for 15 proteins, among these several with potential protective capacity, immunodominant properties or functional and physiological importance e.g. metalloproteases, an aspartyl protease inhibitor and collagen.

A preliminary proteomic characterisation of extracellular vesicles released by the ovine parasitic nematode, Teladorsagia circumcincta

“…Another group of proteins, that represented 10% of the proteins identified in the EV-enriched material and have not been previously identified in exosomes of other organisms, are ‘nematode ES proteins’ ascribed no specific function on the basis of the absence of characteristic motifs in their sequences. However, TDP01869 was found to share homology with the H. contortus 15 kDa ES protein ( Schallig et al, 1997b ); HCP02856, HCP06214 and TDP00176 homologues of the T. circumcincta 20 kDa ES protein ( Nisbet et al, 2013 ); OOP00884, TDP00436 and TDP00589 homologues of the O. ostertagi ‘putative L3 ES protein’ ( De Maere et al, 2002 ); and TDP00713 homologue of the T. colubriformis 30 kDa glycoprotein ( Savin et al, 1990 ). Each of the homologous proteins ( H. contortus 15 kDa ES protein, T. circumcincta 20 kDa ES protein, O. ostertagi ‘putative L3 ES protein’ and T. colubriformis 30 kDa glycoprotein) has been described as a vaccine candidate in previous studies.…”

“…Furthermore, the T. circumcincta 20 kDa ES protein (Tci-ES20) is one of the components of the eight-protein recombinant ‘cocktail’ mentioned above ( Nisbet et al, 2013 ). The O. ostertagi ‘putative L3 ES protein’ has been proposed as potential protective antigen because it was bound by antibodies from “immune” calves ( De Maere et al, 2002 ), but it remains to be tested in an immunisation trial. Putative functions for the above proteins remain to be established; however, their involvement in several successful vaccine trials indicates their potential as valid candidates.…”

An analysis of the transcriptome of Teladorsagia circumcincta: its biological and biotechnological implications

“…SXC domains have also been identified in other helminths such as Ascaris, Brugia , Trichuris muris and Necator [88]. The function of the motif is not known but it is suggested that it is involved in protein-protein interactions, particularly those associated with nematode surfaces [89] or that it acts as a signalling ligand [90]. In general, SXC motif containing proteins have a putative secretory signal peptide and are therefore extracellular.…”

Progress in the development of a recombinant vaccine for human hookworm disease: The Human Hookworm Vaccine Initiative

“…Vaccine protection relies on the presence of high levels of anti-ASP IgE (Kooyman et al, 2000). (2) Antibodies obtained from the abomasal mucus and draining lymph nodes from calves immunized with multiple infections of Ostertagia ostertagi recognize an ASP orthologue (De Maere et al, 2002). In addition fractions of helminth antigens that protect cattle against O. ostertagi infection are enriched in single domain ASPs (Geldhof et al, 2003).…”

“…MTP-1 is an immunodominant protein and was first cloned and isolated by screening an A. caninum cDNA expression library with pooled sera from hookworm-infected individuals who harbor low worm burdens and are putatively resistant (Zhan et al, 2002a). Calves immunized with O. ostertagi L3 also recognize an MTP-1 orthologue (De Maere et al, 2002). Studies examining the vaccine potential of Ac-MTP-1 from A. caninum are under evaluation, as is an orthologue from Ancylostoma ceylanicum (see below).…”