Roadmap for nematode vaccine development

Generation of a protective immune response against a number of parasite species using parasite-derived (or native) proteins/glycoproteins

• Lack of a natural boosting effect from field exposure if hidden antigens are used.
• Several different antigens may be needed for each parasite species.
• The different antigens may interfere with each other e.g. enzymatic degradation/inhibition.
• Producing sufficient native parasite material for vaccine trials and commercial scale-up.
• Producing consistent vaccine batches free from adventitious agents.

• Identify antigens that are physiologically important for the parasite’s development and or survival e.g. digestive enzymes – secreted or hidden.
• Identify secreted antigens or those in extracellular vesicles that the parasite uses to modulate host responses.
• “Fractionate and vaccinate” approach has had some success (e.g. Haemonchus)

Production of sufficient quantity of native antigen for trials and/or commercial scale-up. Requires consistent source of parasite material (e.g. donor animals/abattoir collection) and efficient protein extraction and purification processes.

• Native protein prototype vaccines are being trialled/used for Haemonchus (Commercial product, Barbervax/Wirevax, launched 2014 (Smith et al., Moredun).
• A recombinant Hc23 H. contortus antigen has shown potential in sheep (Fawzi et al., 2015, Universidad Complutense de Madrid)).
• Ostertagia and Cooperia: Native ASP-based vaccines effective, recombinant subunit not (Geldhof et al., UGent)