Roadmap for nematode vaccine development

What are acceptable challenge models for screening of vaccine candidates e.g. in vitro vs in vivo?

• Complexities of the immune response and protection mechanisms during a trickle challenge as compared to a bolus challenge.
• Trickle challenge is better but usually doesn’t involve >1 species so different to field situation.
• Co-infection with other (potentially immunomodulatory) pathogens is usually excluded in the challenge model but will be present in field situation.
• What happens if animals are treated with anthelmintic
• Different grazing management in different regions (e.g. winter housing vs. permanent grazing) needs to be accounted for (e.g. by field trials in different management systems).

• Always performing challenge in livestock model, (avoiding/supplementing mouse models).
• Perform single and multi-species challenges but have the tools to identify species-specific responses.
• Model responses based on empirical data.
• Comprehensive analysis of all vaccine studies, successful and otherwise

• What would regulators accept in relation to minimal efficacy
• To what extent would regulatory authorities accept model data
• Understanding role of parasite strain and inherent genetic variability at population level

• Good mono-specific models established for trickle infections of Ostertagia, Cooperia, Teladorsagia, Trichostrongylus