Roadmap for the development of candidate vaccines for liver fluke

What are we trying to achieve and why? What is the problem we are trying to solve?

• What are acceptable challenge models for screening of vaccine candidates
• Will we obtain different results with bolus as compared with trickle infections?

What are the scientific and technological challenges (knowledge gaps needing to be addressed)?

• Is there a difference in the vaccine response to trickle (field) and bolus challenges
• Can we predict differences in vaccine protection based on fluke strain
• Is there a non-challenge proxy for estimating protective capacity

What approaches could/should be taken to address the research question?

Meta-analysis of previous trials used in an attempt to determine and standardise the optimum vaccine challenge model

What else needs to be done before we can solve this need?

• What would regulators accept in relation to minimal efficacy
• Understand the contribution of fluke genetic variability on protection following vaccination

Existing knowledge including successes and failures

Protective effect has been observed using both trickle, and bolus, challenge models to date. The same is true for non-protective trials