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?

Establish the identity of suitable adjuvants for conventional (an effective antigen delivery system) and/or nucleic acid-based vaccines including an effective delivery system.

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

There is comparatively little empirical knowledge on the mechanism of action of available adjuvants
In the case of newer adjuvants, many are within the IP portfolio of animal health companies
There is a need to investment in the development of “smart adjuvants” capable of targeting the qualitative aspects of
immune responses

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

• Trial different delivery platforms
• Work with animal health companies to trial proprietary adjuvants with vaccine candidates
• Establish the immune response and protection levels generated using various combinations of antigens and adjuvants

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

Precise identity of protective immune response – Th1/Th2.
Precise Identity of protective antigens.

Existing knowledge including successes and failures

The analysis of a large number of trials carried out in both cattle and sheep by a number of groups independently has shown that it is possible to deliver protection of the order of 40-50% reduction in fluke burden. However, for unknown reasons, these results are variable, and some trials with identical protocols have not delivered protection.