This cattle‐specific vaccine delivery system can readily deliver and express antigens against a range of diseases that affect cattle, offering the potential to provide long term immunity and protection. It can also be used to deliver therapeutic proteins to improve productivity in cattle.
Human health is intimately linked to animal health through the impact of infectious agents on livestock productivity and their potential for zoonosis. A major source of zoonotic infections is cattle which threaten human health through their capacity to transmit bacterial infections including E. coli, Salmonella, Campylobacter, Brucella and Mycobacteria. The use of vaccines is a well-established method of improving animal health and welfare and controlling zoonoses. Although subunit vaccines are considered safer than conventional attenuated or inactivated ones, they have a number of disadvantages including low levels of immunogenicity; the need to use strong adjuvants; and, typically, a requirement for repeat dosing.
Most cattle are infected with the parasite Trypanosoma theileri (T. theileri); however, it causes no ill effects. University of Edinburgh researchers have engineered this parasite to express ‘foreign’ molecules, i.e. immunogenic antigens from diseases that cause severe infections in cattle. When these recombinant parasites are introduced into cattle they express steady sustained levels of antigen in the bloodstream producing a sustained immune response over time without the need for vaccine boosters. This system is flexible and can be adapted to deliver multiple antigens against a single host, or cocktails of antigens against a range of different pathogens.
Using versions of T. theileri expressing antigen at different stages of the parasite life cycle we have demonstrated that antigen secreted into the bloodstream generates the highest antibody response. Additionally, the antigen is expressed at levels safe and sustainable for 12 weeks post-inoculation, at levels at least equivalent to those reported for conventional prime-boost immunisation strategy using the same antigen, and antigen-specific antibodies are generated.
Please note, the header image is purely illustrative.