Adapting recombinant anti-tick vaccines to livestock in Africa

Group Leader: Prof Christine Maritz-Olivier

Ticks rank second to mosquitoes as global vectors of human diseases, but are the most relevant vectors of disease-causing pathogens in domestic and wild animals. Ticks and tick borne diseases place a major constraint on livestock production throughout much of the developing world, nowhere more so than in Sub-Saharan Africa. Factors such as climate, host movement, animal husbandry practices, vector distribution and vector population changes, affect tick distribution and occurrence of tick-borne diseases.

The feasibility of vaccinating against at least one tick species, Rhipicephalus (Boophilus) microplus, has been demonstrated using the recombinant antigen Bm86 and commercially developed vaccines.

This tick species has long been considered of minor importance in most of Africa, virtually absent throughout West Africa. However, in recent years it has been found that B. microplus has spread rapidly, infesting previously unaffected regions. Moreover, it has been found that B. microplus has displaced “endemic” species, Boophilus decoloratus, throughout much of its range in eastern and southern Africa, including the Limpopo province in South Africa. Therefore, given the fecundity of this species, its adaptability to different climatic zones, efficiency as a disease vector and ability to develop pesticide resistance, the full impact of its introduction to the African continent is difficult to estimate and likely to be catastrophic in the long term. The latter necessitates the development and implimentation of effective control strategies to alleviate the increasing pressure this species places on livestock in Africa. Anti-tick vaccines offer the advantage of controlling both tick numbers and disrupting the tick vector-pathogen interface. Our group utilize cutting edge technologies (including transcriptome analysis, bioinformatics and immunoinformatics, in vivo and in situ gene silecing, molecular biology, recombiant protein expression, protein-protein interactions, and animal vaccination trials) to identify and validate protective antigens as vaccine candidates in order to lessen the socio-economical burdens associated with ticks and tick-borne pathogens.