Molecular epidemiology network for promotion and support of delivery of life vaccines against Theileria parva and Theileria annulata infection in Eastern and Northern Africa

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Tropical theileriosis (Theileria annulata) and East Coast fever (ECF, caused by T. parva) are major constraints for development of livestock where the diseases are endemic. Currently, management of theileriosis relies on chemotherapy, tick control using acaricides and to a certain degree immunization. After nearly a century of acaricide utilization, it is now clear that this alone cannot provide a sustainable solution to the control of theileriosis. Infection and treatment vaccination (ITM) for control of ECF is an alternative control method involving inoculation with live T. parva sporozoites and simultaneous treatment with a long-acting dose of oxytetracycline. The recent first successful large scale deployment of the orginal trivalent Muguga cocktail (TV) version of ITM without apparent breakthrough infections in pastoralist systems in Tanzania has renewed the desire for more extensive deployment. We are currently supporting ITM deployment by using markers for the genetic composition of stabilates comprising the TV to assess if vaccination induces a persistent, tick transmissible infection (carrier state) with foreign parasite genotpyes that could result in enhanced disease problems. We propose to continue our DFG collaboration to set the stage for wider deployment of ITM. In particular, we will address the issue of to what extent the gene pools of cattle and African buffalo-derived T. parva populations are separate, both in Tanzania and in the new target regions for deployment in Southern Sudan and Central Uganda. In addition, we also propose to bridge the host genetics gap in the development of broadly protective multi-epitope subunit vaccines against T. parva and further explore a vaccination strategy based on T. parva-infected B-lymphocytes. A live vaccine for T. annulata based on inoculation of attenuated schizont-infected leukocytes has been established in Egypt and Sudan in phase 2. The aim of the project is to: (i) ascertain whether attenuated vaccines can protect animals from tropical theileriosis under field conditions in Egypt and Sudan, (ii) assess whether attenuated vaccines can be improved by combining them with subunit vaccines, (iii) assess attenuation of candidate T. annulata culture vaccines based on the up- and down-regulation of attenuation markers identified in phase 2, (iv) achieve an evidence-based statement of the design, development and safety criteria of attenuated live vaccines.Of particular interest is the situation in Southern Sudan where we have recently demonstrated for the first time the geographical spread of T. parva towards the north of South Sudan (Marcellino et al, 2016). The latter is particular interesting since it makes South Sudan unique as the only country in the world where T. annulata and T. parva both occur and there is preliminary data suggesting co-existence in certain herds. We propose to assess the impact of this co-existence on the outcome of immunization trials.