Following the 2016 ECF Consortium annual meeting in May 2016, participants in the project drafted short blog posts about different aspects of their work related to East Coast fever (ECF) vaccine development. This post was contributed by James Nyagwange (ILRI).
The current ECF vaccine is based on the infection of the host with live sporozoites (the infective life cycle stage) and subsequent treatment with long acting oxytetracyclin (antibiotic).
Although this infection and treatment method (ITM) confers protective immunity, it has disadvantages in that it requires a liquid nitrogen cold chain for delivery and oxytetracycline (antibiotic) co-treatment making it expensive. In addition, production of the vaccine from infected ticks is laborious, and animals vaccinated by the ITM protocol remain life-long carries of the parasite. Therefore, development of an effective, affordable vaccine with minimal risks is necessary.
The partial success of subunit vaccine candidates based on sporozoite proteins give rise to the belief that sporozoite surface antigens might constitute neutralizing vaccine candidates. This milestone together with the protective immunity of whole sporozoite infection and treatment vaccination can be further built upon in order to ultimately achieve protection against ECF infection with a multivalent subunit vaccine. To aid this, a thorough assessment of the T. parva sporozoite protein composition is required so that the best candidates are identified and evaluated.
We have employed mass spectrometry to characterize the sporozoite proteins. This data provides an excellent base line on proteins expressed in T. parva sporozoites. Where as in the past researchers were dependent on predicted proteins while selecting candidate vaccine antigens, now they can be confident of expressed proteins in the sporozoites and novel antigens can now be revealed.