Plasmodium parasite

Wikipedia

Malaria vaccine candidates that aim to eradicate the parasite worldwide rather than just control the disease are to receive more investment from a leading initiative.

The PATH Malaria Vaccine Initiative (MVI) — the main public-private partnership for developing malaria vaccines — announced that it will "invest heavily" in vaccines that prevent transmission of the Plasmodium parasite responsible for the disease and could tackle malaria on the population level.

Such vaccines produce antibodies lethal to replicating parasites. When a mosquito picks up blood from an infected, vaccinated person, it also picks up antibodies and immune cells lethal to the replicating parasites. The method has proved viable in pilot studies on humans.

The MVI will also focus on making vaccines that consist of the live parasite at the stage when it initially infects the liver -- the sporozoite stage. Producing such a vaccine is a challenge but Sanaria, a company in Maryland, United States, has reached the phase I clinical trial stage, and this will end in June 2010. As a result, the MVI intends to support a number of labs using sporozoites in a similar way.

The initiative's aim is to have next-generation vaccines more than 80 per cent effective by 2025. The best current candidate, GlaxoSmithKline Biologicals' RTS,S, has a long way to go if that goal is going to be reached — currently it is only around 50 per cent effective. Combining vaccines that target different stages of the parasite's life cycle might be the answer.

Link to full article/paper in Nature