Australian mosquito on leaf

Vaccination validation

European Union backs Australian malaria vaccine ideas

A malaria vaccine being developed by James Cook University researcher Professor Denise Doolan could save half a million lives a year.

“Malaria is one of the oldest diseases and is probably the disease that has had the biggest effect on the human genome, by driving evolutionary changes,” says Professor Doolan. “The sickle cell trait, for example, is a genetic abnormality in the human genome that has arisen in Africa to deal with malaria.”

Despite dedicated efforts spanning half a century, a vaccine against malaria has been difficult to achieve, however, because of malaria’s complexity.

“The malaria parasite expresses more than 5,000 proteins, and theoretically any one of those could be a good target for a vaccine,” says Professor Doolan. “By contrast, if you’re looking at a virus, such as the SARS-CoV2 virus, only a handful of antigens are good targets.”

Many researchers have tried to develop vaccines based on a single protein, typically expressed on the sporozoite surface or in the blood stage of the parasite life cycle. But Professor Doolan is taking a different approach, supported by funding from the European Union and Australia’s National Health and Medical Research Council (NHMRC).

“My work focuses on the liver stage of the parasite life cycle because an effective vaccine against that stage will stop the clinical disease which occurs in the blood stage, and will stop the transmission of malaria which occurs in the subsequent sexual stage. And my approach is based on the complete genome of the parasite, to identify the set of proteins from the 5000 proteins expressed by the parasite that are the most important ones seen by the human immune system. Many of these proteins have never been studied before, so new approaches and tools are needed to discover them.  

Her vaccine would induce T cell responses against liver stage parasites, using a different arm of the human immune system to many other vaccine approaches.

“Most conventional vaccine platforms are designed to induce antibody responses, and that’s easy,” says Professor Doolan. “But that’s not what we need.”