A promising malaria vaccine

A promising malaria vaccine that has shown up to 90 percent protection in early studies is moving into the next phase. During a meeting in Antwerp, researchers from the European CAPTIVATE consortium, including BPRC, recently shared new results and determined the next steps.

The CAPTIVATE project is part of the portfolio of the European Vaccine Initiative (EVI) and brings together partners from across Europe, including the Biomedical Primate Research Centre (BPRC) and the Leiden University Medical Center (LUMC).

“The project meeting in Antwerp was meant to share results, but also to see each other”, says Erica Pasini, malaria researcher at BPRC and participant in the consortium. “You work intensively together for months. And then suddenly you are all in the same room. That gives energy. You notice: we are really doing this together.”

‘This work does not stop at five o’clock’

That collaboration is much needed, because the goal of CAPTIVATE, fully CorrelAtes of Protective immuniTy-driven Investigation of malaria VAccine combinaTion stratEgies, is ambitious. The aim is to develop a more effective vaccine against Plasmodium falciparum, the most deadly form of malaria. Behind that goal lie years of research. Long days, and sometimes nights in the lab. Experiments that do not always succeed the first time. Starting over, adjusting and continuing.

“This work does not stop at five o’clock”, says Erica Pasini. “A lot of time and dedication go into it. That is exactly why it is special to now see that we are really making progress.”

Attenuated variant

And that progress is there. Within the consortium, a new approach has been developed in which not only parts of the parasite are used in a vaccine, but a full, controlled and attenuated variant of the malaria parasite itself.

“After vaccination, the parasite reaches the liver, just like in a real infection”, the researcher explains. “But here is the difference: this attenuated variant is designed to stop there. It cannot develop further or multiply. This gives the immune system the opportunity to recognize and eliminate the parasite at that early stage, before it enters the bloodstream and can cause disease.”

This makes the approach fundamentally different from existing vaccines, which often use only separate components of the parasite. At present, those provide between about 30 and 75 percent protection in the field. In early studies at LUMC, this new strategy shows promising results, with protection that can reach up to 90 percent.

Closer to reality

Still, Erica Pasini is cautiously optimistic. “What works in a controlled environment does not automatically work in the field. In areas where malaria is common, we often see effectiveness decrease. We want to understand why that happens.”

This is where BPRC plays an important role. By studying the tissues of monkeys, researchers can better understand how the immune system responds and where the difference lies between lab and practice.

“We can look much deeper at what happens in the body”, says Erica. “Which immune responses are activated? Why does it sometimes work and sometimes less well? Those are the kinds of questions we are trying to answer.”

Important milestone

During the CAPTIVATE meeting, all these perspectives came together. Immunologists, physicians, engineers, parasitologists, vaccine developers, data scientists, each with their own expertise, but with the same goal in mind. And just as important: human connection.

“In between sessions you talk to each other, eat together, share experiences”, the malaria researcher says. “That is where collaboration really takes shape. Not only in presentations, but especially outside them.”

An important milestone has now been reached, Erica explains. “We succeeded in developing and producing a form of the monkey malaria parasite that stops in the liver for research. This variant resembles the malaria found in humans and gives the consortium new opportunities to make progress more quickly.”

The coming months will be important. In June, the first results of the research with monkeys are expected. We will also receive important samples that help us better understand how the immune system builds protection.

After that, new studies will follow, for example to understand how the vaccine works in people who have previously had malaria.

‘You see that all that work is leading somewhere’

Developing a vaccine takes time. Often years. But according to Erica, these are the moments that show why it is worth it. “You see that all that work is leading somewhere”, she says. “And that you are doing it together, with people from different countries, with different expertise, but with one goal. Step by step we are working towards a vaccine that can really make a difference.”