Malaria prevention using the vaccine CIS42LS: A field trial for malaria prevention in the pyrizoites form of the P.P. parasites

Immunologist Robert Seder and malaria epidemiologist Kassoum Kayentao talk to Nature about their work and how they think the parasitic disease could be controlled in the future.

KK: Potential cost savings to our public-health systems are worth considering. The use of drugs and other health care resources needed to care for a person who becomes sick with Malaria could be reduced as a result of a vaccine that would prevent the disease.

RS: The first antibody that we isolated was CIS43, from people who had taken part in a prior vaccine trial that I had overseen. The mosquitoes deliver when they bite people are caused by a proteins in the pyrizoite form of the P.P. parasites. The sporozoites are stopped before they leave the body and reach the liver. But antibodies have a short half-life — only about 21 days — which limits their usefulness. We created a version of the LS defect, called CIS42LS. This allows the antibody to last around 60–80 days.

This is the first field trial where we have faced intense seasonal transmission. We could demonstrate protective efficacy in adults with a relatively high dose ofvenous administration. We can give a protective dose to young children by injecting them with something in the body, because the amount of antibodies is determined by the person’s weight. Our ultimate goal is to administer monoclonal antibodies subcutaneously in adults too.

Kassoum Kayentao: When it comes to certain populations, we need to use intravenous administration even if we don’t have a monoclonal Antibody that can be givenSublingually. One dose during the early stages of a pregnant woman’s health should be enough to protect her until birth.

Malaria Venture and Nagasaki University: An Emerging Market for Medicines for Malaria and Implications for Children and Families

We can continue to iterate to get greater potency, and then focus on optimizing commercial production. To ensure global equity and control costs, manufacturing facilities should be built in endemic countries.

We also have an ongoing phase II study of L9LS in children aged 5 months to 5 years in Kenya. We can compare that with seasonal transmission data from different areas, and assess the effect of giving one dose compared with two, over a year.

We are able to use antibodies with other interventions. If you have to use the antibodies every year until kids are four years old, then you should be able to wait until then to have the vaccine. I think we need to be very open minded. Over the next several years, we’ll get a good idea of what makes the most sense.

Medicines for Malaria Venture and Nagasaki University are supported by financial support from Ehime University. This Outlook is produced using funding from the Bill and Melinda Gates Foundation, GHIT Fund, and Eiken Chemical. As always, Nature retains sole responsibility for all editorial content.

A strategy was adopted by member states of the World Health Organization to reduce their mortality rates from Malaria by at least 90%. We are now at the halfway point, but the rates have hardly changed. There were nearly 250 million cases of malaria in 2021, and around 620,000 deaths.