An internationalist team of researchers has just successfully finished the first human trials of a new malaria vaccine. Tested on 100 West African children susceptible to malaria, the trial showed a high level of relevant antibodies a year after the vaccine was administered.
From a Howard Hughes Medical Institute press release:
Plowe [Christopher V. Plowe, MD, MPH, a professor of medicine at the University of Maryland School of Medicine] and a group of U.S. and Belgian collaborators from the Walter Reed Army Institute of Research, USAID and GlaxoSmithKline Biologicals have been developing and testing the vaccine with a large team of researchers led by Professors Ogobara K. Doumbo and Mahamadou A. Thera at the University of Bamako in Mali.
Plowe and his colleagues tested a vaccine that targets a molecule on the malaria parasite known as apical membrane antigen 1 (AMA1). The molecule sits on the surface of the merozoite form of the parasite and helps it invade red blood cells. The human immune system recognizes the presence of AMA1 molecules and generates antibodies that prevent invasion of red blood cells by the merozoites. But the body generates antibodies only after repeated exposure to malaria. If researchers could develop a vaccine that primes the immune system to recognize AMA1 before malaria infection occurs, it would be a major advance in the effort to control and eventually eradicate the disease.
In the trial, 100 healthy Malian children received either the vaccine or, as a control, a rabies vaccine. Some of the children experienced temporary pain and swelling at the site of the injections, but the effects were generally “well-tolerated,” according to Plowe.
Prior to receiving the vaccine, the children in the trial had only low levels of antibodies against AMA1 in their blood. Those antibody levels increased more than 100-fold in the children receiving the malaria vaccine and remained high during a year of follow-up blood tests.
Based on its safety profile and strong immune response, Plowe and his U.S. and Malian collaborators are now testing the vaccine in 400 children. The results of the larger trial will shed light on a key uncertainty surrounding malaria vaccines. The AMA1 molecule occurs in many different forms both within Africa and around the world, and a vaccine against some forms of the molecule may not protect against other forms.
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Full paper in PLoS ONE: Safety and Immunogenicity of an AMA1 Malaria Vaccine in Malian Children: Results of a Phase 1 Randomized Controlled Trial