Researchers have discovered a human antibody that has prevented malaria when used in mice.
The antibody, known as CIS43, provided protection by binding to a specific portion of a surface protein called the circumsporozoite protein, or CSP, that is found in nearly all malaria strains.
The antibody's protective effect and the discovery of the new binding site could have important implications for efforts to create a vaccine and prevent the disease in humans as well.
"This is an antibody that was isolated, which was a human antibody we know can protect in vivo, so it could be used for prophylaxis to give this antibody passively and to protect people," Marie Pancera, PhD, a structural biologist at the Fred Hutchinson Cancer Research Center and co-author of the study, told Drug Topics.
The study into using the CIS43 human antibody in mice was a joint effort between the Fred Hutchinson Cancer Research Center and NIH's National Institute of Allergy and Infectious Diseases.
A vaccine against malaria that is in development, known as RTS,S, uses a truncated version of CSP, but doesn't include the binding site discovered in this study. This new finding opens the door for new possibilities in vaccine design.
"Probably for the next generation that region at least should be included in a vaccine because it does induce a good immune response," Pancera said.
The current RTS,S vaccine has been found to protect about a third of the children who receive it, according to a statement that announced these findings.
Pancera said while the RTS,S vaccine—which will be in pilot studies soon in areas of Ghana, Kenya, and Malawi—has been found to provide some protection, it has issues with durability.
"The idea here is to try to improve upon that vaccine," Pancera said.
Other malaria prevention strategies include insecticides, mosquito bed nets, and preventative malaria drugs which must be taken daily. Despite these efforts, malaria continues to be significant world health concern. In 2016, it was estimated that malaria was responsible for 216 million clinical episodes across the world and 445,000 deaths, according to the World Health Organization.
Researchers in the CIS43 study isolated the antibody in the blood of a human volunteer who had received an earlier experimental vaccine, PfSPZ Vaccine-Sanaria, made from malaria parasites and who did not become infected after being exposed to the disease. They tested the antibody's protective effect using two different mice models and found CIS43 provided protection for the study subjects.
Further testing into its implications and its safety in humans is still needed before its efficacy can be fully assessed in a human population. The NIAID Vaccine Research Center plans to begin controlled human malaria infection challenge trials next year, according to an NIH statement.