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| Image Credits - Alpha Tauri 3D Animation |
There are already some drugs that can temporarily protect people from P. falciparum. Many travelers that travels to malaria-plagued regions take them. The drugs are also used in some populations who live in regions with malaria seasons, which are typically linked to rain and an explosion of mosquito populations. But these are not effective ones that can protect properly from malaria. P. falciparum still sickens at least 200 million people a year and kills an estimated 400,000.
The preventive antibody binds to a small portion of the circumsporozoite protein (CSP) that studs the surface of the sporozoites that causes malaria. “It’s the first study that actually assesses the potency of an antibody against the CSP target in humans,” says Hedda Wardemann, an immunologist who studies antimalarial antibodies at the German Cancer Research Center. Researchers followed some antibody production and testing steps-
Isolation of CSP antibody:
A research team first isolated the CSP antibody against P. falciparum from a person who received an experimental malaria vaccine. Hopping between mosquitoes and people, the parasite has a complex, multistage life cycle and the antibody blocks sporozoites from infecting liver cells, where they would mature into another form that can destroy red blood cells and cause disease.
Production of modified antibodies:
The team, led by immunologist Robert Seder of the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases, then engineered Chinese hamster ovary cells to churn out mass quantities of a version of the antibody modified to more than double the time it can persist in the body before being degraded.
Testing on people:
In the proof-of-principle study, the team gave infusions of the antibody to people and then allowed mosquitoes carrying P. falciparum to feed on their arms. None receiving the antibody in this “challenge” trial had detectable blood levels of the parasite, whereas five of six people in an untreated control group did, the research team reports in The New England Journal of Medicine.
Benifits of Monoclonal antibodies against malaria:
Seder envisions that travelers, people in the military, or health care workers visiting malarial regions for prolonged periods would receive monoclonal antibodies—which companies can produce in bulk. Ideally, he says, a clinic would administer a relatively low dose of the antibodies with a subcutaneous injection, a much easier and cheaper option than the relatively high doses that this study gave via infusions into the bloodstream.
A more ambitious use of antimalarial monoclonals would administer them in geographic regions that have a high burden of the disease. The antibodies might prove especially helpful to children, as they have not had time to develop much natural immunity, and to pregnant women, who are at increased risk of severe disease from a P. falciparum infection. Seder recognizes that people who are repeatedly exposed to P. falciparum develop complicated immune responses to the parasite, which have compromised experimental malaria vaccines that worked well in clinical trials of unexposed people.
Wardemann says monoclonals ultimately might contribute to a multipronged elimination strategy. “I doubt that an antibody alone will do it,” she says. “No single measure has done it so far.” Bed nets, drugs, and vaccines have contributed to suppressing malaria in some locations. “An antibody on top may help,” she says.
- Material provided by Sciencemag.
- A Monoclonal antibody for Malaria Prevention Journal
