Our molecular test for malaria acts like a crystal ball for clinical trials and field studies it can detect infections with extremely low parasite levels which older tests can’t said Dr. Sean Murphy professor of laboratory medicine and pathology and director of the Malaria Molecular Diagnostic Lab at the University of Washington School of Medicine.

The findings, published this month in Nature Medicine highlight a study led by first author Jeff Skinner from the NIH’s National Institute of Allergy and Infectious Diseases. The team assessed an experimental monoclonal antibody designed to target Plasmodium falciparum the deadliest malaria parasite transmitted by mosquitoes from person to person.

The antibody known as CIS43LS was developed by the National Institutes of Health (NIH). It targets a surface protein on the malaria parasite, neutralizing it before it can cause infection.

To validate its effectiveness, researchers used a molecular diagnostic test during a randomized double-blind trial held in Mali, West Africa in 2021. In the study, 330 adults were first treated with antimalarial drugs to clear any existing infections. They then received either CIS43LS at doses of 40 mg/kg or 10 mg/kg or a placebo.

Participants were monitored throughout Mali’s six-month malaria season using multiple tests for infection. One of the initial methods, the thick blood smear, has been a standard malaria detection tool in clinics and research for over 100 years.

Thick blood smears involve spreading a blood sample on a slide staining it and examining it under a microscope to detect malaria parasites. Using this method, researchers found that the higher dose of the antibody reduced infection risk by 88.2%, while the lower dose lowered risk by 75% during the study.

Despite these encouraging results the thick blood smear lacks sensitivity noted Weston Staubus, a research scientist in Dr. Murphy’s Malaria Molecular Diagnostic Lab.

A blood sample typically needs about 40,000 parasites per milliliter to detect infection via smear. This means low-level infections may have gone unnoticed Staubus explained.

To verify trial results, researchers used a highly sensitive molecular test about 2,000 times more accurate than traditional blood smears that detects as few as 20 parasites per milliliter. Called the Plasmodium 18S rRNA qRT PCR assay, it targets parasite RNA with remarkable precision. Using this test, CIS43LS antibody infusions were confirmed to be 87.4% effective at the higher dose and 77% at the lower. With Gates Foundation support, efforts are underway to expand this testing through a Malaria Molecular Diagnostic Network across high-risk regions like Africa.

Source: https://newsroom.uw.edu/news-releases/molecular-test-confirms-antimalarial-antibodys-efficacy