Tampa, FL – University of South Florida researchers have identified an unknown weakness in a malaria parasite that could support development of a vaccine against recurring infections.
The discovery involves Plasmodium vivax, the most widespread malaria parasite outside sub-Saharan Africa and a major cause of illness in Central and South America and Southeast Asia.
Researchers found a previously uncharacterized epitope, or region recognized by antibodies, on the parasite’s circumsporozoite protein. Laboratory testing showed that antibodies directed at this site could prevent the parasite from invading liver cells.
Blocking liver infection is important because P. vivax can form dormant parasites that remain in the body after an initial infection. They can reactivate months or years later, causing additional malaria episodes and allowing transmission to continue.
Noah Sather, a professor in the USF College of Public Health, said relapses account for an estimated three-quarters of P. vivax transmission. A vaccine aimed at the newly identified site could potentially prevent dormant infections from becoming established.
Sather and USF researcher John Adams initially studied the parasite independently. Adams examined the parasite and naturally occurring immune responses, while Sather analyzed the same region at the molecular level as a possible vaccine target.
The researchers discovered they had identified the same vulnerability when Sather visited USF. Their findings were later combined and published in the peer-reviewed journal Immunity.
The research remains an early step. Scientists must develop a vaccine formulation and conduct additional testing before human trials can begin. Researchers estimate a usable vaccine remains several years away.
P. vivax caused seven locally acquired malaria cases in Sarasota and Manatee counties in 2023. All seven patients recovered.