University of South Florida researchers say they have discovered a previously unknown vulnerability in Plasmodium vivax, a malaria parasite that infects millions of people in Central and South America and Southeast Asia and is the most widespread form of the parasite found outside sub-Saharan Africa. The findings, published in the journal Immunity, identify a specific site on the parasite that antibodies can target to block it from invading liver cells — potentially stopping the parasite from establishing the dormant form that allows malaria to return months or even years after the initial infection, according to Mirage News.
Researchers Identify New Weakness in Malaria Parasite
Targeting a 40-Year-Old Blind Spot
Noah Sather, a professor in USF’s College of Public Health Department of Global, Environmental and Genomic Health Sciences, said no one had found a new way to target the parasite’s major surface antigen, known as circumsporozoite protein or CSP, in more than 40 years. This is truly a game-changing, paradigm-shifting discovery,
Sather said.
Sather and USF researcher John Adams identified a previously uncharacterized epitope — a specific region of the CSP antigen that can be recognized by antibodies. Their research showed that antibodies targeting this newly identified site can block P. vivax from infecting the liver, an outcome that matters because the parasite can establish dormant liver-stage forms that persist long after the initial infection before later reactivating and causing repeated bouts of malaria.
Why Relapse Infections Matter
According to Sather, roughly three-quarters of P. vivax transmissions come from relapse infections rather than from the initial mosquito bite. Our vaccine and our antibodies can prevent the formation of the dormant form, so this could actually tackle the major source of both transmission and disease,
Sather said, according to Mirage News. Sather compared the discovery to finding the parasite’s Achilles’ heel. We identified a new kind of gap in the armor, so to speak, that nobody knew about,
he said. We found that we can exploit that to prevent the bug from infecting.
Two Independent Studies Converge
Adams, a parasitologist, had been studying the parasite and humans’ natural immune responses, while Sather, a vaccine immunologist, was separately examining the same region at the molecular level as a possible vaccine target while still working at the University of Washington and as a principal investigator at Seattle Children’s Research Institute. Neither knew about the other’s progress until Sather visited USF while considering joining the College of Public Health’s malaria research program, according to the Business Observer. Sather was hired by USF in February. Together, our data fit together like puzzle pieces to complete a very complicated picture,
Sather said.
Local Relevance and Next Steps
The Business Observer noted that the same strand of parasite was responsible for an outbreak of seven locally-acquired malaria cases in Sarasota and Manatee counties between May and July 2023, according to the Centers for Disease Control and Prevention. The CDC said those patients were believed to have been infected within a tight, four-mile radius, and all eventually recovered.
USF officials described the discovery as an early step toward a vaccine, one that will likely take several years to complete. We're a few developmental steps away from being able to advance this into humans, but the feasibility is already established,
Sather said. Our next step is to translate this discovery into effective vaccine formulations.