"Binding proteins and receptors are locks and keys," Zimmerman said. "If the parasite has one key and there's one lock, you may be able to block that. But if it has more keys and there are more locks, there are multiple ways in."
The researchers say the duplication may be a cause of the growing infections among Duffy negative people, but it's too early to tell.
Zimmerman, Serre and colleagues aim to find the answer with the newly-funded research project. They'll begin by studying blood samples taken from 1,500 patients at each of two locations in Madagascar.
They and colleagues have great concern that a loss of resistance to P. vivax infection will now enable the parasite to travel the 250 miles across the Mozambique Channel to Africa. There, falciparum malaria is wrecking havoc on a population that has for the most part lived P. vivax-free. In some regions of the continent, 100 percent of the population is Duffy negative.
The researchers will conduct similar studies on P. vivax carrying the new proteins, in samples taken from Asia, Africa and South America.
In addition to studying patients, they plan to study the mutated parasites in the lab. Parasites that live a day or two could have enough time to invade new blood cells, but not many. Brian Grimburg, assistant professor of international health at the Case Western Reserve School of Medicine, is developing a scanning process that will enable the team to look through millions of red blood cells in a few minutes and spot newly infected cells. They will test the parasites in Duffy negative and Duffy positive red cells.
Zimmerman and Serre believe the work could help lead to a vaccinethat's the overall goal. The mechanisms P. vivax uses to attach and enter a cell could be targets.
|Contact: Kevin Mayhood|
Case Western Reserve University