A Game-Changer in Hookworm Infection
By: Caroline Trent-Gurbuz
Hookworm, a chronic parasitic infection primarily affecting children in poor, rural areas of the tropics, counts more than 400 million infected around the globe, but two George Washington University (GW) researchers believe they have a game-changer on their hands: a potential vaccine.
“Worldwide, [a hookworm vaccine] would be huge,” says David Diemert, MD, associate professor of microbiology, immunology, and tropical medicine at the GW School of Medicine and Health Sciences (SMHS). “A major effect, clinically, is development of iron deficiency and anemia, and that causes problems with physical and cognitive development, [which] affects school attendance and school performance. On to adulthood, it affects economic productivity, cognitive functioning, and so on. That could all be prevented if we have a vaccine.”
That’s where Diemert and Jeffrey Bethony, PhD, professor of microbiology, immunology, and tropical medicine at SMHS, come in.
The two previously completed a Phase I trial of their recombinant vaccine, during which they tested its safety with volunteers. Those volunteers were infected with hookworm to create a controlled human infection model, Bethony says. Now, with a $3 million grant from the National Institutes of Health, he and Diemert will move on to Phase II with a new set of volunteers, who will help test the vaccine’s efficacy.
“Our Phase I trials really only looked at safety and immune responses to the vaccines, and now we’re actually going to see if they’re effective at preventing infection,” Diemert says. “The way we’re going to do that is we’ll vaccinate volunteers and then deliberately challenge them with an infection of hookworm, since we’ve been developing that infection-challenge model here at GW for the past couple of years.”
The volunteers will receive three injections of the vaccine over four months. A month after the last injection, they’ll get a dose of hookworm larvae, and Diemert and Bethony will monitor them for another nine months. All told, Diemert says, Phase II should take about two years, with 48 volunteers.
While he and Bethony, along with collaborating GW researchers, are aiming to see if immunization with the vaccine leads to protection against hookworm, they also have a secondary goal: testing the effects of novel immunostimulants given with the vaccine to see if a boost to the immune system aids the vaccine’s performance. The immunostimulants, or more specifically Toll-Like Receptor immunostimulants, have never before been tested in those with hookworm infection and a boosted immune system, Bethony says.
“A lot of effort in this award is going toward determining the immune response to these novel immunostimulants,” he explains. “Our vaccine studies always attempt to add something to the general knowledge of vaccines and not just to the vaccine-pathogen being studied.”