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Virus Profilers Race To Figure Out What Makes Zika Tick

While some scientists seek ways to stop the spread of Zika by mosquitoes, others have received new funding from the National Institutes of Health to track the genes and habits of the virus itself.
Felipe Dana
While some scientists seek ways to stop the spread of Zika by mosquitoes, others have received new funding from the National Institutes of Health to track the genes and habits of the virus itself.

When Carolyn Coyne's lab at the University of Pittsburgh recently tried to order a sample of Zika virus from a major laboratory supplier, they were told it was out of stock.

"They are actually back-ordered until July for the virus," Coyne says. "At least that's what we were told." She ended up obtaining Zika from another source, and it arrived at her lab Tuesday.

She's just one of a growing number of lab researchers who are racing to investigate Zika virus in the wake of reports that it may be linked to some cases of microcephaly, the birth defect that leaves babies with small heads and brains.

Zika virus was discovered back in 1947, but until recently, almost no one studied it. If you type "Zika" into a searchable database of grants from the National Institutes of Health, just one name pops up: Scott Weaver of the University of Texas Medical Branch in Galveston.

"I've been really working on Zika for a long time because in Africa it circulates with three other viruses that, until recently, were considered a lot more important," Weaver tells NPR.

He says really, though, those other viruses were his focus — his lab did very little with Zika, which was thought to cause a mild illness, if any. But everything changed last fall, when Weaver went to a conference and heard the shocking news that Zika might be linked to microcephaly.

"Most of our work now is on Zika," Weaver says. "We really shifted dramatically and ramped up our efforts."

His university has a collection of mosquito-borne viruses that it provides to other labs, on request — and he says requests for Zika are pouring in.

Scott Weaver, of the University of Texas Medical Branch, was one of only a few scientists studying Zika before the latest outbreak in Latin America.
/ Courtesy of University of Texas Medical Branch
Courtesy of University of Texas Medical Branch
Scott Weaver, of the University of Texas Medical Branch, was one of only a few scientists studying Zika before the latest outbreak in Latin America.

"Probably a year ago, for Zika we would have gotten one or two requests in a whole year," says Weaver. "Now we're getting several each day." Every week, he and his colleagues have been shipping out dozens of Zika samples to labs around the world.

What's more, government officials have been reaching out to virologists who study pathogens that are closely related to Zika, offering extra funding and support for any work on Zika, says Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

Fauci explains they can do this by just supplementing researchers' existing grants. "There's a limited amount of money that you can do on a supplement," says Fauci, "but enough to get people started quickly."

One of the scientists contacted by the NIH is Dr. Michael Diamond, an infectious disease specialist at Washington University in St. Louis.

"This is one of the few times that I have been an investigator when the NIH has called me," says Diamond, noting that it usually works the other way around.

"We need vaccines, we need therapies, we need diagnostics," says Diamond. "We need to know how this virus works."

In addition to trying to create Zika-specific antibodies that could be used for better diagnostic tests or even potentially as a treatment, his lab has been trying to find a way to recreate in a lab animal the same signs and symptoms the virus produces in humans.

"There really hadn't been any work done in about 40 years on Zika virus in animals," says Diamond.

Typically, adult mice don't get sick from Zika, he says, but he and his colleagues are trying it in different kinds of mice, using different viral strains in different doses.

Scientists also have been looking at the Zika virus itself — to see if it has mutated in any way that could explain this large, unusual outbreak among people.

"The thing about working with Zika virus is that almost everything is a big unknown," says Helen Lazear, who studies Zika at the University of North Carolina at Chapel Hill.

Scientists in Brazil have sequenced the genes of Zika viruses circulating there, she says, so that they can be compared to Zika viruses collected earlier around the world.

"There are some differences in the sequence between the viruses," Lazear says, "but we don't know if that's just a chance variation in the sequence, or if this is something that impacts disease. We're working on having the systems in place to test that."

And then, of course, there's the big scientific question everyone wants answered: What exactly is the link between Zika and birth defects? After all, that's the main driver of all this attention and concern.

Epidemiologists in Brazil are still trying to nail down the nature of that link and consider other factors that might be involved, but lab researchers are on the case, too.

"This is one of those situations that we feel intrigued by the science, of course, but we really feel we have here a moral obligation to act as rapidly as possible," says Dr. Yoel Sadovsky, a physician-researcher at the Magee-Womens Research Institute in Pittsburgh.

Along with Coyne, he studies cells in the placenta that normally act as a first line of defense to protect the fetus from viruses in the mother's blood. The researchers want to study how those cells react to Zika.

They'll also explore the relationship between Zika and a closely related virus, dengue, which is common in Brazil, says Coyne. "It's possible that the pre-exposure to dengue virus in some way may alter the ability of Zika virus to infect these women and/or cross the placenta," she says.

Coyne is not the only one wondering what role, if any, dengue may play in these unusual manifestations of a Zika infection.

Doctors already know, Diamond says, that a person who has been infected with one dengue strain can later have a much more severe form of the disease if they get a second infection with a related, but not identical strain of dengue.

"Zika is actually not that far away from dengue in the genetic scheme of things" he says. "So the concept that immunity to Zika might influence dengue, or that immunity to dengue might influence Zika is certainly a possibility."

He says it's already clear that there are a lot of antibodies in dengue patients that cross-react to Zika, which can complicate the diagnosis with standard tests.

"Do those antibodies actually do anything?" he says. "We don't know."

Scientists are designing the lab experiments that could answer those questions, but Diamond says there's just no way to say how long it's going to take.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Nell Greenfieldboyce is a NPR science correspondent.
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