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depots inside cells. Flaviviruses dengue and hepatitis C (a more distant relative) exploit those droplets in different ways when they invade cells. If Zika also uses those droplets in some fashion, “perhaps there’s a niche to exploit,” Ott muses.
Beyond the biological mysteries of Zika, there’s another hurdle: Who should get a vaccine, if and when one is produced? Pregnant women are, to date, the highest risk group. But testing any experimental medicine—let alone a new vaccine against an ill-understood viral foe—in pregnant women is extremely difficult. (In the emergency rush to develop and test vaccines during the most recent Ebola outbreak, Johnson & Johnson’s Janssen division vaccinated 1,200 people across 10 different studies. But it has not yet vaccinated pregnant women, according to a spokesman.)
“The issue is getting it to women of child bearing age who may become pregnant,” says Adam Urato, a specialist in maternal-fetal medicine who sees patients at the Tufts University School of Medicine near Boston. “That’s the time to think about vaccinating people. From my standpoint you can’t put anything into a pregnant woman and say there’s no risk.”
While some companies and researchers are plotting attacks on the Zika virus, others want to kill mosquitoes. An all-out pesticide assault would be impractical, expensive, and potentially more toxic than the Zika infection itself. Aedes thrives in urban areas and can breed in a few drops of standing water.
Enter the genetically modified mosquito. One version has been tested in Brazil, Malaysia, and Grand Cayman—and won regulatory approval in Brazil—and just got tentative FDA approval for a field trial in Florida’s Key West. The mosquito engineers at Oxitec, a British division of Germantown, MD-based Intrexon (NYSE: XON), release genetically altered males into the wild. They mate with wild females, and the offspring are born with a self-destruction gene that kills them before adulthood.
The idea is to reduce populations by at least 90 percent, as Oxitec says it has done in other field tests. The current 50 percent threshold that the Florida Keys Mosquito Control District says it achieves with pesticides is not considered enough to halt the spread of diseases spread by Aedes.
FDA released Friday its assessment of the planned test. It would not have negative impacts on people, animals, or the local ecosystem, the agency said, based mainly on Oxitec’s own report, which was also posted on the FDA site Friday. (Note: Link downloads a very large PDF file.)
FDA is giving the public one month to comment before Oxitec can move ahead with the test, which was originally conceived to fight the spread of dengue—as were the tests in Brazil and elsewhere—after a outbreak in Key West infected at least 88 people in 2009 and 2010. As the outbreak subsided, local officials got cold feet, however, and delayed the project. But the rapid spread of Zika via the same mosquito has rekindled the project.
Oxitec says its mosquito won’t mutate out of control, passing new traits from generation to generation upon its release, because of the built-in self-destruction. (In fact, there’s a recurrent cash flow for the company in the technology; long-term abatement projects would need intermittent releases of new genetically modified mosquitoes.)
The uncertainty here is at least two-fold: Will the altered mosquitoes actually bring down the Aedes population and halt the spread of disease without unintended consequences? And will Oxitec actually get the chance to find out? A petition to stop the Florida Keys project has gathered more than 160,000 signatures to date.
The next month of public comments should be lively, to say the least, based on the back and forth from a December 2014 public meeting.
Not just in the Florida Keys, but everywhere Zika is spreading, emotions are running high. “The big thing we need, number one, is more information,” says Urato.