Cure to Zika Virus|May Be in Existing Drugs

     (CN) — A new vaccine to fight the Zika virus may not be necessary at all, after a specialized drug screen test revealed two classes of compounds that could potentially be used to halt or hinder the virus’s progress.
     In a paper published Monday in the journal Nature Medicine, researchers presented their findings of 6,000 screenings of existing compounds currently in late-stage clinical trials or already approved for human use for other conditions.
     The researchers separated the promising drugs into two classes — neuroprotective drugs, which prevent the activation of mechanisms that cause cell death, and antiviral drugs, which slow or stop viral infection or replication.
     “It takes years if not decades to develop a new drug,” said Hongjun Song, a co-author and researcher from Johns Hopkins University. “In this sort of global health emergency, we don’t have that kind of time.”
     The new findings are an extension of previous work by the research team, which found that Zika primarily targets specialized stem cells that eventually give rise to neurons in the cortex, the brain’s outer layer.
     Zika’s effects in two- and three-dimensional cell cultures called “mini-brains,” which resemble the structures of the human brain, allowed researchers to study the effects of the virus in a more accurate model for human infection.
     The researchers exposed similar cell cultures to the virus and the drugs one at a time. They then measured for indicators of cell death, including caspase-3 activity — a chemical marker of cell death — and ATP, a molecule whose presence is indicative of cell vitality.
     Hengli Tang, a professor of biological sciences at Florida State University and co-author of the study, said that after Zika infection, the damage done to neural cells is typically “dramatic and irreversible.”
     However, some of the compounds tested allowed the cells to survive longer and in some cases fully recover from infections, Tang added.
     Three drugs showed significant enough results to warrant further study, including PHA-690509, an investigational compound with antiviral properties; emricasan, now in clinical trials to reduce liver damage from the hepatitis C virus shown to possess neuroprotective effects; and niclosamide, a drug already used in humans and livestock to combat parasitic infections. Niclosamide worked as an antiviral agent in these experiments.
     Despite the potential value of these drugs, Song maintained that further research must be performed to ensure the efficacy of such therapies in the treatment of Zika infections.
     While the three drugs were effective against Zika in the dish, “we don’t know if they can work in humans in the same way,” he said.
     Niclosamide has been proven to safely treat parasites in the human gastrointestinal tract, but researchers have yet to determine whether the drug can penetrate the central nervous system of adults — or a fetus inside an infected woman’s womb — to treat the brain cells targeted by Zika.
     Whether these drugs are safe for pregnant women is another issue that must be examined.
     The World Health Organization and the U.S. Centers for Disease Control and Prevention have warned that further research must be conducted to determine the risk associated with prescribing niclosamide to pregnant women.
     “Independently of evaluating the potential benefits and risks for pregnant women, niclosamide could be used to reduce viral load in infected men and nonpregnnant women, which could reduce transmission and potentially prevent Guillain-Barre syndrome and other Zika-related complications in humans,” the study says.
     It is also unclear which symptoms and health conditions that stem from Zika infections the drugs would ultimately be able to fight against.
     The team’s next step will likely be testing the efficacy of these drugs in animal models to see if they have the ability to combat Zika in a living organism.
     “To address these questions, additional studies need to be done in animal models as well as humans to demonstrate their ability to treat Zika infection,” said co-author Guo-li Ming. “So we could still be years away from finding a treatment that works.”

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