New drug thwarts Zika, dengue, West Nile in cell cultures

"When you target a host function rather than a viral protein, it's usually much more difficult for a virus to develop resistance," researcher Jan Carette said.
By Brooks Hays  |  Dec. 13, 2017 at 12:20 PM
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Dec. 13 (UPI) -- Lab tests prove a new drug called NGI-1 is capable of shutting down flaviviruses, the family that includes mosquito-borne viruses like Zika, dengue and West Nile.

The new drug works by cutting off access to key proteins in mammalian cells that invading viruses rely on. By robbing them of their energy sources, researchers say, the drug thwarts invasion.

Remarkably, the technique lends NGI-1 potency against not one, but an entire family of viruses. Researchers detailed the drug's promise in a new paper published this week in the journal Cell Reports.

"Generally, when you develop a drug against a specific protein in dengue virus, for instance, it won't work for yellow fever or Zika, and you have to develop new antivirals for each," senior study author Jan Carette, an assistant professor of microbiology and immunology at Stanford University School of Medicine, said in a news release. "Here, by targeting the host rather than a specific virus, we've been able to take out multiple viruses at once."

Flaviviruses are single-stranded, non-segmented RNA viruses mostly spread by mosquitoes and ticks. The viruses are responsible for thousands of deaths every year.

While most drugs work by targeting specific components of a virus, Carette and his research partners decided to focus on the parts of the host cell essential to the invader.

Previous studies revealed the importance of host cells' oligosaccharyltransferase, or OST, complex to flaviviruses. The OST complex is responsible for supplying proteins with sugar molecules called glycans.

To thwart invading flaviviruses, the scientists genetically engineered OST-free host cells -- and the viruses were unable to invade the cell cultures.

Of course, engineering the OST complex out of a patient's cells isn't an option, so the researchers teamed up with scientists at Yale University to develop a drug capable of blocking OST activity. They designed NGI-1.

The latest tests showed low concentrations of NGI-1 are sufficient to prevent flaviviruses from replication. The drug works without blocking OST activity entirely, thus allowing the host cells to function normally.

According to Carette, viruses wouldn't be able to easily adapt to the new drug.

"When you target a host function rather than a viral protein, it's usually much more difficult for a virus to develop resistance," he said.

Scientists aren't yet sure exactly what function the OST complex plays in enabling virus replication. When researchers blocked OST's ability to supply proteins with sugars -- its most well-known function, called glycosylation -- the viruses were still able to replicate.

"This means whatever OST is doing for the viruses is really unrelated," said Carette. "It also means we may be able to develop a drug that can more specifically inhibit the viral complex."

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