Though important advances have been made in treating RNA virus infections such as hepatitis C and influenza, a broad spectrum antiviral drug that throws a blanket over all of them, including more deadly variants like Ebola, has remained out of reach. Scientists are now reporting the discovery of a drug-like molecule that could be used to combat all RNA viruses, by triggering an innate immune response that suppresses and controls the infections.

As a virus spreads through the body, it takes over individual cellular machinery and uses it to make copies of itself, infecting other cells in the process. While the body can fight off some viruses on its own, others are able to mutate to elude these natural defence mechanisms and go on replicating. Drugs have been developed to treat specific viruses, such as hepatitis C, but they are expensive and some hold concerns that their ongoing use may give rise to drug resistance.

So a team led by scientists from the University of Washington set out to better equip the body's immune system to fight off viral RNA. It has developed a compound that targets a molecule contained in the body's cells called RIG-1. This molecule is a pathogen recognition receptor, which means that it detects the presence of viral RNA and sets off an innate immune response inside the cell.

This includes the expression of antiviral genes, pro-inflammatory cytokines, chemokines and interferons, which work in collaboration to suppress and control the viral infection. By activating this immune response and promoting these weapons against infection, the team was able to "significantly decrease" viral RNA in cells and suppress infectious virus reproduction.

"Our compound has an antiviral effect against all these viruses," says Michael Gale Jr., University of Washington professor of immunology, referring to a range of RNA viruses, including West Nile, dengue, hepatitis C, influenza A, respiratory syncytial, Nipah, Lassa and Ebola.

The researchers say they have successfully tested the approach in cells and mice, and they are now turning their attention to exploring dosage and stability in animal models. Human trials could follow thereafter, with a timeline of somewhere between two and five years.

The research was published in the Journal of Virology and can be read online here.

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