A New Way To Stop Viruses

DAVID GREENE, HOST:

It is not easy to treat viral infections, but scientists in Massachusetts think they may have found a new way to stop viruses from making people sick by using what amounts to a pair of molecular scissors. NPR science correspondent Joe Palca explains.

JOE PALCA, BYLINE: When a virus infects a cell in our bodies, it hijacks the cell's molecular machinery to make copies of itself. Those new viruses can go on to spread the infection through your body.

CAMERON MYHRVOLD: We need to be able to cut the virus at a fast enough rate to slow down replication or to stop replication from happening.

PALCA: Cameron Myhrvold is a postdoc at the Broad Institute in Cambridge. Myhrvold works with so-called RNA viruses - viruses that package their genetic information in RNA, a chemical cousin of DNA. To cut the viral RNA, he uses a molecular tool called CRISPR - in this case, CRISPR-Cas3 - that can target a specific region of RNA.

MYHRVOLD: Cas13, when it finds its target, it can become very active and start to cut other RNAs.

PALCA: Finding the right target is key. There's a lot of RNAs inside cells that are necessary for the cell to survive. So it's important to find an RNA target that's unique to the virus you're trying to control. Myhrvold says RNA viruses are particularly difficult to control because they're a bit like shape shifters. They tend to change their genetic sequences when you try to pin them down.

MYHRVOLD: They really want to understand what the virus is doing in response to Cas13 treatment.

PALCA: Myhrvold's colleague Catherine Freije says what the virus does in response to treatment should be informative.

CATHERINE FREIJE: That could potentially teach us about what parts of the virus are particularly important for its function.

PALCA: And that, in turn, will show the best places to target the virus in order to disable it. So far, Freije and Myhrvold say they've only showed their anti-viral treatment works in cells. But Pardis Sabeti, head of the lab they work in, is bullish about using the CRISPR-Cas13 system to treat viral infections in people.

PARDIS SABETI: There's still a bunch of things we want to work out, but we feel pretty confident that this will work as a therapy if it can be delivered in the right way.

PALCA: By delivering, she means getting the CRISPR-Cas13 tool into the right cells inside an infected patient. Now, CRISPR-Cas13 specifically targets RNA, so it will only be useful for illnesses caused by RNA viruses, like flu and Zika. But Janice Chen says researchers are now finding a variety of CRISPRs with different properties. Chen is chief research officer at Mammoth Biosciences, a company that hopes to capitalize on CRISPR technology.

JANICE CHEN: Having a broader CRISPR toolbox is really important to figuring out what is the specific need for any given application.

PALCA: Progress in building that toolbox has proceeded quite quickly. After all, it's only been six years since scientists first became aware of how powerful a tool CRISPR could be. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.