The technique may help people with hepatitis B
Scientists may have found a new way to treat the virus that causes hepatitis B - launching a strike on the genetic material it needs to spread.
The study, on mice, is further evidence of the promise of the technique, called "RNA interference".
Some experts are hoping it will eventually have a role against HIV.
Hepatitis B is the most common serious liver infection in the world, causing up to a million deaths worldwide a year.
Although a vaccine is available against hepatitis B, once infected, the range of treatments available is limited.
A team of researchers from California injected a biochemical called RNA into mice infected with hepatitis B.
This binds with RNA which is part of the virus, effectively "silencing" a key part of the virus' genetic machinery.
This hampers the virus' efforts to replicate itself, and spread to infect other cells.
While the RNA treatment managed this in mice, there is no certainty that the effects would be the same in humans.
The researchers wrote: "Here, we show that RNA interference can inhibit all the steps of hepatitis B virus replication that occur in cell culture and in mice."
Further studies will be carried out to ensure that side-effects from the treatment are minimised.
But the researchers warned that care must be taken to avoid producing viral strains resistant to the treatment.
Nigel Hughes, the chief executive of the British Liver Trust, said that the treatment was promising, although he cautioned that this "very early" research might not translate into human treatments.
He told BBC News Online: "Our current therapies do have drawbacks - the 'holy grail' is a one pill cure."
The study was published in the journal Nature Biotechnology.