They discovered that a mysterious gene carried by the herpes simplex-1 virus — the one that causes cold sores — allows the virus to lay low in the nerves it infects.

It does so via microRNAs, little pieces of genetic material that regulate the activity of many viruses, the researchers report in the journal Nature.

It may be possible to “wake up” the virus and then kill it with standard antiviral drugs such as acyclovir, said Jennifer Lin Umbach of Duke University in North Carolina, who worked on the study.

“We are trying to go into animal trials,” Umbach said in a telephone interview.

The Duke team is discussing a potential collaboration with Regulus Therapeutics LLC, a joint venture between Alnylam Pharmaceuticals Inc. and Isis Pharmaceuticals Inc. that specializes in microRNAs.

Herpes viruses cause permanent infections. They head straight to nerve cells, where they stay latent for the life of an animal or person, often causing periodic outbreaks.