As anyone who suffers from recurrent cold sores knows, herpes is a master escapist. This family of viruses – including strains that cause lesions on the genitals, infectious mononucleosis (glandular fever) and, in some cases, blindness and birth defects – is able to wriggle free of the body's defences, reactivating after lying dormant for long periods. Now a new drug that denies the virus its means of escape could lead to treatments that keep herpes locked up for good.
When the virus infects cells, the body defends itself by wrapping up the viral genome in a structure that blocks its genes from being expressed. The virus can escape this straitjacket, though, by hijacking some of the cell's own enzymes to unwrap itself. Once freed, the virus takes hold and spreads.
Thomas Kristie at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, and colleagues have developed a drug that inhibits the enzymes the virus uses to free itself – stopping it from escaping. "The virus becomes silent," says Kristie.