A cheap drug has shown promise in stamping out hidden pockets of HIV in three people who have long been infected with the virus.

Four patients who had been on long-term HAART treatment were given a drug called enfurvitide twice daily for 4 to 6 weeks to intensify the effect of the HAART drugs. They were then given valproic acid, a drug which is usually used to treat epilepsy, twice daily for 3 months.

Valproic acid inhibits an enzyme called histone deacetylase, which is known to help HIV linger in its dormant, hidden state. In 3 of the 4 patients, levels of latent HIV fell by 75%.