AIDS researchers have had very preliminary success against a longstanding hurdle in the battle against HIV: awakening the many dormant copies of the virus that hibernate in the body and thus avoid eradication by the immune system.

The achievement comes from a pilot study in Denmark that had too few patients — just six — to be considered a major breakthrough. But it still points the way to how doctors could eventually succeed at flushing out HIV from its hiding spots in infected people's cells and eliminating it.

Ultimately, scientists hope that if all the dormant copies of the virus can be roused, they can then be eliminated using the current blend of anti-HIV drugs.

The latest research was presented yesterday at the International AIDS Conference in Melbourne, Australia, by Danish scientists.

Over a two-week span, they gave the anti-cancer drug romidepsin to six HIV-infected patients. It succeeded in ramping up production of HIV particles by two to four times more than normal in infected cells, a sign that dormant copies of the virus were reawakening. Five of the patients started to show detectable amounts of HIV in their blood.

However, it's not known how many copies of the virus stay dormant in the body, so it was impossible for the Danish team to say whether their method could possibly flush out all the so-called latent HIV.

Dormant virus eludes immune system

The problem of dormant HIV — known as HIV reservoirs — is a reason a cure for the virus has remained so elusive.

The current crop of anti-HIV medicines block the virus from replicating in infected people, allowing their immune systems to attack it. But the immune system can't track down the latent copies of the virus. If someone infected with HIV stops taking their medication, the latent copies can reactivate and start spreading through the body again.

Current thinking is that if all that dormant HIV can be activated and pushed into the open, the immune system will be able to eliminate it and patients will effectively be disease-free.

Some previous efforts to try to reactivate HIV have not proved successful, however.

The latest findings were presented in Melbourne by study co-author Ole Schmeltz Sogaard of Aarhus University Hospital in Aarhus, Denmark.