An anti-cancer drug can activate hidden HIV to levels readably detectable in the blood by standard methods, scientists have found.
The anti-cancer drug romidepsin increased the virus production in HIV-infected cells between 2.1 and 3.9 times above normal and the viral load in the blood increased to measurable levels in five out of six patients with HIV infection, researchers found.
The researchers from Aarhus University and Aarhus University Hospital in Denmark had previously shown that the drug panobinostat can activate hidden HIV in the cells.
But this is the first time the researchers have been able to demonstrate that it is possible to activate hidden virus to levels readably detectable in the blood by standard methods.
HIV can hide in a "state of hibernation" in the so-called CD4 cells. These cells are a part of the body's immune system, but the CD4 cells cannot fight the virus themselves; killer T-cells can.
However, killer T-cells cannot tell if a CD4 cell contains "hibernating" HIV virus. That is why HIV continues to be a chronic disease.
The results, presented by researchers at the annual international AIDS conference in Melbourne, found that when the virus is activated and moves towards the bloodstream it leaves a trace on the outside of the infected CD4 cells.
In principle this means that the killer T cells can now trace and destroy the HIV-infected CD4 cells.
In addition to measuring the increased viral load in six HIV-infected test persons, the researchers have tested the side effects of the medicine.
The test persons experienced transient fatigue and nausea, which are known side effects of romidepsin. And so, the pilot study does not cause immediate concern for special side effects in HIV-infected persons.
The researchers also investigated if the total HIV reservoir in the body is lowered when the killer T-cells are now able to trace and destroy the HIV-infected CD4 cells.
However, the researchers were not able to demonstrate that.
"We have now shown that we can activate a hibernating virus with romidepsin and that the activated virus moves into the bloodstream in large amounts," said senior researcher and medical doctor Ole Schmeltz Sogaard.
"This is a step in the right direction; but there is still a long way to go and many obstacles to overcome before we can start talking about a cure against HIV," said Sogaard.
The next step is a bigger trial where the researchers will combine romidepsin activation of hidden HIV with a vaccine (vacc-4x) to strengthen the ability of killer T-cells to fight HIV virus.