Scientists have discovered how HIV manages to avoid being eradicated by the latest antiretroviral drugs.
Scientists hope to track down all cells infected with HIV
The finding could eventually contribute to more effective therapies.
While modern drugs can wipe out most HIV viruses, a few manage to avoid destruction, and form a "reservoir" somewhere in the body.
If antiretroviral therapy is halted, the virus re-emerges.
This means patients must take expensive treatments for life in order to keep HIV under control, and there is no guarantee that the effectiveness of the drugs will not wane in time.
Hunting down the "reservoir" so that a way can be found to attack it is the priority of researchers from Massachusetts Medical School.
In normal circumstances, HIV attacks immune system cells called T-cells.
It was thought that HIV could only infect these cells when they were in an active state, responding to an "invader".
However, the evidence suggests that the virus has found a roundabout method to infect T-cells even when they are in their inactive state.
HIV lurking in these cells would be unreachable by current antiretrovirals.
The research team found that HIV was able to infect a separate cell called a macrophage.
This prompts it to release a chemical which alters the behaviour of a third cell called a B cell.
When these altered B-cells come into contact with the inactive, or "resting" T-cells, it renders them vulnerable to HIV infection.
Roger Pomerantz, an HIV researcher from Thomas Jefferson University said that the discovery of this complex interplay could assist scientists in their search for ways to eradicate HIV.
In theory, it might be possible to interrupt or inhibit this process, preventing HIV from getting a foothold in the inactive T-cells.
He said: "The aim will be not only to decrease the production of HIV-1 but also to destroy the cellular reservoirs that have so far kept us from being able to eradicate HIV-1 infection."
The research was published in the journal Nature.