HIV, once it gets into the cell, incorporates its own genetic material into the genetic material of the individual's cells. This infected cell then becomes a factory for producing infected cells. In addition, HIV is a chronic infection. Once it occurs, it stays in the body indefinitely. Even patients who are in effective therapy continue to have infected cells in their body, which remain as a spark to ignite an outbreak when therapy is discontinued.
Antiviral drugs interfere with the virus life cycle.
In the context of HIV, it has been in blocking the reverse transcriptase enzyme, which is a critical step in early reproduction. The protease inhibitors also block a crucial step in the reproduction of infected cells. They can persist for ten years or longer. Despite being able to suppress viral loads to undetectable levels there is evidence that viral replication is going on at low levels. It may be because the patients are not taking the medications consistently or maintaining the levels of the drugs at high levels.