HIV treatments are grouped by class according to the stage of the HIV life cycle that they block.
Firstly, we have the entry inhibitor – a class of antiretroviral that prevents HIV from entering the CD4 cell.
Second up, we have the reverse transcriptase inhibitor which inhibits the enzymes that convert the genetic material of HIV from RNA into DNA it compatible with human DNA.
Once this stage is complete (and if someone is not on treatment) HIV DNA is then inserted or integrated into the DNA of the CD4 cell. The treatments that block this stage of HIV replication are called integrase inhibitors.
Once HIV DNA enters the nucleus of the CD4 cell (integration), the CD4 cell becomes a sort of HIV factory that produces building blocks for new HIV.
Protease inhibitors prevent viral replication by selectively binding to viral protease which normally cuts long chains of HIV proteins into smaller individual proteins. When HIV protease does not work properly, new HIV cannot be made.