When HIV inserts itself into the host cell's DNA, the virus takes over the cell's mechanisms. The virus forces the cell to make more virus. Eventually, the virus eats up the cell's resources normally used to protect itself against other foreign invaders. Currently there are two points of attack for the antiviral drugs for HIV, but other possible drug targets are being studied. Although the virus can still enter cells, it cannot attack the DNA of the cells it enters.
Protease plays an important role in the final step of making a virus particle.
During an infection, the NRTIs are more likely to be take up by viral DNA than host DNA because the viral DNA is already outcompeting the host DNA for resources. Once the NRTIs are incorporated into the growing viral DNA strand, further growth is prevented. The double-stranded virus that was made is now incomplete. Without incorporation into the host cell's DNA, no new virus is produced, and the progression of HIV is slowed. Each of the drugs in this class has a different set of side effects.