Antiretroviral treatment are medications that treat HIV. The drugs do not kill or cure the virus. However, when taken in combination they can prevent the growth of the virus. When the virus is slowed down, so is HIV disease. Antiretroviral drugs are referred to as ARV. Combination ARV therapy (cART) is referred to as highly active ART (HAART). Each type, or “class”, of ARV drugs attacks HIV in a different way. The first class of anti-HIV drugs was the nucleoside reverse transcriptase inhibitors (also called NRTIs or “nukes”.) These drugs block step 4, where the HIV genetic material is used to create DNA from RNA.