HIV is a retrovirus, which means that its genetic material is initially stored in the form of RNA, as opposed to the DNA which human cells use. Antiretroviral therapies, which are used to treat HIV infections, target several different steps in the life cycle of a retrovirus to keep it from infecting human cells.
Nucleoside Reverse Transcriptase Inhibitors
One important step in the life cycle of HIV is the virus turning its genetic material from RNA to DNA. This is done by a protein called reverse transcriptase, which uses molecules called nucleosides to make new DNA, AIDS Infonet explains. One type of antiretroviral therapy is nucleoside reverse transcriptase inhibitors. These drugs are similar to nucleosides, but once they bind to reverse transcriptase they disable it. Examples of this kind of drug include zidovudine, abacavir, stavudine and didanosine.
Non-nucleoside Reverse Transcriptase Inhibitors
Non-nucleoside reverse transctiptase inhibitors also work by inhibiting reverse transcriptase, but they do not mimic nucleosides. Instead, they block the enzyme by binding to other parts of it. Examples of this kind of antiretroviral therapy include nevirapine, delavirdine, efavirenz and etravirine, according to the HIV/AIDS resource, TheBody.com.
Protease Inhibitors
Protease inhibitors are a form of antiretroviral therapy that block the action of an enzyme called HIV protease. This enzyme is needed for the virus to reorganize its proteins after entering into a human cell. Without this reorganization the virus cannot take over the human cell. Protease inhibitors include ritonavir, atazanavir and nelfinavir, MayoClinic.com notes.
Fusion Inhibitor
In order to enter into a human cell, the virus has to fuse its membrane with the human cell's membrane. Fusion inhibitors are a type of antiretroviral therapy which interferes with this process, preventing the virus from infecting other cells. The only two drugs in this class are maraviroc and enfuvirtide
Integrase Inhibitors
Integrase inhibitors are the newest type of antiretroviral therapy, the AIDS charity, Avert, explains, having first been approved for use in 2007. This class of drug works by preventing the virus from inserting its genetic material into the host cell, which keeps it from replicating. The only example of this type of drug is raltegravir.
