Antiretroviral Therapy

Antiretroviral therapy is a way of combating the most common retroviral disease, HIV/AIDS. The key to understanding how antiretroviral therapy works is to look at the life cycle of a retrovirus. By interrupting various stages of the retroviral life cycle, the spread can be controlled and the lifespan of the host can be significantly increased.

What Is a Retrovirus

• A retrovirus is a virus that uses RNA to insert itself and replace the DNA of the host cell with its own DNA using an enzyme known as the integrase enzyme. By inserting its own DNA into a cell, the cell goes on to produce new retrovirus that go on to infect other cells.

Lifecycle of the HIV Virus

• An infection of the HIV/AIDS virus begins with the virus being transmitted to the blood stream of the host. The virus attaches to a cell wall and inserts its contents into the cell. The HIV cell inserts its RNA into the host cell and, via an enzyme known as the integrase enzyme, replicates the HIV virus DNA in the cell. As the infected cell reproduces, it creates the material for the formation of new HIV viruses. That material begins to form as a new retrovirus and eventually pushes its way out of the host cell. As the immature cell breaks free of the host, the protease enzyme creates a new virus.

Antiretroviral Drugs

• Antiretroviral drugs work by interrupting various steps of the HIV/AIDS life cycle. The goal is to either prevent the virus from reproducing or to decrease its lifespan to prevent the manufacture of new retrovirus.

Types of Drugs

• There are five general types of antiretroviral drugs. The first type is nucleoside reverse transcriptase inhibitors (NRTI), which are sometimes called nukes. They work by stopping the retrovirus from creating DNA based on its own RNA. The second type uses a different way of achieving the same goal. These drugs are called non-nucleoside reverse transcriptase inhibitors (NNRTI), or sometimes non-nukes. A third type of antiretroviral drugs are protease inhibitors. Protease inhibitors block the creation of material that will eventually become the building blocks of a new retrovirus. A fourth type of newer antiretroviral drugs are entry inhibitors. These drugs stop the retrovirus from entering the cell. The fifth, and newest, type of antiretroviral drugs is the integrase inhibitor, which prevents the retrovirus from inserting its genetic code into host cells.

Combination Pills

• In many cases, several antiretroviral drugs are required to control an infection. To facilitate this, drug manufacturers produce some standard combination antiretroviral pills that contain different types of antiretroviral drugs. However, doctors are still free to try different combinations and ratios of drugs in cases that don't respond well to existing combination pills.