HIV Drugs and the HIV Lifecycle

Table of Contents

• The Basics
• The HIV Lifecycle
• Approved HIV Drugs
• Combining HIV Drugs
• The Bottom Line

The Basics

HIV drugs cannot cure HIV but they can help you stay healthy by preventing the virus from reproducing (making copies of itself). When HIV cannot reproduce, it cannot infect new cells in your body and your . viral load remains low.

HIV must go through a number of different steps in order to make copies of itself. This is called the HIV lifecycle. All HIV drugs work by interrupting a step in HIV's lifecycle, thereby stopping HIV "in its tracks."

The HIV Lifecycle

Once HIV is in the body, it targets and infects a certain type of white blood cell called a CD4 cell. HIV then takes over or "hijacks" these cells and turns them into factories that produce thousands of copies of the virus. The steps HIV goes through to complete this process are as follows:

1. Binding and Fusion
   HIV begins to enter a CD4 cell by binding (or attaching) itself to a specific point, called a CD4 receptor, on the cell's surface. HIV must then bind to a second co-receptor, either the CCR5 co-receptor or the CXCR4 co-receptor. This allows the virus to join with the CD4 cell in a process called fusion. After fusion, HIV releases its RNA (genetic material) and enzymes (proteins that cause chemical reactions) into the CD4 cell.
2. Reverse Transcription
   HIV's RNA contains the "instructions" that will reprogram the CD4 cell so that it produces more viruses. In order to be effective, HIV's RNA must be changed into DNA. An HIV enzyme called reverse transcriptase changes the HIV RNA into HIV DNA.
3. Integration
   Next, the newly-formed HIV DNA enters the nucleus (command center) of the CD4 cell. Another HIV enzyme called integrase combines or integrates HIV's DNA with the CD4 cell's DNA.
4. Transcription
   Once the virus has become part of (is integrated into) the CD4 cell, it commands the CD4 cell to start making new HIV proteins. The proteins are the building blocks for new HIV viruses. They are produced in long chains.
5. Assembly
   An HIV enzyme called protease cuts the long chains of HIV proteins into smaller pieces. As the smaller protein pieces come together with copies of HIV's RNA, a new virus is put together (assembled).
6. Budding
   The newly-assembled virus pushes ("buds") out of the original CD4 cell. This new virus is now able to target and infect other CD4 cells.