- HIV cannot multiply on its own.
- HIV attaches itself to an immune system ‘T-helper’ cell, fuses with it, takes control of its DNA, replicates itself inside the cell, and then releases new HIV into the blood.
- Different HIV treatment drugs stop the virus fusing, stop it integrating its genetic code, and stop it releasing new copies of itself into the bloodstream.
Understanding how HIV infects the body is important to help explain how HIV drugs work to treat the virus. The science behind the virus and the HIV life cycle help put wider prevention, treatment, and general HIV awareness into context.
The immune system and HIV
The HIV virus attacks a type of white blood cell called T-helper cells (also called CD4 cells). These cells are important when it comes to having a healthy immune system as they help us fight off diseases and infections.
HIV cannot grow or reproduce on its own. Instead, it makes new copies of itself inside T-helper cells. This damages the immune system and gradually weakens our natural defences. This process of infected T-helper cells multiplying is called the HIV life cycle.
How quickly the virus develops depends on your overall health, how early you are diagosed and started on treatment, and how consistently you take your treatment. It’s important to know that antiretroviral treatment will keep the immune system healthy if taken correctly, preventing the symptoms and illnesses associated with AIDS developing.
The HIV life cycle
There are several steps in the life cycle of HIV that can happen over many years. Antiretroviral treatment works by interrupting the cycle and protecting your immune system. There are different drugs offered depending on the particular stage of the HIV life cycle.
Understanding the HIV life cycle helps scientists to know how to attack the virus when it is weak and reduce its ability to multiply. Drug resistance means a person’s HIV treatment no longer prevents the virus from multiplying. This usually happens if treatment has not been taken correctly, allowing the virus to mutate.
Stages of the HIV life cycle
1. Binding and fusion
First, the HIV virus attaches itself to a T-helper cell and releases HIV into the cell.
Drugs that can stop this part of the process are called fusion or entry inhibitors.
2. Conversion and integration
Once inside the cell, HIV changes its genetic material so it can enter the nucleus of the cell and take control of it.
Drugs that can stop this part of the process are called NRTIs (nucleoside reverse transcriptase inhibitors), NNRTIs (non-nucleoside reverse transcriptase inhibitors) and integrase inhibitors.
The cell then produces more HIV proteins that can be used to produce more HIV.
4. Assembly, budding and maturation
New HIV particles are then released from the T-helper cell into the bloodstream. These are now ready to infect other cells and begin the process all over again.
Drugs that can stop this part of the process are called protease inhibitors.
Antiretroviral treatment (or ART for short) uses a number of different HIV medicines to treat HIV infection. By combining different drugs that target different steps in the HIV life cycle ART is now very effective at preventing HIV from multiplying, and enables people who are on treatment to live longer, healthier lives.
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