HIV Overview

The HIV Life Cycle

Last Reviewed: August 4, 2021

Key Points

  • HIV attacks and destroys the CD4 cells (CD4 T lymphocyte) of the immune system. CD4 cells play a major role in protecting the body from infection.
  • HIV uses the machinery of the CD4 cells to multiply and spread throughout the body. This process, which is carried out in seven steps or stages, is called the HIV life cycle. HIV medicines protect the immune system by blocking HIV at different stages of the HIV life cycle.
  • Antiretroviral therapy (ART) is the use of a combination of HIV medicines to treat HIV infection. People on ART take a combination of HIV medicines from at least two different HIV drug classes every day. Because each class of drugs is designed to target a specific step in the HIV life cycle, ART is very effective at preventing HIV from multiplying.

What is the HIV life cycle?

HIV attacks and destroys the CD4 cells (CD4 T lymphocyte) of the immune system. CD4 cells are a type of white blood cell that play a major role in protecting the body from infection. HIV uses the machinery of the CD4 cells to multiply and spread throughout the body. This process, which is carried out in seven steps or stages, is called the HIV life cycle.

What is the connection between the HIV life cycle and HIV medicines?

Antiretroviral therapy (ART) is the use of a combination of HIV medicines to treat HIV infection. People on ART take a combination of HIV medicines (called an HIV treatment regimen) every day. HIV medicines protect the immune system by blocking HIV at different stages of the HIV life cycle. HIV medicines are grouped into different drug classes according to how they fight HIV. Each class of drugs is designed to target a specific step in the HIV life cycle.

Because an HIV treatment regimen includes HIV medicines from at least two different HIV drug classes, ART is very effective at preventing HIV from multiplying. Having less HIV in the body protects the immune system and prevents HIV from advancing to acquired immunodeficiency syndrome (AIDS).

ART cannot cure HIV, but HIV medicines help people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission (the spread of HIV to others).

What are the seven stages of the HIV life cycle?

The seven stages of the HIV life cycle are: 1) binding, 2) fusion, 3) reverse transcription, 4) integration, 5) replication, 6) assembly, and 7) budding.

To understand each stage in the HIV life cycle, it helps to first imagine what HIV looks like.

An HIV virus particle with the following parts labeled: the envelope, RNA, capsid, enzymes, and glycoproteins.

Now, follow each stage in the HIV life cycle as HIV attacks a CD4 cell and uses the machinery of the cell to multiply.

The seven steps of the HIV lifecycle and the medicines that stop each step: binding (prevented by CCR5 antagonists and post-attachment inhibitors), fusion (prevented by fusion inhibitors), reverse transcription (prevented by nucleoside and non-nucleoside reverse transcriptase inhibitors), integration (prevented by integrase inhibitors), multiplication, assembly, and budding (prevented by protease inhibitors).