What is a Latent HIV Reservoir?
Key Points
- A latent HIV reservoir is a group of CD4 T lymphocytes (CD4 cells) in the body that are infected with HIV but are not actively producing new HIV virus particles.
- Finding ways to target and either destroy or silence latent reservoirs is a major challenge facing HIV researchers who are exploring different strategies for curing HIV infection.
What is a latent HIV reservoir?
A latent HIV reservoir is a group of immune system cells in the body that are infected with HIV but are not actively producing new virus particles.
HIV primarily attacks the immune system cells called CD4 cells (CD4 T lymphocytes). Although HIV almost always infects these cells, it does not always use them to replicate and create more HIV. When HIV uses CD4 cells to replicate, it produces a large amount of viral RNA, viral proteins, and virus particles.
Like most other viral infections, these infected cells that produce the virus are eventually recognized as a threat to the body and destroyed by the immune system.
However, some HIV-infected CD4 cells go into a resting or latent state. While in this resting state, the infected but latent cells do not produce new virus particles or viral products. Therefore, these cells are not recognized as harmful infected cells by the immune system and are not destroyed.
HIV can hide inside these cells for years, forming a latent HIV reservoir. These cells can be stored throughout the body, including within the central nervous system, lymphatic system, and genital tract.
Importantly, cells in the latent reservoir can become active again at any time and start making more virus particles. To find out more about how HIV attacks cells, read the HIV Life Cycle fact sheet from HIVinfo.
Do HIV medicines work against latent HIV reservoirs?
HIV medicines prevent HIV from multiplying by interfering with the HIV life cycle, which reduces the amount of the virus in the body (called the viral load). Because the HIV-infected cells in a latent reservoir are not producing new copies of the virus, HIV medicines have no effect on them.
People with HIV must take HIV medicines (called an HIV treatment regimen) to keep their viral loads low and to stay healthy. If a person stops taking their HIV medicines, the infected cells of the latent reservoir can begin making HIV again, and the person's viral load will increase.
Although HIV medicines may not get rid of latent HIV reservoirs, it is important to continue taking HIV medicines as prescribed to prevent HIV from becoming active and replicating, even when viral load is low.
Are researchers studying ways to target latent HIV reservoirs?
Finding ways to target and destroy latent reservoirs is a major challenge facing HIV researchers. Researchers are exploring different strategies for destroying HIV reservoirs or making them permanently dormant, including:
- Using gene therapy (manipulating genes to treat or prevent disease) to cut out certain HIV genes and inactivate the virus in HIV-infected immune cells.
- Developing drugs or other methods to reactivate latent HIV so that the HIV can be destroyed by the immune system or new HIV therapies.
- The “shock and kill” or “kick and kill” strategy aims to reactivate latent HIV to make the virus visible to the immune system and susceptible to new HIV therapies. For example, broadly neutralizing antibodies (bNAbs) may help find and destroy CD4 cells hosting latent HIV. Additionally, immune checkpoint inhibitors may help eliminate reactivated HIV reservoirs.
- The “block and lock” strategy permanently silences all HIV reservoirs, even after treatment interruption. A substantial part of the human DNA genome contains ancient retrovirus DNA (the same type as HIV) that is permanently dormant.
Although no method has been fully effective in removing latent HIV reservoirs yet, researchers are investigating new approaches like immunotherapy and combination strategies to eliminate latent HIV reservoirs. Success in these areas could potentially lead to a cure for HIV in time.
What happens if you have a latent HIV reservoir?
Most people with HIV, including those who are taking HIV medicines, will have an HIV reservoir. Unless new research (such as investigational drugs or vaccines) shows the ability to eliminate HIV particles from the body, it’s safe to assume you have a latent HIV reservoir if you have HIV, even if your viral load is undetectable.
While some HIV may remain in the body, HIV medicines can effectively reduce the amount of virus in the body, and allow people with HIV to live long, healthy lives. People with HIV should focus on maintaining an undetectable viral load to stay as healthy as possible while reducing the chances of transmitting HIV to others.
This fact sheet is based on information from the following sources:
From the National Institute of Allergy and Infectious Diseases:
Also see the HIV Source collection of HIV links and resources.