HIV Overview

What is a Latent HIV Reservoir?

Last Reviewed: May 14, 2024

Key Points

  • latent HIV reservoir is a group of immune system 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?

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 attacks immune system cells in the body, mainly the infection-fighting CD4 cells (CD4 T lymphocytes) and uses the cells’ own machinery to make copies of itself. After HIV infects CD4 cells, it produces a large amount of viral RNA and viral proteins, and virus particles. As with most other viral infections, these infected cells that produce virus are eventually recognized as foreign to the body and destroyed by the host 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 infected cells by the immune system and are not destroyed. HIV can hide inside these cells for years, forming a latent HIV reservoir but, at any time, cells in the latent reservoir can become active again and start making more viruses.

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 a daily combination of 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. That is why it is important to continue taking HIV medicines every day as prescribed, even when viral load levels are 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. This method of eliminating latent HIV reservoirs is sometimes known as the “shock and kill” or “kick and kill” strategy. Another strategy, known as “block and lock,” 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. Researchers are hoping to develop therapeutics that activate this permanent latency in HIV.