Antiretroviral therapy stops HIV from replicating (making copies of itself) in the body. This benefits the health of the person living with HIV and prevents sexual transmission of the virus to others. However, effective treatment does not completely eliminate the virus from the body. HIV lies dormant inside a small number of cells in the body, resulting in viral reservoirs. If treatment is stopped, these reservoirs can become active and start producing HIV. This newly produced virus infects additional cells, HIV begins replicating again, and transmission can occur. Because of the persistence of these reservoirs, antiretroviral therapy does not cure HIV, although it is an effective treatment that restores health, greatly improves quality of life and prevents HIV transmission.

To keep HIV suppressed in the body, antiretroviral medications must be taken daily as prescribed. To monitor the treatment's effectiveness, people living with HIV should undergo regular viral load testing as directed by their health care teams. A viral load test measures the level of HIV RNA -- the virus' genetic material -- in blood plasma, and it is an accurate indicator of how well treatment is working.

When HIV infection is untreated, viral load is very high, indicating that HIV is actively replicating and producing new infectious viral particles. For almost everyone who takes antiretroviral therapy daily as prescribed, viral load will drop to a level so low that it is undetectable. Clinical studies have shown that people living with HIV who have achieved and maintained an undetectable viral load for at least six months will not sexually transmit the virus to an HIV-negative partner. To learn more about viral load and HIV transmission, see 10 Things to Know About HIV Suppression.

Related: 17 Top Questions About Starting HIV Treatment

Understanding the Presence of HIV RNA and DNA

Researchers are working to better understand how HIV persists in the body in viral reservoirs, with the ultimate goal of developing a cure for HIV. To identify and define HIV reservoirs, many studies have assessed the presence of HIV RNA and/or DNA, two types of genetic material, in the body's tissues and in other bodily fluids, such as semen. When HIV infects a cell, it uses the cell's machinery to replicate. During the replication process, the virus' genetic material (stored within the virus as RNA) gets integrated into the cell's DNA. Effective antiretroviral therapy does not eliminate this HIV DNA, which is also called proviral DNA. Detecting HIV RNA or DNA in tissues and bodily fluids such as semen requires very sensitive tests that are only performed in research settings. These are not the same as clinical tests to determine plasma viral load.

Can I Be Infected by HIV RNA or DNA Reportedly Found in the Semen or Testes of a Virally Suppressed Person?

No. Because effective antiretroviral therapy does not eradicate HIV from the body's tissues, it is expected that HIV genetic material will be present in tissues and bodily fluids such as semen, even in people who have achieved and maintained an undetectable viral load for years. Scientific detection of very small amounts of HIV RNA or DNA in tissues or semen does not correlate with a person's risk of transmitting HIV to others, provided that they are on effective therapy and have an undetectable viral load. Research has delivered clear-cut evidence that staying on treatment and maintaining a durably undetectable plasma viral load results in effectively no risk of sexually transmitting HIV to an HIV-negative partner. To learn more, see Treatment as HIV Prevention.

[Note from TheBody: This article was created by NIAID, who last updated it on Mar. 6, 2018. We have cross-posted it with their permission.]