human immunodeficiency virus type 1

infectious agent

Also known as: HIV-1, human T-cell lymphotropic virus, type III(Show More)

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 29, 2026

Quick Summary

Human immunodeficiency virus type 1 (HIV-1) is a retrovirus that attacks the immune system, specifically targeting CD4 T cells. This weakens the body's ability to fight off infections and diseases. HIV-1 is the most common and virulent type of HIV worldwide.123

The virus spreads through specific bodily fluids, including blood, semen, and breast milk. If left untreated, HIV can progress to acquired immunodeficiency syndrome (AIDS), a condition where the immune system is severely compromised, leading to opportunistic infections and certain cancers. While there is no cure for HIV, antiretroviral therapy can effectively manage the virus, allowing individuals to live long and healthy lives.43561

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

7 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

AIDS
The origin of HIV
…strain of HIV, known as HIV-1 group M, have indicated that the virus emerged between 1884 and 1924 in central and western Africa. Researchers estimate that that strain of the virus began spreading throughout those areas in the late 1950s. Later, in the mid-1960s, an evolved strain called HIV-1 group…
Read More
…strain of HIV, known as HIV-1 group M, have indicated that the virus emerged between 1884 and 1924 in central and western Africa. Researchers estimate that that strain of the virus began spreading throughout those areas in the late 1950s. Later, in the mid-1960s, an evolved strain called HIV-1 group…
Read More