HIV

The human immunodeficiency virus, commonly called HIV, is a retrovirus that primarily infects vital components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. It also directly and indirectly destroys CD4+ T cells. As CD4+ T cells are required for the proper functioning of the immune system, when enough CD4+ cells have been destroyed by HIV, the immune system barely works, leading to AIDS. HIV also directly attacks certain human organs, such as the kidneys, the heart and the brain leading to acute renal failure, cardiomyopathy, dementia and encephalopathy. Many of the problems faced by people infected with HIV results from the failure of the immune system to protect them from certain opportunistic infections and cancers.

Introduction

In 1983, scientists in France led by Luc Montagnier, first discovered the virus that causes AIDS {{ref|Barré-Sinoussi}}. They called it lymphadenopathy-associated virus (LAV). A year later, Robert Gallo of the United States, confirmed the discovery of the virus, and they named it human T lymphotropic virus type III (HTLV-III) {{ref|Popovic}}. In 1986, both names were dropped in favour of the term human immunodeficiency virus (HIV) {{ref|Coffin}}.

Related Topics:
France - Luc Montagnier - AIDS - Robert Gallo

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HIV is a member of the genus lentivirus {{ref|ICTVdb6106}}, part of the family of retroviridae {{ref|ICTVdb61}}. Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long duration illnesses associated with a long period of incubation {{ref|Lévy}}. Lentiviruses are transmitted as single-stranded negatively-sensed enveloped RNA viruses. Upon infection of the target-cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase which is present in the virus particle. This viral DNA is then integrated into the cellular DNA for replication using cellular machinery. Once the virus enters the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function or the virus becomes active, replicates and a large number of virus particles are liberated which can infect other cells.

Related Topics:
Lentivirus - Retroviridae - RNA virus - Genome - DNA - Reverse transcriptase - Latent

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Two species of HIV infect humans: HIV-1 and HIV-2. HIV-1 is the more virulent and easily transmitted, and is the source of the majority of HIV infections throughout the world; HIV-2 is largely confined to west Africa {{ref|Reeves}}. Both species originated in west and central Africa, jumping from primates to humans in a process known as zoonosis. HIV-1 has evolved from a simian immunodeficiency virus (SIVcpz) found in the chimpanzee subspecies, Pan troglodyte troglodyte {{ref|Gao}}. HIV-2 crossed species from a different strain of SIV, found in sooty mangabeys, an old world monkey of Guinea-Bissau {{ref|Reeves}}.

Related Topics:
Zoonosis - Simian immunodeficiency virus - Chimpanzee - Sooty mangabeys - Old world monkey - Guinea-Bissau

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