HIVviruset

HIVviruset, commonly referred to as HIV, is a lentivirus in the family Retroviridae that attacks the body's immune system, specifically CD4+ T cells, leading to Acquired Immunodeficiency Syndrome (AIDS) if untreated. There are two main types: HIV-1, responsible for the global pandemic, and HIV-2, largely confined to West Africa and typically progressing more slowly. The virus is enveloped and carries a positive-sense, single-stranded RNA genome of about 9.7 kilobases. Its genome encodes structural genes gag, pol, and env, as well as regulatory and accessory genes such as tat, rev, nef, vif, vpr, and vpu.

HIV uses the CD4 molecule as the primary receptor and chemokine co-receptors CCR5 or CXCR4 for entry. After binding, the viral envelope fuses with the host cell membrane, releasing the RNA genome and enzymes including reverse transcriptase, integrase, and protease. Reverse transcription converts RNA into DNA, which is integrated into the host genome by integrase. The provirus is transcribed and translated by the host cell, producing new virions that assemble at the cell membrane and bud, maturing via protease action.

Transmission occurs mainly through unprotected sexual contact, blood exposure, and from mother to child during pregnancy, birth, or breastfeeding. Symptoms vary; many infections are asymptomatic in early stages. Without treatment, HIV gradually depletes CD4 T cells, weakening immune function and leading to AIDS. Antiretroviral therapy (ART) suppresses viral replication, preserves immune function, and prevents progression, though it is not curative. Prevention focuses on safe sex practices, harm reduction, PrEP and PEP, testing, and counseling. Vaccines remain under development.