Lentiviren

Lentiviren, or lentiviruses, are a genus of retroviruses in the family Retroviridae, subfamily Orthoretrovirinae. They are characterized by long incubation periods and persistent, slowly progressive infections in their hosts. The best known members are the human immunodeficiency viruses HIV-1 and HIV-2, the causative agents of AIDS.

The lentiviral genome is a positive-sense, single-stranded RNA of about 9.7 kilobases, encapsulated by an envelope and flanked by long terminal repeats. During replication, the virus reverse transcribes its RNA into DNA, which integrates into the host genome as proviral DNA. Lentiviruses encode the core Gag and Pol proteins and the envelope Env, along with regulatory and accessory proteins such as Tat, Rev, and Nef (as well as Vif, Vpr, and Vpu/Vpx in HIV-1 and HIV-2).

Transmission occurs primarily through exposure to infected bodily fluids, including blood, semen, vaginal secretions, and breast milk. In the absence of treatment, infection is lifelong and, in the case of HIV, leads to progressive immune dysfunction with CD4+ T-cell depletion, culminating in Acquired Immunodeficiency Syndrome (AIDS) if untreated.

HIV-1 is globally dominant and responsible for the majority of AIDS cases; HIV-2 is less transmissible and largely confined to West Africa with a slower rate of disease progression. Prevention focuses on reducing exposure to infected fluids through safe sex practices, harm reduction for people who inject drugs, screening of blood products, and preventing mother-to-child transmission. Antiretroviral therapy, typically a combination regimen, suppresses viral replication, preserves immune function, and reduces transmission risk. No widely effective vaccine exists today, though research continues.

Other lentiviruses are found in animals, including SIV in non-human primates, FIV in cats, and EIAV in horses, all sharing the characteristic of chronic, integrated infections.