lentiviruses

Lentivirus is a genus of enveloped, positive-sense RNA retroviruses in the family Retroviridae. Members have long incubation periods and can establish lifelong infections. The genus includes human and animal pathogens as well as nonpathogenic relatives. Primates include HIV-1 and HIV-2 (with SIV as their simian precursors); other lentiviruses infect cats (FIV), horses (EIAV), and ruminants (CAEV and MVV).

Virions are enveloped, about 100–120 nm in diameter. The genome is roughly 9–10 kb of single-stranded RNA that is reverse-transcribed to DNA and integrated as a provirus. The genome encodes gag, pol, and env, plus regulatory/accessory genes such as tat and rev that influence transcription and replication.

Replication involves entry, reverse transcription, integration, transcription by host RNA polymerase II, and production and assembly of new virions. Lentiviruses cause persistent infections and often slow disease progression. HIV infection progresses to AIDS without treatment; in other species, lentiviral infections cause chronic disease with immune dysfunction or neurologic signs.

Diagnosis uses serology for antibodies and molecular tests for viral RNA or proviral DNA. Antiretroviral therapy can suppress HIV replication but is not curative; vaccines for lentiviruses are limited, and control in animals relies on management and prevention of transmission.

Lentiviruses are also widely used as gene-delivery tools. Lentiviral vectors can transduce dividing and non-dividing cells for stable transgene expression, making them valuable in research and gene therapy, though safety concerns such as insertional mutagenesis must be addressed.