retrovirus

A retrovirus is a type of virus that replicates through a process unique to RNA viruses. Unlike DNA viruses, retroviruses have a genome composed of RNA. During their life cycle, retroviruses use an enzyme called reverse transcriptase to convert their RNA genome into DNA. This newly synthesized DNA is then integrated into the host cell's genome, becoming a permanent part of the host's genetic material. This integrated viral DNA is called a provirus.

The provirus can remain dormant for a period or be transcribed by the host cell's machinery to produce new viral RNA and proteins. These components then assemble to form new virus particles, which bud off from the host cell to infect other cells. This process of reverse transcription is a hallmark of retroviruses and is essential for their replication.

Prominent examples of retroviruses include the human immunodeficiency virus (HIV), which causes AIDS, and certain types of leukemia and lymphoma in animals and humans. The study of retroviruses has been crucial in understanding viral replication, gene expression, and has led to the development of important antiviral therapies. The ability of retroviruses to integrate their genetic material into the host genome also makes them valuable tools in molecular biology for gene therapy and genetic engineering.