What is a virus that is integrated into a host's genome called?

A virus that is integrated into a host's genome is called a provirus. This term specifically refers to the viral DNA that has been incorporated into the DNA of a host cell. When a virus infects a host, particularly in the case of retroviruses, it can reverse transcribe its RNA genome into DNA and then integrate this DNA into the host cell’s genome. Once integrated, the provirus can be replicated along with the host cell's DNA whenever the cell divides. This allows the virus to persist in the host for long periods, often without causing immediate harm, and can potentially reactivate later to produce new viral particles.

In contrast, a plasmid is a small, circular piece of DNA found in bacteria and can replicate independently of chromosomal DNA, but it is not involved in viral integration. A viroid is a small infectious agent that primarily infects plants and consists solely of a short strand of circular RNA, lacking the protein coat typical of viruses. A bacteriophage, or phage, is a type of virus that specifically infects bacteria but does not integrate its genome into the host in the same way that a provirus does. Thus, the term "provirus" precisely describes the integration of viral genetic material into a