Provirus

Provirus is a stage in the life cycle of certain viruses, particularly retroviruses and bacteriophages, during which the virus integrates its genome into the DNA of the host cell, which allows the virus to replicate as part of the host's cellular processes.

Overview

A provirus is a virus genome that is integrated into the DNA of a host cell. In the case of bacterial viruses (bacteriophages), this phase of the viral life cycle is called lysogeny. In the case of animal viruses, this is often referred to as viral latency.

Formation

The formation of a provirus occurs when a virus enters a cell and instead of immediately replicating and lysing (breaking open) the cell, it integrates its genetic material into the host genome. This can occur as a normal part of the viral life cycle or can be a more rare event.

Replication

Once integrated into the host genome, the provirus is replicated along with the host DNA each time the host cell divides. This allows the virus to persist in the host organism for extended periods of time, even without causing disease.

Activation

The provirus can be activated by certain triggers to begin producing virus particles. This can result in disease symptoms. In some cases, the activation of a provirus can lead to oncogenesis, the process that leads to the formation of a tumor.

Examples

Examples of viruses that form proviruses include HIV, the virus that causes AIDS, and HTLV-1, a virus that causes a type of leukemia.

See also

• Virus
• Retrovirus
• Bacteriophage
• Lysogeny
• Viral latency
• Oncogenesis