1. Integration: A provirus is a viral genome that has integrated itself into the host cell's DNA. This integration is permanent, meaning the provirus becomes a part of the host cell's genetic material.
2. Replication: During cell division, the host cell replicates its entire genome, including the integrated proviral DNA. This means each daughter cell receives a copy of the provirus.
3. Transmission: As a result, the provirus is passed on to all subsequent generations of host cells. This makes proviral infections persistent and potentially lifelong.
Consequences of Proviral Replication:
* Latency: Proviruses often remain dormant within the host cell, not producing new viral particles. However, they can be reactivated under certain conditions, leading to viral production and disease.
* Genetic Changes: Integration of the provirus can disrupt host cell genes, potentially causing mutations or altering gene expression.
* Immunosuppression: Some viruses, like HIV, integrate into the genome of immune cells, impairing the immune system's ability to fight infection.
Examples:
* HIV: The provirus of HIV, known as "HIV-1 DNA," integrates into the genome of CD4+ T cells, ultimately leading to the destruction of these immune cells.
* Herpesviruses: Herpesviruses, like varicella-zoster virus (causing chickenpox and shingles), remain latent in neurons as proviruses. They can reactivate under stress, causing recurrent infections.
In summary, when a host cell with a provirus replicates, the provirus is copied and passed on to the daughter cells, ensuring its persistence in the host. This can have various consequences for the host, depending on the specific virus and its integration site.
