Provirus

Definition

A provirus is a form of viral genetic material that has integrated into the host cell's genome. This integration allows the virus to remain dormant within the host's DNA, and it can be reactivated later to produce new viral particles. Understanding proviruses is essential for recognizing how certain viruses establish long-term infections and evade the immune response.

5 Must Know Facts For Your Next Test

1. Proviruses are critical for understanding how certain viruses can persist in host organisms, leading to chronic infections.
2. The integration of a provirus into the host genome can disrupt normal cellular functions, potentially leading to cancer in some cases.
3. Proviruses are often involved in diseases caused by retroviruses, such as HIV, where they play a key role in the virus's ability to evade the immune system.
4. When conditions are favorable, a provirus can reactivate and begin producing new viral particles, entering the lytic cycle.
5. The presence of a provirus can complicate treatment strategies since antiviral therapies may not target dormant viral particles.

Review Questions

• How does a provirus integrate into a host's genome, and what implications does this have for long-term viral infections?
  • A provirus integrates into a host's genome through specific enzymes that facilitate the incorporation of viral DNA into the host DNA. This integration allows the virus to remain dormant for extended periods, enabling it to evade detection by the immune system. The implications of this are significant because it means that even after initial infection has cleared, the virus can reactivate and lead to recurrent disease, complicating treatment and control efforts.
• Discuss the relationship between retroviruses and proviruses, particularly regarding their replication strategies.
  • Retroviruses are unique in that they replicate by converting their RNA genome into DNA through reverse transcription. Once this DNA is formed, it integrates into the host cell's genome as a provirus. This relationship is crucial because it allows retroviruses to become part of the host’s genetic material, which can lead to persistent infections and contributes to challenges in eradicating these viruses from infected individuals.
• Evaluate the impact of proviruses on host cell function and how they can contribute to disease states such as cancer.
  • Proviruses can significantly impact host cell function by integrating into critical regions of the genome, disrupting normal gene expression and regulatory mechanisms. This disruption can lead to uncontrolled cell growth and contribute to cancer development. Additionally, when proviruses reactivate, they can produce new viral particles that further compromise cellular integrity and provoke immune responses, creating a cycle that exacerbates disease progression.

Related terms

Lysogenic Cycle: A phase in the viral life cycle where the viral DNA integrates into the host's genome, allowing the virus to remain dormant until it enters the lytic cycle.

Retrovirus: A type of virus that uses reverse transcription to convert its RNA into DNA, which can then integrate into the host's genome as a provirus.

Latent Infection: An infection in which a virus remains dormant within the host cells, often as a provirus, without causing immediate symptoms or illness.