Retrovirus

Definition

A retrovirus is a type of RNA virus that uses reverse transcription to convert its RNA genome into DNA after entering a host cell. This unique process allows retroviruses to integrate their genetic material into the host's genome, enabling them to replicate and persist within the host. Retroviruses are known for their association with various diseases, including certain types of cancer and acquired immunodeficiency syndrome (AIDS).

5 Must Know Facts For Your Next Test

1. Retroviruses are characterized by their single-stranded RNA genomes and their ability to reverse transcribe this RNA into DNA.
2. After the reverse transcription process, the resulting viral DNA can integrate into the host's chromosomes, making it a permanent part of the host's genetic material.
3. HIV (Human Immunodeficiency Virus) is one of the most well-known retroviruses, leading to AIDS and affecting millions worldwide.
4. Retroviruses can enter a latent phase where they remain inactive within the host cell, potentially reactivating later to produce new viruses.
5. Some retroviruses can contribute to cancer development by activating oncogenes within the host's genome, leading to uncontrolled cell proliferation.

Review Questions

• How does the process of reverse transcription differentiate retroviruses from other types of viruses?
  • Reverse transcription is a defining feature of retroviruses that sets them apart from other viruses. While most viruses directly use their genetic material (either RNA or DNA) to replicate, retroviruses first convert their RNA into DNA using the enzyme reverse transcriptase. This newly formed viral DNA then integrates into the host's genome, which allows it to be replicated alongside the host's genetic material during cell division. This unique mechanism enables retroviruses to persist in the host and can have significant implications for infection and disease progression.
• Discuss how retroviruses utilize both lytic and lysogenic cycles during their life cycle.
  • Retroviruses primarily engage in a lysogenic cycle after reverse transcription when their viral DNA integrates into the host genome. This integration allows the virus to remain dormant within the host cell until certain conditions trigger its activation, leading to the production of new virions and a lytic phase. The ability of retroviruses to switch between these two cycles is crucial for their survival; they can remain hidden from the host's immune system during latency while having the potential to reactivate and cause infection when conditions favor viral replication.
• Evaluate the impact of retroviral integration on the host genome and its potential implications for human health.
  • The integration of retroviral DNA into the host genome can have profound implications for human health, particularly when it leads to gene disruption or activation of oncogenes. This process can result in mutations that may contribute to cancer development or other diseases. For example, when a retrovirus integrates near or within a gene that regulates cell growth, it can alter normal cellular functions, leading to uncontrolled proliferation. Understanding these interactions is essential for developing targeted therapies for diseases caused by retroviral infections, highlighting the importance of studying retroviruses in virology and medicine.

Related terms

Reverse Transcriptase: An enzyme that retroviruses use to transcribe their RNA genome into DNA, which is then integrated into the host's DNA.

Lysogenic Cycle: A viral replication cycle in which the viral DNA is integrated into the host's genome and can remain dormant before being activated to produce new virions.

Oncogene: A gene that has the potential to cause cancer when mutated or expressed at high levels, some retroviruses can activate oncogenes leading to tumor formation.