Integrase

Definition

Integrase is an enzyme produced by certain viruses, notably retroviruses, that facilitates the integration of viral DNA into the host cell's genome. This enzyme plays a critical role in the life cycle of these viruses, allowing them to establish persistent infections by inserting their genetic material into the host's DNA, which can then be replicated and transcribed along with the host's genes.

5 Must Know Facts For Your Next Test

1. Integrase specifically recognizes the viral DNA ends and catalyzes the insertion of this DNA into the host cell's chromosomal DNA.
2. This enzyme is essential for the replication of retroviruses, including HIV, as it enables the virus to become a permanent part of the host's genetic material.
3. Integrase inhibitors are a class of antiretroviral drugs designed to block the activity of integrase, preventing viral integration and replication.
4. The integration process occurs during the lysogenic phase of the viral life cycle, allowing for long-term persistence of the virus within the host.
5. Failure of integrase to function properly can result in ineffective viral replication and may lead to a reduction in viral load.

Review Questions

• How does integrase contribute to the life cycle of retroviruses and their ability to persist in host cells?
  • Integrase is crucial for retroviruses because it enables them to insert their viral DNA into the host cell's genome. Once integrated, the viral DNA, known as provirus, becomes part of the host's genetic material. This allows for ongoing replication of the virus whenever the host cell divides, leading to persistent infections. Without integrase, retroviruses would not be able to establish long-term infections.
• Discuss how integrase inhibitors function and their significance in treating retroviral infections.
  • Integrase inhibitors work by blocking the action of integrase, preventing the viral DNA from integrating into the host genome. This is significant in treating retroviral infections such as HIV because it stops the virus from establishing latency and reduces viral replication. By inhibiting this critical step in the viral life cycle, these drugs help manage infection and improve patient outcomes by lowering viral load and reducing transmission.
• Evaluate the role of integrase in both lytic and lysogenic cycles, especially in relation to how it affects viral persistence and replication.
  • Integrase plays a distinct role in both lytic and lysogenic cycles. During the lysogenic cycle, integrase facilitates the integration of viral DNA into the host genome, allowing for a dormant state where the virus can remain undetected and replicate alongside host DNA during cell division. In contrast, during the lytic cycle, while integrase is not directly involved in causing cell lysis, understanding its function is essential for grasping how viruses switch between these cycles. The ability to integrate also influences viral persistence since integrated viruses can reactivate during conditions that favor lytic replication, highlighting integrase's importance in managing both acute and chronic phases of infection.

Related terms

Retrovirus: A type of virus that contains RNA as its genetic material and uses reverse transcriptase to convert its RNA into DNA inside the host cell.

Reverse Transcriptase: An enzyme used by retroviruses to transcribe their RNA genome into DNA, which is a crucial step before integration into the host genome.

Provirus: The integrated viral DNA that remains dormant within the host's genome and can be activated to produce new viral particles.