release from viral latency

Definition

Target type: biologicalprocess

The process by which a virus begins to replicate following a latency replication decision (switch). [GOC:dos, GOC:jl]

Viral latency is a state in which a virus integrates its genetic material into the host cell's genome but remains dormant, not actively producing viral proteins or progeny. This allows the virus to evade the host's immune system and persist within the host for extended periods. However, under certain conditions, the virus can reactivate from latency and enter a lytic phase, leading to the production of new viral particles and ultimately cell lysis. This reactivation process is complex and involves multiple factors.

**Triggers for Reactivation:**

* **Stress:** Stressful conditions, such as physical or psychological stress, can trigger reactivation in some viruses. For example, stress hormones like cortisol can promote viral gene expression.
* **Immune Suppression:** Weakening of the immune system due to factors like aging, disease, or immunosuppressive drugs can allow latent viruses to reactivate.
* **Environmental Factors:** Certain environmental factors, such as exposure to ultraviolet radiation or specific chemicals, can induce reactivation in some viruses.

**Molecular Mechanisms of Reactivation:**

* **Transcriptional Activation:** Reactivation typically involves the reactivation of viral gene transcription, which is often controlled by specific viral regulatory proteins. These proteins bind to specific DNA sequences in the viral genome and activate gene expression.
* **Chromatin Remodeling:** The viral DNA is often integrated into the host cell's genome in a compact, inactive form. Reactivation requires changes in chromatin structure to allow access of transcription factors to the viral genome.
* **Post-translational Modification:** Viral proteins involved in reactivation often undergo post-translational modifications, such as phosphorylation or acetylation, which can alter their activity and promote viral gene expression.

**Release from Latency:**

Once viral gene expression is reactivated, the virus begins to produce viral proteins, including capsid proteins, enzymes, and regulatory proteins. These proteins assemble into new viral particles.

**Modes of Release:**

* **Lysis:** Some viruses induce cell lysis, releasing new viral particles to infect neighboring cells.
* **Budding:** Other viruses bud from the cell membrane, acquiring an envelope as they exit. This process can be less destructive to the cell than lysis.

**Specific Examples:**

* **Herpes Simplex Virus (HSV):** HSV can cause oral or genital herpes. Reactivation of HSV is often triggered by stress, fever, or sunburn.
* **Varicella-zoster Virus (VZV):** VZV causes chickenpox and shingles. Reactivation of VZV can occur in older adults and leads to shingles.
* **Human Immunodeficiency Virus (HIV):** HIV can become latent in CD4+ T cells. Reactivation of HIV can occur in individuals with weakened immune systems and contributes to the progression of AIDS.

**Clinical Significance:**

Reactivation of latent viruses can cause significant disease, ranging from mild symptoms to severe, life-threatening conditions. Understanding the mechanisms of viral latency and reactivation is crucial for developing antiviral therapies and vaccines.

**Future Directions:**

* Research on the mechanisms of viral latency and reactivation is ongoing.
* Developing new drugs and therapies to prevent or treat viral reactivation is a priority for public health.
* Understanding the role of host factors in viral latency and reactivation is important for developing personalized therapies.'
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Proteins (1)

Compounds (9)