negative regulation by host of viral transcription

Definition

Target type: biologicalprocess

Any process in which a host organism stops, prevents, or reduces the frequency, rate or extent of viral transcription. [GOC:jl]

Negative regulation by host of viral transcription is a crucial antiviral defense mechanism employed by organisms to control and suppress viral replication. This process involves a complex interplay of cellular factors and mechanisms that target various stages of the viral life cycle, effectively dampening viral gene expression and limiting viral propagation.

**1. Transcriptional Interference:**

* Host cells can utilize transcription factors that compete with viral proteins for binding to promoter regions of viral genes. This competitive binding hinders the recruitment of essential transcription machinery, effectively preventing or reducing viral gene expression.
* Some host factors can directly interact with viral promoters, inducing conformational changes that block the access of viral transcription machinery, effectively inhibiting transcription initiation.

**2. RNA Processing Inhibition:**

* Host cells can produce microRNAs (miRNAs) that specifically target viral transcripts. These miRNAs can bind to viral mRNA, leading to its degradation or translational repression.
* Cellular proteins, such as RNA helicases and RNA-binding proteins, can interfere with viral mRNA processing, preventing its proper splicing, capping, or polyadenylation. These processes are essential for generating functional viral transcripts.

**3. Post-Transcriptional Gene Silencing:**

* The host innate immune system employs RNA interference (RNAi) pathways, using small interfering RNAs (siRNAs), to target viral transcripts for degradation. siRNAs are generated from double-stranded RNA intermediates derived from viral replication or from host-encoded transcripts.
* Cellular factors, such as APOBEC3 enzymes, can induce cytidine deaminases, leading to mutations in viral DNA and RNA, resulting in dysfunctional transcripts and hindering viral replication.

**4. Degradation of Viral Transcripts:**

* Host cells possess ribonucleases (RNases) that specifically degrade viral RNA. These enzymes can recognize viral RNA sequences, leading to its rapid degradation and preventing translation into viral proteins.

**5. Inhibition of Viral Transcription Factors:**

* Host cells can produce proteins that inhibit the activity of viral transcription factors. These viral transcription factors are essential for activating viral gene expression, and their inhibition effectively dampens the viral transcriptional program.

**6. Modulation of Chromatin Structure:**

* Host cells can alter the chromatin structure surrounding viral DNA, making it inaccessible to viral transcription machinery. This epigenetic modification can effectively silence viral genes, preventing their expression.

By employing these multifaceted mechanisms, host cells effectively curtail viral transcription, limiting viral replication and minimizing the impact of viral infection.'
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Proteins (3)

Compounds (1,766)