Related Experiment Video
Updated: Apr 16, 2026
10:55
Vaccinia Virus Infection & Temporal Analysis of Virus Gene Expression: Part 2
Published on: April 10, 2009
8.4K
Caps off to poxviruses
1Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Cell Host & Microbe
|March 14, 2015
Abstract:
In this issue of Cell Host & Microbe, Liu et al. (2015) and Burgess and Mohr (2015) describe how two poxvirus mRNA decapping enzymes hijack a host 5'-to-3'-exoribonuclease to evade antiviral innate immunity by limiting accumulation of double-stranded RNA.
Insights
Two poxviruses possess mRNA decapping enzymes that hijack a host enzyme to evade antiviral immunity. This mechanism limits double-stranded RNA accumulation, a key trigger for innate immune responses.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Poxviruses are large DNA viruses that replicate in the cytoplasm.
- Antiviral innate immunity relies on detecting viral components, including double-stranded RNA (dsRNA).
- mRNA decapping is a crucial step in RNA metabolism, typically leading to RNA degradation.
Purpose of the Study:
- To investigate how poxviruses evade host antiviral immunity.
- To understand the role of poxviral mRNA decapping enzymes in this evasion.
- To elucidate the mechanism by which dsRNA accumulation is limited during poxvirus infection.
Main Methods:
- Analysis of poxvirus mRNA decapping enzyme function.
- Investigating interactions between viral and host cellular proteins.
- Assessing the impact of viral enzyme activity on host innate immune signaling pathways.
Main Results:
- Two distinct poxvirus mRNA decapping enzymes were identified.
- These viral enzymes were shown to interact with and hijack a host 5'-to-3'-exoribonuclease.
- This hijacking effectively limits the accumulation of dsRNA, thereby dampening the host antiviral response.
Conclusions:
- Poxviruses employ sophisticated strategies to subvert host antiviral defenses.
- Hijacking host RNA degradation machinery is a novel mechanism for immune evasion by viruses.
- Targeting host exoribonucleases allows poxviruses to control dsRNA levels and escape innate immunity.
Related Concept Videos
00:56Viral Structure
77.0K
Viruses are extraordinarily diverse in shape and size, but they all have several structural features in common. All viruses have a core that contains a DNA- or RNA-based genome. The core is surrounded by a protective coat of proteins called the capsid. The capsid is composed of subunits called capsomeres. The capsid and genome-containing core are together known as the nucleocapsid.
77.0K
01:29Subviral Agents
871
Subviral agents are infectious entities that resemble viruses but lack one or more viral components, such as a capsid or essential replication machinery. These agents include viroids, prions, and satellites, each possessing distinct structural and functional characteristics that influence their mode of infection and replication.Viroids are the simplest subviral agents, consisting of circular, single-stranded RNA molecules without a protein coat. They exclusively infect plants, relying entirely...
871
01:28Introduction to Virus
2.8K
Viruses are unique biological entities that blur the boundary between living and non-living systems. Although they lack cellular structure and metabolic processes, they can exhibit characteristics of life when infecting a host. Their defining feature is a nucleic acid core, composed of either DNA or RNA, encapsulated within a protein coat called a capsid. This simple structure allows them to invade host cells and use their machinery for replication efficiently.Viral Structure and...
2.8K
01:10Retrovirus Life Cycles
50.8K
Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the...
50.8K
02:33Retroviruses
16.1K
Retroviruses and retrotransposons both insert copies of their genetic elements into the genome of the host cell. Thus, the viral genes are passed on when the host genome is replicated or translated. A typical retroviral DNA sequence contains 3-4 genes that encode the different proteins required for its structural assembly and function as a molecular parasite. This DNA is transcribed into a single mRNA, which is very similar in structure to conventional mRNAs, i.e., it is capped at the 5’...
16.1K
01:29Viruses with RNA Genomes
1.4K
RNA viruses are categorized into positive-strand, negative-strand, or double-stranded groups based on their genomic structure and replication mechanisms. This classification dictates how they exploit host cellular machinery for protein synthesis and replication. Some RNA viruses also utilize reverse transcription as part of their life cycle, further diversifying their replication strategies.Positive-Strand RNA VirusesPositive-strand RNA viruses have genomes that function directly as messenger...
1.4K