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Updated: Jun 21, 2026
09:05
MicroRNA-based Regulation of Picornavirus Tropism
Published on: February 6, 2017
RIG-I is cleaved during picornavirus infection.
Paola M Barral1, Devanand Sarkar, Paul B Fisher
1Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, 1101 East Marshall Street, Sanger Hall Building, Room 11-015, Richmond, VA 23298-0033, USA.
Virology
|July 25, 2009
Summary
Picornaviruses degrade RIG-I, a key innate immune sensor, using viral proteinase 3C(pro). This cleavage antagonizes the immune response, helping viruses evade detection during infection.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- The innate immune system detects RNA viruses via Toll-like receptors, RIG-I, and MDA-5.
- RIG-I senses 5'-triphosphate viral RNAs, crucial for detecting paramyxoviruses, influenza, rhabdoviruses, and flaviviruses.
- MDA-5 recognizes dsRNA and senses picornaviruses, which have VPg-linked RNA 5'-ends.
Purpose of the Study:
- To investigate the status of RIG-I (Retinoic acid-inducible gene I) during picornavirus infection.
- To determine the mechanism by which RIG-I is degraded by picornaviruses.
- To understand how RIG-I cleavage contributes to viral immune evasion.
Main Methods:
- Cellular infection models with various picornaviruses (poliovirus, rhinoviruses, echovirus, encephalomyocarditis virus).
- Analysis of RIG-I protein levels and cleavage products in infected cells.
- In vitro cleavage assays using purified viral proteinase 3C(pro) and RIG-I.
- Investigation of potential involvement of caspases and proteasomes in RIG-I degradation.
Main Results:
- RIG-I is degraded in cells infected with multiple picornaviruses.
- Unlike MDA-5 degradation, RIG-I cleavage is not mediated by caspases or the proteasome.
- The viral proteinase 3C(pro) directly cleaves RIG-I both in vitro and within infected cells.
Conclusions:
- Picornaviruses actively degrade RIG-I, a key pattern recognition receptor.
- Viral proteinase 3C(pro) is responsible for RIG-I cleavage during picornavirus infection.
- RIG-I cleavage represents an additional strategy employed by picornaviruses to suppress the innate immune response and facilitate infection.
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