RIG-I is cleaved during picornavirus infection.

Abstract

The innate immune system senses RNA virus infections through membrane-bound Toll-like receptors or the cytoplasmic proteins RIG-I and MDA-5. RIG-I is believed to recognize the 5'-triphosphate present on many viral RNAs, and hence is important for sensing infections by paramyxoviruses, influenza viruses, rhabdoviruses, and flaviviruses. MDA-5 recognizes dsRNA, and senses infection with picornaviruses, whose RNA 5'-ends are linked to a viral protein, VPg, not a 5'-triphosphate. We previously showed that MDA-5 is degraded in cells infected with different picornaviruses, and suggested that such cleavage might be a mechanism to antagonize production of type I IFN in response to viral infection. Here we examined the state of RIG-I during picornavirus infection. RIG-I is degraded in cells infected with poliovirus, rhinoviruses, echovirus, and encephalomyocarditis virus. In contrast to MDA-5, cleavage of RIG-I is not accomplished by cellular caspases or the proteasome. Rather, the viral proteinase 3C(pro) cleaves RIG-I, both in vitro and in cells. Cleavage of RIG-I during picornavirus infection may constitute another mechanism for attenuating the innate response to viral infection.

• Authors: Paola M Barral, Devanand Sarkar, Paul B Fisher, Vincent R Racaniello
• Journal: Virology (Virology) Vol. 391 Issue 2 Pg. 171-6 (Sep 01 2009) ISSN: 1096-0341 [Electronic] United States
• PMID: 19628239 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Receptors, Immunologic
• Viral Proteins
• Cysteine Endopeptidases
• 3C Viral Proteases
• RIGI protein, human
• DEAD Box Protein 58
• DEAD-box RNA Helicases

Topics

• 3C Viral Proteases
• Cell Line
• Cysteine Endopeptidases (metabolism)
• DEAD Box Protein 58
• DEAD-box RNA Helicases (metabolism)
• Humans
• Picornaviridae (immunology, physiology)
• Receptors, Immunologic
• Viral Proteins (metabolism)