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Porcine Deltacoronavirus nsp5 Cleaves DCP1A To Decrease Its Antiviral Activity
Xinyu Zhu1,2, Jiyao Chen1,2, Liyuan Tian1,2
1State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.
Journal of Virology
|May 29, 2020
Summary
Porcine deltacoronavirus nsp5 protease cleaves porcine mRNA-decapping enzyme 1a (pDCP1A), an interferon-stimulated gene, hindering antiviral activity. This cleavage is a common immune evasion strategy used by mammalian coronaviruses.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Porcine deltacoronavirus (PDCoV) is an emerging swine pathogen.
- Coronaviruses (CoVs) utilize nonstructural protein nsp5 (3C-like protease) for polyprotein processing.
- PDCoV nsp5 is known to disrupt host interferon (IFN) production and signaling.
Purpose of the Study:
- To investigate whether PDCoV nsp5 cleaves IFN-stimulated genes (ISGs).
- To identify the specific ISG targeted by PDCoV nsp5 and elucidate the mechanism of immune evasion.
Main Methods:
- Screening of 14 classical ISGs for cleavage by PDCoV nsp5.
- Protease activity assays using PDCoV nsp5 and porcine mRNA-decapping enzyme 1a (pDCP1A).
- Analysis of cleavage site and conservation in mammalian CoVs.
Main Results:
- PDCoV nsp5 specifically cleaved pDCP1A at glutamine 343 (Q343).
- Cleaved pDCP1A fragments lost their ability to inhibit PDCoV infection.
- A mutant pDCP1A (Q343A) resistant to cleavage showed enhanced antiviral activity.
- Cleavage of DCP1A by nsp5 is conserved across various mammalian CoVs.
Conclusions:
- PDCoV nsp5 directly targets and inactivates the antiviral effector pDCP1A by cleavage.
- This cleavage represents a common viral immune evasion mechanism employed by mammalian CoVs.
- PDCoV nsp5 acts as a potent IFN antagonist by targeting multiple host IFN system components.
