Infections by coronaviruses such as severe acute respiratory syndrome （SARS） coronavirus （SCoV） and mouse hepatitis virus A59 （MHV-A59） result in very little type I interferon （IFN） production by host cells, w...Infections by coronaviruses such as severe acute respiratory syndrome （SARS） coronavirus （SCoV） and mouse hepatitis virus A59 （MHV-A59） result in very little type I interferon （IFN） production by host cells, which is potentially responsible for the rapid viral growth and severe immunopathology associated with SARS. However, the molecular mechanisms for the low IFN production in cells infected with coronaviruses remain unclear. Here, we provide evidence that Papain-like protease domain 2 （PLP2）, a catalytic domain of the nonstructural protein 3 （nsp3） of MHV-A59, can bind to IRF3, cause its deubiquitination and prevent its nuclear translocation. As a consequence, co-expression of PLP2 strongly inhibits CARDIF-, TBK1- and IRF3-mediated IFNp reporter activities. In addition, we show that wild-type PLP2 but not the mutant PLP2 lacking the deubiquitinase （DUB） activity can reduce IFN induction and promote viral growth in cells infected with VSV. Thus, our study uncovered a viral DUB which coronaviruses may use to escape from the host innate antiviral responses.展开更多
基金These authors contributed equally to this work. We thank Drs S Vaidya and E Chow （University of California Los Angeles, USA） for their help in setting up critical experimental systems. We greatly thank Dr K Holmes （University of Colorado Health Sciences Center, USA） for sharing with us 17C1-1 cell line and helping to optimize the protocol to produce high titered MHV-A59 virus stock. We also thank Drs R Baric and L Su （University of North Carolina, USA） for the gift of MHV-A59 and guidance of virus infection. We thank Dr K Lim （National Neuroscience Institute, Singapore） for the gift of Ubi plasmids. We thank Dr M Wathelet （University of Cincinnati College of Medicine, USA） for sharing the nsp3 construct. Also we thank Dr G Gao （Institute of Biophysics, CAS） for providing us with VSV. This research was partly supported by grants from the National Natural Science Foundation of China （30728006） to Genhong Cheng and the National Basic Research Program of MOST （2004BA519A61, 2006CB504300, 2007DFC30190） to Hong Tang.
文摘Infections by coronaviruses such as severe acute respiratory syndrome （SARS） coronavirus （SCoV） and mouse hepatitis virus A59 （MHV-A59） result in very little type I interferon （IFN） production by host cells, which is potentially responsible for the rapid viral growth and severe immunopathology associated with SARS. However, the molecular mechanisms for the low IFN production in cells infected with coronaviruses remain unclear. Here, we provide evidence that Papain-like protease domain 2 （PLP2）, a catalytic domain of the nonstructural protein 3 （nsp3） of MHV-A59, can bind to IRF3, cause its deubiquitination and prevent its nuclear translocation. As a consequence, co-expression of PLP2 strongly inhibits CARDIF-, TBK1- and IRF3-mediated IFNp reporter activities. In addition, we show that wild-type PLP2 but not the mutant PLP2 lacking the deubiquitinase （DUB） activity can reduce IFN induction and promote viral growth in cells infected with VSV. Thus, our study uncovered a viral DUB which coronaviruses may use to escape from the host innate antiviral responses.
