Japanese Encephalitis Virus NS5 Inhibits Type I Interferon (IFN) Production by Blocking the Nuclear Translocation of IFN Regulatory Factor 3 and NF-κB.
The type I interferon (IFN) response is part of the first-line defense against viral infection. To initiate replication, viruses have developed powerful evasion strategies to counteract host IFN responses. In the present study, we found that the Japanese encephalitis virus (JEV) NS5 protein could inhibit double-stranded RNA (dsRNA)-induced IFN-β expression in a dose-dependent manner. Our data further demonstrated that JEV NS5 suppressed the activation of the IFN transcriptional factors IFN regulatory factor 3 (IRF3) and NF-κB. However, there was no defect in the phosphorylation of IRF3 and degradation of IκB, an upstream inhibitor of NF-κB, upon NS5 expression, indicating a direct inhibition of the nuclear localization of IRF3 and NF-κB by NS5. Mechanistically, NS5 was shown to interact with the nuclear transport proteins KPNA2, KPNA3, and KPNA4, which competitively blocked the interaction of KPNA3 and KPNA4 with their cargo molecules, IRF3 and p65, a subunit of NF-κB, and thus inhibited the nuclear translocation of IRF3 and NF-κB. Furthermore, overexpression of KPNA3 and KPNA4 restored the activity of IRF3 and NF-κB and increased the production of IFN-β in NS5-expressing or JEV-infected cells. Additionally, an upregulated replication level of JEV was shown upon KPNA3 or KPNA4 overexpression. These results suggest that JEV NS5 inhibits the induction of type I IFN by targeting KPNA3 and KPNA4.IMPORTANCEJEV is the major cause of viral encephalitis in South and Southeast Asia, with high mortality. However, the molecular mechanisms contributing to the severe pathogenesis are poorly understood. The ability of JEV to counteract the host innate immune response is potentially one of the mechanisms responsible for JEV virulence. Here we demonstrate the ability of JEV NS5 to interfere with the dsRNA-induced nuclear translocation of IRF3 and NF-κB by competitively inhibiting the interaction of IRF3 and NF-κB with nuclear transport proteins. Via this mechanism, JEV NS5 suppresses the induction of type I IFN and the antiviral response in host cells. These findings reveal a novel strategy for JEV to escape the host innate immune response and provide new insights into the pathogenesis of JEV.
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Jing
J
Ye
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Zheng
Z
Chen
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Yunchuan
Y
Li
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Zikai
Z
Zhao
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Wen
W
He
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Ali
A
Zohaib
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Yunfeng
Y
Song
Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China.
Chenglin
C
Deng
Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, People's Republic of China.
Bo
B
Zhang
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Huanchun
H
Chen
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China sbcao@mail.hzau.edu.cn.|Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.|The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
Shengbo
S
Cao
D000818:Animals; D002460:Cell Line; D004664:Encephalitis Virus, Japanese / Q000276:immunology / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D006801:Humans; D057131:Immune Evasion; D007108:Immune Tolerance; D050838:Interferon Regulatory Factor-3 / Q000037:antagonists & inhibitors*; D016899:Interferon-beta / Q000037:antagonists & inhibitors*; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D025941:Protein Interaction Mapping; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D028901:alpha Karyopherins / Q000378:metabolism*
D050838:Interferon Regulatory Factor-3; C106306:KPNA3 protein, human; C106259:KPNA4 protein, human; D016328:NF-kappa B; C096041:NS5 protein, flavivirus; D017361:Viral Nonstructural Proteins; D028901:alpha Karyopherins; D016899:Interferon-beta
Japanese encephalitis virus; NS5; innate immunity; nuclear transport