Interferon-mediated ISG15 conjugation restricts dengue virus 2 replication.
ISGylation, an ubiquitin-like post-translational modification by ISG15, has been reported to participate in the interferon (IFN)-mediated antiviral response. In this study, we analyzed the functional role of ISGylation in dengue virus 2 (DENV-2) replication. Overexpression of ISG15 was found to significantly suppress the amount of extracellular infectious virus released, while intracellular viral RNA was unaffected. This effect was not observed with a conjugation-defective ISG15 mutant. In addition, extracellular virus infectivity was decreased by ISG15 overexpression. To further clarify the role of ISGylation in the anti-DENV-2 response, we depleted endogenous ISG15 by RNA interference and analyzed the virus production in the absence or presence of type-I IFN. Results showed a significant reduction in extracellular DENV-2 RNA levels for cells treated with IFN, and that these DENV-2 RNA levels could be partially restored by the ISG15 knockdown. Among various DENV-2 proteins, NS3 and NS5 were subjected to the ISGylation. These results demonstrate that IFN-inducible ISGylation suppresses DENV-2 particle release, and that ISG15 is one of the mediators of IFN-induced inhibition of DENV-2 replication. ISG15 therefore functions as a host antiviral factor against DENV-2 infection.
Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive,Singapore 117599, Singapore; Laboratory of Primate Model, Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, Kyoto 606-8517, Japan.
Takayuki
T
Hishiki
Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive,Singapore 117599, Singapore.
Qi'En
Q
Han
Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, USA.
Kei-ichiro
K
Arimoto
Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine, Ichikawa, Chiba 272-8516, Japan.
Kunitada
K
Shimotohno
Laboratory of Primate Model, Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, Kyoto 606-8517, Japan.
Tatsuhiko
T
Igarashi
Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857, Singapore.
Subhash G
SG
Vasudevan
Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive,Singapore 117599, Singapore; Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857, Singapore. Electronic address: yoichi.suzuki@duke-nus.edu.sg.
Youichi
Y
Suzuki
Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive,Singapore 117599, Singapore. Electronic address: micny@nus.edu.sg.
Naoki
N
Yamamoto
D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D016207:Cytokines / Q000378:metabolism*; D003716:Dengue Virus / Q000187:drug effects / Q000502:physiology*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology*; D034622:RNA Interference; D014452:Ubiquitins / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects*
D016207:Cytokines; D007370:Interferon Type I; D014452:Ubiquitins; D017361:Viral Nonstructural Proteins; C074034:ISG15 protein, human
Antiviral response; Dengue virus; ISG15; ISGylation; Interferon; Non-structural protein