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-␤ 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-B. However, there was no defect in the phosphorylation of IRF3 and degradation of IB, an upstream inhibitor of NF-B, upon NS5 expression, indicating a direct inhibition of the nuclear localization of IRF3 and NF-B 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-B, and thus inhibited the nuclear translocation of IRF3 and NF-B. Furthermore, overexpression of KPNA3 and KPNA4 restored the activity of IRF3 and NF-B and increased the production of IFN-␤ 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.IMPORTANCE JEV 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 dsRNAinduced nuclear translocation of IRF3 and NF-B by competitively inhibiting the interaction of IRF3 and NF-B 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.

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus, which caused an unprecedented epidemic in Latin America. Among all viral non-structural proteins in flavivirus, NS5 is the most highly conserved and has multiple crucial functions, including participating in viral RNA replication and suppressing host innate immunity. Although ZIKV NS5 prominently localizes in the nucleus during infection, its specific nuclear localization signal (NLS), and its role in viral replication and pathogenesis remain controversial. Here, we identified aa 11–90 and aa 370–406 regions that contain NLSs, which are critical for nuclear localization of ZIKV NS5. Further experiments demonstrated that nuclear localization of ZIKV NS5 predominantly participates in suppression of interferon regulatory factor 3 (IRF3)-mediated activation of type I IFN (IFN-I) transcription and inhibition of IFN-I downstream response independent of its effect on signal transducers and activators of transcription 2 (STAT2) degradation. These results suggest that subcellular localization of NS5 is important for its function on innate immune suppression, which provides new insight into ZIKV pathogenesis.

Flaviviruses, such as Zika virus (ZIKV), Japanese encephalitis virus (JEV), Dengue virus (DENV), and West Nile virus (WNV), are important arthropod-borne pathogens that present an immense global health problem. Their unpredictable disease severity, unusual clinical features, and severe neurological manifestations underscore an urgent need for antiviral interventions. Furin, a host proprotein convertase, is a key contender in processing flavivirus prM protein to M protein, turning the inert virus to an infectious particle. For this reason, the current study was planned to evaluate the antiviral activity of decanoyl-Arg-Val-Lys-Arg-chloromethylketone, a specific furin inhibitor, against flaviviruses, including ZIKV and JEV. Analysis of viral proteins revealed a significant increase in the prM/E index of ZIKV or JEV in dec-RVKR-cmk-treated Vero cells compared to DMSO-treated control cells, indicating dec-RVKR-cmk inhibits prM cleavage. Plaque assay, qRT-PCR, and immunofluorescence assay revealed a strong antiviral activity of dec-RVKR-cmk against ZIKV and JEV in terms of the reduction in virus progeny titer and in viral RNA and protein production in both mammalian cells and mosquito cells. Time-of-drug addition assay revealed that the maximum reduction of virus titer was observed in post-infection treatment. Furthermore, our results showed that dec-RVKR-cmk exerts its inhibitory action on the virus release and next round infectivity but not on viral RNA replication. Taken together, our study highlights an interesting antiviral activity of dec-RVKR-cmk against flaviviruses.

Japanese encephalitis virus (JEV) is a mosquito-borne virus and the major cause of viral encephalitis in Asia. NS1 0 , a 52-amino acid C-terminal extension of NS1, is generated with a-1 programmed ribosomal frameshift and is only present in members of the Japanese encephalitis serogroup of flaviviruses. Previous studies demonstrated that NS1 0 plays a vital role in virulence, but the mechanism is unclear. In this study, an NS1 0 defected (rG66A) virus was generated. We found that rG66A virus was less virulent than its parent virus (pSA14) in wild-type mice. However, similar mortality caused by the two viruses was observed in an IFNAR knockout mouse model. Moreover, we found that rG66A virus induced a greater type I interferon (IFN) response than that by pSA14, and JEV NS1 0 significantly inhibited the production of IFN-b and IFN-stimulated genes. Taken together, our results reveal that NS1 0 plays a vital role in blocking type I IFN production to help JEV evade antiviral immunity and benefit viral replication. Keywords Japanese encephalitis virus (JEV) Á NS1 0 Á Type I interferon (IFN-I) Á Immune evasion Electronic supplementary material The online version of this article (

Abstract-In this paper, we present a comprehensive study on sensor-assisted video encoding (SaVE) schemes for video capturing on mobile devices in real-world environments. Our purpose is to reduce the computational complexity of video encoding by leveraging sensors that are increasingly available on mobile devices, e.g., accelerometers and digital compasses. Motion estimation is a key component of video encoding. In this paper, SaVE calculates the rotational movement of a camera (on mobile devices) and then infers the global motion in the camera imager. SaVE subsequently employs the estimated global motion as predictors to simplify motion estimation algorithms for state-of-the-art H.264/AVC video coding. We have constructed a prototype of SaVE and evaluated its performance with a pair of accelerometers, a digital compass, and their combination. Our experimental results show that SaVE can significantly reduce the computations of motion estimation while achieving equal or better video quality. Our results also show that SaVE has a strong noise-resistant capability. Therefore, it can be practically employed in real-world environments.