Publications by authors named "Yuwen Qin"

21 Publications

  • Page 1 of 1

Hardware-efficient blind frequency offset estimation for digital subcarrier multiplexing signals.

Opt Express 2021 Jun;29(13):19879-19890

Since the frequency offset estimation (FOE) must be implemented before the subcarrier de-multiplexing and chromatic dispersion compensation (CDC) for digital subcarrier multiplexing (DSM) signals, traditional FOE algorithms for single carrier transmission is no longer suitable. Here, we propose a hardware-efficient blind FOE solution for the DSM signals by monitoring spectral dips in the frequency domain. With the use of a smoothing filter, the estimation accuracy of FOE can be significantly increased. Moreover, we identify that the proposed FOE method is robust to various transmission impairments, including amplified spontaneous emission (ASE) noise, optical filtering, and fiber nonlinearity. The effective function of the proposed FOE method is numerically and experimentally verified under scenarios of both back-to-back (B2B) and the 2560 km standard single-mode fiber (SSMF) transmission, leading to a FOE error less than 100 MHz with a FFT size of 1024.
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http://dx.doi.org/10.1364/OE.425688DOI Listing
June 2021

Distributed refractive index sensing based on bending-induced multimodal interference and Rayleigh backscattering spectrum.

Opt Express 2021 Jul;29(14):21530-21538

A distributed refractive index (RI) sensor based on high-performance optical frequency domain reflectometry was developed by bending a piece of standard single-mode fiber to excite sets of higher-order modes that penetrate the surrounding medium. External variations in RI modifies the profiles of the sets of excited higher-order modes, which are then partially coupled back into the fiber core and interfere with the fundamental mode. Accordingly, the fundamental mode carries the outer varied RI information, and RI sensing can be achieved by monitoring the wavelength shift of the local Rayleigh backscattered spectra. In the experiment, an RI sensitivity of 39.08 nm/RIU was achieved by bending a single-mode fiber to a radius of 4 mm. Additionally, the proposed sensor maintains its buffer coating intact, which boosts its practicability and application adaptability.
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http://dx.doi.org/10.1364/OE.430637DOI Listing
July 2021

Mode converter with C+L band coverage based on the femtosecond laser inscribed long period fiber grating.

Opt Lett 2021 Jul;46(14):3340-3343

The mode converter (MC) is one of the key components for mode division multiplexing (MDM). Here, we experimentally demonstrate an all-fiber long period grating (LPG) based MC inscribed in the few-mode fiber (FMF) with the line-by-line femtosecond laser irradiation technique. Experimental characterization results agree well with the theoretical calculations, and a clear mode evolution from the mode to the mode is observed with the tuning of the operation wavelength. An average mode conversion efficiency of more than 90% and an average insertion loss of less than 5 dB, together with a polarization-dependent loss of less than 3 dB, are achieved over the C+L band with a good repeatability. The proposed MC based on the LPG inscribed into the FMF has the advantages of mode scalability, compact size, and wideband operation, which is desired for the wavelength division multiplexing (WDM) and MDM hybrid transmission.
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http://dx.doi.org/10.1364/OL.431760DOI Listing
July 2021

Bending-loss-resistant distributed Brillouin curvature sensor based on an erbium-doped few-mode fiber.

Opt Lett 2021 Jul;46(13):3239-3242

We developed a bending-loss-resistant distributed Brillouin curvature sensor based on an erbium-doped few-mode fiber (Er-FMF) and differential pulse-width pair Brillouin optical time-domain analysis. With Er ion amplification compensating for bending-induced optical loss, radii in the ∼0.3 to 2.02 cm range could be monitored correctly. The corresponding Brillouin frequency shift variations were in the range of 91.7 to 9 MHz, which agrees well with theoretical calculations. The sensitivity of the Er-FMF device increased inversely with the bending radius, with the optimal sensitivity of 292.7 MHz/cm obtained at a radius of 0.3 cm. To the best of our knowledge, this is the smallest radius of curvature detected and highest sensitivity reported to date, indicating potential applications in distributed sharp-bend sensing, such as intelligent robotics and structural health monitoring.
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http://dx.doi.org/10.1364/OL.426957DOI Listing
July 2021

Adaptive intensity transformation-based phase retrieval with high accuracy and fast convergence.

Opt Lett 2021 Jul;46(13):3215-3218

Phase-retrieval (PR) receivers can reconstruct complex-valued signals from two de-correlated intensity measurements, without the assistance of any optical carriers. However, both the calculation complexity with hundreds of iterations and the limited PR accuracy prevent it from being applied to high-speed photonic interconnections. Here we propose and demonstrate a PR receiver based on adaptive intensity transformation, with the capability of both fast convergence and high accuracy. Then we numerically reconstruct 56 GBaud QPSK signals after the 80 km standard single-mode fiber transmission by using our proposed PR receiver with only 50 iterations. In comparison with the recently reported PR receiver with the phase reset, our proposed PR receiver can reduce the required optical signal-to-noise ratio by 1.95 and 1.89 dB, in terms of 20% soft-decision and 7% hard-decision forward-error correction, respectively.
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http://dx.doi.org/10.1364/OL.433349DOI Listing
July 2021

Lossy-mode-resonance sensor based on perovskite nanomaterial with high sensitivity.

Opt Express 2021 May;29(11):17602-17612

Lossy-mode-resonance (LMR) is a surface plasmon resonance (SPR)-analogue optical phenomenon, which is sensitive to the surrounding environment variations and can be considered as an important detection signal in biochemical sensors. Compared with the SPR sensor which can only operate under transverse magnetic (TM)-polarized light, the LMR sensor shows a more excellent application prospect and can operate in both TM- and transverse electric (TE)-polarized light. In this work, a CHNHPbBr-based LMR configuration is proposed to apply in optical sensors. When the incident light is in TM mode, the preferred way to improve the performance of the LMR sensor is optimizing the thickness of the matching layer, and the highest sensitivity of 11382 refractive index unit (RIU) is achieved, which is more than 200 times larger than that of the conventional Au-based SPR sensor; when the incident light is in TE mode, it is more advantageous to improve the properties of LMR sensor by optimizing the thickness of CHNHPbBr layer, and a high sensitivity of 21697 RIU is obtained. With such high sensitivity, we believe that the CHNHPbBr-based LMR sensor will find potential applications in biology, medicine, chemistry and other fields.
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http://dx.doi.org/10.1364/OE.426409DOI Listing
May 2021

Reconfigurable generation of double-ring perfect vortex beam.

Opt Express 2021 May;29(11):17353-17364

Perfect vortex beam (PVB), whose ring radius is independent of its topological charge, play an important role in optical trapping and optical communication. Here, we experimentally demonstrate the reconfigurable double-ring PVB (DR-PVB) generation with independent manipulations of the amplitude, the radius, the width, and the topological charge for each ring. Based on complex amplitude modulation (CAM) with a phase-only spatial light modulator (SLM), we successfully verify the proposed DR-PVB generation scheme via the computer-generated hologram. Furthermore, we carry out a quantitative characterization for the generated DR-PVB, in terms of both the generation quality and the generation efficiency. The correlation coefficients of various reconfigurable DR-PVBs are above 0.8, together with the highest generation efficiency of 44%. We believe that, the proposed generation scheme of reconfigurable DR-PVB is desired for applications in both optical tweezers and orbital angular momentum (OAM) multiplexing.
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http://dx.doi.org/10.1364/OE.424664DOI Listing
May 2021

Simple and precise characterization of differential modal group delay arising in few-mode fiber.

Opt Lett 2021 Jun;46(12):2856-2859

In this Letter, we propose a simple and high-precision differential modal group delay (DMGD) characterization method for few-mode fibers (FMF) by using the frequency-modulated continuous wave. Since the detected signals are located at the low-frequency range, our DMGD characterization method waives the use of expensive equipment, such as vector network or optical spectrum analyzers. Due to the high linearity of the used Mach-Zehnder modulator, our DMGD measurement is free from the complex auxiliary interferometer, leading to an improvement of characterization precision. Meanwhile, we propose a novel spectrum recovery algorithm to overcome the shortcoming that the traditional fast Fourier transform (FFT) method is incapable to deal with spectrum features arising in a periodic signal. Therefore, the characterization precision is no longer limited by the FFT length. When a commercial 23299.8 m two-mode fiber is used in the experiment, the DMGD measurement of mode relative to mode has a high precision of ±0.007/ over the C-band. Our proposed method shows the potential for characterizing the wavelength-dependent DMGD of FMF with more than two LP modes.
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http://dx.doi.org/10.1364/OL.423950DOI Listing
June 2021

Trading off security and practicability to explore high-speed and long-haul chaotic optical communication.

Opt Express 2021 Apr;29(8):12750-12762

Recent demonstrations of chaos-based secure communication have proven the feasibility of secured transmission of high-speed (tens of Gbit/s) signals over certain distances (∼100-km), which bring hope for secure communication from theoretical analysis to practical applications. So far, the chaos-based secure communication system with chaos-masking (CMS) encryption is considered as one of the most important and feasible schemes. In this paper, an optical chaotic carrier generated by an opto-electronic oscillator is used to encrypt 112-Gbit/s message by CMS encryption for data transmission over a 1040-km single-mode-fiber. The message is successfully decrypted by combining coherent detection and our proposed blind decryption algorithms, which can successfully separate the chaotic carrier and the message with the bit-error-rate (BER) below the forward error correction (FEC) threshold. Experimental results show that the coherent detection combined digital signal processing algorithms may be a possible way to promote the practical applications of chaotic optical communication in the future. In addition, this paper reveals that the security of the CMS encryption may be not high enough for those systems requiring rigorous confidentiality. Subsequently, we further discuss the bottlenecks encountered in current high-speed chaotic optical communication systems and analyze how to improve and weight the security and practicability.
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http://dx.doi.org/10.1364/OE.423098DOI Listing
April 2021

Panda-type few-mode fiber-enabled microwave photonic filter with a reconfigurable finite impulse response.

Opt Lett 2021 Apr;46(8):1852-1855

Leveraging various physical dimensions of optical signals allows significant scaling of the transmission capacity for optical communications. Here we experimentally demonstrate a reconfigurable microwave photonic filter (MPF) enabled by both mode and polarization division multiplexing arising in a Panda-type few-mode fiber. The , , , and modes are used to realize optical true-time delay lines of the MPF, thus achieving a four-tap finite impulse response (FIR) with a free spectral range of around 2.22 GHz. Due to the employed delay between two orthogonal polarizations, the number of taps arising in its FIR can be doubled. Moreover, the reconfigurable FIR of the MPF can be achieved by loading the corresponding phase pattern onto a spatial light modulator. Finally, the low-pass FIR can be switched to the bandpass FIR due to the introduction of polarization modulation, indicating the flexible manipulation of the FIR for the multi-dimensional division multiplexing enabled MPF.
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http://dx.doi.org/10.1364/OL.422718DOI Listing
April 2021

Germacrone improves liver fibrosis by regulating the PI3K/AKT/mTOR signalling pathway.

Cell Biol Int 2021 Apr 9. Epub 2021 Apr 9.

Molecular Pharmacology Research Center, School of Pharmaceutical Science, Wenzhou Medical University, Wenzhou, Zhejiang, China.

Liver fibrosis is a primary threat to public health, owing to limited therapeutic options. Germacrone (GM) has been shown to exert various curative effects against human diseases, including liver injury. The aim of this study was to investigate the pharmacological effects of GM in the pathophysiology of hepatic fibrosis and determine its potential mechanisms of action. A liver fibrosis rat model was established via carbon tetrachloride (CCl ) treatment, and LX-2 cells were stimulated with TGF-β1. The effects of GM on liver fibrosis and its relationship with the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signalling pathway were investigated. In the CCl fibrosis-induced rat model, GM improved histological damage, inhibited the activity of hepatic α-smooth muscle actin and improved serum alanine aminotransferase and aspartate aminotransferase levels in a dose-dependent manner. GM potently inhibited hepatic stellate cells (HSCs) growth and epithelial-mesenchymal transition (EMT) progression, as reflected by the altered expression of proliferative (Ki-67, PCNA and cleaved caspase-3) and EMT-related (E-cadherin and vimentin) proteins. In TGF-β1-stimulated LX-2 cells, GM significantly inhibited the survival and activation of HSCs and induced cell apoptosis. GM also suppressed the migration ability and reversed the EMT process in HSCs. Following GM treatment, the phosphorylation of the PI3K, AKT and mTOR proteins was reduced in the liver of CCl -treated rats and TGF-β1-stimulated LX-2 cells, indicating that GM may attenuate hepatic fibrosis via the PI3K/AKT/mTOR signalling pathway. These outcomes highlight the anti-fibrotic effects of GM and suggest that it is a potential therapeutic agent for the treatment of liver fibrosis.
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http://dx.doi.org/10.1002/cbin.11607DOI Listing
April 2021

Optimized Volterra filter equalizer based on weighted principal component analysis for IM-DD transmission.

Opt Lett 2021 Apr;46(7):1680-1683

Volterra filter equalizer (VFE) is a commonly-used nonlinear equalizer (NLE) to effectively mitigate both linear and nonlinear impairments arising in intensity-modulation direct-detection (IM-DD) transmission. However, the high calculation complexity of VFE becomes the bottleneck for the high-speed long-reach IM-DD transceiver. To achieve the hardware-efficient NLE, we propose an optimized VFE based on the weighted principal component analysis (WPCA), which uses both supervised weights and unsupervised PCA to extract principal components, so that the number of VFE taps can be significantly reduced without transmission penalty. It is experimentally verified that the proposed method can reduce 40% and 60% taps of traditional VFE, respectively, for C-band 80 Gb/s four-level pulse amplitude modulation (PAM-4) transmission over 20 km chromatic dispersion (CD)-uncompensated standard single-mode fiber (SSMF) and 56 Gb/s PAM-4 transmission over 100 km CD-managed SSMF.
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http://dx.doi.org/10.1364/OL.421467DOI Listing
April 2021

Fast and blind chromatic dispersion estimation with one sample per symbol.

Opt Express 2021 Mar;29(5):7504-7513

We propose a fast and blind chromatic dispersion (CD) estimation method by one sample per symbol after coherent detection. The CD estimation process is non-data aided, without the iterative scanning to obtain the CD values. Moreover, we identify that the proposed CD estimation method is transparent to the used modulation format and robust to the transmission impairments, including amplified spontaneous emission (ASE) noise and fiber nonlinearity. When the 35-GBaud DP-16QAM signal with a roll-off factor of 0.1 is transmitted over standard single mode fiber (SSMF) with a range from 320-km to 560-km, the error of CD estimation is less than 150-ps/nm under the condition of 8192 symbols used.
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http://dx.doi.org/10.1364/OE.418500DOI Listing
March 2021

On-chip high-sensitivity photonic temperature sensor based on a GaAs microresonator.

Opt Lett 2020 Sep;45(18):5105-5108

We demonstrate an on-chip high-sensitivity photonic temperature sensor based on a GaAs microdisk resonator. Based on the large thermo-optic coefficient of GaAs, a temperature sensitivity of 0.142 nm/K with a measurement resolution of 10 mK and low input optical power of only 0.5 µW was achieved. It exhibits great potential for chip-scale biological research and integrated photonic signal processing.
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http://dx.doi.org/10.1364/OL.399397DOI Listing
September 2020

Investigation of the effect of gold coating of gold-coated fiber on distributed strain measurement by differential pulse pair Brillouin optical-time analysis.

Appl Opt 2019 Nov;58(31):8376-8382

Gold-coated fiber (GCF) shows the potential to sense strain at high temperature owing to the hermeticity of gold coating that prevents hydrogen penetration. Nevertheless, there are trivial details of the gold coating of GCF that need to be addressed before using GCF to measure strain at high temperature. In this study, we thoroughly investigate the effect of the gold coating of GCF on strain measurement both at room temperature and high temperature up to 700°C with differential pulse pair Brillouin optical-time analysis (DPP-BOTDA). Owing to the inhomogeneity of gold coating induced by the manufacturing process, it is necessary to select the GCF with the gold coating of better homogeneity via DPP-BOTDA. Due to the residual stress that solidified in the GCF during the cooling process of coating, the GCF would first undergo plastic deformation and then elastic deformation in the strain measurement. After one-time strain measurement to remove the residual stress of GCF, the standard deviation of the strain coefficients at room temperature and high temperature are $ \pm {0.5}\% $±0.5% and $ \pm {1.3}\% $±1.3%, respectively, which is mainly due to the nonuniform thickness of the gold coating and the nonuniformity of silica fiber at high temperature.
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http://dx.doi.org/10.1364/AO.58.008376DOI Listing
November 2019

Sam68 Promotes Hepatitis C Virus Replication by Interaction with Stem-Loop 2 of Viral 5' Untranslated Region.

J Virol 2019 07 28;93(14). Epub 2019 Jun 28.

Institute of Pathogen Biology and Immunology of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan, China

The Src-associated in mitosis 68-kDa (Sam68) protein is a highly conserved nuclear protein and is involved in a series of cellular processes, including transcription and signal transduction. Sam68 is comprised of 443 amino acids and contains an RGG box domain, a KH domain, and a tyrosine-rich domain. Its role in hepatitis C virus (HCV) replication is unknown. Here, we find that Sam68 promotes HCV replication without affecting viral translation. The RNA immunoprecipitation experiments show that the positive strand of HCV RNA interacts with Sam68. HCV infection triggers the translocation of the Sam68 protein from the nucleus to the cytoplasm, where it interacts with the HCV genome. Further study shows that the region of Sam68 spanning amino acids 1 to 157 is the pivotal domain to interact with the stem-loop 2 of the HCV 5' untranslated region (5' UTR) and is responsible for the enhancement of HCV replication. These data suggested that Sam68 may serve as a proviral factor of HCV to facilitate viral replication through interaction with the viral genome. Hepatitis C virus (HCV) is a member of the family, and its infection causes chronic hepatitis, liver cirrhosis, and even hepatocellular carcinoma. No vaccine is available. Many host factors may be implicated in the pathogenesis of HCV-related diseases. This study discloses a new host factor that binds to the HCV 5' UTR and promotes HCV replication. Sam68 may play an important role in HCV-related diseases, and further investigation is highly encouraged to explore its specific actions in HCV pathogenesis.
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http://dx.doi.org/10.1128/JVI.00693-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6600183PMC
July 2019

Long Noncoding RNA ITPRIP-1 Positively Regulates the Innate Immune Response through Promotion of Oligomerization and Activation of MDA5.

J Virol 2018 09 16;92(17). Epub 2018 Aug 16.

Institute of Pathogen Biology and Immunology of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, China

Emerging evidence indicates that long noncoding RNAs (lncRNAs) regulate various biological processes, especially innate and adaptive immunity. However, the relationship between lncRNAs and the interferon (IFN) pathway remains largely unknown. Here, we report that lncRNA ITPRIP-1 (lncITPRIP-1) is involved in viral infection and plays a crucial role in the virus-triggered IFN signaling pathway through the targeting of melanoma differentiation-associated gene 5 (MDA5). LncITPRIP-1 can be induced by viral infection, which is not entirely dependent on the IFN signal. Besides, there is no coding potential found in the lncITPRIP-1 transcript. LncITPRIP-1 binds to the C terminus of MDA5, and it possesses the ability to boost the oligomerization of both the full length and the 2 caspase activation and recruitment domains of MDA5 in a K63-linked polyubiquitination-independent manner. Amazingly, we also found that MDA5 can suppress hepatitis C virus (HCV) replication independently of IFN signaling through its C-terminal-deficient domain bound to viral RNA, in which lncITPRIP-1 plays a role as an assistant. In addition, the expression of lncITPRIP-1 is highly consistent with MDA5 expression, indicating that lncITPRIP-1 may function as a cofactor of MDA5. All the data suggest that lncITPRIP-1 enhances the innate immune response to viral infection through the promotion of oligomerization and activation of MDA5. Our study discovers the first lncRNA ITPRIP-1 involved in MDA5 activation. Hepatitis C virus infection is a global health issue, and there is still no available vaccine, which makes it urgent to reveal the underlying mechanisms of HCV and host factors. Although RIG-I has been recognized as the leading cytoplasmic sensor against HCV for a long time, recent findings that MDA5 regulates the IFN response to HCV have emerged. Our work validates the significant role of MDA5 in IFN signaling and HCV infection and proposes the first lncRNA inhibiting HCV replication by promoting the activation of MDA5 and mediating the association between MDA5 and HCV RNA, the study of which may shed light on the MDA5 function and treatment for hepatitis C patients. Our suggested model of how lncITPRIP-1 orchestrates signal transduction for IFN production illustrates the essential role of lncRNAs in virus elimination.
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http://dx.doi.org/10.1128/JVI.00507-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6096792PMC
September 2018

NLRX1 Mediates MAVS Degradation To Attenuate the Hepatitis C Virus-Induced Innate Immune Response through PCBP2.

J Virol 2017 12 14;91(23). Epub 2017 Nov 14.

Institute of Pathogen Biology and Immunology of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan, China

Activation of innate immunity is essential for host cells to restrict the spread of invading viruses and other pathogens. However, attenuation or termination of signaling is also necessary for preventing immune-mediated tissue damage and spontaneous autoimmunity. Here, we identify nucleotide binding oligomerization domain (NOD)-like receptor X1 (NLRX1) as a negative regulator of the mitochondrial antiviral signaling protein (MAVS)-mediated signaling pathway during hepatitis C virus (HCV) infection. The depletion of NLRX1 enhances the HCV-triggered activation of interferon (IFN) signaling and causes the suppression of HCV propagation in hepatocytes. NLRX1, a HCV-inducible protein, interacts with MAVS and mediates the K48-linked polyubiquitination and subsequent degradation of MAVS via the proteasomal pathway. Moreover, poly(rC) binding protein 2 (PCBP2) interacts with NLRX1 to participate in the NLRX1-induced degradation of MAVS and the inhibition of antiviral responses during HCV infection. Mutagenic analyses further revealed that the NOD of NLRX1 is essential for NLRX1 to interact with PCBP2 and subsequently induce MAVS degradation. Our study unlocks a key mechanism of the fine-tuning of innate immunity by which NLRX1 restrains the retinoic acid-inducible gene I-like receptor (RLR)-MAVS signaling cascade by recruiting PCBP2 to MAVS for inducing MAVS degradation through the proteasomal pathway. NLRX1, a negative regulator of innate immunity, is a pivotal host factor for HCV to establish persistent infection. Innate immunity needs to be tightly regulated to maximize the antiviral response and minimize immune-mediated pathology, but the underlying mechanisms are poorly understood. In this study, we report that NLRX1 is a proviral host factor for HCV infection and functions as a negative regulator of the HCV-triggered innate immune response. NLRX1 recruits PCBP2 to MAVS and induces the K48-linked polyubiquitination and degradation of MAVS, leading to the negative regulation of the IFN signaling pathway and promoting HCV infection. Overall, this study provides intriguing insights into how innate immunity is regulated during viral infection.
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http://dx.doi.org/10.1128/JVI.01264-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5686720PMC
December 2017

ISG12a Restricts Hepatitis C Virus Infection through the Ubiquitination-Dependent Degradation Pathway.

J Virol 2016 08 11;90(15):6832-45. Epub 2016 Jul 11.

Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, China Research Center of Cancer Prevention and Treatment, Translational Medicine Research Center of Liver Cancer, Hunan Provincial Tumor Hospital (Affiliated Tumor Hospital of Xiangya Medical School of Central South University), Changsha, China

Unlabelled: Interferons (IFNs) restrict various kinds of viral infection via induction of hundreds of IFN-stimulated genes (ISGs), while the functions of the majority of ISGs are broadly unclear. Here, we show that a high-IFN-inducible gene, ISG12a (also known as IFI27), exhibits a nonapoptotic antiviral effect on hepatitis C virus (HCV) infection. Viral NS5A protein is targeted specifically by ISG12a, which mediates NS5A degradation via a ubiquitination-dependent proteasomal pathway. K374R mutation in NS5A domain III abrogates ISG12a-induced ubiquitination and degradation of NS5A. S-phase kinase-associated protein 2 (SKP2) is identified as an ubiquitin E3 ligase for NS5A. ISG12a functions as a crucial adaptor that promotes SKP2 to interact with and degrade viral protein. Moreover, the antiviral effect of ISG12a is dependent on the E3 ligase activity of SKP2. These findings uncover an intriguing mechanism by which ISG12a restricts viral infection and provide clues for understanding the actions of innate immunity.

Importance: Upon virus invasion, IFNs induce numerous ISGs to control viral spread, while the functions of the majority of ISGs are broadly unclear. The present study shows a novel antiviral mechanism of ISGs and elucidated that ISG12a recruits an E3 ligase, SKP2, for ubiquitination and degradation of viral protein and restricts viral infection. These findings provide important insights into exploring the working principles of innate immunity.
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http://dx.doi.org/10.1128/JVI.00352-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4944290PMC
August 2016

Inhibition of hepatitis C virus infection by NS5A-specific aptamer.

Antiviral Res 2014 Jun 5;106:116-24. Epub 2014 Apr 5.

Department of Molecular Medicine, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, China; Research Center of Cancer Prevention & Treatment, Translational Medicine Research Center of Liver Cancer, Hunan Provincial Tumor Hospital (Affiliated Tumor Hospital of Xiangya Medical School of Central South University), Changsha, China. Electronic address:

To increase efficacy of hepatitis C treatment, future regiments will incorporate multiple direct-acting antiviral drugs. HCV NS5A protein was expressed and purified. Aptamers against NS5A were screened and obtained by the selective evolution of ligands by exponential enrichment approach and the antiviral actions of the aptamers were tested. The mechanisms through which the aptamers exert their antiviral activity were explored. The aptamers NS5A-4 and NS5A-5 inhibit HCV RNA replication and infectious virus production without causing cytotoxicity in human hepatocytes. The aptamers do not affect hepatitis B virus replication in HepG2.2.15 cells. Interferon beta (IFN-β) and interferon-stimulated genes (ISGs) are not induced by the aptamers in HCV-infected hepatocytes. Further study shows that domain I and domain III of NS5A protein are involved in the suppression of HCV RNA replication and infectious virus production by NS5A-4. Y2105H within NS5A is the major resistance mutation identified. NS5A aptamer disrupts the interaction of NS5A with core protein. The data suggest that the aptamers against NS5A protein may exert antiviral effects through inhibiting viral RNA replication, preventing the interaction of NS5A with core protein. Aptamers for NS5A may be used to understand the mechanisms of virus replication and assembly and served as potential therapeutic agents for hepatitis C.
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http://dx.doi.org/10.1016/j.antiviral.2014.03.020DOI Listing
June 2014

Complete replication of hepatitis B virus and hepatitis C virus in a newly developed hepatoma cell line.

Proc Natl Acad Sci U S A 2014 Apr 10;111(13):E1264-73. Epub 2014 Mar 10.

Department of Molecular Medicine, College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, China.

The absence of a robust cell culture system for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection has limited the analysis of the virus lifecycle and drug discovery. We have established a hepatoma cell line, HLCZ01, the first cell line, to the authors' knowledge, supporting the entire lifecycle of both HBV and HCV. HBV surface antigen (HBsAg)-positive particles can be observed in the supernatant and the lumen of the endoplasmic reticulum of the cells via electron microscopy. Interestingly, HBV and HCV clinical isolates propagate in HLCZ01 cells. Both viruses replicate in the cells without evidence of overt interference. HBV and HCV entry are blocked by antibodies against HBsAg and human CD81, respectively, and the replication of HBV and HCV is inhibited by antivirals. HLCZ01 cells mount an innate immune response to virus infection. The cell line provides a powerful tool for exploring the mechanisms of virus entry and replication and the interaction between host and virus, facilitating the development of novel antiviral agents and vaccines.
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http://dx.doi.org/10.1073/pnas.1320071111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3977290PMC
April 2014
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