由主机锌指抗病毒蛋白抑制乙型肝炎病毒复制

StephenW

http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1003494
Research Article
Inhibition of Hepatitis B Virus Replication by the Host Zinc Finger Antiviral Protein

    Richeng Mao equal contributor,

    Hui Nie equal contributor,

    Dawei Cai,

    Jiming Zhang,

    Hongyan Liu,

    Ran Yan,

    Andrea Cuconati,

    Timothy M. Block,

    Ju-Tao Guo,

    Haitao Guo mail

   

About the Authors

Richeng Mao, Hui Nie, Dawei Cai, Ran Yan, Timothy M. Block, Ju-Tao Guo, Haitao Guo
    Institute for Biotechnology and Virology Research, Department of Microbiology and Immunology, Drexel University College of Medicine, Doylestown, Pennsylvania, United States of America
Richeng Mao, Jiming Zhang, Hongyan Liu
    Key Laboratory of Medical Molecular Virology of the Ministries of Education and Health, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
Andrea Cuconati, Timothy M. Block
    Institute for Hepatitis and Virus Research, Hepatitis B Foundation, Doylestown, Pennsylvania, United States of America

Abstract

The zinc finger antiviral protein (ZAP) is a mammalian host restriction factor that inhibits the replication of a variety of RNA viruses, including retroviruses, alphaviruses and filoviruses, through interaction with the ZAP-responsive elements (ZRE) in viral RNA, and recruiting the exosome to degrade RNA substrate. Hepatitis B virus (HBV) is a pararetrovirus that replicates its genomic DNA via reverse transcription of a viral pregenomic (pg) RNA precursor. Here, we demonstrate that the two isoforms of human ZAP (hZAP-L and -S) inhibit HBV replication in human hepatocyte-derived cells through posttranscriptional down-regulation of viral pgRNA. Mechanistically, the zinc finger motif-containing N-terminus of hZAP is responsible for the reduction of HBV RNA, and the integrity of the four zinc finger motifs is essential for ZAP to bind to HBV RNA and fulfill its antiviral function. The ZRE sequences conferring the susceptibility of viral RNA to ZAP-mediated RNA decay were mapped to the terminal redundant region (nt 1820–1918) of HBV pgRNA. In agreement with its role as a host restriction factor and as an innate immune mediator for HBV infection, ZAP was upregulated in cultured primary human hepatocytes and hepatocyte-derived cells upon IFN-α treatment or IPS-1 activation, and in the livers of hepatitis B patients during immune active phase. Knock down of ZAP expression increased the level of HBV RNA and partially attenuated the antiviral effect elicited by IPS-1 in cell cultures. In summary, we demonstrated that ZAP is an intrinsic host antiviral factor with activity against HBV through down-regulation of viral RNA, and that ZAP plays a role in the innate control of HBV replication. Our findings thus shed light on virus-host interaction, viral pathogenesis, and antiviral approaches.
Author Summary

The dynamics of virus and host interaction greatly influence viral pathogenesis, and host cells have evolved multiple mechanisms to inhibit viral replication. Since it was first discovered as a cellular restriction factor for retroviruses, the host-encoded zinc finger antiviral protein (ZAP) has been shown to antagonize a variety of viral species, possibly through a common mechanism by which ZAP targets viral RNA for degradation. Here we report that hepatitis B virus (HBV) is also vulnerable to ZAP-mediated viral RNA reduction. ZAP is able to interact with HBV RNA through its zinc finger motifs, and the ZAP-responsive element which determines ZAP's antiviral specificity and activity is located within the 100-nucleotide-long terminal redundant region in the viral RNA genome. While the replication of HBV is constitutively restricted under the basal expression of intrahepatic ZAP, activation of host innate defenses, and potentially the acquired immune responses as well, could further elevate ZAP expression to suppress HBV replication. Therefore, our study not only expands the antiviral spectrum of ZAP, but also provides cumulative and novel information for a better understanding of ZAP biology and antiviral mechanisms. We also envision that the endogenous or engineered ZAP could be utilized in the future for development of therapeutic means to treat chronic hepatitis B, which currently affects more than 5% of the world's population.

StephenW

锌指抗病毒蛋白（ZAP）是哺乳动物宿主限制因子，抑制RNA病毒，包括反转录病毒，甲病毒，丝状病毒，通过与ZAP-反应元件（ZRE）病毒RNA的相互作用的各种复制和招聘外切体降解RNA底物。乙型肝炎病毒（HBV）是一种pararetrovirus复制其基因组DNA，通过反转录前基因组的病毒（皮克）RNA前体。在这里，我们展示了这两个亚型人类ZAP（hZAP-L和-S）在人类肝细胞衍生的细胞，通过抑制乙肝病毒复制，病毒前基因组的转录后下调。机械，锌指结构基序的含有N-末端hZAP负责的HBV RNA的减少，和四个锌指基序的完整性的ZAP对HBV RNA结合并履行其抗病毒的功能是必不可少的。 ZRE序列赋予易感性的病毒RNA为ZAP-介导的RNA降解被映射到终端HBV前基因组的冗余区域（新台币1820至1918年）。在其作为主机的制约因素的作用和HBV感染先天免疫调解协议，ZAP上调原代培养的人体肝细胞和α-干扰素治​​疗后或IPS-1活化，肝源性细胞和肝脏中的肝炎乙肝患者在免疫活性相。击倒ZAP的表达水平增高，乙肝病毒RNA和部分减毒抗病毒的作用引起的IPS-1在细胞培养。综上所述，我们表明，ZAP是一种内在的宿主抗病毒因子，具有抗HBV活性的病毒RNA通过下调，而ZAP HBV复制的先天控制起到了重要作用。因此，我们的研究结果揭示病毒 - 宿主相互作用，病毒的发病机制，抗病毒的方法。
作者总结

病毒与宿主相互作用的动力学极大地影响病毒发病机制和宿主细胞已经发展了多种机制抑制病毒复制。由于这是首次发现的逆转录病毒作为蜂窝制约因素，主机编码锌指抗病毒蛋白（ZAP）已被证明对抗多种病毒物种，可能通过一个通用的机制，通过它的ZAP针对病毒RNA降解。在这里，我们报告说，乙肝病毒（HBV）是也容易ZAP-介导的病毒RNA减少。 ZAP是通过其锌指基序，能与HBV RNA相互作用，决定ZAP的抗病毒的特异性和活性的ZAP-反应元件位于内的100个核苷酸长的端子在病毒RNA基因组中的冗余区域。虽然乙肝病毒的复制下的基础表达肝内ZAP，主机激活先天免疫防御，并有可能获得性免疫反应，以及组成的限制，可能会进一步提升ZAP的表达来抑制HBV的复制。因此，我们的研究不仅扩展了ZAP的抗病毒谱，而且还提供了累积和ZAP生物学和抗病毒机制更好地了解新的信息。而且，我们设想，内源性或工程化的ZAP治疗手段治疗慢性乙型肝炎，目前影响超过5％的世界人口在将来的发展可以利用。