干扰素诱导的MX2是乙型肝炎病毒复制的宿主限制因素

StephenW

Interferon-inducible MX2 is a host restriction factor of hepatitis B virus replication [url=]Yong-Xiang Wang[/url]1,∗,[url=]Correspondence information about the author  Yong-Xiang Wang[/url]Email the author  Yong-Xiang Wang
,  [url=]Matthias Niklasch[/url]2
,  [url=]Tiantian Liu[/url]1
,  [url=]Yang Wang[/url]1
,  [url=]Bisheng Shi[/url]4
,  [url=]Wenjie Yuan[/url]1
,  [url=]Thomas F. Baumert[/url]3
,  [url=]Zhenghong Yuan[/url]1
,  [url=]Shuping Tong[/url]1
,  [url=]Michael Nassal[/url]2
,  [url=]Yu-Mei Wen[/url]1

DOI: https://doi.org/10.1016/j.jhep.2019.12.009 |

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Highlights

• •IFN-α inducible MX2 potently inhibited HBV replication driven by episomal templates.
• •MX2 reduced HBV RNA by significantly decreasing HBV RNA transcription and slightly accelerating its decay.
• •MX2 contributes substantially to the anti-HBV activity of IFN-α.
• •MX2 but not the homologous MX1 efficiently inhibited HBV infection of HepG2-NTCP cells and primary human hepatocytes.
• •Multiple MX2 determinants including GTPase activity and oligomerization status were required for anti-HBV activity.
  

Background & AimsNon-cytolytic cure of HBV-infected hepatocytes by cytokines, including type I interferons (IFNs), is of importance for resolving acute and chronic infection. However, as IFNs stimulate hundreds of genes, those most relevant for HBV suppression remain largely unknown. Amongst them are the large myxovirus resistance (Mx) GTPases. Human MX1 (or MxA) is active against many RNA viruses, while MX2 (or MxB) was recently found to restrict HIV-1, HCV, and herpesviruses. Herein, we investigated the anti-HBV activity of MX2.


MethodsThe potential anti-HBV activity of MX2 and functional variants were assessed in transfected and HBV-infected hepatoma cells and primary human hepatocytes, employing multiple assays to analyze the synthesis and decay of HBV nucleic acids. The specific roles of MX2 in IFN-α-driven inhibition of HBV transcription and replication were assessed by MX2-specific shRNA interference (RNAi).


ResultsBoth MX2 alone and IFN-α substantially inhibited HBV replication, due to significant deceleration of the synthesis and slight acceleration of the turnover of viral RNA. RNAi knockdown of MX2 significantly reduced the inhibitory effects of IFN-α. Strikingly, MX2 inhibited HBV infection by reducing covalently closed circular DNA (cccDNA), most likely by indirectly impairing the conversion of relaxed circular DNA to cccDNA rather than by destabilizing existing cccDNA. Various mutations affecting the GTPase activity and oligomerization status reduced MX2's anti-HBV activity.


ConclusionMX2 is an important IFN-α inducible effector that decreases HBV RNA levels but can also potently inhibit HBV infection by indirectly impairing cccDNA formation. MX2 likely has the potential for therapeutic applications aimed at curing HBV infection by eliminating cccDNA.


Lay summaryThis study shows that the protein MX2, which is induced by interferon-α, has important anti-hepatitis B virus (HBV) effector functions. MX2 can reduce the amount of covalently closed circular DNA, which is the form of DNA that HBV uses to maintain viral persistence within hepatocytes. MX2 also reduces HBV RNA levels by downregulating synthesis of viral RNA. MX2 likely represents a novel intrinsic HBV inhibitor that could have therapeutic potential, as well as being useful for improving our understanding of the complex biology of HBV and the antiviral mechanisms of interferon-α.



Keywords:                [url=https://www.journal-of-hepatology.eu/action/doSearch?searchType=quick&occurrences=all<rlSrch=true&searchScope=fullSite&searchText=Hepatitis B virus&code=jhepat-site]Hepatitis B virus[/url], [url=https://www.journal-of-hepatology.eu/action/doSearch?searchType=quick&occurrences=all<rlSrch=true&searchScope=fullSite&searchText=Covalently closed circular DNA&code=jhepat-site]Covalently closed circular DNA[/url], Interferon, [url=https://www.journal-of-hepatology.eu/action/doSearch?searchType=quick&occurrences=all<rlSrch=true&searchScope=fullSite&searchText=Interferon stimulated gene&code=jhepat-site]Interferon stimulated gene[/url], [url=https://www.journal-of-hepatology.eu/action/doSearch?searchType=quick&occurrences=all<rlSrch=true&searchScope=fullSite&searchText=Antiviral mechanism&code=jhepat-site]Antiviral mechanism[/url], Replication, Transcription, Infection

StephenW

干扰素诱导的MX2是乙型肝炎病毒复制的宿主限制因素
王永祥1，*，'关于作者王永祥的通讯信息给作者王永祥发送电子邮件
，Matthias Niklasch2
刘天天1
杨旺1
，毕升生4
袁文杰1
，托马斯·鲍默特3
袁正宏1
，束树平1
，迈克尔·纳萨尔2
，温玉梅1
DOI：https：//doi.org/10.1016/j.jhep.2019.12.009 |
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强调

    •IFN-α诱导的MX2有效抑制游离模板驱动的HBV复制。
    •MX2通过显着降低HBV RNA转录并稍微加速其衰变来降低HBV RNA。
    •MX2在很大程度上增强了IFN-α的抗HBV活性。
    •MX2而非同源MX1有效抑制了HepG2-NTCP细胞和原代人肝细胞的HBV感染。
    •抗HBV活性需要多个MX2决定簇，包括GTPase活性和低聚状态。

背景与目标

通过细胞因子（包括I型干扰素（IFN））的非细胞溶性治愈HBV感染的肝细胞对于解决急性和慢性感染至关重要。但是，随着IFN刺激数百种基因，与HBV抑制最相关的那些基因仍然未知。其中包括大的粘液病毒抗药性（Mx）GTPases。人MX1（或MxA）对许多RNA病毒具有活性，而最近发现MX2（或MxB）可限制HIV-1，HCV和疱疹病毒。在此，我们研究了MX2的抗HBV活性。
方法

使用多种测定方法分析了HBV核酸的合成和衰变，从而评估了MX2和功能性变体在转染和HBV感染的肝癌细胞和原代人肝细胞中的潜在抗HBV活性。通过MX2特异性shRNA干扰（RNAi）评估了MX2在IFN-α驱动的HBV转录和复制抑制中的特定作用。
结果

由于合成的显着减速和病毒RNA周转的轻微加速，单独的MX2和IFN-α都基本上抑制了HBV复制。 MX2的RNAi敲除显着降低了IFN-α的抑制作用。令人惊讶的是，MX2通过减少共价闭合的环状DNA（cccDNA）来抑制HBV感染，这很可能是间接损害了松弛的环状DNA向cccDNA的转化，而不是通过破坏现有cccDNA的稳定性。影响GTPase活性和低聚状态的各种突变降低了MX2的抗HBV活性。
结论

MX2是一种重要的IFN-α诱导型效应子，可降低HBV RNA水平，但也可通过间接削弱cccDNA的形成来有效抑制HBV感染。 MX2可能具有通过消除cccDNA来治愈HBV感染的治疗应用潜力。
放置摘要

这项研究表明，干扰素-α诱导的MX2蛋白具有重要的抗乙型肝炎病毒（HBV）效应子功能。 MX2可以减少共价封闭的环状DNA的数量，环状DNA是HBV用于维持肝细胞内病毒持久性的DNA形式。 MX2还通过下调病毒RNA的合成来降低HBV RNA水平。 MX2可能代表了一种新颖的内在性HBV抑制剂，可能具有治疗潜力，并有助于增进我们对HBV复杂生物学和干扰素-α的抗病毒机制的了解。
关键字：
乙型肝炎病毒，共价闭合环状DNA，干扰素，干扰素刺激基因，抗病毒机制，复制，转录，感染