Kaposi's sarcoma associated herpesvirus tegument protein ORF75 is essential for viral lytic replication and plays a critical role in the antagonization of ND10-instituted intrinsic immunity.
Kaposi's sarcoma associated herpesvirus tegument protein ORF75 is essential for viral lytic replication and plays a critical role in the antagonization of ND10-instituted intrinsic immunity.
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DOI：
10.1371/journal.ppat.1003863
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发表时间：
2014-01
期刊：
影响因子：
6.7
通讯作者：
Ensser A
中科院分区：
文献类型：
--
作者：
Full F;Jungnickl D;Reuter N;Bogner E;Brulois K;Scholz B;Stürzl M;Myoung J;Jung JU;Stamminger T;Ensser A
核结构域10(ND10)是抑制疱疹病毒复制的限制性因子。不同疱疹病毒的效应蛋白可以通过多种策略来对抗这种限制，包括降解或重新定位ND10蛋白。我们研究了Kaposi肉瘤相关疱疹病毒(KSHV)感染与核结构域10(ND10)组分的细胞防御的相互作用。在原代人细胞中的击倒实验表明，KSHV的感染受ND10组分PML和Sp100的限制，而不受ATRX的限制。在KSHV感染后，ATRX被有效地耗尽，Daxx从ND10中分散出来，表明这两个ND10组分可以被KSHV拮抗。然后我们鉴定了KSHV的ORF75被膜蛋白是导致ATRX消失和Daxx重新定位的病毒因子。ORF75属于病毒蛋白家族(病毒FGARATs)，在所有伽马疱疹病毒中都有同源蛋白。ORF75在原代细胞中的分离表达导致PML的重新定位和Sp100的扩散，表明该病毒效应蛋白能够影响多种ND10成分。此外，通过构建在ORF75开头含有终止密码子的KSHV突变体，我们可以证明ORF75对于病毒复制和病毒即刻早期基因表达的启动是绝对必要的。使用携带Flag或YFP标记的ORF75变体的重组病毒，我们可以进一步证实ORF75在ND10介导的内源性免疫的抗原化中的作用，并表明它不依赖于PML拮抗剂vIRF3。病毒FGARAT家族的成员针对不同的ND10组分，这表明病毒FGARAT蛋白的ND10靶点在进化过程中发生了多样化。我们认为，克服ND10的内在防御是所有疱疹病毒复制的关键事件；另一方面，ND10组件限制疱疹病毒复制也可能导致潜伏期作为感染的默认结果。卡波西肉瘤相关疱疹病毒(KSHV)在人类中建立了一种终生持续感染，并与肿瘤和淋巴增生性疾病有关，特别是在免疫抑制方面。病毒必须克服细胞固有免疫，以便在初次感染时启动病毒蛋白表达和基因组复制。我们证明了KSHV受一种称为核结构域10(ND10)的细胞固有免疫复合体的限制，并确定了KSHV ORF75蛋白在这一过程中的关键作用，它是病毒颗粒的一部分。我们发现ORF75对病毒复制是必不可少的，并且ORF75导致ND10蛋白ATRX的消失。此外，它还导致了其他几个ND10组件的重新定位。值得注意的是，到目前为止研究的所有疱疹病毒都进化了ND10的对抗机制，表明这一步骤对疱疹病毒复制的重要性。然而，不同的疱疹病毒之间的个体机制，包括ND10的抗凝程度，是有相当大的差异的。我们推测，与甲型疱疹病毒的高效裂解复制相反，效率较低的ND10中和作用可能代表着伽马疱疹病毒潜伏感染的途径。
Nuclear domain 10 (ND10) components are restriction factors that inhibit herpesviral replication. Effector proteins of different herpesviruses can antagonize this restriction by a variety of strategies, including degradation or relocalization of ND10 proteins. We investigated the interplay of Kaposi's Sarcoma-Associated Herpesvirus (KSHV) infection and cellular defense by nuclear domain 10 (ND10) components. Knock-down experiments in primary human cells show that KSHV-infection is restricted by the ND10 components PML and Sp100, but not by ATRX. After KSHV infection, ATRX is efficiently depleted and Daxx is dispersed from ND10, indicating that these two ND10 components can be antagonized by KSHV. We then identified the ORF75 tegument protein of KSHV as the viral factor that induces the disappearance of ATRX and relocalization of Daxx. ORF75 belongs to a viral protein family (viral FGARATs) that has homologous proteins in all gamma-herpesviruses. Isolated expression of ORF75 in primary cells induces a relocalization of PML and dispersal of Sp100, indicating that this viral effector protein is able to influence multiple ND10 components. Moreover, by constructing a KSHV mutant harboring a stop codon at the beginning of ORF75, we could demonstrate that ORF75 is absolutely essential for viral replication and the initiation of viral immediate-early gene expression. Using recombinant viruses either carrying Flag- or YFP-tagged variants of ORF75, we could further corroborate the role of ORF75 in the antagonization of ND10-mediated intrinsic immunity, and show that it is independent of the PML antagonist vIRF3. Members of the viral FGARAT family target different ND10 components, suggesting that the ND10 targets of viral FGARAT proteins have diversified during evolution. We assume that overcoming ND10 intrinsic defense constitutes a critical event in the replication of all herpesviruses; on the other hand, restriction of herpesviral replication by ND10 components may also promote latency as the default outcome of infection. Kaposi's Sarcoma-Associated Herpesvirus (KSHV) establishes a lifelong persistent infection in humans and is associated with tumors and lymphoproliferative disease, particularly upon immunosuppression. The virus has to overcome cellular intrinsic immunity in order to initiate viral protein expression and genome replication in primary infection. We demonstrated that KSHV is restricted by a cellular intrinsic immunity complex called nuclear domain 10 (ND10) and identified a critical role of the KSHV ORF75 protein, which is part of the viral particle, in this process. We found that ORF75 is essential for viral replication and that ORF75 leads to disappearance of the ND10 protein ATRX. Furthermore, it induces the relocalization of several other ND10 components. Noteworthy, all herpesviruses studied so far have evolved mechanisms for ND10 counteraction, indicating the importance of this step for herpesviral replication. The individual mechanisms, however, including the extent of ND10-antagonization, are of considerable variation between different herpesviruses. We speculate that, in contrast to efficient lytic replication of alphaherpesviruses, less effective ND10 counteraction may represent a doorway for gammaherpesviruses to latent infection.
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影响因子：
7.3
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通讯作者：
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