Infectious Entry of Merkel Cell Polyomavirus
Infectious Entry of Merkel Cell Polyomavirus
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DOI：
10.1128/jvi.02004-18
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发表时间：
2019-03-01
影响因子：
5.4
通讯作者：
Schelhaas, Mario
中科院分区：
文献类型：
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作者：
Becker, Miriam;Dominguez, Melissa;Schelhaas, Mario
梅克尔细胞多瘤病毒（MCPyV）是一种与侵袭性皮肤癌梅克尔细胞癌（MCC）相关的小的非包膜肿瘤病毒。MCPyV感染在人群中非常普遍，MCPyV病毒粒子不断从人类皮肤脱落。然而，MCPyV的确切宿主细胞趋向性仍不清楚：MCPyV能够在真皮成纤维细胞的一个亚群中复制，但MCPyV DNA也在多种其他组织中被检测到。然而，MCPyV似乎与其他多瘤病毒不同，因为它需要硫酸酸化多糖，如硫酸肝素和/或硫酸软骨素，以进行初始附着。像其他多瘤病毒一样，MCPyV利用唾液酸作为（co）受体。为了探索MCPyV的感染进入过程，我们分析了MCPyV进入A549细胞的细胞生物学决定因素，A549细胞是一种高度可转导的肺癌细胞系，与已经得到充分研究的猿猴病毒40和其他一些病毒进行了比较。我们的研究结果表明，MCPyV通过腔泡/脂筏介导的内吞作用进入细胞，而不是通过巨噬细胞作用、网格蛋白介导的内吞作用或糖鞘脂富集载体进入细胞。病毒被内化在小的内吞坑中，这些内吞坑引导病毒进入核内体，并从核内体进入内质网。与其他多瘤病毒类似，转运需要微管运输、内体酸化和功能性氧化还原环境。令我们惊讶的是，发现该病毒在核内体内获得了膜包膜，这是其他病毒未报道的现象。只有少量病毒到达内质网，而大多数病毒保留在内体腔室中，这表明内体到内质网的运输是感染进入过程中的瓶颈。MCPyV是第一个与侵袭性人类癌症默克尔细胞癌（MCC）发展直接相关的多瘤病毒。尽管MCPyV不断地从健康皮肤上脱落，但在衰老和免疫功能低下的个体中，MCC的发病率增加。迄今为止，连接最初的MCPyV感染和随后的转化的事件仍然难以捉摸。MCPyV与其他已知多瘤病毒的不同之处在于它的细胞趋向性、进入受体需求和感染动力学。在这项研究中，我们研究了内吞进入的细胞要求以及进入的病毒颗粒的亚细胞定位。彻底了解感染进入途径的决定因素和特定的生物生态位将有助于预防病毒衍生的癌症，如MCC。
Merkel cell polyomavirus (MCPyV) is a small, nonenveloped tumor virus associated with an aggressive form of skin cancer, Merkel cell carcinoma (MCC). MCPyV infections are highly prevalent in the human population, with MCPyV virions being continuously shed from human skin. However, the precise host cell tropism(s) of MCPyV remains unclear: MCPyV is able to replicate within a subset of dermal fibroblasts, but MCPyV DNA has also been detected in a variety of other tissues. However, MCPyV appears different from other polyomaviruses, as it requires sulfated polysaccharides, such as heparan sulfates and/or chondroitin sulfates, for initial attachment. Like other polyomaviruses, MCPyV engages sialic acid as a (co) receptor. To explore the infectious entry process of MCPyV, we analyzed the cell biological determinants of MCPyV entry into A549 cells, a highly transducible lung carcinoma cell line, in comparison to well-studied simian virus 40 and a number of other viruses. Our results indicate that MCPyV enters cells via caveolar/lipid raft-mediated endocytosis but not macropinocytosis, clathrin-mediated endocytosis, or glycosphingolipid-enriched carriers. The viruses were internalized in small endocytic pits that led the virus to endosomes and from there to the endoplasmic reticulum (ER). Similar to other polyomaviruses, trafficking required microtubular transport, acidification of endosomes, and a functional redox environment. To our surprise, the virus was found to acquire a membrane envelope within endosomes, a phenomenon not reported for other viruses. Only minor amounts of viruses reached the ER, while the majority was retained in endosomal compartments, suggesting that endosome-to-ER trafficking is a bottleneck during infectious entry.IMPORTANCE MCPyV is the first polyomavirus directly implicated in the development of an aggressive human cancer, Merkel cell carcinoma (MCC). Although MCPyV is constantly shed from healthy skin, the MCC incidence increases among aging and immunocompromised individuals. To date, the events connecting initial MCPyV infection and subsequent transformation still remain elusive. MCPyV differs from other known polyomaviruses concerning its cell tropism, entry receptor requirements, and infection kinetics. In this study, we examined the cellular requirements for endocytic entry as well as the subcellular localization of incoming virus particles. A thorough understanding of the determinants of the infectious entry pathway and the specific biological niche will benefit prevention of virus-derived cancers such as MCC.