Hyde Jennifer L, Sosnovtsev Stanislav V, Green Kim Y, Wobus Christiane, Virgin Herbert W, Mackenzie Jason M
School of Molecular and Microbial Science, University of Queensland, Brisbane, Queensland 4072, Australia.
J Virol. 2009 Oct;83(19):9709-19. doi: 10.1128/JVI.00600-09. Epub 2009 Jul 8.
Human noroviruses (family Caliciviridae) are the leading cause of nonbacterial gastroenteritis worldwide. Despite the prevalence of these viruses within the community, the study of human norovirus has largely been hindered due to the inability to cultivate the viruses ex vivo and the lack of a small-animal model. In 2003, the discovery of a novel murine norovirus (MNV-1) and the identification of the tropism of MNV-1 for cells of a mononuclear origin led to the establishment of the first norovirus tissue culture system. Like other positive-sense RNA viruses, MNV-1 replication is associated with host membranes, which undergo significant rearrangement during infection. We characterize here the subcellular localization of the MNV-1 open reading frame 1 proteins and viral double-stranded RNA (dsRNA). Over the course of infection, dsRNA and the MNV-1 RNA-dependent RNA polymerase (NS7) were observed to proliferate from punctate foci located in the perinuclear region. All of the MNV-1 open reading frame 1 proteins were observed to colocalize with dsRNA during the course of infection. The MNV-1 replication complex was immunolocalized to virus-induced vesicle clusters formed in the cytoplasm of infected cells. Both dsRNA and MNV-1 NS7 were observed to localize to the limiting membrane of the individual clusters by cryo-immunoelectron microscopy. We show that the MNV-1 replication complex initially associates with membranes derived from the endoplasmic reticulum, trans-Golgi apparatus, and endosomes. In addition, we show that MNV-1 replication is insensitive to the fungal metabolite brefeldin A and consistently does not appear to recruit coatomer protein complex I (COPI) or COPII component proteins during replication. These data provide preliminary insights into key aspects of replication of MNV-1, which will potentially further our understanding of the pathogenesis of noroviruses and aid in the identification of potential targets for drug development.
人诺如病毒(杯状病毒科)是全球非细菌性肠胃炎的主要病因。尽管这些病毒在社区中普遍存在,但由于无法在体外培养该病毒以及缺乏小动物模型,人诺如病毒的研究在很大程度上受到了阻碍。2003年,一种新型鼠诺如病毒(MNV-1)的发现以及MNV-1对单核来源细胞的嗜性鉴定,促成了首个诺如病毒组织培养系统的建立。与其他正义RNA病毒一样,MNV-1复制与宿主膜相关,宿主膜在感染过程中会发生显著重排。我们在此描述了MNV-1开放阅读框1蛋白和病毒双链RNA(dsRNA)的亚细胞定位。在感染过程中,观察到dsRNA和MNV-1 RNA依赖性RNA聚合酶(NS7)从位于核周区域的点状病灶处增殖。在感染过程中,观察到所有MNV-1开放阅读框1蛋白都与dsRNA共定位。MNV-1复制复合体通过免疫定位定位于感染细胞胞质中形成的病毒诱导囊泡簇。通过冷冻免疫电子显微镜观察到dsRNA和MNV-1 NS7都定位于各个簇的限制膜上。我们表明,MNV-1复制复合体最初与源自内质网、反式高尔基体和内体的膜相关。此外,我们表明MNV-1复制对真菌代谢产物布雷菲德菌素A不敏感,并且在复制过程中似乎始终不会募集衣被蛋白复合体I(COPI)或COPII组成蛋白。这些数据为MNV-1复制的关键方面提供了初步见解,这可能会进一步加深我们对诺如病毒发病机制的理解,并有助于确定药物开发的潜在靶点。