Wudiri George A, Nicola Anthony V
Department of Veterinary Microbiology and Pathology and Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA.
Department of Veterinary Microbiology and Pathology and Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
J Virol. 2017 Jun 26;91(14). doi: 10.1128/JVI.00445-17. Print 2017 Jul 15.
Cholesterol is an essential component of cell membranes and is required for herpes simplex virus 1 (HSV-1) entry (1-3). Treatment of HSV-1-infected Vero cells with methyl beta-cyclodextrin from 2 to 9 h postentry reduced plaque numbers. Transport of incoming viral capsids to the nuclear periphery was unaffected by the cholesterol reduction, suggesting that cell cholesterol is important for the HSV-1 replicative cycle at a stage(s) beyond entry, after the arrival of capsids at the nucleus. The synthesis and release of infectious HSV-1 and cell-to-cell spread of infection were all impaired in cholesterol-reduced cells. Propagation of HSV-1 on DHCR24 fibroblasts, which lack the desmosterol-to-cholesterol conversion enzyme, resulted in the generation of infectious extracellular virions (HSV) that lack cholesterol and likely contain desmosterol. The specific infectivities (PFU per viral genome) of HSV and HSV were similar, suggesting cholesterol and desmosterol in the HSV envelope support similar levels of infectivity. However, infected DHCR24 fibroblasts released ∼1 log less infectious HSV and ∼1.5 log fewer particles than release of cholesterol-containing particles (HSV) from parental fibroblasts, suggesting that the hydrocarbon tail of cholesterol facilitates viral synthesis. Together, the results suggest multiple roles for cholesterol in the HSV-1 replicative cycle. HSV-1 infections are associated with a wide range of clinical manifestations that are of public health importance. Cholesterol is a key player in the complex interaction between viral and cellular factors that allows HSV-1 to enter host cells and establish infection. Previous reports have demonstrated a role for cellular cholesterol in the entry of HSV-1 into target cells. Here, we employed both chemical treatment and cells that were genetically defined to synthesize only desmosterol to demonstrate that cholesterol is important at stages following the initial entry and transport of viral capsids to the nucleus. Viral protein expression, encapsidation of the viral genome, and the release of mature virions were impacted by the reduction of cellular cholesterol. Cholesterol was also critical for cell-to-cell spread of infection. These findings provide new insights into the cholesterol dependence of HSV-1 replication.
胆固醇是细胞膜的重要组成部分，也是单纯疱疹病毒1型（HSV-1）进入细胞所必需的（1-3）。在病毒进入细胞后2至9小时，用甲基-β-环糊精处理HSV-1感染的Vero细胞可减少噬斑数量。胆固醇减少并未影响进入细胞的病毒衣壳向核周的转运，这表明细胞胆固醇在衣壳到达细胞核后、进入细胞后的某个阶段对HSV-1复制周期很重要。在胆固醇减少的细胞中，感染性HSV-1的合成与释放以及细胞间感染传播均受到损害。HSV-1在缺乏羊毛甾醇向胆固醇转化酶的DHCR24成纤维细胞上繁殖，产生了缺乏胆固醇且可能含有羊毛甾醇的感染性细胞外病毒粒子（HSV）。HSV和HSV的比感染性（每病毒基因组的空斑形成单位）相似，表明HSV包膜中的胆固醇和羊毛甾醇支持相似水平的感染性。然而，与亲代成纤维细胞释放含胆固醇的病毒粒子（HSV）相比，感染的DHCR24成纤维细胞释放的感染性HSV少约1个对数，释放粒子少约1.5个对数，这表明胆固醇的烃链有助于病毒合成。总之，这些结果表明胆固醇在HSV-1复制周期中具有多种作用。HSV-1感染与一系列具有公共卫生重要性的临床表现相关。胆固醇是病毒与细胞因子复杂相互作用中的关键因素，使HSV-1能够进入宿主细胞并建立感染。先前的报道已证明细胞胆固醇在HSV-1进入靶细胞过程中发挥作用。在此，我们采用化学处理和仅合成羊毛甾醇的基因定义细胞，以证明胆固醇在病毒衣壳最初进入细胞并转运至细胞核后的阶段很重要。细胞胆固醇的减少影响病毒蛋白表达、病毒基因组的包装以及成熟病毒粒子的释放。胆固醇对细胞间感染传播也至关重要。这些发现为HSV-1复制对胆固醇的依赖性提供了新见解。
