Herpesvirus Interactions With Cell Surface Receptors

单纯疱疹病毒（HSV）感染许多培养细胞，如Vero细胞，是通过受体结合并与细胞表面融合启动的。HSV进入不同细胞系的研究表明，中国仓鼠卵巢（CHO）和HeLa细胞支持HSV的内吞、pH依赖性进入途径。在这些细胞类型中，但不是Vero细胞，亲溶酶体剂，如弱碱性氯化铵和离子载体莫能菌素，缓冲细胞器的低pH值，以浓度依赖性方式阻断HSV进入。非细胞毒性浓度的这些药物在早期，postbinding步骤期间感染的几个菌株的两种血清型。这些试剂阻断由HSV细胞受体HveA、nectin-1或nectin-2介导的CHO细胞进入。在感染后< 5分钟，通过电子显微镜（EM）在囊泡中容易地检测到包膜病毒体。细胞能量的消耗阻断了内吞作用，阻止了CHO和HeLa细胞中HSV的细胞摄取和感染。进入Vero细胞不受能量消耗的影响。荧光显微镜显示，亲溶酶体剂巴弗洛霉素A1阻断传入病毒的HeLa和CHO细胞的细胞核，但不是Vero细胞。从所有三种细胞的细胞表面摄取HSV的动力学是相似的，与所利用的进入途径无关（t1/2，5-10 min）。在注射后15-20分钟，从CHO-连接蛋白-1细胞回收的内化病毒粒子保持感染性，因此被包膜。感染性病毒的恢复下降了30分钟，表明衣壳释放到细胞溶质（渗透）已经发生。在巴弗洛霉素的存在下，感染性的细胞内病毒体在感染后4小时内恢复，表明它们确实被困在了核内体中。我们认为HSV有能力通过内吞摄取有效地进入细胞，随后是低pH触发的步骤。

Herpes simplex virus (HSV) infection of many cultured cells, such as Vero cells, is initiated by receptor-binding and fusion with the cell surface. A survey of HSV entry into diverse cell lines indicated that Chinese hamster ovary (CHO) and HeLa cells support an endocytic, pH-dependent entry pathway for HSV. In these cell types, but not Vero cells, lysosomotropic agents, such as the weak base ammonium chloride and the ionophore monensin which buffer the low pH of organelles, blocked HSV entry in a concentration-dependent manner. Noncytotoxic concentrations of these agents acted at an early, postbinding step during infection by several strains of both serotypes. CHO cell entry mediated by the HSV cellular receptors HveA, nectin-1 or nectin-2 was blocked by these agents. Enveloped virions were readily detected in vesicles by electron microscopy (EM) at < 5 min post-infection. Depletion of cellular energy, which blocks endocytosis, prevented cellular uptake and infection by HSV in CHO and HeLa cells. Entry into Vero cells was unaffected by energy depletion. Fluorescence microscopy showed that the lysosomotropic agent bafilomycin A1 blocked delivery of incoming virus to the nucleus of HeLa and CHO cells, but not Vero cells. Kinetics of HSV uptake from the cell surface of all three cells were similar regardless of the entry pathway utilized (t1/2, 5-10 min). At 15-20 min p.i., internalized virions recovered from CHO-nectin-1 cells remained infectious, and therefore enveloped. Recovery of infectious virus declined by 30 min, suggesting capsid release into the cytosol (penetration) had occurred. In the presence of bafilomycin, infectious, intracellular virions were recovered for as long as 4 hr p.i., indicating they indeed were trapped in endosomes. We propose that HSV has the capacity to efficiently enter cells by endocytic uptake followed by a low pH-triggered step.