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，是由受体结合和与细胞表面融合引起的。一项对HSV进入多种细胞系的调查表明，中国仓鼠卵巢（CHO）和HeLa细胞支持HSV的内吞，ph依赖的进入途径。在这些细胞类型中（而不是Vero细胞），溶酶性收缩剂，如缓冲低pH细胞器的弱碱氯化铵和离子载体莫能菌素，以浓度依赖的方式阻止HSV进入。在两种血清型的几种菌株感染期间，这些药物的无细胞毒性浓度在结合后的早期阶段起作用。由HSV细胞受体HveA、nectin-1或nectin-2介导的CHO细胞进入被这些药物阻断。在感染后小于5分钟，电子显微镜（EM）很容易在囊泡中检测到包膜病毒粒子。在CHO和HeLa细胞中，细胞能量的消耗会阻断内吞作用，从而阻止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，嗜溶酶体剂巴菲霉素A1阻断了进入的病毒向HeLa和CHO细胞细胞核的传递，但对Vero细胞没有作用。无论采用何种进入途径，这三种细胞从细胞表面摄取HSV的动力学是相似的（t1/2, 5-10分钟）。在15- 20min p.i，从CHO-nectin-1细胞中回收的内化病毒粒子仍然具有传染性，因此被包裹。感染病毒的恢复时间下降了30分钟，表明发生了衣壳释放到细胞质（渗透）中。在巴菲霉素存在的情况下，传染性的细胞内病毒粒子被恢复长达4小时，表明它们确实被困在核内体中。我们提出HSV具有通过内吞摄取和低ph触发步骤有效进入细胞的能力。

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.