Kite Joanne, Hill Monica, Preston Natasha, Rubina Anzelika, Kollnberger Simon, Wang Eddie Chung Yern, Elliott Gillian
Section of Virology, Department of Microbial Sciences, School of Biosciences, University of Surrey, Guildford GU2 7XH, UK.
Present address: Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK.
J Gen Virol. 2024 Mar;105(3). doi: 10.1099/jgv.0.001969.
Many viruses downregulate their cognate receptors, facilitating virus replication and pathogenesis via processes that are not yet fully understood. In the case of herpes simplex virus 1 (HSV1), the receptor binding protein glycoprotein D (gD) has been implicated in downregulation of its receptor nectin1, but current understanding of the process is limited. Some studies suggest that gD on the incoming virion is sufficient to achieve nectin1 downregulation, but the virus-encoded E3 ubiquitin ligase ICP0 has also been implicated. Here we have used the physiologically relevant nTERT human keratinocyte cell type - which we have previously shown to express readily detectable levels of endogenous nectin1 - to conduct a detailed investigation of nectin1 expression during HSV1 infection. In these cells, nectin1, but not nectin2 or the transferrin receptor, disappeared from the cell surface in a process that required virus protein synthesis rather than incoming virus, but did not involve virus-induced host shutoff. Furthermore, gD was not only required but was sufficient for nectin1 depletion, indicating that no other virus proteins are essential. NK cells were shown to be activated in the presence of keratinocytes, a process that was greatly inhibited in cells infected with wild-type virus. However, degranulation of NK cells was also inhibited in ΔgD-infected cells, indicating that blocking of NK cell activation was independent of gD downregulation of nectin1. By contrast, a superinfection time-course revealed that the ability of HSV1 infection to block subsequent infection of a GFP-expressing HSV1 was dependent on gD and occurred in line with the timing of nectin1 downregulation. Thus, the role of gD-dependent nectin1 impairment during HSV infection is important for virus infection, but not immune evasion, which is achieved by other mechanisms.
许多病毒会下调其同源受体,通过尚未完全了解的过程促进病毒复制和发病机制。就单纯疱疹病毒1型(HSV1)而言,受体结合蛋白糖蛋白D(gD)与下调其受体nectin1有关,但目前对该过程的了解有限。一些研究表明,进入病毒体的gD足以实现nectin1的下调,但病毒编码的E3泛素连接酶ICP0也与之有关。在这里,我们使用了生理相关的nTERT人角质形成细胞类型——我们之前已证明该细胞类型能表达易于检测到的内源性nectin1水平——来详细研究HSV1感染期间nectin1的表达。在这些细胞中,nectin1而非nectin2或转铁蛋白受体从细胞表面消失,这一过程需要病毒蛋白合成而非进入的病毒,但不涉及病毒诱导的宿主关闭。此外,gD不仅是必需的,而且足以导致nectin1耗竭,这表明没有其他病毒蛋白是必不可少的。结果显示,自然杀伤细胞(NK细胞)在角质形成细胞存在的情况下被激活,而在感染野生型病毒的细胞中这一过程受到极大抑制。然而,在感染ΔgD病毒的细胞中,NK细胞的脱颗粒也受到抑制,这表明NK细胞激活的阻断与gD下调nectin1无关。相比之下,一项重复感染时间进程研究表明,HSV1感染阻断后续表达绿色荧光蛋白(GFP)的HSV1感染的能力取决于gD,且与nectin1下调的时间一致。因此,HSV感染期间gD依赖性nectin1损伤的作用对病毒感染很重要,但对免疫逃逸并不重要,免疫逃逸是通过其他机制实现的。