Dysregulated nuclear export of the late herpes simplex virus 1 transcriptome through the vhs-VP22 axis uncouples virus cytopathic effect and virus production
Dysregulated nuclear export of the late herpes simplex virus 1 transcriptome through the vhs-VP22 axis uncouples virus cytopathic effect and virus production
复制标题
晚期单纯疱疹病毒1转录组通过vhs-VP22轴的核输出失调，使病毒细胞病变效应和病毒产生脱钩
DOI：
10.1101/2022.11.02.514834
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Pheasant K
中科院分区：
文献类型：
--
作者：
Pheasant K
单纯疱疹病毒1型（HSV1）以经典级联方式表达其基因，最终产生大量结构蛋白以促进病毒组装。缺乏病毒蛋白VP22（Δ 22）的HSV 1表现出晚期翻译关闭，这是一种归因于病毒体宿主关闭（vhs）蛋白的不受限制的活性的表型，病毒编码的核糖核酸内切酶在感染期间诱导mRNA降解。我们先前已经表明，VHS也参与调节病毒转录组的核质区室化，并且在没有VP22的情况下，许多病毒转录物在感染后期被隔离在细胞核中。在这里，我们表明，尽管表达最少量的结构蛋白并且未能在人成纤维细胞上形成噬斑，但菌株17 Δ 22病毒的复制和传播与Wt病毒一样有效，但不会引起细胞病变效应（CPE）。尽管如此，CPE引起的病毒自发地出现在Δ 22感染的人成纤维细胞上，并且以这种方式分离的四种病毒都在vhs中获得了点突变，这挽救了病毒mRNA的输出和后期蛋白质翻译。然而，与缺失vhs的病毒不同，这些病毒仍然诱导细胞mRNA的降解，这表明在不存在VP22的情况下vhs突变对于克服mRNA输出而不是mRNA降解中的干扰是必要的。因此，VHS中的二次突变的最终结果是拯救由后期蛋白质合成引起的病毒诱导的CPE，而HSV1突变VHS以优化后期结构蛋白的生产存在明显的选择压力，其目的是超过病毒生产的目的。病毒基因组复制后，大量产生结构蛋白，使大量感染性子代的快速组装和释放成为可能。感染的细胞还表现出细胞病变效应（CPE），形态学变化，例如细胞变圆和细胞间接触的破坏，促进病毒传播。在这里，我们表明，HSV1的突变，导致病毒mRNA的核滞留和随之而来的晚期蛋白质合成的关闭，也未能引起CPE。然而，出乎意料的是，我们发现这种病毒仍然能够释放大量的感染性病毒，这些病毒可以在细胞之间传播，而没有任何细胞损伤的证据。尽管如此，尽管病毒生产效率高，但该病毒自发突变以挽救晚期蛋白质生产和CPE，突变映射到mRNA输出过程。因此，对HSV 1有明显的选择压力来优化晚期结构蛋白的合成，但其目的超过了病毒生产的目的，这一结果暗示了为什么病毒通常表达如此大量的结构蛋白。
Herpes simplex virus 1 (HSV1) expresses its genes in a classical cascade culminating in the production of large amounts of structural proteins to facilitate virus assembly. HSV1 lacking the virus protein VP22 (Δ22) exhibits late translational shutoff, a phenotype that has been attributed to the unrestrained activity of the virion host shutoff (vhs) protein, a virus-encoded endoribonuclease which induces mRNA degradation during infection. We have previously shown that vhs is also involved in regulating the nuclear-cytoplasmic compartmentalisation of the virus transcriptome, and in the absence of VP22 many virus transcripts are sequestered in the nucleus late in infection. Here we show that despite expressing minimal amounts of structural proteins and failing to plaque on human fibroblasts, the strain 17 Δ22 virus replicates and spreads as efficiently as Wt virus, but without causing cytopathic effect (CPE). Nonetheless, CPE-causing virus spontaneously appeared on Δ22-infected human fibroblasts, and four viruses isolated in this way had all acquired point mutations in vhs which rescued viral mRNA export and late protein translation. However, unlike a virus deleted for vhs, these viruses still induced the degradation of cellular mRNA, suggesting that vhs mutation in the absence of VP22 is necessary to overcome a disturbance in mRNA export rather than mRNA degradation. The ultimate outcome of secondary mutations in vhs is therefore the rescue of virus-induced CPE caused by late protein synthesis, and while there is a clear selective pressure on HSV1 to mutate vhs for optimal production of late structural proteins, the purpose of this is over and above that of virus production.Author SummaryHSV is a human pathogen that lytically infects cells of the epidermis. Following viral genome replication, structural proteins are produced in abundance to enable the rapid assembly and release of large quantities of infectious progeny. Infected cells also exhibit cytopathic effect (CPE), morphological changes that are exemplified by cell rounding and the breakage of cell-to-cell contacts, facilitating virus dissemination. Here we show that HSV1 with a mutation that results in the nuclear retention of viral mRNA and concomitant shutdown of late protein synthesis, also fails to cause CPE. However, unexpectedly, we found that this virus is still able to release large numbers of infectious virus which can spread between cells without any evidence of cell damage. Nonetheless, despite efficient virus productivity, this virus spontaneously mutates to rescue late protein production and CPE, with mutations mapping to the process of mRNA export. There is therefore a clear selective pressure on HSV1 to optimize the synthesis of late structural proteins, but the purpose of this is over and above that of virus production, a result that has implications for why viruses in general express such large amounts of structural proteins.