Section of Virology, Department of Microbial Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.
Present address: Department of Medicine, New York University School of Medicine, New York, USA.
J Gen Virol. 2019 Dec;100(12):1701-1713. doi: 10.1099/jgv.0.001343.
The Glasgow s17 syn+ strain of herpes simplex virus 1 (HSV1) is arguably the best characterized strain and has provided the reference sequence for HSV1 genetic studies. Here we show that our original s17 syn+ stock was a mixed population from which we have isolated a minor variant that, unlike other strains in the laboratory, fails to be efficiently released from infected cells and spreads predominantly by direct cell-to-cell transmission. Analysis of other s17-derived viruses that had been isolated elsewhere revealed a number with the same release phenotype. Second-generation sequencing of 8 plaque-purified s17-derived viruses revealed sequences that vary by 50 single-nucleotide polymorphisms (SNPs), including approximately 10 coding SNPs. This compared to interstrain variations of around 800 SNPs in strain Sc16, of which a quarter were coding changes. Amongst the variations found within s17, we identified 13 variants of glycoprotein C within the original stock of virus that were predominantly a consequence of altered homopolymeric runs of C residues. Characterization of seven isolates coding for different forms of gC indicated that all were expressed, despite six of them lacking a transmembrane domain. While the release phenotype did not correlate directly with any of these identified gC variations, further demonstration that nine clinical isolates of HSV1 also fail to spread through extracellular release raises the possibility that propagation in tissue culture had altered the HSV1 s17 transmission phenotype. Hence, the s17 intrastrain variation identified here offers an excellent model for understanding both HSV1 transmission and tissue culture adaptation.
单纯疱疹病毒 1（HSV1）的格拉斯哥 s17 syn+ 株可以说是研究最为充分的病毒株，为 HSV1 的遗传研究提供了参考序列。在这里，我们发现我们最初的 s17 syn+ 病毒株是一个混合群体，从中我们分离出一个次要变体，与实验室中的其他毒株不同，它不能有效地从受感染的细胞中释放出来，主要通过直接细胞间传播扩散。对其他在其他地方分离出的源自 s17 的病毒的分析表明，有许多具有相同释放表型的病毒。对 8 个经噬菌斑纯化的源自 s17 的病毒的第二代测序揭示了 50 个单核苷酸多态性（SNP）的序列差异，包括大约 10 个编码 SNP。相比之下，Sc16 株的菌株间变异约为 800 个 SNP，其中四分之一是编码变化。在所发现的 s17 内的变异中，我们在原始病毒库中鉴定出 13 种糖蛋白 C 的变体，主要是由于 C 残基的改变同源多聚体序列。对编码不同形式 gC 的七个分离物的特征分析表明，尽管其中六个缺乏跨膜结构域，但所有这些分离物都能表达 gC。尽管释放表型与这些鉴定的 gC 变异没有直接相关，但进一步表明九种临床分离的 HSV1 也不能通过细胞外释放传播，这增加了组织培养改变 HSV1 s17 传播表型的可能性。因此，这里鉴定的 s17 株内变异为理解 HSV1 的传播和组织培养适应提供了一个极好的模型。
