Abstract The large dsDNA virus herpes simplex virus 1 (HSV-1) is considered to be genetically stable, yet it can rapidly evolve in response to strong selective pressures such as antiviral treatment. Deep sequencing has revealed that clinical and laboratory isolates of this virus exist as populations that contain a mixture of minor alleles or variants, similar to many RNA viruses. The classic virology approach of plaque purifying virus creates a genetically homogenous population, but it is not clear how closely this represents the mixed virus populations found in nature. We sought to study the evolution of mixed versus highly purified HSV-1 populations in controlled cell culture conditions, to examine the impact of this genetic diversity on evolution. We found that a mixed population of HSV-1 acquired more genetic diversity and underwent a more dramatic phenotypic shift than a plaque-purified population, producing a viral population that was almost entirely syncytial after just ten passages. At the genomic level, adaptation and genetic diversification occurred at the level of minor alleles or variants in the viral population. Certain genetic variants in the mixed viral population appeared to be positively selected in cell culture, and this shift was also observed in clinical samples during their first passages in vitro. In contrast, the plaque-purified viral population did not appear to change substantially in phenotype or overall quantity of minor allele diversity. These data indicate that HSV-1 is capable of evolving rapidly in a given environment, and that this evolution is facilitated by diversity in the viral population.

中文翻译：

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单纯疱疹病毒 1 (HSV-1) 的体外进化揭示了细胞培养中合胞体和其他微小变异的选择

摘要：大型 dsDNA 病毒单纯疱疹病毒 1 (HSV-1) 被认为是遗传稳定的，但它可以响应抗病毒治疗等强选择压力而快速进化。深度测序表明，该病毒的临床和实验室分离株以包含微小等位基因或变体混合物的群体形式存在，类似于许多 RNA 病毒。噬菌斑纯化病毒的经典病毒学方法创建了一个遗传同质的群体，但尚不清楚这与自然界中发现的混合病毒群体有多接近。我们试图研究混合与高度纯化的 HSV-1 群体在受控细胞培养条件下的进化，以检验这种遗传多样性对进化的影响。我们发现，与噬菌斑纯化的群体相比，HSV-1 的混合群体获得了更多的遗传多样性，并经历了更显着的表型转变，产生了仅十次传代后几乎完全合胞体的病毒群体。在基因组水平上，适应和遗传多样化发生在病毒群体的次要等位基因或变异水平上。混合病毒群体中的某些遗传变异似乎在细胞培养中被积极选择，并且在首次体外传代期间的临床样本中也观察到这种转变。相比之下，噬斑纯化的病毒群体的表型或次要等位基因多样性的总量似乎没有显着变化。这些数据表明 HSV-1 能够在给定环境中快速进化，并且病毒群体的多样性促进了这种进化。