Center for Predictive Medicine, University of Louisville, Louisville, KY, USA.
Department of Medicine, University of Louisville, Louisville, KY, USA.
Sci Rep. 2024 Oct 25;14(1):25265. doi: 10.1038/s41598-024-76788-x.
The high mutation rate of RNA viruses provides viral populations with the ability to adapt to new environments but also makes them vulnerable to extinction due to the deleterious effects of mutations, which is the conceptual basis for the antiviral activity of RNA mutagens. However, there are still gaps in the quantitative understanding of the dynamics between the mutations induced by an RNA mutagen and its effects on viral fitness. To address this, we used Venezuelan Equine Encephalitis Virus (VEEV) and the potent RNA mutagen β-d-N4-hydroxycytidine (NHC) as a model to analyze virus replication competency and mutation frequency following treatment in the total and replication-competent viral populations separately. We found that NHC induced transition mutations in a concentration dependent manner in the total population, while the replication-competent population maintained itself within an increased, yet narrow, mutation spectrum. The incorporation of NHC mainly happened during the positive sense RNA synthesis of VEEV. A growth kinetic analysis of VEEV population treated with NHC pointed to a lower but more diverse distribution in mutational fitness, demonstrating that NHC-induced mutations negatively and broadly affect the fitness of the virus. Together, our study provides mechanistic insight into how RNA mutagens affect viral population landscape and the potential of RNA mutagens as an antiviral strategy for alphaviruses.
RNA 病毒的高突变率使病毒种群具有适应新环境的能力，但也使它们容易因突变的有害影响而灭绝，这是 RNA 诱变剂抗病毒活性的概念基础。然而，对于 RNA 诱变剂诱导的突变与病毒适应性之间的动态的定量理解仍然存在差距。为了解决这个问题，我们使用委内瑞拉马脑炎病毒（VEEV）和强效 RNA 诱变剂β-d-N4-羟基胞苷（NHC）作为模型，分别在总病毒群体和复制性病毒群体中分析了处理后病毒复制能力和突变频率。我们发现，NHC 以浓度依赖的方式在总群体中诱导转换突变，而复制性群体在增加但狭窄的突变谱内维持自身。NHC 的掺入主要发生在 VEEV 的正链 RNA 合成过程中。用 NHC 处理的 VEEV 群体的生长动力学分析表明，突变适应性的分布较低但更多样化，表明 NHC 诱导的突变对病毒适应性具有负面影响和广泛影响。总之，我们的研究提供了对 RNA 诱变剂如何影响病毒群体景观以及 RNA 诱变剂作为抗甲病毒策略的潜在机制的深入了解。
