Host traits drive viral life histories across phytoplankton viruses

Viruses are integral to ecological and evolutionary processes, but we have a poor understanding of what drives variation in key traits across diverse viruses. For lytic viruses, burst size, latent period, and genome size are primary characteristics controlling host-virus dynamics. Here we synthesize data on these traits for 75 strains of phytoplankton viruses, which play an important role in global biogeochemistry. We find that primary traits of the host (genome size, growth rate) explain 40-50% of variation in burst size and latent period. Specifically, burst size and latent period both exhibit saturating relationships vs. the host:virus genome size ratio, with both traits increasing at low genome size ratios while showing no relationship at high size ratios. In addition, latent period declines as host growth rate increases. We analyze a model of latent period evolution to explore mechanisms that could cause these patterns. The model predicts that burst size may often be set by the host genomic resources available for viral construction, while latent period evolves to permit this maximal burst size, modulated by host metabolic rate. These results suggest that general mechanisms may underlie the evolution of diverse viruses. Future extensions of this work could help explain viral regulation of host populations, viral influence on community structure and diversity, and viral roles in biogeochemical cycles.

病毒是生态与演化过程中不可或缺的组成部分，但我们对驱动多样病毒关键性状变异的核心机制仍缺乏深入认知。对于裂解性病毒（lytic virus）而言，裂解量（burst size）、潜伏期（latent period）与基因组大小是调控宿主-病毒动态（host-virus dynamics）的核心特征。
本研究整合了75株浮游植物病毒（phytoplankton virus）的上述性状数据，这类病毒在全球生物地球化学循环中发挥着关键作用。分析结果显示，宿主的核心性状（基因组大小、生长速率）可解释40%~50%的裂解量与潜伏期变异。具体而言，裂解量与潜伏期均与宿主-病毒基因组大小比值（host:virus genome size ratio）呈现饱和关系：在比值较低时，两种性状均随比值升高而递增；而在比值较高时，二者则无显著相关关系。此外，潜伏期随宿主生长速率的提升而缩短。
本研究通过构建潜伏期演化模型，探究了驱动上述观测模式的潜在机制。模型预测，裂解量通常由宿主可用于病毒组装的基因组资源所决定，而潜伏期则演化至适配该最大裂解量，其过程受宿主代谢速率调控。上述结果表明，多样病毒的演化可能存在通用机制。
本研究的后续拓展工作将有助于阐释病毒对宿主种群的调控作用、病毒对群落结构与多样性的影响，以及病毒在生物地球化学循环中的功能角色。