Bacteriophage lambda overcomes a perturbation in its host‐viral genetic network through mutualism and evolution of life history traits

An important driver of viral evolution is natural selection to optimize the use of their hosts’ genetic network. To learn how viruses respond to this pressure, we disrupted the genetic network of Escherichia coli to inhibit replication of its virus, bacteriophage lambda, and then observed how λ evolved to compensate. We deleted E. coli's dnaJ gene, which lambda uses to initiate DNA replication. Lambda partially restored its ability to reproduce with just two adaptive mutations associated with genes J and S. The location of the mutations was unexpected because they were not in genes that directly interact with DnaJ, rather they affected seemingly unrelated life history traits. A nonsynonymous J mutation increased λ’s adsorption rate and an S regulatory mutation delayed lysis timing. λ also recovered some of its reproductive potential through intracellular mutualism. This study offers two important lessons: first, viruses can rapidly adapt to disruptive changes in their host's genetic net...

病毒进化的重要驱动力之一，是通过自然选择优化对宿主遗传网络的利用效率。为探究病毒如何应对这一选择压力，我们通过破坏大肠杆菌（Escherichia coli）的遗传网络，以抑制其寄生的λ噬菌体（bacteriophage lambda）的复制，并随后观察λ噬菌体如何通过进化产生补偿机制。我们敲除了大肠杆菌的dnaJ基因——该基因是λ噬菌体启动DNA复制所必需的宿主因子。仅通过与J基因和S基因相关的两处适应性突变，λ噬菌体便部分恢复了增殖能力。突变的位置出乎预料：它们并未位于与DnaJ直接互作的基因中，而是影响了看似无关的生活史性状。一处发生在J基因的非同义突变提升了λ噬菌体的吸附率，而S基因的调控突变则延迟了其裂解时间。λ噬菌体还通过胞内互利共生途径，恢复了部分增殖潜能。本研究得出两点重要结论：其一，病毒可快速适应宿主遗传网络的破坏性改变……