Department of Mathematics, Statistics, and Computer Science, St. Olaf College, Northfield, MN 55057, USA.
Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
J Theor Biol. 2021 Aug 21;523:110710. doi: 10.1016/j.jtbi.2021.110710. Epub 2021 Apr 9.
The canonical bacteriophage is obligately lytic: the virus infects a bacterium and hijacks cell functions to produce large numbers of new viruses which burst from the cell. These viruses are well-studied, but there exist a wide range of coexisting virus lifestyles that are less understood. Temperate viruses exhibit both a lytic cycle and a latent (lysogenic) cycle, in which viral genomes are integrated into the bacterial host. Meanwhile, chronic (persistent) viruses use cell functions to produce more viruses without killing the cell; chronic viruses may also exhibit a latent stage in addition to the productive stage. Here, we study the ecology of these competing viral strategies. We demonstrate the conditions under which each strategy is dominant, which aids in control of human bacterial infections using viruses. We find that low lysogen frequencies provide competitive advantages for both virus types; however, chronic viruses maximize steady state density by eliminating lysogeny entirely, while temperate viruses exhibit a non-zero 'sweet spot' lysogen frequency. Viral steady state density maximization leads to coexistence of temperate and chronic viruses, explaining the presence of multiple viral strategies in natural environments.
病毒感染细菌并劫持细胞功能以产生大量新病毒，这些新病毒从细胞中爆发。这些病毒已经得到了很好的研究，但也存在着广泛的共存病毒生活方式，这些方式还不太了解。温和噬菌体表现出裂解周期和潜伏（溶源）周期，其中病毒基因组整合到细菌宿主中。同时，慢性（持续性）病毒利用细胞功能产生更多的病毒而不杀死细胞；慢性病毒除了有生产阶段外，还可能表现出潜伏阶段。在这里，我们研究了这些竞争病毒策略的生态学。我们证明了每种策略占主导地位的条件，这有助于利用病毒控制人类细菌感染。我们发现，低溶原频率为两种病毒类型提供了竞争优势；然而，慢性病毒通过完全消除溶原来最大限度地提高病毒的稳定状态密度，而温和病毒则表现出非零的“甜蜜点”溶原频率。病毒稳定状态密度的最大化导致温和病毒和慢性病毒的共存，这解释了自然环境中存在多种病毒策略的原因。
