Cenens William, Makumi Angela, Govers Sander K, Lavigne Rob, Aertsen Abram
Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
Laboratory of Gene Technology, Department of Biosystems, Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
PLoS Genet. 2015 Dec 31;11(12):e1005770. doi: 10.1371/journal.pgen.1005770. eCollection 2015 Dec.
Monitoring the complex transmission dynamics of a bacterial virus (temperate phage P22) throughout a population of its host (Salmonella Typhimurium) at single cell resolution revealed the unexpected existence of a transiently immune subpopulation of host cells that emerged from peculiarities preceding the process of lysogenization. More specifically, an infection event ultimately leading to a lysogen first yielded a phage carrier cell harboring a polarly tethered P22 episome. Upon subsequent division, the daughter cell inheriting this episome became lysogenized by an integration event yielding a prophage, while the other daughter cell became P22-free. However, since the phage carrier cell was shown to overproduce immunity factors that are cytoplasmically inherited by the P22-free daughter cell and further passed down to its siblings, a transiently resistant subpopulation was generated that upon dilution of these immunity factors again became susceptible to P22 infection. The iterative emergence and infection of transiently resistant subpopulations suggests a new bet-hedging strategy by which viruses could manage to sustain both vertical and horizontal transmission routes throughout an infected population without compromising a stable co-existence with their host.
在单细胞分辨率下监测细菌病毒（温和噬菌体P22）在其宿主（鼠伤寒沙门氏菌）群体中的复杂传播动态，揭示了宿主细胞中一个短暂免疫亚群的意外存在，该亚群源自溶原化过程之前的特殊情况。更具体地说，最终导致溶原菌的感染事件首先产生一个携带极性连接的P22附加体的噬菌体载体细胞。在随后的分裂中，继承该附加体的子细胞通过整合事件形成前噬菌体而被溶原化，而另一个子细胞则不含P22。然而，由于噬菌体载体细胞被证明会过量产生免疫因子，这些因子由不含P22的子细胞在细胞质中遗传，并进一步传递给其姐妹细胞，从而产生了一个短暂抗性亚群，当这些免疫因子被稀释时，该亚群又会变得易受P22感染。短暂抗性亚群的反复出现和感染表明了一种新的风险对冲策略，通过这种策略，病毒可以在不影响与宿主稳定共存的情况下，在整个受感染群体中维持垂直和水平传播途径。
