For virus infections of multicellular hosts, narrow genetic bottlenecks during transmission and within-host spread appear to be widespread. These bottlenecks will affect the maintenance of genetic variation in a virus population and the prevalence of mixed-strain infections, thereby ultimately determining the strength with which different random forces act during evolution. Here we consider different approaches for estimating bottleneck sizes and weigh their merits. We then review quantitative estimates of bottleneck size during cellular infection, within-host spread, horizontal transmission, and finally vertical transmission. In most cases we find that bottlenecks do regularly occur, although in many cases they appear to be virion-concentration dependent. Finally, we consider the evolutionary implications of genetic bottlenecks during virus infection. Although on average strong bottlenecks will lead to declines in fitness, we consider a number of scenarios in which bottlenecks could also be advantageous for viruses.

中文翻译：

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大小问题：病毒感染的遗传瓶颈及其对进化的潜在影响。

对于多细胞宿主的病毒感染，在传播和宿主内部传播过程中狭窄的遗传瓶颈似乎很普遍。这些瓶颈将影响病毒种群中遗传变异的维持以及混合菌株感染的流行，从而最终确定进化过程中不同随机作用力发挥作用的强度。在这里，我们考虑了估计瓶颈大小并权衡其优点的不同方法。然后，我们回顾了细胞感染，宿主内部传播，水平传播以及最终垂直传播过程中瓶颈大小的定量估计。在大多数情况下，我们发现瓶颈确实经常发生，尽管在许多情况下，瓶颈似乎与病毒体浓度有关。最后，我们考虑病毒感染期间遗传瓶颈的进化意义。尽管平均而言，强大的瓶颈会导致适应性下降，但我们考虑了在许多情况下瓶颈也可能对病毒有利的情况。