The United Graduate School of Agricultural Science, Iwate University, Morioka 020-8550, Japan.
Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
Viruses. 2020 Jun 12;12(6):638. doi: 10.3390/v12060638.
Single-stranded (ss)RNA viruses are thought to evolve rapidly due to an inherently high mutation rate. However, it remains unclear how ssRNA viruses adapt to novel environments and/or how many and what types of substitutions are needed to facilitate this evolution. In this study, we followed the adaptation of the ssRNA bacteriophage Qβ using thermally adapted as a host, which can efficiently grow at temperatures between 37.2 and 45.3 °C. This made it possible to evaluate Qβ adaptation to the highest known temperature that supports growth, 45.3 °C. We found that Qβ was capable of replication at this temperature; within 114 days (1260 generations), we detected more than 34 novel point mutations in the genome of the thermally adapted Qβ population, representing 0.8% of the total Qβ genome. In addition, we returned the 45.3 °C-adapted Qβ populations to 37.2 °C and passaged them for 8 days (124 generations). We found that the reverse-adapted Qβ population showed little to no decrease in fitness. These results indicate that Qβ can evolve in response to increasing temperatures in a short period of time with the accumulation of point mutations.
单链 (ss)RNA 病毒由于固有突变率高，被认为进化迅速。然而，ssRNA 病毒如何适应新环境以及需要多少和哪些类型的替换来促进这种进化仍然不清楚。在这项研究中，我们使用热适应的 作为宿主，跟踪 ssRNA 噬菌体 Qβ 的适应性，该宿主可以在 37.2 至 45.3°C 之间的温度下高效生长。这使得评估 Qβ 适应已知最高支持生长温度（45.3°C）成为可能。我们发现 Qβ能够在该温度下复制；在 114 天（约 1260 代）内，我们在热适应 Qβ群体的基因组中检测到超过 34 个新的点突变，占 Qβ基因组的 0.8%。此外，我们将适应 45.3°C 的 Qβ群体返回 37.2°C 并传代 8 天（约 124 代）。我们发现，反向适应的 Qβ群体的适应性几乎没有下降。这些结果表明，Qβ可以在短时间内通过积累点突变来响应温度升高而进化。
