Center for Study of Emerging and Re-emerging Viruses, Korea Virus Research Institute, Institute for Basic Science (IBS), Daejeon 34126, Republic of Korea.
College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju 28644, Republic of Korea.
Cell Rep. 2023 Sep 26;42(9):113077. doi: 10.1016/j.celrep.2023.113077. Epub 2023 Sep 6.
With the emergence of multiple predominant SARS-CoV-2 variants, it becomes important to have a comprehensive assessment of their viral fitness and transmissibility. Here, we demonstrate that natural temperature differences between the upper (33°C) and lower (37°C) respiratory tract have profound effects on SARS-CoV-2 replication and transmissibility. Specifically, SARS-CoV-2 variants containing the NSP12 mutations P323L or P323L/G671S exhibit enhanced RNA-dependent RNA polymerase (RdRp) activity at 33°C compared with 37°C and high transmissibility. Molecular dynamics simulations and microscale thermophoresis demonstrate that the NSP12 P323L and P323L/G671S mutations stabilize the NSP12-NSP7-NSP8 complex through hydrophobic effects, leading to increased viral RdRp activity. Furthermore, competitive transmissibility assay reveals that reverse genetic (RG)-P323L or RG-P323L/G671S NSP12 outcompetes RG-WT (wild-type) NSP12 for replication in the upper respiratory tract, allowing markedly rapid transmissibility. This suggests that NSP12 P323L or P323L/G671S mutation of SARS-CoV-2 is associated with increased RdRp complex stability and enzymatic activity, promoting efficient transmissibility.
随着多种主要 SARS-CoV-2 变体的出现，全面评估它们的病毒适应性和传染性变得尤为重要。在这里，我们证明了上呼吸道（33°C）和下呼吸道（37°C）之间的自然温差对 SARS-CoV-2 的复制和传染性有深远的影响。具体来说，与 37°C 相比，含有 NSP12 突变 P323L 或 P323L/G671S 的 SARS-CoV-2 变体在 33°C 下表现出增强的 RNA 依赖性 RNA 聚合酶（RdRp）活性和高传染性。分子动力学模拟和微尺度热泳分析表明，NSP12 的 P323L 和 P323L/G671S 突变通过疏水作用稳定 NSP12-NSP7-NSP8 复合物，从而提高病毒 RdRp 活性。此外，竞争性传染性测定表明，反向遗传学（RG）-P323L 或 RG-P323L/G671S NSP12 在复制过程中比 RG-WT（野生型）NSP12 在上呼吸道更具竞争力，从而允许更快的传播速度。这表明 SARS-CoV-2 的 NSP12 P323L 或 P323L/G671S 突变与 RdRp 复合物稳定性和酶活性的增加有关，从而促进了有效的传染性。
