️ 38: Viral Journeys — Tracing the Ancestral Bat Origins of SARS-CoV and SARS-CoV-2

️ Episode 38: The Recency and Geographical Origins of Bat Viruses Ancestral to SARS-CoV and SARS-CoV-2 In this episode of Base by Base, we delve into a landmark study by Pekar et al. (2025) in Cell that harnesses recombination-aware phylogenetic and spatial analyses to trace how the closest bat coronavirus ancestors of SARS-CoV-1 and SARS-CoV-2 circulated mere years before spilling over into humans. By dissecting non-recombinant genomic segments and applying tailored molecular clock models, the authors reveal when and where these viral lineages emerged—and challenge past assumptions about transmission solely via bat host movement . Key highlights of the study include: the discovery that fragments of human SARS coronaviruses share most recent common ancestors with bat viruses within the decade preceding each outbreak; evidence that both SARS-CoV-1-like and SARS-CoV-2-like viruses have circulated broadly across Asia for millennia; phylogeographic reconstructions pinpointing Western China (Yunnan, Sichuan, Guizhou) and Northern Laos as likely origins of the direct bat virus ancestors; and the striking finding that these ancestors moved at rates surpassing typical horseshoe bat dispersal to reach the sites of human emergence in Guangdong and Hubei provinces . Conclusion: By integrating recombination-aware dating with continuous phylogeography, this work inaugurates a new paradigm in Mendelian spillover studies—demonstrating that human SARS viruses arose from bat reservoirs via rapid, long-distance jumps likely involving intermediate hosts or wildlife trade, rather than passive dispersal through bat populations alone . Reference: Pekar, J. E., Lytras, S., Ghafari, M., et al. (2025). The recency and geographical origins of the bat viruses ancestral to SARS-CoV and SARS-CoV-2. Cell, 188, 1–17. https://doi.org/10.1016/j.cell.2025.03.035 License: This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – http://creativecommons.org/licenses/by/4.0/

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