summary - Identifies a polybasic furin cleavage site (PRRA insertion) at the spike protein’s S1-S2 junction as notably unique to SARS-CoV-2 among related lineage B betacoronaviruses, and argues it “most likely arose through natural selection” rather than laboratory manipulation: similar cleavage sites exist in other coronavirus lineages and can emerge through natural evolutionary processes, and pangolin coronaviruses with a receptor-binding domain nearly identical to SARS-CoV-2’s were independently found - together offering, in the authors’ words, “a much stronger and more parsimonious explanation” than any laboratory scenario. Concludes SARS-CoV-2 is not a laboratory construct or a purposefully manipulated virus. Published as a brief correspondence/comment reacting to the earliest lab-origin speculation, not a full research article presenting new sequencing data.
relevance_note - The most widely cited scientific argument that the furin site is natural - the direct genomic counterweight to Segreto & Deigin 2021 (separate source node, this slice) on the same feature. Like nearly every genomic source in this slice, it reasons over the shared SARS-CoV-2 reference genome/GISAID sequence collection plus then-available relatives (RaTG13, pangolin CoVs) - flagged per the recurring-dataset note, but its target claim (furin-site plausibility) is a distinct analysis from Segreto/Bruttel’s engineering-signature claims or Pekar’s lineage-divergence claim, not a restatement.