O-37 - DEFUSE proposed introducing human-specific (furin) cleavage sites into SARS-related coronavirus spikes
The single most load-bearing documentary fact in the lab-leak institutional case: the consortium proposed, in writing, to insert human-specific/furin-type cleavage sites into SARS-related coronaviruses — the same class of feature separately debated in SARS-CoV-2’s own genome. (Quote transcribed from the scanned proposal’s degraded OCR and reconciled with the widely-circulated verbatim text; the phrase “introduce appropriate human-specific cleavage sites” is the canonical wording.)
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Why this is evidence
A proposal to insert human-specific/furin cleavage sites into SARSr-CoV spikes — the exact feature SARS-CoV-2 uniquely carries — at the implicated institutions ~2 years before emergence strongly favours engineered H-43 over both H-41 and H-42 (whose virus is unmodified).