--- type: Topic title: Furin cleavage site and molecular features description: "Technical discussion of the furin cleavage site, receptor binding domain and other genomic features." tags: - topic - covid-19 document_count: 394 sources: - { id: baric_ti, resource: /sources/baric-ti.md, title: Baric Transcribed Interview (Redacted), author: "process:senate-hsgac-release", last_modified: 2026-07-23 } - { id: daszak_cbp, resource: /sources/daszak-cbp.md, title: Daszak CBP Package, author: "process:senate-hsgac-release", last_modified: 2026-07-17 } - { id: diary_prequel, resource: /sources/diary-prequel.md, title: Diary Prequel Package, author: "process:senate-hsgac-release", last_modified: 2026-07-27 } - { id: fauci_diary, resource: /sources/fauci-diary.md, title: Tony's Diary Package, author: "process:senate-hsgac-release", last_modified: 2026-07-24 } - { id: fauci_intel, resource: /sources/fauci-intel.md, title: Fauci Intelligence Community Release, author: "process:senate-hsgac-release", last_modified: 2026-06-11 } - { id: gates, resource: /sources/gates.md, title: Gates Package, author: "process:senate-hsgac-release", last_modified: 2026-07-31 } - { id: letter_dni, resource: /sources/letter-dni.md, title: Chairman Paul Letter to DNI Gabbard, author: "process:senate-hsgac-release", last_modified: 2025-10-30 } - { id: monkeypox_release, resource: /sources/monkeypox-release.md, title: NIH Monkeypox Smuggling Release, author: "process:senate-hsgac-release", last_modified: 2026-06-05 } - { id: reading_room, resource: /sources/reading-room.md, title: Reading Room Production, author: "process:senate-hsgac-release" } - { id: slack_pm, resource: /sources/slack-pm.md, title: Slack / Private Message Drop, author: "process:senate-hsgac-release" } generated: { by: randpaul-corpus-pipeline/1.0, at: "2026-08-01T12:42:27Z" } status: stable --- Technical discussion of the furin cleavage site, receptor binding domain and other genomic features. Tagged on **394** documents. # Principal voices * [Robert F. Garry](/people/robert-f-garry.md) - 113 documents * [Kristian G. Andersen](/people/kristian-g-andersen.md) - 64 documents * [Edward C. Holmes](/people/edward-c-holmes.md) - 52 documents * [Andrew Rambaut](/people/andrew-rambaut.md) - 40 documents * [Ralph S. Baric](/people/ralph-s-baric.md) - 16 documents * [Anthony S. Fauci](/people/anthony-s-fauci.md) - 15 documents * [Clare Thomas](/people/clare-thomas.md) - 8 documents * [Erik Stemmy](/people/erik-stemmy.md) - 8 documents * [Ashley Sanders](/people/ashley-sanders.md) - 4 documents * [Christina Salazar](/people/christina-salazar.md) - 3 documents * Darpa Commandant OF THE Marine Corps Fellow - 1 documents * [Francis S. Collins](/people/francis-s-collins.md) - 1 documents * [John Mascola](/people/john-mascola.md) - 1 documents * Kristian G. Andersen M - 1 documents * Yinda Kwe Claude - 1 documents # Statement timeline Attributed statements in chronological order. Each is quoted verbatim and cited to its page. * **2020-01-31** — [John Mascola](/people/john-mascola.md) (asserts): "Tony, I will track and will review data on the "furin cleavage site" of 2019-nCoV." [^fauci_intel] * **2020-01-31** — [John Mascola](/people/john-mascola.md) (asserts): "This is the site that is analogous to the furin cleavage site between gp120 and gp41 of HIV." [^fauci_intel] * **2020-02-01** — [Anthony S. Fauci](/people/anthony-s-fauci.md) (asserts): "Zheng-Li Shi at the University of Wuhan has been working for years in GOF in coronaviruses to allow adaptation of the spike protein to bind to the human ACE2 receptor, we could not let this go." [^fauci_diary] * **2020-03-06** — Kristian G. Andersen M (asserts): "More specifically, they focused on two important features of the spike protein: the receptor-binding vu domain (RBD), a kind of grappling hook that grips onto host cells, and the cleavage site, a molecular can opener that allows the virus to crack open and…" [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "Evidence for natural evolution The scientists found that the RBD portion of the SARS-CoV-2 spike proteins had evolved to effectively target a molecular feature on the outside of human cells called ACE2, a receptor involved in regulating blood pressure." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "The SARS-CoV-2 spike protein was so effective at binding the human cells, in fact, that the scientists concluded it was the result of natural selection and not the product of genetic engineering." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (denies): ""These two features of the virus, the mutations in the RBD portion of the spike protein and its distinct backbone, rules out laboratory manipulation as a potential origin for SARS-CoV-2" said Andersen." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "In this scenario, both of the distinctive features of SARS-CoV-2's spike protein--the RBD portion that binds to cells and the cleavage site that opens the virus up--would have evolved to their current state prior to entering humans." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "For instance, some coronaviruses from pangolins, armadillo-like mammals found in Asia and Africa, have an RBD structure very similar to that of SARS-CoV-2." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "Then the other distinct spike protein characteristic of SARS-CoV-2, the cleavage site, could have evolved within a human host, possibly via limited undetected circulation in the human population prior to the beginning of the epidemic." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "The researchers found that the SARS-CoV-2 cleavage site, appears similar to the cleavage sites of strains of bird flu that has been shown to transmit easily between people." [^fauci_intel] * **2020-03-06** — Kristian G. Andersen M (asserts): "SARS-CoV-2 could have evolved such a virulent cleavage site in human cells and soon kicked off the current epidemic, as the coronavirus would possibly have become far more capable of spreading between people." [^fauci_intel] * **2020-05-01** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "I also had a pretty heated discussion with him on one of the WH committee calls where I mentioned that the RBD would probably lead to high affinity binding and the furin site being active." [^slack_pm] * **2020-05-02** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "Speaking of furin - Bob, your old buddy is on the Virological again and it's a pretty nice theory for how the furin site was acquired in bats - just need to add a little extra divergence and there you have…" [^slack_pm] * **2020-05-12** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "The furin site is clearly active in tissue culture." [^slack_pm] * **2020-05-12** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "Typically SARS-like CoVs are cultured in the presence of trypsin (to allow for cleavage of S1/S2), but if trypsin isn't added, there's a *huge* selection pressure for gaining a furin site." [^slack_pm] * **2020-05-12** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "The example from bovine CoVs (post #6 on the thread on virological) is exactly a 12bp insertion seen in tissue culture creating a furin cleavage site.3." [^slack_pm] * **2020-05-12** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "They're not furin sites, but there seems to be some affinity specifically for12bp insertions (in T/C) - and of course, the furin cleavage site is exactly 12bp." [^slack_pm] * **2020-05-16** — [Robert F. Garry](/people/robert-f-garry.md) (asserts): ""_However, since we observed all notable SARS-CoV-2 features, including the optimized RBD and polybasic cleavage site, in related coronaviruses in nature, we do not believe that *any* type of laboratory-based scenario isplausible."_" [^slack_pm] * **2020-05-18** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "When it comes to the selection argument, what is still most telling to be is the RBD." [^slack_pm] * **2020-05-18** — [Kristian G. Andersen](/people/kristian-g-andersen.md) (asserts): "SARS-CoV-2 is already'perfect' for binding, so it doesn't need to - BUT that 'perfect' RBD is found in a pangolin CoV, so clearly it already exists in nature - no further adaptation needed it seems." [^slack_pm] * **2020-05-22** — [Andrew Rambaut](/people/andrew-rambaut.md) (questions): "But I wonder if you'd have time at least to cast your eye over this very brief set of notes (responding to a number of points in the Nature Medicine paper) that I have received from a molecular biologist contact of mine, who has long experience in vaccine…" [^slack_pm] * **2020-05-22** — [Andrew Rambaut](/people/andrew-rambaut.md) (acknowledges): "New polybasic cleavage sites have been observed only after prolonged passage oflow-pathogenicity avian influenza virus in vitro or in vivo17.Yes if you postulated the virus found these 4 amino substitutions one by one - I agree this is highly…" [^slack_pm] * **2020-05-22** — [Andrew Rambaut](/people/andrew-rambaut.md) (asserts): "Subsequent generation of a polybasic cleavage site would have then required repeated passage in cell culture or animals with ACE2 receptors similar to those of humans, but such work has also not previously been described." [^slack_pm] * **2020-05-22** — [Andrew Rambaut](/people/andrew-rambaut.md) (acknowledges): "If they did indeed find a bat virus in their stocks with99% identity apart from the polybasic cleavage site then would they be comfortable to disclose this as then the only conclusion was that COVID19 was artificially created in their lab." [^slack_pm] # Matching terms High-confidence: `furin cleavage`, `furin site`, `cleavage site`, `receptor binding domain`, `rbd`, `ace2 receptor`, `spike protein` Supporting: `genome`, `sequence`, `mutation`, `polybasic`, `backbone`, `ace2`, `phylogenetic`, `rat g13`, `banal` # Sources [^baric_ti]: [baric_ti](/sources/baric-ti.md) [^daszak_cbp]: [daszak_cbp](/sources/daszak-cbp.md) [^diary_prequel]: [diary_prequel](/sources/diary-prequel.md) [^fauci_diary]: [fauci_diary](/sources/fauci-diary.md) [^fauci_intel]: [fauci_intel](/sources/fauci-intel.md) [^gates]: [gates](/sources/gates.md) [^letter_dni]: [letter_dni](/sources/letter-dni.md) [^monkeypox_release]: [monkeypox_release](/sources/monkeypox-release.md) [^reading_room]: [reading_room](/sources/reading-room.md) [^slack_pm]: [slack_pm](/sources/slack-pm.md)