SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor
2020 · paper · Biomedicine
Shows that SARS-CoV-2 uses the receptor ACE2 to enter cells and the protease TMPRSS2 to prime its spike protein. A clinically approved TMPRSS2 inhibitor blocked entry, and sera from convalescent SARS patients cross-neutralized entry.
Checked: PDF from europepmc.org, fetched 4 Oct 2026. Page numbers are those of that PDF.
7 findings
Reference or label Introduction (p3) attributes the bat-reservoir claim "Chinese horseshoe bats serve as natural reservoir hosts for SARS-CoV (Lau et al., 2005; Li et al., 2005a)" to a reference listed on p12 as "Li, F., Li, W., Farzan, M., and Harrison, S.C. (2005a). Structure of SARS coronavirus spike receptor-binding domain complexed with receptor. Science 309, 1864-1868."
- p. 3 Introduction
Chinese horseshoe bats serve as natural reservoir hosts for SARS-CoV (Lau et al., 2005; Li et al., 2005a).
- p. 12 Reference list
Li, F., Li, W., Farzan, M., and Harrison, S.C. (2005a). Structure of SARS coronavirus spike receptor-binding domain complexed with receptor. Science 309, 1864–1868.
- p. 3 Introduction, first paragraph
Chinese horseshoe bats serve as natural reservoir hosts for SARS-CoV (Lau et al., 2005; Li et al., 2005a)
- p. 3 Introduction paragraph 1
(Lau et al., 2005; Li et al., 2005a)
Only the authors can say what is right here.
Judge's note: Read crop C001-a and full page extract/png/main-p003.png: the sentence and the two-citation parenthesis are printed as quoted. Read crop C001-b and full page extract/png/main-p012.png: the 2005a entry is the Li, F. et al. Science 309 crystal-structure paper of the RBD/ACE2 complex; the 2005b entry is Li, W. et al., EMBO J. 24, on receptor and viral determinants of adaptation to human ACE2. Neither title concerns bat reservoirs, and no other Li 2005 entry exists in the list (p12 shows Li 2003, 2005a, 2005b, 2017). The same 2005a key is used correctly on p4 for the atomic-level SARS-S/ACE2 interface. The accompanying Lau et al., 2005 entry (Proc. Natl. Acad. Sci. USA 102, 14040-14045, "Severe acute respiratory syndrome coronavirus-like virus in Chinese horseshoe bats") does support the claim, so only the second key is mismatched. Only the authors can say which reference was intended, hence author_query.
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Reference or label Reference list (p11) prints the Huang et al. entry as "Huang, C., Wang, Y., Li, X., Ren, L., Zhao, J., Hu, Y., Zhang, L., Fan, G., Xu, J., Gu, X., et al. (2020). Clinical features of patients infected with 2019 novel coronavirus in Wuhan (China: Lancet).", with the place name and journal merged into a parenthesis and no volume or page numbers.
- p. 11 Reference list
Clinical features of patients infected with 2019 novel coronavirus in Wuhan (China: Lancet).
- p. 11 Reference list
Huang, C., Wang, Y., Li, X., ... (2020). Clinical features of patients infected with 2019 novel coronavirus in Wuhan (China: Lancet).
- p. 3 Introduction, second paragraph
emerged in Wuhan, Hubei province, China (Huang et al., 2020;
Judge's note: Read crop C009-b and the full page extract/png/main-p011.png: the entry is printed exactly as quoted, the title ending "in Wuhan" followed by "(China: Lancet)" and a full stop, with no journal styling, volume or pages. Every other journal entry on the same page carries journal, volume and pages (e.g., Chan et al., 2020, Lancet 395, 514-523) or, when ahead of print, a DOI (e.g., Corman et al., 2020; Iwata-Yoshikawa et al., 2019). The source is cited in the Introduction (crop C009-c, p3). A pointer/reference-formatting defect, S2, with the evident fix of restoring "in Wuhan, China. Lancet ...".
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Reference or label The supplemental caption reads "Figure S2. Extended Version of the Phylogenetic Tree, Related to Figure 2B", but the phylogenetic tree in the article is Figure 2A; Figure 2B is the receptor binding motif alignment.
- p. 19 Figure S2 caption
Figure S2. Extended Version of the Phylogenetic Tree, Related to Figure 2B
- p. 6 Figure 2 legend, panels A and B
(A) The S protein of SARS-CoV-2 clusters phylogenetically with S proteins of known bat-associated betacoronaviruses (see Figure S2 for more details).
- p. 5 Results, "SARS-CoV-2 Employs the SARS-CoV Receptor"
clusters with SARS-CoV-related viruses from bats (SARSr-CoV), of which some but not all can use ACE2 for host cell entry (Figure 2A; Figure S2)
- p. 19 Figure S2 caption
Extended Version of the Phylogenetic Tree, Related to Figure 2B
Judge's note: Read crop C023-a (caption on p. 19, with the extended tree above it) and the full page image extract/png/main-p006.png: panel A of Figure 2 is the neighbor-joining tree of bat/human SARS-related coronavirus S proteins, panel B is the S-protein domain schematic with the RBM amino-acid alignment. The Figure 2 legend itself (crop C023-b) says under (A) "clusters phylogenetically ... (see Figure S2 for more details)", and the Results text (crop C023-c) pairs "(Figure 2A; Figure S2)". The supplemental caption therefore points at the wrong panel; the figure content is fine.
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Reference or label The Key Resources Table (p15) lists "MEGA 7.0.26 | Kumar et al., 2018 | https://www.megasoftware.net" and the Method Details (p17) says analysis "was performed using the MEGA7.0.26 software", while the cited reference (p12) is "Kumar, S., Stecher, G., Li, M., Knyaz, C., and Tamura, K. (2018). MEGA X: Molecular Evolutionary Genetics Analysis across Computing Platforms. Mol Biol Evol 35, 1547-1549."
- p. 15 Key Resources Table, Software and Algorithms
MEGA 7.0.26 Kumar et al., 2018 https://www.megasoftware.net
- p. 12 Reference list
Kumar, S., Stecher, G., Li, M., Knyaz, C., and Tamura, K. (2018). MEGA X: Molecular Evolutionary Genetics Analysis across Computing Platforms. Mol Biol Evol 35, 1547–1549.
- p. 17 Method Details, Phylogenetic analysis
was performed using the MEGA7.0.26 software
- p. 15 Software
MEGA 7.0.26
Only the authors can say what is right here.
Judge's note: Read crop C011-a (Software and Algorithms rows on page 15), crop C011-e (Phylogenetic analysis paragraph on page 17) and crop C011-b plus the full page extract/png/main-p012.png for the reference entry. The software version stated twice is 7.0.26, but the only citation given is the paper whose own title names MEGA X, a different release; the version is also written two ways ("MEGA 7.0.26" / "MEGA7.0.26"). Which of version or citation is correct can only be settled by the authors, hence author_query; the data are unaffected, so S2.
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Reference or label MRC-5 cells are listed among the cultured cell lines in the methods (p15, "MRC-5 (human, lung)") and assayed in Figure 1C, but no MRC-5 row appears in "Experimental Models: Cell Lines" of the Key Resources Table (pp13-14), so no source or identifier is given for them.
- p. 15 Cell cultures, primary cells, viral strains
LLC-PK1 (pig, kidney), MRC-5 (human, lung), MyDauLu/47.1
- p. 15 Figure S1, panel title
MRC-5
- p. 13 Key Resources Table, Experimental Models: Cell Lines
A549 ... BEAS-2B ... Calu-3 ... NCI-H1299 ... Huh-7 ... Caco-2
Only the authors can say what is right here.
Judge's note: Read crop C007-b/C012-a (page 15 cell-culture paragraph, which lists MRC-5 (human, lung) among lines incubated in DMEM), the Figure 1C axis labels on extract/png/main-p004.png (A549, BEAS-2B, Calu-3, H1299, MRC-5, 293T, Huh-7, Caco-2, Vero, LLC-PK1, MDBK, MDCKII, RhiLu/1.1, MyDauLu/47.1, BHK-21, NIH3T3), and both Key Resources Table pages extract/png/main-p013.png and extract/png/main-p014.png. The cell-line rows are A549, BEAS-2B, Calu-3, NCI-H1299, Huh-7, Caco-2, Vero, Vero-TMPRSS2, LLC-PK1, MDBK, MDCKII, RhiLu/1.1, MyDauLu/47.1, BHK-21, NIH/3T3, HAE and 293T; there is no MRC-5 row under any name. A missing provenance entry, not a wrong result, so S2; only the authors can supply the source.
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Reference or label The control anti-DC-SIGN antibody is sourced to two different suppliers: "As control, an unrelated anti-DC-SIGN antibody (Serotec, goat, 20 mg/mL) was used" in Method Details (p16) versus the Key Resources Table row "Polyclonal anti-DC-SIGN antibody | Santa Cruz | Cat.#: sc-11038; RRID:AB_639038" (p13).
- p. 16 Method Details, Pseudotyping of VSV and transduction experiments
As control, an unrelated anti-DC-SIGN antibody (Serotec, goat, 20 mg/mL) was used.
- p. 13 Key Resources Table, Antibodies
Polyclonal anti-DC-SIGN antibody Santa Cruz Cat.#: sc-11038; RRID:AB_639038
- p. 13 Key resources table
Polyclonal anti-DC-SIGN antibody
- p. 16 Transduction methods
anti-DC-SIGN antibody (Serotec, goat, 20 mg/mL)
Only the authors can say what is right here.
Judge's note: Read crop C014-d (page 16 transduction paragraph), which names Serotec for the goat anti-DC-SIGN control immediately after the anti-ACE2 antibody "(R&D Systems, goat, AF933)", and the full Key Resources Table page extract/png/main-p013.png, whose Antibodies block lists exactly one anti-DC-SIGN entry, from Santa Cruz (sc-11038). The anti-ACE2 reagent matches between the two places (R&D Systems AF933), so the discrepancy is specific to the control antibody. Only one control antibody is described in either place, and only the authors can say which supplier is correct; the data are unaffected, so S2.
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Reference or label The statistics section (p. 17) states "For all statistical analyses, the GraphPad Prism 7 software package was used (GraphPad Software)", while the Key Resources Table (p. 15) lists the single entry "GraphPad Prism (version 8.3.0(538))".
- p. 17 QUANTIFICATION AND STATISTICAL ANALYSIS
For all statistical analyses, the GraphPad Prism 7 software package was used (GraphPad Software).
- p. 15 Key Resources Table, Software and Algorithms
GraphPad Prism (version 8.3.0(538))
- p. 17 QUANTIFICATION AND STATISTICAL ANALYSIS
the GraphPad Prism 7 software package was used
- p. 17 Statistical analysis
GraphPad Prism 7 software package
Only the authors can say what is right here.
Judge's note: Read crop C021-a and full page extract/png/main-p017.png (the sentence reads exactly "For all statistical analyses, the GraphPad Prism 7 software package was used (GraphPad Software).") and crop C021-b with full page extract/png/main-p015.png (Software and Algorithms block lists one GraphPad entry, "GraphPad Prism (version 8.3.0(538))"). I searched the Method Details and the statistics section for any statement that two Prism versions were used (e.g. one for plotting, one for tests); there is none. The two statements about the same software version disagree; only the authors can say which is right.
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12 minor (typos and the like; most checked by the judge only)
Wording Discussion (p9) supports "critical for spread of several clinically relevant viruses, including influenza A viruses and coronaviruses" with seven references (Gierer et al., 2013; Glowacka et al., 2011; Iwata-Yoshikawa et al., 2019; Kawase et al., 2012; Matsuyama et al., 2010; Shulla et al., 2011; Zhou et al., 2015) whose reference-list titles all concern coronaviruses (one also filoviruses), none influenza A virus.
- p. 9 Discussion, TMPRSS2 paragraph
critical for spread of several clinically relevant viruses, including influenza A viruses and coronaviruses (Gierer et al., 2013; Glowacka et al., 2011; Iwata-Yoshikawa et al., 2019; Kawase et al., 2012; Matsuyama et al., 2010; Shulla et al., 2011; Zhou et al., 2015)
- p. 11 Reference list
Bertram, S., Glowacka, I., Blazejewska, P., ... (2010). TMPRSS2 and TMPRSS4 facilitate trypsin-independent spread of influenza virus in Caco-2 cells. J. Virol. 84, 10016–10025.
- p. 11 Reference list
Gierer, S., ... (2013). The spike protein of the emerging betacoronavirus EMC uses a novel coronavirus receptor for entry, can be activated by TMPRSS2, and is targeted by neutralizing antibodies.
Only the authors can say what is right here.
Judge's note: Read the full page image extract/png/main-p009.png for the sentence and the citation string, then each entry on extract/png/main-p011.png and extract/png/main-p012.png: Gierer 2013 (betacoronavirus EMC spike), Glowacka 2011 (SARS-coronavirus spike/TMPRSS2), Iwata-Yoshikawa 2019 (TMPRSS2 after coronavirus infection in mice), Kawase 2012 (SARS coronavirus entry), Matsuyama 2010 (SARS coronavirus spike activation by TMPRSS2), Shulla 2011 (SARS receptor-linked serine protease), Zhou 2015 ("Protease inhibitors targeting coronavirus and filovirus entry"). The list does contain influenza/TMPRSS2 entries not attached here, Bertram et al. 2010 (TMPRSS2 and TMPRSS4 facilitate trypsin-independent spread of influenza virus in Caco-2 cells) and Bertram et al. 2012 (Influenza and SARS-coronavirus activating proteases TMPRSS2 and HAT), the latter cited earlier in the same paragraph for a different point. The influenza half of the claim is thus left without a matching citation; only the authors can say which references were intended, so author_query at S3 rather than a substantive error.
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Typo Introduction (p3) prints "the disease, now termed coronavirus disease 19 (COVID-19) rapidly spread within China", expanding the acronym with "19" rather than "2019".
- p. 3 Introduction, second paragraph
the disease, now termed coronavirus disease 19 (COVID-19) rapidly spread within China
- p. 3 Introduction, second paragraph
now termed coronavirus dis-ease 19 (COVID-19)
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: that COVID-19 is the abbreviation of "coronavirus disease 2019" (WHO naming), which is not stated anywhere in the files. Verified the printed wording on crop C002-a (page 3): the line reads "and the disease, now termed coronavirus dis-ease 19 (COVID-19) rapidly spread within China", with the hyphen being only a line break; the digits printed are "19". Cosmetic as printed, so CONFIRMED_MINOR/S4.
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Typo Last paragraph of the Introduction (p4) prints the German conjunction: "SARS-S und SARS-2-S share ~76% amino acid identity."
- p. 4 Introduction, final paragraph (right column)
SARS-S und SARS-2-S share ~76% amino acid identity.
- p. 4 Introduction, last paragraph
SARS-S und SARS-2-S share
- p. 4 Introduction, last paragraph
SARS-S und SARS-2-S share 76% amino acid iden-
- p. 9 STAR Methods contents
EXPERIMANTAL MODEL AND SUBJECT DETAILS
Judge's note: Read crop C003-c and the full page extract/png/main-p004.png. The right column clearly prints "SARS-S und SARS-2-S share ~76% amino acid iden-tity" in an otherwise English sentence, so this is not a text-layer artefact. Evident fix ("and"), hence correction, S4. One reviewer also raised "EXPERIMANTAL" in this cluster; that misspelling is real (seen on crop C003-d, p9) but is adjudicated under C007.
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Typo Figure 1 legend (p4) states "gray arrow heads indicate bands corresponding to the S2 subunit", whereas in panel B the S2 bands are marked with unfilled (open/white) arrowheads beside the solid black arrowheads used for S0.
- p. 4 Figure 1 legend (B)
gray arrow heads indicate bands corresponding to the S2 subunit
Judge's note: Read crop C004-a for the legend text and the full page image extract/png/main-p004.png for panel B. In both blot panels two arrowheads sit at the right of the Spike bands: the upper one (S0, ~180/130 kDa) is solid black and the lower one (~90 kDa) is an outlined triangle with a light interior, i.e. open rather than gray-filled. At the available page resolution an open outline could loosely be described as "gray", so this is a cosmetic descriptive mismatch only; marked observation.
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Typo Results (p5) prints "authentic SARS-CoV-2 infected BHK-21 cells transfected to express ACE2 cells but not parental BHK-21 cells with high efficiency (Figure 3C)", with a stray second "cells" after ACE2.
- p. 5 Results, "SARS-CoV-2 Employs the SARS-CoV Receptor for Host Cell Entry"
authentic SARS-CoV-2 infected BHK-21 cells transfected to express ACE2 cells but not parental BHK-21 cells with high efficiency (Figure 3C)
- p. 5 Results, ACE2 section
transfected to express ACE2 cells but not parental BHK-21 cells
- p. 5
infected BHK-21 cells trans- fected to express ACE2 cells but not parental BHK-21 cells
Judge's note: Read crop C005-c, which shows the right column of page 5: "Finally, authentic SARS-CoV-2 infected BHK-21 cells trans-fected to express ACE2 cells but not parental BHK-21 cells with high efficiency (Figure 3C)". The duplicated word is printed, not an extraction artefact. Meaning is recoverable, so S4 with the evident fix of deleting the second "cells".
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Typo The STAR Methods heading is misspelled "EXPERIMANTAL MODEL AND SUBJECT DETAILS" both in the contents list (p9) and as the section heading (p15).
- p. 9 STAR+METHODS contents list
EXPERIMANTAL MODEL AND SUBJECT DETAILS
- p. 15 STAR Methods section heading
EXPERIMANTAL MODEL AND SUBJECT DETAILS
Judge's note: Read crop C003-d/C007-a context on page 9 (also checked full page extract/png/main-p009.png), where the bulleted contents list prints "EXPERIMANTAL MODEL AND SUBJECT DETAILS", and crop C007-b from page 15, where the red section heading prints the same misspelling above "Cell cultures, primary cells, viral strains". Printed in both places, not an OCR artefact; evident fix "EXPERIMENTAL".
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Typo The supplier of the anti-VSV-M antibody is capitalised two ways: "KeraFast" in the Key Resources Table (p13) and "Kerafast, EB0011" in the Method Details (p16).
- p. 13 Key resources
KeraFast
- p. 16 Methods
Kerafast, EB0011
Judge's note: Read the full Key Resources Table page extract/png/main-p013.png, where the row "Monoclonal anti-VSV-M (23H12) antibody | KeraFast | Cat.#: EB0011; RRID: AB_2734773" appears, and crop C010-b from page 16, which reads "mouse anti-VSV matrix protein (Kerafast, EB0011, 1:2,500)". Same reagent and catalogue number, two spellings of the company name; purely cosmetic, either capitalisation identifies the supplier.
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Typo Cell cultures section (p15) prints "cells were incubated in Dulbecco's' modified Eagle medium (PAN-Biotech)", with a doubled apostrophe.
- p. 15 Cell cultures, primary cells, viral strains
cells were incubated in Dulbecco's' modified Eagle medium (PAN-Biotech)
- p. 15 Cell cultures
Dulbecco’s’ modified Eagle medium
Judge's note: Read crop C007-b, which shows the same page-15 paragraph at high magnification: the line reads "kidney) cells were incubated in Dulbecco's' modified Eagle medium (PAN-Biotech)", with an apostrophe both inside and after "Dulbecco". Printed on the page, not an apostrophe-mapping artefact; evident fix.
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Typo Plasmids section (p16) prints "and cloned in into the pCG1 expression vector via BamHI and XbaI restriction sites", with a superfluous "in".
- p. 16 Method Details, Plasmids
and cloned in into the pCG1 expression vector via BamHI and XbaI restriction sites
- p. 16 Plasmids
cloned in into the pCG1 expression vector
Judge's note: Read crop C015-b, which shows the end of the Plasmids paragraph on page 16: "... (NCBI Reference Sequence: YP_009724390.1) and cloned in into the pCG1 expression vector via BamHI and XbaI restriction sites." The duplication is printed on the page, not a line-break artefact (the words sit together mid-line). Cosmetic, evident fix. (The same page also prints "diluted in in skim milk solution" and "an in in house-prepared" elsewhere, consistent with a copy-editing slip pattern.)
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Typo Page 16 immunoblotting paragraph contains three printed duplications of "in" plus a doubled closing parenthesis: "incubated over night at 4C with the primary antibody (diluted in in skim milk solution))", "with the secondary antibody (diluted in in skim milk solution)" and "imaged using an in in house-prepared enhanced chemiluminescent solution".
- p. 16 Method Details, Analysis of SARS-2-S expression and particle incorporation
incubated over night at 4C with the primary antibody (diluted in in skim milk solution))
- p. 16 Method Details, Analysis of SARS-2-S expression and particle incorporation
with the secondary antibody (diluted in in skim milk solution)
- p. 16 Method Details, Analysis of SARS-2-S expression and particle incorporation
imaged using an in in house-prepared enhanced chemiluminescent solution
- p. 16 Analysis of SARS-2-S expression, immunoblot
an in in house-prepared enhanced chemiluminescent solution
Judge's note: Read crops C016-a and C016-c and the full page image extract/png/main-p016.png. All three "in in" occurrences and the doubled ")" after "skim milk solution" are visible in the typeset page, so they are printed duplications, not extraction artefacts. Cosmetic copy-editing defects.
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Typo Page 16: "subjected to high-speed centrifugation (25.000 g for 120 min at 4C)" prints the centrifugal force with a period where the rest of the paper uses a comma as thousands separator ("5,000 iterations", "1:2,500", "1:2,000").
- p. 16 Method Details, Analysis of SARS-2-S expression and particle incorporation
subjected to high-speed centrifugation (25.000 g for 120 min at 4C)
- p. 16 Particle incorporation
25.000 g for 120 min
- p. 16 same section
1:2,500
Judge's note: Read crops C017-a and C017-c and the full page image extract/png/main-p016.png. The page plainly shows "25.000 g"; the same paragraph prints "1:2,500", "1:2,000" and "1:10000", and page 17 prints "5,000 iterations", so the period here is an inconsistent (European-style) thousands separator. In Cell's convention the period is the decimal point, so as printed the figure reads as 25 g, which conflicts with the label "high-speed centrifugation". A punctuation/separator defect rather than a wrong measurement, hence minor.
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Typo Figure S1 legend (p. 18): "The indicated cells lines were inoculated with pseudoparticles" - should read "cell lines".
- p. 18 Figure S1 legend
The indicated cells lines were inoculated with pseudoparticles
Judge's note: Read crop C022-a, which shows the typeset Figure S1 legend; "cells lines" is printed in the PDF, so it is not an extraction artefact. Cosmetic.
Second check: none (judge only)