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Cited by 671SARS-CoV-2 and COVID-19 ResearchRNA Interference and Gene DeliverySARS-CoV-2 detection and testing

A thermostable mRNA vaccine against COVID-19

Open access
Zhang, Na-Na, Li, Xiao-Feng, Deng, Yong-Qiang, Zhao, Hui, Huang, Yi-Jiao, Yang, Guan, Huang, Wei-Jin, Gao, Peng +23 more·2020·Cell
DOI 10.1016/j.cell.2020.07.024PMC PMC7377714
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Abstract

There is an urgent need for vaccines against coronavirus disease 2019 (COVID-19) because of the ongoing SARS-CoV-2 pandemic. Among all approaches, a messenger RNA (mRNA)-based vaccine has emerged as a rapid and versatile platform to quickly respond to this challenge. Here, we developed a lipid nanoparticle-encapsulated mRNA (mRNA-LNP) encoding the receptor binding domain (RBD) of SARS-CoV-2 as a vaccine candidate (called ARCoV). Intramuscular immunization of ARCoV mRNA-LNP elicited robust neutralizing antibodies against SARS-CoV-2 as well as a Th1-biased cellular response in mice and non-human primates. Two doses of ARCoV immunization in mice conferred complete protection against the challenge of a SARS-CoV-2 mouse-adapted strain. Additionally, ARCoV is manufactured as a liquid formulation and can be stored at room temperature for at least 1 week. ARCoV is currently being evaluated in phase 1 clinical trials.

AI snapshot

Written from the paper’s full text.

TL;DR

ARCoV is a lipid nanoparticle-encapsulated mRNA vaccine encoding the SARS-CoV-2 receptor-binding domain (RBD). In mice and cynomolgus macaques it induced neutralizing antibodies and Th1-biased cellular responses, and two doses fully protected mice against a mouse-adapted SARS-CoV-2 challenge.

Key findings

  • ARCoV mRNA-LNP had an average particle size of 88.85 nm with more than 95% encapsulation; it was stable at 4°C and 25°C for at least 7 days, and storage at 37°C for 7 days caused only an ∼13% reduction in relative photon flux.
  • Two-dose mouse immunization with 2 or 10 μg ARCoV produced NT50 titers of ∼1/2,540 and ∼1/7,079 and PRNT50 titers of ∼1/2,194 and ∼1/5,704 at day 28; sera cross-neutralized three epidemic SARS-CoV-2 strains.
  • Two doses of 2 or 10 μg ARCoV fully protected mice against intranasal MASCp6 challenge: no measurable viral RNA in lungs or trachea, whereas placebo mice had ∼10^9 and 10^7 RNA copy equivalents per gram, respectively; PRNT50 correlated inversely with lung viral RNA (R² = 0.8419, p < 0.0001), with a cutoff of ∼1:1,009 PRNT50 for full protection.
  • In cynomolgus macaques, two doses of 100 or 1,000 μg ARCoV induced IgG titers of ∼1/5,210 and ∼1/22,085 and NT50 titers of ∼1/699 and ∼1/6,482 on day 28; IFN-γ ELISPOT responses were stimulated, with no significant IL-4+/CD4+ difference, and 1,000 μg did not cause obvious adverse effects.

Methods

  • mRNA encoding SARS-CoV-2 RBD (amino acids 319–541) was encapsulated in LNPs; formulations were characterized by dynamic light scattering, cryo-TEM, in vitro expression, ACE2 binding, and pseudovirus inhibition assays.
  • Mouse studies used BALB/c and ICR mice with single or two-dose intramuscular immunization (2, 10, or 30 μg); challenge used mouse-adapted SARS-CoV-2 MASCp6 at 6,000 PFU intranasally, followed by viral RNA qRT-PCR, histopathology, ISH, immunostaining, ELISPOT, and flow cytometry.
  • Non-human primate studies used 30 cynomolgus macaques immunized intramuscularly with 100 or 1,000 μg ARCoV or PBS and boosted at 14 days; antibody responses were measured by ELISA, pseudovirus neutralization, and PRNT, with IFN-γ and IL-4 assays. Thermostability was assessed using FLuc reporter mRNA-LNP stored at 4°C, 25°C, or 37°C for 1, 4, and 7 days before bioluminescence imaging in mice.

Limitations

  • The paper states that challenge experiments used a mouse-adapted SARS-CoV-2 strain, so further challenge experiments with wild-type SARS-CoV-2 in transgenic ACE2 mice or non-human primates are needed.
  • The paper states that the duration of neutralizing antibodies induced by ARCoV has yet to be determined, long-term immune responses and human effectiveness require future studies, and long-term stability assays with clinical-grade ARCoV are under investigation.
  • Evident from the text: no human efficacy or safety data are reported, and ARCoV was only entering phase 1 trials; non-human primate protection efficacy data were not obtained because of biosafety facility limitations, and investigators were not blinded to allocation or outcome assessment except for RT-qPCR.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.cell.2020.07.024

Cites

54 of 54 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

16 of 29 cited sources checked · 8 supported · 0 flagged · accuracy not yet measured

  • Findingcitation

    RBD protein expressed from mRNA functionally inhibited entry of a VSV-based pseudovirus expressing the SARS-CoV-2 S protein in Huh7 cells.

    “and functionally inhibited entry of a vesicular stomatitis virus (VSV)-based pseudovirus expressing the SARS-CoV-2 S protein (Nie et al., 2020) in Huh7 cells (Figure 1D).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Nie et al., 2020 source
  • Premisecitation

    S-specific IgG antibodies have been suggested to cause acute pulmonary injury in vaccine challenge animal models of SARS-CoV.

    “S-specific IgG antibodies have been suggested to cause acute pulmonary injury in vaccine challenge animal models of SARS-CoV (Liu et al., 2019)”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Liu et al., 2019 source
  • Interpretationcitation

    Protective immunity can be expected in most macaques immunized with two doses of ARCoV.

    “protective immunity can be expected in most macaques immunized with two doses of ARCoV.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Gao et al., 2020 source

      The paper’s account of the macaque challenge study (Abstract; Fig. 3) reports that vaccinated animals were largely protected. But it tested PiCoVacc given three times, not ARCoV given twice, so it does not support the claimed vaccine or dosing schedule. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
    • cites Yu et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Premisecitation

    Antibodies targeting the SARS-CoV-2 RBD at various concentrations did not induce ADE infection in a recent in vitro study.

    “A recent in vitro study also suggests that antibodies targeting the SARS-CoV-2 RBD at various concentrations did not induce ADE infection (Quinlan et al., 2020).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Quinlan et al., 2020 source
  • Findingown data

    Intramuscular immunization of ARCoV mRNA-LNP elicited a Th1-biased cellular response in mice and non-human primates.

    “Intramuscular immunization of ARCoV mRNA-LNP elicited robust neutralizing antibodies against SARS-CoV-2 as well as a Th1-biased cellular response in mice and non-human primates.”
    Quote in the paperSubstantial claim
  • May combine two claims. 27
  • Classified as probably not a substantial claim. 24
  • The quote only partly states this claim. 4

  • May combine two claims.

    Premisecitation

    The full-length S protein, S1, and RBD of SARS-CoV-2 are capable of inducing highly potent neutralizing antibodies and T cell-mediated immunity and have been widely selected as promising targets for coronavirus vaccine development.

    “The full-length S protein, S1, and RBD are capable of inducing highly potent neutralizing antibodies and T cell-mediated immunity and, therefore, have been widely selected as promising targets for coronavirus vaccine development (Amanat and Krammer, 2020).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Amanat and Krammer, 2020 source

      In “What Do We Know about Betacoronavirus Vaccine Design?” (page unavailable), the paper calls the S protein an ideal vaccine target and says spike-targeting antibodies can neutralize SARS-CoV-2. Its Figure 1 caption identifies the RBD as a main target of neutralizing antibodies, and “The Current Pipeline for SARS-CoV-2 Vaccines” lists multiple S-focused candidates. The copy does not establish that full-length S, S1, and RBD each induce highly potent neutralizing antibodies and T-cell-mediated immunity, or that S1 and RBD were each widely selected as vaccine targets. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    mRNA-based therapy is an effective platform for treatment of infectious diseases and cancer.

    “Messenger RNA (mRNA)-based therapy recently emerged as an effective platform for treatment of infectious diseases and cancer (Jackson et al., 2020; Mascola and Fauci, 2020).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Jackson et al., 2020 source

      The Introduction describes mRNA vaccines as a platform for preventing infectious diseases, but says clinical efficacy and safety remain to be proven. The Summary likewise describes potential advantages rather than established effectiveness. These passages do not support the claim that mRNA therapy is already effective for treating infectious diseases or cancer; the paper does not address cancer treatment. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites Mascola and Fauci, 2020 source

      The Influenza section reports that mRNA vaccines produced robust antibody responses in two phase I trials and describes their potential as a platform against infectious agents. It does not address cancer or establish mRNA-based therapy as an effective treatment for either cancer or infectious disease; its evidence concerns vaccination, and its broader conclusion is prospective. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The SARS-CoV-2 S protein mediates viral entry into host cells by binding to ACE2 through the RBD at the C terminus of the S1 subunit, subsequently causing fusion between the viral envelope and host cell membrane through the S2 subunit.

    “First, the S protein mediates viral entry into host cells by binding to its receptor, angiotensin-converting enzyme 2 (ACE2), through the receptor-binding domain (RBD) at the C terminus of the S1 subunit, which subsequently causes fusion between the viral envelope and the host cell membrane through the S2 subunit (Hoffmann et al., 2020).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Hoffmann et al., 2020 source

      The Results section (‘SARS-CoV-2 Employs the SARS-CoV Receptor for Host Cell Entry’; page unavailable) identifies ACE2 as the receptor and the receptor-binding motif within the RBD as contacting ACE2. The Introduction (page unavailable) says S1 mediates receptor binding and S2 drives membrane fusion after protease priming. Our copy does not state that the RBD is at the C terminus of S1. (LLM, conf=0.85)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Immunization with recombinant RBD of SARS-CoV-2 induced high titers of neutralizing antibodies in the absence of antibody-dependent enhancement (ADE) of infection.

    “Some recent studies also demonstrated that immunization with the recombinant RBD of SARS-CoV-2 induced high titers of neutralizing antibodies in the absence of antibody-dependent enhancement (ADE) of infection (Quinlan et al., 2020; Tai et al., 2020).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Quinlan et al., 2020 source
    • cites Tai et al., 2020 source

      The Results and discussion report that sera from mice immunized with SARS-CoV RBD neutralized SARS-CoV-2 pseudovirus, with a neutralizing antibody titer of 1:323. They do not report immunization with SARS-CoV-2 RBD or assess antibody-dependent enhancement (ADE), so those parts of the claim are unsupported. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Two or three doses of inactivated SARS-CoV-2 virus vaccine could induce neutralizing antibodies at levels of ∼1/50, which provides full protection against SARS-CoV-2 in rhesus macaques.

    “It has been reported that two or three doses of inactivated SARS-CoV-2 virus vaccine could induce neutralizing antibodies at levels of ∼1/50, which provides full protection against SARS-CoV-2 in rhesus macaques (Gao et al., 2020).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Gao et al., 2020 source

      The macaque challenge results report neutralizing-antibody titers of about 50 after three doses, but do not establish protection after two doses. The Abstract distinguishes partial protection at the 3 μg dose from complete protection at the 6 μg dose; it does not show that a titer of about 50 itself provides full protection. (LLM, conf=0.92)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationcitation

    Compared with full-length S protein, RBD antigen may induce fewer non-neutralizing antibodies, lowering the risk of potential ADE of SARS-CoV-2 infection.

    “Compared with the full-length S protein, RBD antigen may induce fewer non-neutralizing antibodies, lowering the risk of potential ADE of SARS-CoV-2 infection”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Olsen et al., 1992 source
    • cites Quinlan et al., 2020 source

  • May combine two claims.

    Findingcitation

    LNPs stimulated massive infiltration of monocytes and macrophages, which functioned as adjuvants.

    “and LNPs also stimulated massive infiltration of monocytes and macrophages, which functioned as adjuvants, as described previously (Maugeri et al., 2019).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Maugeri et al., 2019 source

      The Results section, “Expression of inflammatory cytokines against systemic delivery of EVs and LNPs” (page not provided), reports that injected LNPs elicited inflammatory cytokines in mice. It does not report massive infiltration of monocytes or macrophages, or show that those cells functioned as adjuvants. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The expression pattern was similar to results from other LNP formulations.

    “which was similar to the results from other LNP formulations (Bahl et al., 2017; Pardi et al., 2015).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Bahl et al., 2017 source
    • cites Pardi et al., 2015 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Experience from other human coronaviruses has indicated the possibility of re-infection because of a waning antibody response.

    “Experience from other human coronaviruses has indicated the possibility of re-infection because of a waning antibody response (Callow et al., 1990; Wu et al., 2007).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Callow et al., 1990 source
    • cites Wu et al., 2007

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingown data

    Transfection of RBD-encoding mRNA in multiple cell lines (HeLa, Huh7, HEK293T, and Vero) resulted in high expression of recombinant RBD in culture supernatants, with up to 917.4 ng/mL of RBD in mRNA-transfected HEK293F cells.

    “Transfection of the RBD-encoding mRNA in multiple cell lines (HeLa, Huh7, HEK293T, and Vero) resulted in high expression of recombinant RBD in culture supernatants (Figure 1B), with up to 917.4 ng/mL of RBD in mRNA-transfected HEK293F cells (Figure S2 A).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    ARCoV is manufactured as a liquid formulation and can be stored at room temperature for at least 1 week.

    “Additionally, ARCoV is manufactured as a liquid formulation and can be stored at room temperature for at least 1 week.”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Findingown data

    Booster immunization with ARCoV increased IgG titers to approximately 1/5,210 and 1/22,085 on day 28 after initial immunization in monkeys receiving low or high dose.

    “the booster immunization resulted in a notable increase in IgG titers to ∼1/5,210 and ∼1/22,085 on day 28 after initial immunization (Figure 7B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Sera from all ARCoV vaccinated mice showed a similar neutralizing capability against all three SARS-CoV-2 epidemic strains, with no significant difference in PRNT50 titers.

    “As expected, sera from all ARCoV vaccinated mice showed a similar neutralizing capability against all three SARS-CoV-2 epidemic strains, and there was no significant difference in PRNT50 titers (Figure 3E).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Mice vaccinated with 2 μg of ARCoV showed partial protection; viral RNA levels in the trachea only had an approximately 10-fold reduction compared with mice immunized with placebo LNPs.

    “Mice vaccinated with 2 μg of ARCoV showed partial protection; viral RNA levels in the trachea only had an approximately 10-fold reduction compared with mice immunized with placebo LNPs.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    Two doses of ARCoV completely blocked viral replication in the lungs and trachea and prevented pulmonary pathology in mice challenged with MASCp6.

    “two doses of immunization of ARCoV completely blocked viral replication in the lungs and trachea and prevented pulmonary pathology in mice (Figure 5).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gu et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • The quote only partly states this claim.

    Findingown data

    There was no reduction in FLuc expression between groups after storage of FLuc reporter mRNA-LNP at different temperatures for 1, 4, and 7 days.

    “there was no reduction in FLuc expression between all groups”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The final stock of ARCoV, manufactured under GMP conditions, had an average particle size of 88.85 nm and more than 95% encapsulation.

    “The final stock of SARS-CoV-2 RBD encoding mRNA-LNP (ARCoV), manufactured under good manufacturing practice (GMP) conditions, showed an average particle size of 88.85 nm (Figure 1F) with more than 95% encapsulation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    ISH assay detected SARS-CoV-2-specific RNA in placebo mice but no viral RNA in lung sections from all ARCoV-vaccinated animals.

    “Similarly, an ISH assay by RNAScope also detected SARS-CoV-2-specific RNA in placebo mice but no viral RNA in lung sections from all ARCoV-vaccinated animals (Figure 5D).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The mRNA-encoded RBD protein can be recognized by a panel of monoclonal antibodies against SARS-CoV-2 RBD and by convalescent sera from three COVID-19 patients.

    “Immunostaining further demonstrated that this RBD protein can be recognized by a panel of monoclonal antibodies (mAbs) against SARS-CoV-2 RBD (Figure S2B) as well as convalescent sera from three COVID-19 patients (Figure 1E).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Ex vivo imaging analysis showed that the liver was the most abundant RBD-expressing tissue, and a slightly luminescent signal was also detected in the spleen and muscle tissues.

    “Further ex vivo imaging analysis of ARCoV-immunized BALB/c mice showed that the liver was the most abundant RBD-expressing tissue, and a slightly luminescent signal was also detected in the spleen and muscle tissues (Figure 2B).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Mice vaccinated with empty LNPs developed typical lung lesions characterized by denatured epithelial tissues, thickened alveolar septa, and activated inflammatory cell infiltration, whereas no such pathological changes were seen in lung sections from all ARCoV-immunized animals.

    “More importantly, mice vaccinated with empty LNPs developed typical lung lesions characterized by denatured epithelial tissues, thickened alveolar septa, and activated inflammatory cell infiltration, whereas no such pathological changes were seen in lung sections from all ARCoV-immunized animals (Figure 5E).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    A second immunization with 2 or 10 μg of ARCoV mRNA-LNP resulted in rapid elevation of IgG and neutralizing antibodies in mice, whereas no SARS-CoV-2-specific IgG and neutralizing antibodies were detected in sera from mice vaccinated with empty LNPs.

    “Remarkably, a second immunization with 2 or 10 μg of ARCoV mRNA-LNP resulted in rapid elevation of immunoglobulin G (IgG) and neutralizing antibodies in mice (Figures 3B–3D), whereas no SARS-CoV-2-specific IgG and neutralizing antibodies were detected in sera from mice vaccinated with empty LNPs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Following immunization, no local inflammation response at the injection site or other adverse effects were observed during the observation period.

    “Following immunization, no local inflammation response at the injection site or other adverse effects were observed during the observation period.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Cryo-TEM analysis showed that ARCoV particles exhibit homogeneous morphologies of solid spheres that lack an aqueous core, demonstrating a key difference between RNA-loaded LNPs and conventional liposomes.

    “Cryo-transmission electron microscopy (TEM) analysis showed that ARCoV particles exhibit homogeneous morphologies of solid spheres that lack an aqueous core (Figure 1G), which demonstrates a key difference between RNA-loaded LNPs and conventional liposomes.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Subcutaneous injection led to robust FLuc expression in the upper abdomen, whereas no signal was detected in mice receiving intranasal inoculation.

    “Subcutaneous (s.c.) injection also led to robust FLuc expression in the upper abdomen, whereas no signal was detected in mice receiving intranasal (i.n.) inoculation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    All mice vaccinated with 30 μg of ARCoV mRNA-LNP showed markedly reduced levels of viral RNAs in the lungs (>1,000-fold) and virtually no detectable viral RNA in the trachea.

    “All mice vaccinated with 30 μg of ARCoV mRNA-LNP showed markedly reduced levels of viral RNAs in the lungs (>1,000-fold) and virtually no detectable viral RNA in the trachea (Figures S5C and S5D).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    A single immunization with ARCoV mRNA-LNP (2 and 30 μg) induced production of SARS-CoV-2 RBD-specific IgG antibodies and neutralizing antibodies.

    “A single immunization with ARCoV mRNA-LNP (2 and 30 μg) induced production of SARS-CoV-2 RBD-specific IgG antibodies (Figure S5 A) and neutralizing antibodies with 50% neutralization titer (NT50) approached ∼1/278 and ∼1/559 28 days after immunization (Figure S5B)”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Preclinical studies have demonstrated that mRNA-based vaccines induce potent and broadly protective immune responses against various pathogens in small and large animals, with an acceptable safety profile.

    “Preclinical studies have demonstrated that mRNA-based vaccines induce potent and broadly protective immune responses against various pathogens in small and large animals, with an acceptable safety profile (Maruggi et al., 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Maruggi et al., 2019 source

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    None of the mRNA vaccines against COVID-19 at the clinical stage have been evaluated in animal models; the mechanisms of mRNA vaccines against COVID-19 are unclear, and their effectiveness has yet to be proven.

    “However, none of these mRNA vaccines at the clinical stage have been evaluated in animal models; the mechanisms of mRNA vaccines against COVID-19 are unclear, and their effectiveness has yet to be proven (Jiang, 2020).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jiang, 2020 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Lipid nanoparticles (LNPs) are one of the most appealing and commonly used mRNA delivery tools.

    “Lipid nanoparticles (LNPs) are one of the most appealing and commonly used mRNA delivery tools (Ickenstein and Garidel, 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Ickenstein and Garidel, 2019 source

  • Classified as probably not a substantial claim.

    Study design and conductown data

    To exclude a potential effect of the N501Y mutation on the antibody response, neutralizing antibody titers of mouse sera from ARCoV-immunized mice were compared against MASCp6 and wild-type SARS-CoV-2 strain 131.

    “To exclude a potential effect of the N501Y mutation on the antibody response, we also compared neutralizing antibody titers of mouse sera from ARCoV-immunized mice against MASCp6 and wild-type SARS-CoV-2 strain 131, respectively.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The final stock of ARCoV was manufactured under good manufacturing practice (GMP) conditions.

    “manufactured under good manufacturing practice (GMP) conditions”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data

    Empty LNPs were used as a placebo in immunization experiments.

    “empty LNPs were used as a placebo.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Two doses of ARCoV vaccination completely prevent SARS-CoV-2 replication in the lower respiratory tract and protect mice from lung lesions.

    “These results demonstrate that two doses of ARCoV vaccination completely prevent SARS-CoV-2 replication in the lower respiratory tract and protect mice from lung lesions.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    In the aforementioned studies, all animals exhibited anamnestic antibody responses following challenge, suggesting that vaccine protection was probably not sterilizing.

    “In the aforementioned studies, all animals exhibited anamnestic antibody responses following challenge, suggesting that vaccine protection was probably not sterilizing”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Two doses of immunization with a DNA vaccine candidate elicits mean neutralization titers between ∼1/70 and ∼1/170 in rhesus macaques.

    “A recent report showed that two doses of immunization with a DNA vaccine candidate elicits mean neutralization titers between ∼1/70 and ∼1/170 in rhesus macaques (Yu et al., 2020).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Yu et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationown data

    The mRNA-LNP formulations have the capability to deliver mRNA in vivo and recruit antigen-presenting cells to process the expressed antigens.

    “These results highlight the capability of our mRNA-LNP formulations to deliver mRNA in vivo and recruit antigen-presenting cells to process the expressed antigens.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A yellow fever mRNA vaccine delivered by LNP was mainly expressed at the injection site as well as in draining lymph nodes in cynomolgus macaques.

    “A recent study has shown that a yellow fever mRNA vaccine delivered by LNP was mainly expressed at the injection site as well as in draining lymph nodes in cynomolgus macaques (Lindsay et al., 2019).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Lindsay et al., 2019 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The duration of neutralizing antibodies induced by ARCoV has yet to be determined.

    “Another limitation of our study is that the duration of neutralizing antibodies induced by ARCoV has yet to be determined.”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Interpretationown data

    The ARCoV mRNA LNP formulation is safe.

    “highlighting the safety of our mRNA LNP formulation.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Convalescent sera were collected from COVID-19 patients from the 5th Medical Center of Chinese PLA General Hospital with written informed consent.

    “Convalescent sera were collected from COVID-19 patients from the 5th Medical Center of Chinese PLA General Hospital with written informed consent.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All experiments involving infectious SARS-CoV-2 were performed under Biosafety Level 3 facilities in AMMS.

    “All experiments involving infectious SARS-CoV-2 were performed under Biosafety Level 3 facilities in AMMS.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All animal procedures were reviewed and approved by the Animal Experiment Committee of Laboratory Animal Center, Academy of Military Medical Sciences (AMMS), China (Assurance Number: IACUC-DWZX-2020-001).

    “All animal procedures were reviewed and approved by the Animal Experiment Committee of Laboratory Animal Center, Academy of Military Medical Sciences (AMMS), China (Assurance Number: IACUC-DWZX-2020-001).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All formulations were tested for particle size, distribution, RNA concentration and encapsulation.

    “All formulations were tested for particle size, distribution, RNA concentration and encapsulation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The investigators were not blinded to allocation during experiments and outcome assessment unless indicated (RT-qPCR).

    “The investigators were not blinded to allocation during experiments and outcome assessment unless indicated (RT-qPCR).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

    Study design and conductnone given

    Twenty female ICR mice were randomly divided into two groups of ten for the in vivo RBD expression experiment.

    “Twenty mice were randomly divided into two groups (n = 10/group).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    No statistical methods were used to predetermine sample size, unless indicated.

    “No statistical methods were used to predetermine sample size, unless indicated.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All animal studies were performed in strict accordance with the guidelines set by the Chinese Regulations of Laboratory Animals and Laboratory Animal-Requirements of Environment and Housing Facilities.

    “All animal studies were performed in strict accordance with the guidelines set by the Chinese Regulations of Laboratory Animals and Laboratory Animal-Requirements of Environment and Housing Facilities.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The SARS-CoV-2 challenge model based on the mouse adapted strain MASCp6 has been characterized in detail.

    “The SARS-CoV-2 challenge model based on the mouse adapted strain MASCp6 has been characterized in detail (Gu et al., 2020).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Gu et al., 2020

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

49 of 49

  • The paper relies on this without support.

    Animal model results (immunogenicity and protection in mice) are predictive of clinical outcomes in humans.

    “which supports further clinical development in humans.”

  • The paper relies on this without support.

    The FLuc reporter mRNA-LNP formulation is representative of the ARCoV mRNA-LNP vaccine for assessing thermostability.

    “The thermal stability of the ARCoV mRNA-LNP vaccine was evaluated using the FLuc reporter mRNA-LNP formulation.”

  • The paper relies on this without support.

    No prior report exists that an mRNA vaccine can protect animals from SARS-CoV-2 infection or identify an immune correlate of protection.

    “there is no report that an mRNA vaccine can protect animals from SARS-CoV-2 infection or the immune correlate of protection.”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Conflicting placebo for the macaque study

    Major

    The results say the macaque placebo group received PBS, whereas the methods say its placebo was empty LNPs.

  • Conflicting sample size for the two-dose 10 μg mouse group

    Minor

    The Figure 3 caption lists eight mice in the 10 μg group, while the methods list five mice for the same two-dose group.

2 of 2

Cites

Flagged first, then by citations

4 of the 58 references couldn’t be matched to a known paper.

Cited by

Sorted by citations

Related

Authors
Zhang, N.-N., Li, X.-F., Deng, Y.-Q., Zhao, H., Huang, Y.-J., Yang, G., Huang, W.-J., Gao, P., Zhou, C., Zhang, R.-R., Guo, Y., Sun, S.-H., Fan, H., Zu, S.-L., Chen, Q., He, Q., Cao, T.-S., Huang, X.-Y., Qiu, H.-Y., Nie, J.-H., Jiang, Y., Yan, H.-Y., Ye, Q., Zhong, X., Xue, X.-L., Zha, Z.-Y., Zhou, D., Yang, X., Wang, Y.-C., Ying, B., & Qin, C.-F.
Affiliations
  • Academy of Military Medical Sciences (CN)
  • Beijing Proteome Research Center (CN)
  • National Institutes for Food and Drug Control (CN)
Corresponding author
  • Wang, You-Chun
  • Ying, Bo
  • Qin, Cheng-Feng
ORCID
Venue
Cell
Publisher
Elsevier BV
Published
2020-09
Volume
182
Issue
5
Pages
1271-1283.e16
ISSN
0092-8674 (ISSN-L)
DOI
10.1016/j.cell.2020.07.024
PMC
PMC7377714
OpenAlex
W3043991892
Semantic Scholar
89744e35b95d0e269d46e1bf2f3d7c3b72d73e37
Cited by
671
References
58
Citations by year
2026: 35 · 2025: 66 · 2024: 95 · 2023: 110 · 2022: 150 · 2021: 183 · 2020: 32
FWCI
14.54
Type
journal article
Language
en
Open access
Licence
Locations
  • Cell (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (submittedVersion)
Funders
  • National Natural Science Foundation of China
  • National Key Research and Development Program of China Stem Cell and Translational Research
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › RNA Interference and Gene Delivery
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 detection and testing
Keywords
COVID-19 vaccines, SARS-CoV-2, mRNA vaccines, lipid nanoparticle encapsulation, receptor binding domain, neutralizing antibodies, intramuscular vaccination, non-human primates, room temperature storage
MeSH terms
Immunogenicity, Vaccine, COVID-19 Vaccines, Animals, Binding Sites, Chlorocebus aethiops, Female, HeLa Cells, Humans, Injections, Intramuscular, Macaca fascicularis, Male, Mice, Inbred ICR, RNA, Messenger, RNA, Viral, Vaccines, Synthetic, Vero Cells, Viral Vaccines, Coronavirus Infections, Th1 Cells, Mice, Nanoparticles, Antibodies, Neutralizing, HEK293 Cells, Vaccine Potency, Spike Glycoprotein, Coronavirus

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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