SARS-CoV-2 D614G Variant Exhibits Enhanced Replication ex vivo and Earlier Transmission in vivo
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Abstract
The D614G substitution in the S protein is most prevalent SARS-CoV-2 strain circulating globally, but its effects in viral pathogenesis and transmission remain unclear. We engineered SARS-CoV-2 variants harboring the D614G substitution with or without nanoluciferase. The D614G variant replicates more efficiency in primary human proximal airway epithelial cells and is more fit than wildtype (WT) virus in competition studies. With similar morphology to the WT virion, the D614G virus is also more sensitive to SARS-CoV-2 neutralizing antibodies. Infection of human ACE2 transgenic mice and Syrian hamsters with the WT or D614G viruses produced similar titers in respiratory tissue and pulmonary disease. However, the D614G variant exhibited significantly faster droplet transmission between hamsters than the WT virus, early after infection. Our study demonstrated the SARS-CoV2 D614G substitution enhances infectivity, replication fitness, and early transmission.
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SciScore for 10.1101/2020.09.28.317685: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IACUC: hACE2 mice infection and titration: Mouse study was performed in accordance with Animal Care and Use Committee guidelines of the University of North Carolina at Chapel Hill. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable Syrian hamsters (females, 4-6 weeks old) were purchased from Envigo (Madison, WI) and allowed to acclimate for a minimal of three days at BSL-3 agriculture containment at the Influenza Research Institute (University of Wisconsin). Cell Line Authentication not detected. Table 2: Resources
Antibodies Sentences Resources Antibodies: Monoclonal SARS-CoV-2 RBD-binding neutralizing antibodies (nAb) … SciScore for 10.1101/2020.09.28.317685: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IACUC: hACE2 mice infection and titration: Mouse study was performed in accordance with Animal Care and Use Committee guidelines of the University of North Carolina at Chapel Hill. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable Syrian hamsters (females, 4-6 weeks old) were purchased from Envigo (Madison, WI) and allowed to acclimate for a minimal of three days at BSL-3 agriculture containment at the Influenza Research Institute (University of Wisconsin). Cell Line Authentication not detected. Table 2: Resources
Antibodies Sentences Resources Antibodies: Monoclonal SARS-CoV-2 RBD-binding neutralizing antibodies (nAb) B38 and H4 were synthesized at UNC Protein Expression and Purification core based on previously reported protein sequences (27). H4suggested: NonePolyclonal antibodies targeting the SARS-CoV N protein PA1-41098 and ANT-180 were purchased from Invitrogen and Prospec, respectively. ANT-180suggested: NoneThe SARS-CoV-2 N antigen was stained with polyclonal rabbit anti-SARS-CoV N protein (Invitrogen PA1-41098, 0.5 ug/mL),and using species-specific secondary antibodies as previously described (4). anti-SARS-CoV N proteinsuggested: (Rockland Cat# 200-401-A50, RRID:AB_828403)To detect SARS-CoV-2 Nucleocapsid protein in immunohistochemistry (IHC), tissue sections were incubated with a rabbit polyclonal antibody (Prospec, ANT-180) as the primary antibodies, and peroxidase-labeled polymer-conjugated anti-rabbit immunoglobulin (EnVision/HRP, DAKO) as the secondary antibody. anti-rabbit immunoglobulin (EnVision/HRPsuggested: NoneExperimental Models: Cell Lines Sentences Resources Cells and viruses: Simian kidney cell lines Vero-81 (ATCC # CCL81), Vero-E6 (ATCC # CRL1586) were maintained in Eagle’s Minimum Essential Medium (Gibco) supplemented with 10% fetal calf serum (FBS, Hyclone). Vero-81suggested: NoneVero-E6suggested: NoneHuh7 and A549-ACE2 cells were maintained in Dulbecco’s Modified Eagle Medium (Gibco) with 10% FBS. A549-ACE2suggested: NoneA clonal A549-ACE2 stable cell line was generated by overexpressing human ACE2 in the A549 cell line (ATCC # CCL185) using the Sleeping Beauty Transposon system. A549suggested: NoneAll viral infections were performed under biosafety level 3 (BSL-3) conditions at negative pressure, and Tyvek suits connected with personal powered-air purifying respirators. nLuc virus entry assay: Monolayers of Vero-E6, Vero-81, A549-ACE2 and Huh7 cells were cultured in black-walled 96-well plates (Corning 3904) overnight. Huh7suggested: Noneneutralization assay: Vero E6 cells were plated at 20,000 cells per well in black-walled 96-well plates (Corning 3904) Vero E6suggested: NoneExperimental Models: Organisms/Strains Sentences Resources Serum samples collected from BALB/c mice vaccinated with WA1 spike protein (D-form) were generated in our laboratory previously (4, BALB/csuggested: RRID:IMSR_ORNL:BALB/cRl)HFH4-hACE2 transgenic mice were bred and maintained at UNC. HFH4-hACE2suggested: NoneSoftware and Algorithms Sentences Resources ImageJ was used to measure the relative apical culture surface covered by multiciliated cells. ImageJsuggested: (ImageJ, RRID:SCR_003070)Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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SciScore for 10.1101/2020.09.28.317685: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar …
SciScore for 10.1101/2020.09.28.317685: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
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