Rescue of SARS-CoV-2 from a Single Bacterial Artificial Chromosome

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Abstract

The pandemic coronavirus (CoV) disease 2019 (COVID-19) caused by severe acute respiratory syndrome CoV-2 (SARS-CoV-2) is a major threat to global human health. To date, there are no approved prophylactics or therapeutics available for COVID-19. Reverse genetics is a powerful approach to understand factors involved in viral pathogenesis, antiviral screening, and vaccine development. In this study, we describe the feasibility of generating recombinant SARS-CoV-2 (rSARS-CoV-2) by transfection of a single bacterial artificial chromosome (BAC). Importantly, rSARS-CoV-2 possesses the same phenotype as the natural isolate in vitro and in vivo . This is the first description of a BAC-based reverse genetics system for SARS-CoV-2 and the first time that an rSARS-CoV-2 isolate has been shown to be phenotypically identical to a natural isolate in a validated animal model of SARS-CoV-2 infection. The BAC-based reverse genetics approach will facilitate the study of SARS-CoV-2 and the development of prophylactics and therapeutics for the treatment of COVID-19.

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  1. SciScore for 10.1101/2020.07.22.216358: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIACUC: Biosafety (IBC) and Animal Care and Use (IACUC) committees.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablePathogenicity studies in golden Syrian hamsters: Twelve-week-old female golden Syrian hamsters were purchased from Charles River and maintained in the animal facility at Texas Biomed under specific pathogen-free conditions.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Cells were incubated overnight with 1 μg/ml of a SARS-CoV cross-reactive N monoclonal antibody 1C7 at 4°C, washed with PBS, and stained with a FITC-labeled goat anti-mouse IgG (1:200).
    anti-mouse IgG
    suggested: None
    Then, cells were blocked with 2.5% bovine serum albumin (BSA) in PBS for 1 h at 37 °C, followed by incubation with 1 µg/ml of the anti-N SARS-CoV monoclonal antibody 1C7 diluted in 1% BSA for 1 h at 37 °C.
    anti-N SARS-CoV
    suggested: (MyBioSource Cat# MBS432038, RRID:AB_2184133)
    Experimental Models: Cell Lines
    SentencesResources
    Briefly, confluent monolayers of Vero E6 cells (106 cells/well, 6-well plates, triplicates) were transfected, using LPF2000, with 4.0 μg/well of SARS-CoV-2 BAC, or empty BAC as internal control.
    Vero E6
    suggested: RRID:CVCL_XD71)
    Software and Algorithms
    SentencesResources
    Raw reads were quality filtered using Trimmomatic v0.39 (32) and mapped to a SARS-CoV-2 reference genome (Genbank Accession No. MN985325) with Bowtie2 v2.4.1 (33)
    Trimmomatic
    suggested: (Trimmomatic, RRID:SCR_011848)
    Bowtie2
    suggested: (Bowtie 2, RRID:SCR_016368)
    We genotyped each sample for low frequency variants with LoFreq* v2.1.3.1 (35) and filtered sites with less than 100x read depth or minor allele frequencies less than 1%.
    LoFreq*
    suggested: None
    Finally, we used SnpEff v4.3t (36) to identify the impact of potential variants on the protein coding regions in the SARS-CoV-2 reference genome.
    SnpEff
    suggested: (SnpEff, RRID:SCR_005191)
    After incubation with the primary antibody, cells were washed three times with PBS, counterstained with the Vectastain ABC kit, and developed using the DAB Peroxidase Substrate kit (Vector Laboratory, Inc, CA, USA) according to the manufacturers’ instructions.
    Vector Laboratory
    suggested: None
    Evaluation of lung pathological lesions: Macroscopic pathology scoring was evaluated using ImageJ software to determine the percent of the total surface area of the lung (dorsal and ventral view) affected by consolidation, congestion, and atelectasis, as previously described (38).
    ImageJ
    suggested: (ImageJ, RRID:SCR_003070)

    Results from OddPub: Thank you for sharing your data.


    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.

    About SciScore

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