The anti‐HIV drug nelfinavir mesylate (Viracept) is a potent inhibitor of cell fusion caused by the SARSCoV‐2 spike (S) glycoprotein warranting further evaluation as an antiviral against COVID‐19 infections

This article has been Reviewed by the following groups

Read the full article

Abstract

Severe acute respiratory syndrome coronavirus‐2 (SARS CoV‐2) is the causative agent of the coronavirus disease‐2019 (COVID‐19) pandemic. Coronaviruses enter cells via fusion of the viral envelope with the plasma membrane and/or via fusion of the viral envelope with endosomal membranes after virion endocytosis. The spike (S) glycoprotein is a major determinant of virus infectivity. Herein, we show that the transient expression of the SARS CoV‐2 S glycoprotein in Vero cells caused extensive cell fusion (formation of syncytia) in comparison to limited cell fusion caused by the SARS S glycoprotein. Both S glycoproteins were detected intracellularly and on transfected Vero cell surfaces. These results are in agreement with published pathology observations of extensive syncytia formation in lung tissues of patients with COVID‐19. These results suggest that SARS CoV‐2 is able to spread from cell‐to‐cell much more efficiently than SARS effectively avoiding extracellular neutralizing antibodies. A systematic screening of several drugs including cardiac glycosides and kinase inhibitors and inhibitors of human immunodeficiency virus (HIV) entry revealed that only the FDA‐approved HIV protease inhibitor, nelfinavir mesylate (Viracept) drastically inhibited S‐n‐ and S‐o‐mediated cell fusion with complete inhibition at a 10‐μM concentration. In‐silico docking experiments suggested the possibility that nelfinavir may bind inside the S trimer structure, proximal to the S2 amino terminus directly inhibiting S‐n‐ and S‐o‐mediated membrane fusion. Also, it is possible that nelfinavir may act to inhibit S proteolytic processing within cells. These results warrant further investigations of the potential of nelfinavir mesylate to inhibit virus spread at early times after SARS CoV‐2 symptoms appear.

Article activity feed

  1. SciScore for 10.1101/2020.04.24.060376: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    The primary antibodies used were as follows: mouse anti-myc antibody (Abcam, MA, USA), mouse anti-FLAG antibody (Abcam, MA, USA).
    anti-myc
    suggested: None
    anti-FLAG
    suggested: (Abcam Cat# ab124462, RRID:AB_11000959)
    Goat anti-mouse antibody conjugated with HRP (Invitrogen, Inc. CA, USA) was used as a secondary antibody.
    anti-mouse
    suggested: None
    Goat anti-mouse antibody conjugated with alexa fluorophore 647 and goat anti-rabbit antibody conjugated with alexa fluore 488 (Invitrogen, Inc. CA, USA) were used for immuno-fluorescence (IFA) assay.
    anti-rabbit
    suggested: None
    Experimental Models: Cell Lines
    SentencesResources
    Cell line: African green monkey kidney (Vero) cells were maintained in Dulbeco Modified Eagle’s Media (DMEM) with 10% fetal bovine serum (FBS) and 2% primocin (Invitrogen, Inc. CA, USA).
    Vero
    suggested: None
    Software and Algorithms
    SentencesResources
    Computational Methods: Docking of the nelfinavir mesylate to the spike protein of SARS CoV-2 was performed using Autodock (35).
    Autodock
    suggested: (AutoDock, RRID:SCR_012746)
    Structures within 2 kcal/mol from the lowest energy docked structures were represented as final possible docked structures using PyMol software (Schrodinger).
    PyMol
    suggested: (PyMOL, RRID:SCR_000305)
    Olympus IX71 fluorescent microscope was used for live and phase contrast images using Cellsens software.
    Cellsens
    suggested: None
    Zeiss Axio Observer Z1 fluorescent microscope was used for fluorescent images using Zen software.
    Zen
    suggested: None

    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: Please consider improving the rainbow (“jet”) colormap(s) used on pages 16, 13 and 15. At least one figure is not accessible to readers with colorblindness and/or is not true to the data, i.e. not perceptually uniform.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • No funding statement was detected.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.