Ocular tropism of SARS-CoV-2 with retinal inflammation through neuronal invasion in animal models

  1. Gi Uk Jeong
  2. Hyung-Jun Kwon
  3. Hyun Woo Moon
  4. Gun Young Yoon
  5. Hye Jin Shin
  6. Ji Soo Chae
  7. Seong-Jun Kim
  8. In-Chul Lee
  9. Dae-Gyun Ahn
  10. Kyun-Do Kim
  11. Suresh Mahalingam
  12. Young-Chan Kwon

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Abstract

Although ocular manifestations are commonly reported in patients with coronavirus disease 2019 (COVID-19), there is currently no consensus on ocular tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To investigate this, we infected K18-hACE2 mice with SARS-CoV-2 using various routes. We observed ocular manifestation and retinal inflammation with cytokine production in the eyes of intranasally (IN) infected mice. An intratracheal (IT) injection resulted in virus spread from the lungs to the brain and eyes via trigeminal and optic nerves. Ocular and neuronal invasion were confirmed by an intracerebral (IC) infection. Notably, eye-dropped (ED) virus did not infect the lungs and was undetectable with time. Using infectious SARS-CoV-2-mCherry clones, we demonstrated the ocular and neurotropic distribution of the virus in vivo by a fluorescence-imaging system. Evidence for the ocular tropic and neuroinvasive characteristics of SARS-CoV-2 was confirmed in wild-type Syrian hamsters. Our data provides further understanding of the viral transmission; SARS-CoV-2 clinical characteristics; and COVID-19 control procedures.

Summary

SARS-CoV-2 can spread from the respiratory tract to the brain and eyes via trigeminal and optic nerves in animal models. This ocular tropism of SARS-CoV-2 through neuronal invasion likely causes ocular manifestation and retinal inflammation.

Graphical Abstract

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  1. ScreenIT

    SciScore for 10.1101/2022.04.17.488607: (What is this?)

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

    Table 1: Rigor

    EthicsIACUC: All protocols were approved by the Institutional Animal Care and Use Committee (Protocol ID 8A-M6, IACUC ID 2021-8A-02-01 & 2021-8A-03-03).
    Sex as a biological variableAnimals: Mice: Eight-week-old male B6.Cg-Tg(K18-hACE2)2Prlmn/J mice were purchased from the Jackson Laboratory and maintained in a biosafety level 2 (BSL-2) animal facility in the Korea Research Institute of Chemical Technology (KRICT).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    Briefly, 3 μg of plasmid DNA was transfected into BHK-21 cells (CCL-10, ATCC) in a six-well plate using Lipofectamine LTX with Plus reagent (15338100, Invitrogen, Waltham, MA, USA) as per the manufacturer’s instructions.
    BHK-21
    suggested: None
    Three days post transfection, the supernatant was transferred to Vero cells in a T25 flask.
    Vero
    suggested: None
    Culture medium was removed from 24-well plated Vero E6 cells (approximately 1 × 105 per/well) a day before the assay, and the inoculum was transferred onto triplicate cell monolayers.
    Vero E6
    suggested: None
    Experimental Models: Organisms/Strains
    SentencesResources
    Animals: Mice: Eight-week-old male B6.Cg-Tg(K18-hACE2)2Prlmn/J mice were purchased from the Jackson Laboratory and maintained in a biosafety level 2 (BSL-2) animal facility in the Korea Research Institute of Chemical Technology (KRICT).
    B6.Cg-Tg(K18-hACE2)2Prlmn/J
    suggested: None
    Recombinant DNA
    SentencesResources
    pCC1-4K-SARS-CoV-2-mCherry clone ( GenBank Accession No. MT926411) was used for the rescue of infectious virus following the protocol developed by Rihn et al (Rihn et al., 2021).
    pCC1-4K-SARS-CoV-2-mCherry
    suggested: None
    Software and Algorithms
    SentencesResources
    The retinal thickness was measured using Nuance 3.02 software (PerkinElmer, Waltham, MA, USA)
    Nuance
    suggested: None
    All data were analyzed using the GraphPad Prism 8.0 software (GraphPad Software, San Diego, CA, USA).
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    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.

    Results from scite Reference Check: We found no unreliable references.

    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.

  2. Version published to 10.1101/2022.04.17.488607 on bioRxiv