Clinicopathologic features of a feline SARS-CoV-2 infection model parallel acute COVID-19 in humans

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Abstract

The emergence and ensuing dominance of COVID-19 on the world stage has emphasized the urgency of efficient animal models for the development of therapeutics and assessment of immune responses to SARS-CoV-2 infection. Shortcomings of current animal models for SARS-CoV-2 include limited lower respiratory disease, divergence from clinical COVID-19 disease, and requirements for host genetic modifications to permit infection. This study validates a feline model for SARS-CoV-2 infection that results in clinical disease and histopathologic lesions consistent with severe COVID-19 in humans. Intra-tracheal inoculation of concentrated SARS-CoV-2 caused infected cats to develop clinical disease consistent with that observed in the early exudative phase of COVID-19. A novel clinical scoring system for feline respiratory disease was developed and utilized, documenting a significant degree of lethargy, fever, dyspnea, and dry cough in infected cats. In addition, histopathologic pulmonary lesions such as diffuse alveolar damage, hyaline membrane formation, fibrin deposition, and proteinaceous exudates were observed due to SARS-CoV-2 infection, imitating lesions identified in people hospitalized with ARDS from COVID-19. A significant correlation exists between the degree of clinical disease identified in infected cats and pulmonary lesions. Viral loads and ACE2 expression were quantified in nasal turbinates, distal trachea, lung, and various other organs. Natural ACE2 expression, paired with clinicopathologic correlates between this feline model and human COVID-19, encourage use of this model for future translational studies.

Author Summary

Identifying an ideal animal model to study COVID-19 has been difficult, and current models come with challenges that restrict their potential in translational studies. Few lab animals naturally express the receptors necessary for viral infection (ACE2), and many fail to manifest clinical signs or pathology similar to that seen in humans. Other models (non-human primates, mink) are ideal for disease and transmission studies, but are restricted by cost, husbandry challenges, and scarce availability. Alternatively, cats naturally express ACE2 receptors, are naturally infected with SARS-CoV-2 and can transmit virus from cat-to-cat. Prior to this study, cats infected by oral/nasal routes have not displayed significant clinical disease or lung pathology. However, we demonstrate that direct inoculation of concentrated SARS-CoV-2 virus in the trachea of cats induces analogous clinical and pathologic features to hospitalized patients with acute COVID-19. Our results show that infected cats exhibit significant clinical signs during experimental infection (coughing, increased respiratory effort, lethargy, and fever) and exhibit extensive lung lesions that mimic severe COVID-19 pathology such as diffuse alveolar damage and hyaline membrane formation – highlighting the immeasurable potential for this feline model to address translational approaches for COVID-19 and to better understand the role of cats in transmission and disease.

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  1. SciScore for 10.1101/2021.04.14.439863: (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.

    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 found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).


    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

    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.