Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Aug 6;12(8):e0391623.
doi: 10.1128/spectrum.03916-23. Epub 2024 Jul 16.

Ronapreve (REGN-CoV; casirivimab and imdevimab) reduces the viral burden and alters the pulmonary response to the SARS-CoV-2 Delta variant (B.1.617.2) in K18-hACE2 mice using an experimental design reflective of a treatment use case

Lee Tatham #  1   2 , Anja Kipar #  3   4 , Jo Sharp  1   2 , Edyta Kijak  1   2 , Joanne Herriott  1   2 , Megan Neary  1   2 , Helen Box  1   2 , Eduardo Gallardo Toledo  1   2 , Anthony Valentijn  1   2 , Helen Cox  1   2 , Henry Pertinez  1   2 , Paul Curley  1   2 , Usman Arshad  1   2 , Rajith Kumar Reddy Rajoli  1   2 , Steve Rannard  2   5 , James P Stewart  4 , Andrew Owen  1   2
Affiliations

Ronapreve (REGN-CoV; casirivimab and imdevimab) reduces the viral burden and alters the pulmonary response to the SARS-CoV-2 Delta variant (B.1.617.2) in K18-hACE2 mice using an experimental design reflective of a treatment use case

Lee Tatham et al. Microbiol Spectr. .

Abstract

With some exceptions, global policymakers have recommended against the use of existing monoclonal antibodies in COVID-19 due to loss of neutralization of newer variants. The purpose of this study was to investigate the impact of Ronapreve on compartmental viral replication using paradigms for susceptible and insusceptible variants. Virological efficacy and impact on pathogenicity was assessed in K18-hACE2 mice inoculated with either the Delta or BA.1 Omicron variants. Ronapreve reduced sub-genomic viral RNA levels in lung and nasal turbinate, 4 and 6 days post-infection, for the Delta variant but not the Omicron variant. It also blocked brain infection, which is seen with high frequency in K18-hACE2 mice after Delta variant infection. At day 6, the inflammatory response to lung infection with the Delta variant was altered to a multifocal granulomatous inflammation in which the virus appeared to be confined. The current study provides evidence of an altered tissue response to SARS-CoV-2 after treatment with a monoclonal antibody combination that retains neutralization activity. These data demonstrate that experimental designs that reflect treatment use cases are achievable in animal models for monoclonal antibodies. Extreme caution should be taken when interpreting prophylactic experimental designs that may not be representative of treatment.IMPORTANCEFollowing the emergence of the SARS-CoV-2 Omicron variant, the WHO recommended against the use of Ronapreve in its COVID-19 treatment guidelines due to a lack of efficacy based on current pharmacokinetic-pharmacodynamic understanding. However, the continued use of Ronapreve, specifically in vulnerable patients, was advocated by some based on in vitro neutralization data. Here, the virological efficacy of Ronapreve was demonstrated in both the lung and brain compartments using Delta as a paradigm for a susceptible variant. Conversely, a lack of virological efficacy was demonstrated for the Omicron variant. Comparable concentrations of both monoclonal antibodies were observed in the plasma of Delta- and Omicron-infected mice. This study made use of a reliable murine model for SARS-CoV-2 infection, an experimental design reflective of treatment, and demonstrated the utility of this approach when assessing the effectiveness of monoclonal antibodies.

Keywords: SARS-CoV-2; mAb; preclinical PK/PD.

PubMed Disclaimer

Conflict of interest statement

A.O. and S.R. are directors of Tandem Nano Ltd. and co-inventors of patents relating to drug delivery. A.O. has been a co-investigator on funding received by the University of Liverpool from ViiV Healthcare and Gilead Sciences unrelated to COVID-19 in the past 3 years. A.O. has received personal fees from Gilead and Assembly Biosciences in the past 3 years unrelated to COVID-19. A.O. was a member of the Trial Management Group for the AGILE phase I/II platform trial until January 2023 and AGILE received funding from Ridgeback and GSK in the past 3 years for which A.O. was not a co-investigator. S.R. has received research funding from ViiV and AstraZeneca, and consultancy from Gilead not related to the current paper. No other conflicts are declared by the authors.

Figures

Fig 1
Fig 1
Mouse weights separated by treatment group and infection status. Weights are the percentage of the initial weight recorded at day 0 prior to infection. Standard deviations are indicated by the dashed plots.
Fig 2
Fig 2
Viral quantification of SARS-CoV-2 sub-genomic RNA (sgE), relative to 18S, using qRT-PCR from nasal turbinate (a) and lung (b) samples harvested from each group on days 4 and 6 post-infection. Mice infected with the Delta variant were administered with a single IP dose of either saline (n = 12) or Ronapreve, 400 µg/mouse, in saline (n = 16). Equally, mice infected with the Omicron variant were administered with a single IP dose of either saline (n = 16) or Ronapreve, 400 µg/mouse, in saline (n = 16). Data for individual animals are shown with the mean value represented by a black line. NS, not significant; *, P ≤ 0.05 (unpaired, two-tailed t-test).
Fig 3
Fig 3
Virological efficacy of Ronapreve in K18-hACE2 mice infected with SARS-CoV-2 Delta. Viral quantification of SARS-CoV-2 sub-genomic RNA (sgE), relative to 18S, using qRT-PCR in lung and brain samples harvested from each group 9 days post-infection. Infected mice were administered with a single IP dose of either saline (n = 4) or Ronapreve, 400 µg/mouse, in saline (n = 4). Data for individual animals are shown with the mean value represented by a black line. *, P ≤ 0.05 (unpaired, two-tailed t-test). One complete brain from the saline-administered mice was used for another in situ study. The remaining brain samples (n = 3) were available for qPCR analysis.
Fig 4
Fig 4
Left lung, longitudinal sections, K18-hACE2 mice. SARS-CoV-2 N expression at day 4 (a-d) and day 6 (e-h) post-infection with 103 PFU of SARS-CoV-2 Delta variant (B.1.617.2; a, c, e, g) or Omicron variant (b, d, f, h), followed after 24 hours by an intraperitoneal injection of 100 µL saline control (a, b, e, f) or 400 µg Ronapreve (c, d, g, h), diluted in saline. (a) Delta-variant-infected mouse (C1.2) treated with saline control, 4 dpi. Abundant large, partly coalescing patches of alveoli with SARS-CoV-2 N positive epithelial cells are found disseminated throughout the parenchyma. The inset confirms infection of both type I (arrowhead) and type II (arrow) pneumocytes. (b) Omicron-variant-infected mouse (C2.1) treated with saline control, 4 dpi. There are multiple disseminated small patches of alveoli with positive epithelial cells. A large patch (arrow) of positive alveoli is seen in association with focal desquamation of alveolar epithelial cells (inset: large arrowhead) and the presence of activated (inset: small arrowhead) and syncytial (inset: arrow) type II pneumocytes. (c) Delta-variant-infected mouse (R1.5) treated with Ronapreve, 4 dpi. There are numerous small disseminated patches of alveoli with positive epithelial cells, and larger patches (arrow) in association with focal activation (inset: arrowhead) and syncytia formation (inset: small arrow) in type II pneumocytes, desquamation of alveolar epithelial cells, occasional degenerate cells, and a few infiltrating lymphocytes and neutrophils (inset: large arrow). (d) Omicron-variant-infected mouse (R2.6) treated with Ronapreve, 4 dpi. Viral antigen expression is seen in epithelial cells of random small patches of alveoli. (e) Delta-variant-infected mouse (C3.5) treated with saline control, 6 dpi. Multifocal extensive, partly coalescing large patches of alveoli with positive epithelial cells are found disseminated throughout the parenchyma. (f) Omicron-variant-infected mouse (C4.8) treated with saline control, 6 dpi. There are multiple disseminated, mainly small patches of alveoli with positive epithelial cells. (g) Delta-variant-infected mouse (R3.4) treated with Ronapreve, 6 dpi. There are disseminated very small patches of alveoli with positive epithelial cells (inset arrowhead: type I pneumocyte, arrow: type II pneumocyte). Positive cells are also observed in focal infiltrates (arrow; see Fig. 4). (h) Omicron-variant-infected mouse (C4.8) treated with Ronapreve, 6 dpi. There are numerous disseminated, mainly small patches of alveoli with pos epithelial cells. Immunohistochemistry for SARS-CoV-2 N, hematoxylin counterstain, and HE stain (insets in b and c). Bars = 500 µm (overviews) and 50 µm (insets).
Fig 5
Fig 5
Lungs, K18-hACE2 mice at day 6 post-infection with 103 PFU of SARS-CoV-2 Delta variant (B.1.617.2), followed after 24 hours by an intraperitoneal injection of 100 µL saline control or 400 µg Ronapreve, diluted in saline. (a-f) Saline-treated animal (C3.1). (a) The parenchyma shows a focal consolidated area (asterisk) and several areas with increased cellularity (arrow) in the parenchyma. (b) Macrophages (Iba1+) are abundant in the consolidated area (asterisk). (c-f) Closer view of the consolidated area confirming that macrophages (d; Iba1+) are the dominant inflammatory cells, with a few intermingled individual T cells (e; CD3+, arrowheads) and B cells (f; CD45R/B220, arrowheads). (g-n) Ronapreve-treated animal (R3.2). (g) The parenchyma exhibits several well-delineated, dense inflammatory infiltrates (arrows). (h) The infiltrates (arrows) appear to comprise macrophages (Iba1+). (i-l) Focal inflammatory infiltrate. (j) Macrophages (Iba1+) are the dominant inflammatory cells and are also seen to emigrate from a vessel (arrowhead). T cells (k) and B cells (l) are seen intermingled in small numbers. (m, n) Closer view of a focal inflammatory infiltrate. The mononuclear infiltrate (m) contains viral antigen (n) within a few pneumocytes (arrows) and cell free or phagocytosed within macrophages (arrowheads). (a, c, g, I, m) HE stain; (b, d-g, h, j-l, n) immunohistochemistry. Bars = 500 µm (a, b, g, h) and 25 µm (all others).
Fig 6
Fig 6
Heads with olfactory epithelium (OE) and brain, K18-hACE2 mice. SARS-CoV-2 N expression at day 4 (a-d) and day 6 (e-h) post-infection with 103 PFU of SARS-CoV-2 Delta variant (B.1.617.2; a, c, e, g) or Omicron variant (b, d, f, h), followed after 24 hours by an intraperitoneal injection of 100 µL saline control (a, b, e, f) or 400 µg Ronapreve (c, d, g, h), diluted in saline. (a) Delta-variant-infected mouse (C1.1) treated with saline control, 4 dpi. The virus is widespread in the OE (arrow and inset showing a large patch of positive epithelial cells [arrow] and a few individual positive epithelial cells [arrowhead]) and has spread to the brain; there are patches of neurons positive for viral antigen in frontal cortex, cerebral nuclei (caudoputamen), hypothalamus/thalamus, midbrain, and pons. The arrowhead depicts a large patch of positive neurons in the frontal cortex of which a closer view is provided in the inset. (b) Omicron-variant-infected mouse (C2.3) treated with saline control, 4 dpi. There is no evidence of viral antigen expression in the OE and brain. (c) Delta-variant-infected mouse (R1.1) treated with Ronapreve, 4 dpi. There is no evidence of viral antigen expression in the brain. The OE exhibits a small patch with positive epithelial cells. Inset: OE with viral antigen expression in intact individual olfactory epithelial cells (arrowheads) and in degenerate cells in the lumen of the nasal cavity. (d) Omicron-variant-infected mouse (R2.5) treated with Ronapreve, 4 dpi. There is no evidence of viral antigen expression in the OE and brain. (e) Delta-variant-infected mouse (C3.3) treated with saline control, 6 dpi. There is widespread viral antigen expression in abundant neurons throughout the brain including the olfactory bulb (left, arrow), with the exception of the cerebellum. (f) Omicron-variant-infected mouse (C4.1) treated with saline control, 6 dpi. There is no evidence of viral antigen expression in the OE and brain. (g) Delta-variant-infected mouse (R3.3) treated with Ronapreve, 6 dpi. There is no evidence of viral antigen expression in the OE and brain. (h) Omicron-variant-infected mouse (C4.7) treated with Ronapreve, 6 dpi. There is no evidence of viral antigen expression in the OE and brain. Immunohistochemistry, hematoxylin counterstain. Bars = 1 mm.
See this image and copyright information in PMC

Update of

Similar articles

See all similar articles

Cited by

References

    1. WHO . 2022. Vaccine equity. https://wwwwhoint/campaigns/vaccine-equity.
    1. Horby P. 2021. Antiviral drug resistance and the use of directly acting antiviral drugs (DAAs) for COVID-19. New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) - https://wwwgovuk/government/publications/nervtag-antiviral-drug-resistan....
    1. Hiscox JA, Khoo SH, Stewart JP, Owen A. 2021. Shutting the gate before the horse has bolted: is it time for a conversation about SARS-CoV-2 and antiviral drug resistance J Antimicrob Chemother 76:2230–2233. doi:10.1093/jac/dkab189 - DOI - PMC - PubMed
    1. O’Brien MP, Forleo-Neto E, Musser BJ, Isa F, Chan K-C, Sarkar N, Bar KJ, Barnabas RV, Barouch DH, Cohen MS, et al. . 2021. Subcutaneous REGEN-COV antibody combination to prevent COVID-19. N Engl J Med 385:1184–1195. doi:10.1056/NEJMoa2109682 - DOI - PMC - PubMed
    1. Simões EAF, Forleo-Neto E, Geba GP, Kamal M, Yang F, Cicirello H, Houghton MR, Rideman R, Zhao Q, Benvin SL, Hawes A, Fuller ED, Wloga E, Pizarro JMN, Munoz FM, Rush SA, McLellan JS, Lipsich L, Stahl N, Yancopoulos GD, Weinreich DM, Kyratsous CA, Sivapalasingam S. 2021. Suptavumab for the prevention of medically attended respiratory syncytial virus infection in preterm infants. Clin Infect Dis 73:e4400–e4408. doi:10.1093/cid/ciaa951 - DOI - PMC - PubMed

MeSH terms

Supplementary concepts

LinkOut - more resources