Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model

Abstract Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus with a geographic range that has expanded over recent years. Maintained in a transmission cycle between mosquito vectors and avian reservoirs the virus can cause large seasonal outbreaks in bird populations, but spillover into mamma...

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Main Authors: Johanna M. Duyvestyn, Eleanor M. Marshall, Peter J. Bredenbeek, Barry Rockx, Martijn J. van Hemert, Marjolein Kikkert
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:npj Viruses
Online Access:https://doi.org/10.1038/s44298-025-00089-x
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author Johanna M. Duyvestyn
Eleanor M. Marshall
Peter J. Bredenbeek
Barry Rockx
Martijn J. van Hemert
Marjolein Kikkert
author_facet Johanna M. Duyvestyn
Eleanor M. Marshall
Peter J. Bredenbeek
Barry Rockx
Martijn J. van Hemert
Marjolein Kikkert
author_sort Johanna M. Duyvestyn
collection DOAJ
description Abstract Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus with a geographic range that has expanded over recent years. Maintained in a transmission cycle between mosquito vectors and avian reservoirs the virus can cause large seasonal outbreaks in bird populations, but spillover into mammalian hosts has also been reported. While usually mild or asymptomatic in humans, neurological disorders are increasingly observed, which has boosted interest and the need for better understanding of the pathogenesis of various USUV lineages. In this study we inoculated interferon α/β receptor knockout (Ifnar−/−) mice with decreasing doses of USUV, monitoring symptoms and survival to determine a less lethal dose, and we directly compared isolates from three different viral lineages. We found that a Dutch isolate of USUV Africa-3 lineage is lethal at a dose of 20 pfu per mouse, which is considerably lower than what was anticipated based upon the literature. A Europe-2 strain showed an even higher virulence in this mouse model, compared to strains from Africa-3 and Europe-3 lineages—though this was not reflected in in vitro studies. These results enhance our understanding of the pathogenicity of different USUV strains and provide guidance for the use of low doses for inoculation in an Ifnar−/− animal model.
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spelling doaj-art-bc1ae2dd816943fe9b1290631b23ab822025-02-02T12:11:59ZengNature Portfolionpj Viruses2948-17672025-01-013111310.1038/s44298-025-00089-xDose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse modelJohanna M. Duyvestyn0Eleanor M. Marshall1Peter J. Bredenbeek2Barry Rockx3Martijn J. van Hemert4Marjolein Kikkert5Molecular Virology Laboratory, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical CenterDepartment of Viroscience, Erasmus University Medical CenterMolecular Virology Laboratory, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical CenterDepartment of Viroscience, Erasmus University Medical CenterMolecular Virology Laboratory, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical CenterMolecular Virology Laboratory, Leiden University Center for Infectious Diseases (LUCID), Leiden University Medical CenterAbstract Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus with a geographic range that has expanded over recent years. Maintained in a transmission cycle between mosquito vectors and avian reservoirs the virus can cause large seasonal outbreaks in bird populations, but spillover into mammalian hosts has also been reported. While usually mild or asymptomatic in humans, neurological disorders are increasingly observed, which has boosted interest and the need for better understanding of the pathogenesis of various USUV lineages. In this study we inoculated interferon α/β receptor knockout (Ifnar−/−) mice with decreasing doses of USUV, monitoring symptoms and survival to determine a less lethal dose, and we directly compared isolates from three different viral lineages. We found that a Dutch isolate of USUV Africa-3 lineage is lethal at a dose of 20 pfu per mouse, which is considerably lower than what was anticipated based upon the literature. A Europe-2 strain showed an even higher virulence in this mouse model, compared to strains from Africa-3 and Europe-3 lineages—though this was not reflected in in vitro studies. These results enhance our understanding of the pathogenicity of different USUV strains and provide guidance for the use of low doses for inoculation in an Ifnar−/− animal model.https://doi.org/10.1038/s44298-025-00089-x
spellingShingle Johanna M. Duyvestyn
Eleanor M. Marshall
Peter J. Bredenbeek
Barry Rockx
Martijn J. van Hemert
Marjolein Kikkert
Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model
npj Viruses
title Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model
title_full Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model
title_fullStr Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model
title_full_unstemmed Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model
title_short Dose and strain dependent lethality of Usutu virus in an Ifnar−/− mouse model
title_sort dose and strain dependent lethality of usutu virus in an ifnar mouse model
url https://doi.org/10.1038/s44298-025-00089-x
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