A Chimeric Virus-Mouse Model System for Evaluating the Function and Inhibition of Papain-Like Proteases of Emerging Coronaviruses

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  • Xufang Deng
    • Other Affiliation: Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
  • Sudhakar Agnihothram
    • Other Affiliation: Departments of Epidemiology and Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
  • Anna M. Mielech
    • Other Affiliation: Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
  • Daniel B. Nichols
    • Other Affiliation: Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
  • Michael W. Wilson
    • Other Affiliation: Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
  • Sarah E. St. John
    • Other Affiliation: Departments of Biological Science and Chemistry, Purdue University, West Lafayette, Indiana, USA
  • Scott D. Larsen
    • Other Affiliation: Vahlteich Medicinal Chemistry Core, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, USA
  • Andrew D. Mesecar
    • Other Affiliation: Departments of Biological Science and Chemistry, Purdue University, West Lafayette, Indiana, USA
  • Deborah J. Lenschow
    • Other Affiliation: Department of Internal Medicine and Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
  • Ralph S. Baric
    • Other Affiliation: Departments of Epidemiology and Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
  • Susan Baker
    • ORCID: https://orcid.org/0000-0001-6485-8143
    • Other Affiliation: Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
Abstract
  • To combat emerging coronaviruses, developing safe and efficient platforms to evaluate viral protease activities and the efficacy of protease inhibitors is a high priority. Here, we exploit a biosafety level 2 (BSL-2) chimeric Sindbis virus system to evaluate protease activities and the efficacy of inhibitors directed against the papain-like protease (PLpro) of severe acute respiratory syndrome coronavirus (SARS-CoV), a biosafety level 3 (BSL-3) pathogen. We engineered Sindbis virus to coexpress PLpro and a substrate, murine interferon-stimulated gene 15 (ISG15), and found that PLpro mediates removal of ISG15 (deISGylation) from cellular proteins. Mutation of the catalytic cysteine residue of PLpro or addition of a PLpro inhibitor blocked deISGylation in virus-infected cells. Thus, deISGylation is a marker of PLpro activity. Infection of alpha/beta interferon receptor knockout (IFNAR−/−) mice with these chimeric viruses revealed that PLpro deISGylation activity removed ISG15-mediated protection during viral infection. Importantly, administration of a PLpro inhibitor protected these mice from lethal infection, demonstrating the efficacy of a coronavirus protease inhibitor in a mouse model. However, this PLpro inhibitor was not sufficient to protect the mice from lethal infection with SARS-CoV MA15, suggesting that further optimization of the delivery and stability of PLpro inhibitors is needed. We extended the chimeric-virus platform to evaluate the papain-like protease/deISGylating activity of Middle East respiratory syndrome coronavirus (MERS-CoV) to provide a small-animal model to evaluate PLpro inhibitors of this recently emerged pathogen. This platform has the potential to be universally adaptable to other viral and cellular enzymes that have deISGylating activities.
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  • Article
Rights statement
  • In Copyright
Journal title
  • Journal of Virology
Journal volume
  • 88
Journal issue
  • 20
Page start
  • 11825
Page end
  • 11833
Language
  • English
ISSN
  • 1098-5514
  • 1070-6321
  • 0022-538X
Publisher
  • American Society for Microbiology

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