Fluoroquinolone Antibiotics Exhibit Low Antiviral Activity against SARS-CoV-2 and MERS-CoV
Stacey L. P. Scroggs,
Danielle K. Offerdahl,
Dylan P. Flather,
Ciera N. Morris,
Benjamin L. Kendall,
Rebecca M. Broeckel,
Paul A. Beare,
Marshall E. Bloom
Affiliations
Stacey L. P. Scroggs
Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Danielle K. Offerdahl
Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Dylan P. Flather
Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Ciera N. Morris
Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Benjamin L. Kendall
Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Rebecca M. Broeckel
Innate Immunity and Pathogenesis Section Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Paul A. Beare
Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Marshall E. Bloom
Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
Repurposing FDA-approved drugs that treat respiratory infections caused by coronaviruses, such as SARS-CoV-2 and MERS-CoV, could quickly provide much needed antiviral therapies. In the current study, the potency and cellular toxicity of four fluoroquinolones (enoxacin, ciprofloxacin, levofloxacin, and moxifloxacin) were assessed in Vero cells and A549 cells engineered to overexpress ACE2, the SARS-CoV-2 entry receptor. All four fluoroquinolones suppressed SARS-CoV-2 replication at high micromolar concentrations in both cell types, with enoxacin demonstrating the lowest effective concentration 50 value (EC50) of 126.4 μM in Vero cells. Enoxacin also suppressed the replication of MERS-CoV-2 in Vero cells at high micromolar concentrations. Cellular toxicity of levofloxacin was not found in either cell type. In Vero cells, minimal toxicity was observed following treatment with ≥37.5 μM enoxacin and 600 μM ciprofloxacin. Toxicity in both cell types was detected after moxifloxacin treatment of ≥300 μM. In summary, these results suggest that the ability of fluoroquinolones to suppress SARS-CoV-2 and MERS-CoV replication in cultured cells is limited.
