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In vitro virucidal activity of Echinaforce®, an Echinacea purpurea preparation, against coronaviruses, including common cold coronavirus 229E and SARS-CoV-2

Authors
  • Signer, Johanna1
  • Jonsdottir, Hulda R.1
  • Albrich, Werner C.2
  • Strasser, Marc1
  • Züst, Roland1
  • Ryter, Sarah1
  • Ackermann-Gäumann, Rahel1
  • Lenz, Nicole1
  • Siegrist, Denise1
  • Suter, Andreas3
  • Schoop, Roland3
  • Engler, Olivier B.1
  • 1 SPIEZ LABORATORY, Austrasse, Spiez, 3700, Switzerland , Spiez (Switzerland)
  • 2 Kantonsspital St. Gallen, St. Gallen, Switzerland , St. Gallen (Switzerland)
  • 3 A.Vogel AG, Roggwil, Switzerland , Roggwil (Switzerland)
Type
Published Article
Journal
Virology Journal
Publisher
Springer (Biomed Central Ltd.)
Publication Date
Sep 09, 2020
Volume
17
Issue
1
Identifiers
DOI: 10.1186/s12985-020-01401-2
Source
Springer Nature
Keywords
License
Green

Abstract

BackgroundCoronaviruses (CoVs) were long thought to only cause mild respiratory and gastrointestinal symptoms in humans but outbreaks of Middle East Respiratory Syndrome (MERS)-CoV, Severe Acute Respiratory Syndrome (SARS)-CoV-1, and the recently identified SARS-CoV-2 have cemented their zoonotic potential and their capacity to cause serious morbidity and mortality, with case fatality rates ranging from 4 to 35%. Currently, no specific prophylaxis or treatment is available for CoV infections. Therefore we investigated the virucidal and antiviral potential of Echinacea purpurea (Echinaforce®) against human coronavirus (HCoV) 229E, highly pathogenic MERS- and SARS-CoVs, as well as the newly identified SARS-CoV-2, in vitro.MethodsTo evaluate the antiviral potential of the extract, we pre-treated virus particles and cells and evaluated remaining infectivity by limited dilution. Furthermore, we exposed cells to the extract after infection to further evaluate its potential as a prophylaxis and treatment against coronaviruses. We also determined the protective effect of Echinaforce® in re-constituted nasal epithelium.ResultsIn the current study, we found that HCoV-229E was irreversibly inactivated when exposed to Echinaforce® at 3.2 μg/ml IC50. Pre-treatment of cell lines, however, did not inhibit infection with HCoV-229E and post-infection treatment had only a marginal effect on virus propagation at 50 μg/ml. However, we did observe a protective effect in an organotypic respiratory cell culture system by exposing pre-treated respiratory epithelium to droplets of HCoV-229E, imitating a natural infection. The observed virucidal activity of Echinaforce® was not restricted to common cold coronaviruses, as both SARS-CoV-1 and MERS-CoVs were inactivated at comparable concentrations. Finally, the causative agent of COVID-19, SARS-CoV-2 was also inactivated upon treatment with 50μg/ml Echinaforce®.ConclusionsThese results show that Echinaforce® is virucidal against HCoV-229E, upon direct contact and in an organotypic cell culture model. Furthermore, MERS-CoV and both SARS-CoV-1 and SARS-CoV-2 were inactivated at similar concentrations of the extract. Therefore we hypothesize that Echinacea purpurea preparations, such as Echinaforce®, could be effective as prophylactic treatment for all CoVs due to their structural similarities.

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