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Evaluation of in vitro activity of copper gluconate against SARS-CoV-2 using confocal microscopy-based high content
Killian Rodriguez1, Florian Saunier2, Josselin Rigaill3
1CIRI, Centre International de Recherche en Infectiologie, GIMAP team, University of Lyon, University of St-Etienne, INSERM U1111, CNRS UMR5308, ENS de Lyon, UCBL1, St-Etienne, France.
Context:
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) that emerged late in 2019 is the etiologic agent of coronavirus disease 2019 (Covid-19). There is an urgent need to develop curative and preventive therapeutics to limit the current pandemic and to prevent the re-emergence of Covid-19. This study aimed to assess the in vitro activity of copper gluconate against SARS-CoV-2.
Methods:
Vero E6 cells were cultured with or without copper gluconate 18-24 hours before infection. Cells were infected with a recombinant GFP expressing SARS-CoV-2. Cells were infected with a recombinant GFP expressing SARS-CoV-2. Infected cells were incubated in fresh medium containing varying concentration of copper gluconate (supplemented with bovine serum albumin or not) for an additional 48 -h period. The infection level was measured by the confocal microscopy-based high content screening method. The cell viability in presence of copper gluconate was assessed by XTT and propidium iodide assays.
Results:
The viability of Vero E6 cells exposed to copper gluconate up to 200 μM was found to be similar to that of unexposed cells, but it dropped below 70 % with 400 μM of this agent after 72 h of continuous exposure. The infection rate was 23.8 %, 18.9 %, 20.6 %, 6.9 %, 5.3 % and 5.2 % in cells treated prior infection with 0, 2, 10, 25, 50 and 100 μM of copper gluconate respectively. As compared to untreated cells, the number of infected cells was reduced by 71 %, 77 %, and 78 % with 25, 50, and 100 μM of copper gluconate respectively (p < 0.05). In cells treated only post-infection, the rate of infection dropped by 73 % with 100 μM of copper gluconate (p < 0.05). However, the antiviral activity of copper gluconate was abolished by the addition of bovine serum albumin.
Conclusion:
Copper gluconate was found to mitigate SARS-CoV-2 infection in Vero E6 cells but this effect was abolished by albumin, which suggests that copper will not retain its activity in serum. Furthers studies are needed to investigate whether copper gluconate could be of benefit in mucosal administration such as mouthwash, nasal spray or aerosols.
Insights
Copper gluconate shows in vitro antiviral activity against SARS-CoV-2, reducing infection rates in cell cultures. However, its effectiveness is diminished in the presence of albumin, suggesting limited efficacy in serum environments.
Area of Science:
- Virology
- Biochemistry
- Pharmacology
Background:
- Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes COVID-19, necessitating novel therapeutic strategies.
- Developing effective treatments is crucial to control the ongoing pandemic and prevent future outbreaks.
Purpose of the Study:
- To evaluate the in vitro antiviral efficacy of copper gluconate against SARS-CoV-2.
- To determine the impact of copper gluconate concentration on viral infection and cell viability.
Main Methods:
- Vero E6 cells were treated with varying concentrations of copper gluconate before and after SARS-CoV-2 infection.
- Viral infection levels were quantified using confocal microscopy and high-content screening.
- Cell viability was assessed using XTT and propidium iodide assays.
Main Results:
- Copper gluconate demonstrated significant reduction in SARS-CoV-2 infection rates at concentrations of 25, 50, and 100 μM.
- Antiviral activity was observed both in pre-treated and post-infected cells.
- The presence of bovine serum albumin abolished the antiviral effect of copper gluconate.
- Cell viability remained unaffected up to 200 μM, with a slight decrease at 400 μM.
Conclusions:
- Copper gluconate exhibits in vitro antiviral properties against SARS-CoV-2 in cell cultures.
- Albumin negates the antiviral activity, indicating potential limitations in serum-containing environments.
- Further research is warranted to explore copper gluconate's potential for mucosal administration (e.g., mouthwash, nasal spray).
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