Viruses remain a significant cause of human disease and death, most notably illustrated through the current Covid-19 pandemic. Control of virus infection continues to pose a significant global health challenge to the human population. Viruses can spread through multiple routes, including via environmental and surface contamination where viruses can remain infectious for days. Methods to inactivate viruses on such surfaces may help mitigate infection. Now, Stephen Bell and colleagues presented evidence identifying a novel ‘virucidal’ product in Rosin soap, which is produced from Tall oil from coniferous trees. They showed that Rosin soap was able to rapidly and potently inactivate influenza virus and other enveloped viruses like SARS-CoV-2. Their study recently appeared in BioRxiv.
To determine whether Rosin Soap Powder could reduce the infectivity of influenza virus (IAV WSN strain), they performed an experiment, in which they incubated influenza virus stocks with rosin acid (2.5% w/v) at 37°C for 5-30 minutes and measured residual infectivity. This experiment revealed that the incubation of IAV with Rosin Soap Powder gave at least a ten-thousand-fold reduction in infectivity.
Next, they hypothesized that, the Rosin soap can also inhibit other viruses. So, they investigated the virucidal activity of Rosin soap against enveloped viruses like IAV strain (H3N2, Udom), RSV, SARS-CoV-2 and non-enveloped encephalomyocarditis virus (EMCV). They carried out same protocol as they used for IAV and measured residual viral activity using specific-specific means. Conditions for these experiments were room temperature for 5 minutes. They found that, all enveloped viruses were inhibited by Rosin soap, demonstrating that the activity of rosin soap is not limited to IAV or WSN. However, this soap cant able to inhibit the non-enveloped EMCV. The susceptibility of enveloped viruses to Rosin acids (and not the non-enveloped virus) suggested that the viral lipid membrane is a major target of inactivation.
Finally, in order to determine whether the virucidal activity of Rosin soap is dependent on concentration or not. They performed experiment with different concentration (2.5, 0.25 and 0.025%) together with varying incubation time (5, 15 and 30 mins) and incubation temperature (37°C). They demonstrated that the virucidal activity of Rosin soap was only dependent on concentration. Meaning, 2.5% concentration provide complete inhibition of viruses and reduction in concentration leads to reduction in inhibition of viruses.
Finally, they demonstrated that, in constrast to concentration, virucidal activity of this soap was completely independent of incubation time and temperature.
“This novel chemical inactivation method against enveloped viruses, could be of great use in preventing virus infections in certain settings.”— they concluded.
Reference: Stephen Bell, Derek J Fairley, Hannele Kettunen, Juhani Vuorenmaa, Juha Orte, Connor G G Bamford, John McGrath, “Rosin Soap Exhibits Virucidal Activity”, bioRxiv 2021.07.19.452918; doi: https://doi.org/10.1101/2021.07.19.452918
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