Viruses, including the coronavirus that causes COVID-19, can be transmitted from person to person through contaminated surfaces. But can some surfaces reduce the risk of this type of transmission without the help of household disinfectants? As reported in ACS applied materials and interfaceswood has natural antiviral properties that can shorten the time viruses persist on its surface – and some woods are more effective than others at reducing infectivity.
Enveloped viruses, such as the coronavirus, can live on surfaces for up to five days; Non-enveloped viruses, including enteroviruses associated with the common cold, can live for weeks, in some cases even if surfaces are disinfected. Previous studies have shown that wood has antibacterial and antifungal properties, making it an ideal material for cutting boards. However, wood’s ability to inactivate viruses has yet to be explored, which is what Varpu Marjomäki and colleagues wanted to study.
The researchers looked at how long enveloped and non-enveloped viruses remained infectious on the surface of six types of wood: Scots pine, silver birch, gray alder, eucalyptus, pedunculate oak and Norway spruce. To determine viral activity, they flushed the surface of a wood sample with a liquid solution at different times and then placed that solution in a petri dish with cultured cells. After incubating the cells with the solution, they measured the number (if any) that were infected with the virus.
The results of their demonstrations with an enveloped coronavirus showed that pine, spruce, birch and alder require one hour to completely reduce the virus’s ability to infect cells, while eucalyptus and oak require two hours. Pine showed the fastest antiviral activity, starting after five minutes. Spruce came in second and showed a sharp drop in infectiousness after 10 minutes.
For a non-enveloped enterovirus, the researchers found that incubation on oak and spruce surfaces resulted in a loss of infectivity within about an hour, with oak having an onset time of 7.5 minutes and spruce at 60 minutes. Pine, birch and eucalyptus reduced the infectivity of the virus after four hours, and alder showed no antiviral effect.
Based on their research data, the researchers concluded that the chemical composition of the wood surface is primarily responsible for its antiviral functionality. While determining the exact chemical mechanisms responsible for viral inactivation requires further research, they say these findings indicate that wood is a promising potential candidate for sustainable, natural antiviral materials.
The authors acknowledge funding from the Research Council of Finland and the Jane and Aatos Erkko Foundation.
