Inactivation of Murine Norovirus on a Range of Copper Alloy Surfaces Is Accompanied by Loss of Capsid Integrity
American Society for Microbiology
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Sarah L. Warnes, Emma N. Summersgill, C. William Keevil
The highly infectious nature of norovirus makes it very difficult to stop the spread of infection from an outbreak, especially as no vaccine or treatment is available and the infection is often passed to the caregivers of infected individuals. Wheeler et al. (30) estimated that for every single case reported in the United Kingdom, this leads to 136 cases in the community. Morter et al. detected norovirus using real-time reverse transcription-quantitative PCR (RT-qPCR) in 31% of more than 30 surfaces tested in a hospital environment over a 4-month period, with 100% contamination on soap and alcohol dispensers, chairs, carpets, and Zimmer frames (28). Our results suggest that incorporation of copper alloy surfaces may help to prevent infection spread from contaminated surfaces. In many norovirus outbreaks reported, contaminated surfaces are responsible for a secondary outbreak that occurs primarily because of inadequate disinfection of vomitus and fecal norovirus contamination. For example, following an initial outbreak in a hospital, ward 2 carpet fitters contracted norovirus 12 days later when replacing the flooring in the outbreak area (29). It is very difficult to reduce the spread of norovirus infection from person to person in an initial outbreak in which segregation and quarantine of infected persons may be the only way to halt the spread of infection, although this is not always practical. There is a need for more-effective and safe disinfectants for decontaminating large areas of norovirus contamination. Incorporation of copper alloys may be very useful in preventing secondary transfer from ineffectively cleaned and highly contaminated surfaces in clinical facilities and closed environments, such as cruise ships, care homes, kitchens, bathrooms, and surfaces.
There is now a large body of evidence describing the importance of copper alloy touch surfaces as antibacterial surfaces; this evidence has been supported by hospital studies worldwide showing reduced bioburden on touch surfaces and decreased rates of infection in intensive care units. Recently, we demonstrated copper alloy antiviral activity against the enveloped and nonenveloped RNA viruses influenza virus and norovirus, respectively. We now report that the mechanism of copper inactivation for norovirus involves not only degradation of the RNA but also destruction of the capsid, which allows copper ions to enter the virus. These studies with RNA viruses suggest that copper alloy surfaces might exhibit antiviral activity against other important RNA viruses for which transmission via touch surfaces is important, including coronavirus (unpublished data) and Ebola virus.
28 Morter S, Bennet G, Fish J, Richards J, Allen DJ, Nawaz S, Iturriza-Gomara M, Brolly S, Gray J, 2011. Norovirus in the hospital setting: virus introduction and spread within the hospital environment. J Hosp Infect 77: 106–112. doi: 10.1016/j.jhin.2010.09.035
29 Rzezutka A, Cook N, 2004. Survival of human enteric viruses in the environment and food. FEMS Microbiol Rev. 28: 441–453. doi: 10.1016/j.femsre.2004.02.001
30 Wheeler JG, Sethi D, Cowden JM, Wall PG, Rodrigues LC, Tompkins DS, Hudson MJ, Roderick PJ, 1999. Study of infectious intestinal disease in England: rates in the community, presenting to general practice, and reported to national surveillance. BMJ: 1046–1050