Inactivation of Norovirus on Dry Copper Alloy Surfaces

Abstract

Noroviruses (family Caliciviridae) are the primary cause of viral gastroenteritis worldwide. The virus is highly infectious and touching contaminated surfaces can contribute to infection spread. Although the virus was identified over 40 years ago the lack of methods to assess infectivity has hampered the study of the human pathogen. Recently the murine virus, MNV-1, has successfully been used as a close surrogate. Copper alloys have previously been shown to be effective antimicrobial surfaces against a range of bacteria and fungi. We now report rapid inactivation of murine norovirus on alloys, containing over 60% copper, at room temperature but no reduction of infectivity on stainless steel dry surfaces in simulated wet fomite and dry touch contamination. The rate of inactivation was initially very rapid and proportional to copper content of alloy tested. Viral inactivation was not as rapid on brass as previously observed for bacteria but copper-nickel alloy was very effective. The use of chelators and quenchers of reactive oxygen species (ROS) determined that Cu(II) and especially Cu(I) ions are still the primary effectors of toxicity but quenching superoxide and hydroxyl radicals did not confer protection. This suggests Fenton generation of ROS is not important for the inactivation mechanism. One of the targets of copper toxicity was the viral genome and a reduced copy number of the gene for a viral encoded protein, VPg (viral-protein-genome-linked), which is essential for infectivity, was observed following contact with copper and brass dry surfaces. The use of antimicrobial surfaces containing copper in high risk closed environments such as cruise ships and care facilities could help to reduce the spread of this highly infectious and costly pathogen.

Destruction of the Capsid and Genome of GII.4 Human Norovirus Occurs during Exposure to Metal Alloys Containing Copper

“…The results presented here are consistent with those of Warnes et al, who performed similar experiments using the cultivable surrogate MNV (13,14). For example, both studies reported evidence of a loss of genome integrity upon exposure to coppercontaining alloys.…”

“…Touch surfaces with antimicrobial properties hold promise to control HuNoV environmental transmission. In this study, we provide evidence that both the genome and capsid of HuNoV are rapidly destroyed during exposure to copper-containing surfaces, a finding supported by data from previous studies using the genetically related and cultivable surrogate MNV (13,14).…”

“…However, little research into the efficacy of copper and its alloys against HuNoV has been performed. Recently, copper alloys were shown to be effective at inactivating murine norovirus (MNV), a cultivable surrogate for HuNoV (13,14). Since MNV differs from …”

Adsorption of MS2 on oxide nanoparticles affects chlorine disinfection and solar inactivation

“…) increases viral inactivation (Park et al, 2014;Warnes and Keevil, 2013). Silver (Ag 0 ) NPs resulted in a 4.0 log removal of the UZ1 bacteriophage after 1 h of exposure, whereas 5.4 mg L À1 of ionic silver (Ag þ ) showed a similar 4 log removal after 5 h (De Gusseme et al, 2010).…”

Lack of Involvement of Fenton Chemistry in Death of Methicillin-Resistant and Methicillin-Sensitive Strains of Staphylococcus aureus and Destruction of Their Genomes on Wet or Dry Copper Alloy Surfaces

“…The use of biocidal surfaces may play a role in preventing infection transmission from contaminated surfaces when combined with stringent cleaning regimes. Laboratory studies have suggested that copper surfaces may be effective against a range of bacteria, fungi, and viruses (8)(9)(10)(11) and that the irreversible pathogen nucleic acid destruction observed may allay fears of biocide resistance (12). A previous study observed that strains of MRSA were killed on copper surfaces in simulated wet-droplet contamination (13).…”