Human Coronavirus 229E Remains Infectious on Common Touch Surface Materials

Warnes, Sarah L.; Little, Zoë R.; Keevil, C. William

The results from this study have shown that a relatively low concentration of enveloped respiratory viruses may retain infectivity on common hard surfaces for longer than previously thought and may present a real risk of infection to anyone who contacts a contaminated surface. However, human coronavirus 229E, an important pathogenic virus but also a surrogate for MERS coronavirus, which is structurally very similar, was rapidly inactivated on copper alloys. Inactivation results from a combination of direct copper ion attack and reactive oxygen species generation. The latter is particularly important as the copper content decreases, ensuring that rapid inactivation still occurs in alloys with lower percentages of copper. Therefore, incorporation of copper alloys in communal areas could help to reduce infection spread from touching surfaces contaminated with coronaviruses. This is especially important in infectious disease where the infectious dose is low, surface contamination is high, and effective therapies are limited. The mechanism of action of copper is complex and may be enhanced by radical formation but is ultimately nonspecific, ensuring continuous kill and inactivation of a wide range of pathogenic microorganisms with completely different morphologies. Concerns about the biocide resistance, possible concomitant drug resistance, and horizontal gene transfer that have been observed with other biocides (51) can be allayed because of the destruction of viral nucleic acid observed following exposure to copper surfaces. It is not feasible to cover every surface in copper, and many materials in the built environment, including stain- of the coronavirus genome revealed a reduction in copy number from virus exposed to copper and cartridge brass surfaces in reverse transcriptase real-time PCR. There was some reduction on stainless steel but none in viral suspension (lightest gray bars), suggesting that this was due to sample drying. (B) Analysis of the entire viral genome is represented in electrophoretic separation of viral RNA extracted from virus exposed to copper (lanes 1, 4, and 7), cartridge brass (lanes 2, 5, and 8), and stainless steel (lanes 3, 6, and 9) for 0 min (lanes 1 to 3), 120 min (lanes 4 to 6), and 240 min (lanes 7 to 9). The genomic RNA from virus exposed to copper and brass degraded with increased contact time. This did not occur on stainless steel; the genomic RNA remained as fragments too large to pass through the gel. However, the total amount of intact RNA was reduced at 4 h, possibly due to drying damage as seen in panel A. Lane 10 represents untreated virus, and the unmarked lane is a Bioline marker (Hyperladder I). The same procedure was used with mock-infected cells, revealing the same pattern of RNA breakdown following application to copper surfaces (not shown).