Purpose: To characterize the destruction of HuNoV after exposure to five copper alloy surfaces (ranging from 60-99.9% copper).
Methods: Diluted stool positive for GI.6 or GII.4 HuNoV or GII.4 virus-like particles (VLPs) were placed onto copper or stainless steel (control) surfaces and recovered by elution at various time points (0 to 240 minutes). To assess HuNoV genome integrity after exposure, viral RNA was extracted and analyzed by RT-qPCR. To assess capsid integrity, exposed VLPs were visualized by transmission electron microscopy (TEM) and also analyzed by SDS-PAGE/Western blot. Additionally, a histo-blood group antigen (HBGA) binding assay was used to evaluate VLP receptor binding ability after exposure to copper surfaces.
Results: Exposure to copper surfaces resulted in higher reduction of HuNoV genome copy number compared to stainless steel surfaces (P < 0.05). Pure copper surfaces reduced HuNoV genome copy number by 4-log RT-qPCR units within 30-60 minutes. As visualized by TEM, exposure to copper (but not stainless steel) resulted in VLP clumping and destruction within 120 and 240 minutes, respectively. Exposure to copper surfaces resulted in significant reduction in protein band intensity by SDS-PAGE/Western blot (P < 0.05) and reduced the ability of VLPs to bind to their HBGA receptor (P < 0.05).
Significance: The results demonstrate that exposure to copper alloy surfaces results in the destruction of the genome and capsid of HuNoV. These surfaces may have utility in preventing spread of HuNoV in settings such as restaurants, schools, and hospitals.