Efficacy of a disinfectant containing silver dihydrogen citrate against GI.6 and GII.4 human norovirus.

AIMS: Human norovirus is a major public health burden and is resistant to numerous sanitizers and disinfectants. In this study, we tested the efficacy of an antimicrobial product containing a blend of silver ions and citric acid (silver dihydrogen citrate; SDC) against GI.6 and GII.4 HuNoV.

METHODS AND RESULTS: Pure(®) hard surface disinfectant (Pure Bioscience, El Cajon, CA) was evaluated using ASTM International virucidal suspension and stainless steel carrier assays. The effect of SDC (or citrate alone) exposure on viral integrity was evaluated using RT-qPCR, transmission electron microscopy, sodium dodecyl sulphate-polyacrylamide gel electrophoresis/Western blot analysis and a receptor-binding assay. Suspension assays showed a 4·0 log10 reduction in RNA copy number within 5 min, while carrier assays showed a 2·0-3·0 log10 reduction in 30 min. Incorporating a simulated soil load into the sample matrix significantly reduced product efficacy. Treated particles displayed deformation and aggregation, a 50% reduction in viral capsid protein band intensity, and an 80% reduction in histo-blood group antigen receptor-binding ability.

CONCLUSIONS: Our results suggest that SDC acts exclusively on the viral capsid, and shows efficacy against HuNoV when used on precleaned surfaces.

SIGNIFICANCE AND IMPACT OF THE STUDY: This study sheds light on the mechanisms and efficacy of a novel antimicrobial against HuNoV. Our results suggest: (i) silver ions exclusively target the viral capsid, and not the RNA genome; (ii) citrate is not crucial for HuNoV capsid deformation.