Purpose: We aimed to compare methods to recover a HuNoV surrogate, feline calicivirus, from carpets.
Methods: Wool and nylon carpet carriers (5 cm²) were inoculated at a titer of ca. 6 log pfu/carrier with a HuNoV surrogate, feline calicivirus (FCV) strain F9, and recovered immediately or held at 30% RH and 25°C for 1 h. FCV was recovered by either bottle extraction (BE), macrofoam tipped swab (MS), or a wet vacuum system (WVS). BE and MS were tested with 2 buffers: 0.01M PBS + 0.02% Tween 80 or ¼ strength Ringers solution, whereas the WVS was only compatible with Butterfield’s buffer. After recovery, BE and WVS solutions were concentrated via Amicon 30K tubes. Viruses were quantified via standard plaque assay.
Results: Recovery efficiency from nylon was 48.7 to 90.6%, 8.2 to 16.3%, and 11.8% when using BE, MS, and WVS, respectively, whereas recovery efficiency from wool was 33.3 to 76.8%, 46.0 to 74.0%, and 31.4% when using BE, MS, and WVS, respectively. Significantly more (P<0.05) infectious FCV was recovered when using BE and WVS compared to MS and more infectious FCV was recovered from wool than nylon carpets, excluding BE with ¼ strength Ringers solutions.
Significance: This is the first study to compare methods to recover viruses from carpets. BE and WVS exhibited higher recovery efficiencies compared to MS. However, each method demonstrates merit for use under different conditions, e.g. standard sanitizing testing and environmental monitoring.