Purpose: We aimed to determine survival of HuNoV surrogates on hard and soft surfaces under environmentally relevant conditions.
Methods: Shaved wool carpet fibers, nylon carpet fibers (0.1 g), and glass coverslips were inoculated with HuNoV surrogates, feline calicivirus (FCV) strain F9 and murine norovirus (MNV) strain 1 at a titer of ca. six log pfu/sample then held at 30% or 70% relative humidity (RH) at 25°C. Surrogates were recovered from carpets using 0.01M PBS + 0.02% Tween 80 in our mini-spin column method and from glass using a previously published method at selected sampling dates. Surrogates were quantified using standard plaque assay and RT-qPCR.
Results: FCV survived for up to 15, 3, and 3 days at 30% RH on wool, nylon, and glass, respectively, and up to 7, 1, and 0 days at 70% RH on wool, nylon, and glass, respectively. MNV survived for up to 15, 7, and 7 days at 30% RH on wool, nylon and glass, respectively, as compared to 7, 3, and 3 days at 70% RH on wool, nylon, and glass, respectively. The highest titer reduction ranged from 3 to <5.3 log pfu/sample when surrogates were enumerated by plaque assay. Minimal reduction (<1.1 log over 60 days) in surrogate genomic copies as determined by RT-qPCR was observed for both environments, excluding glass at 70% RH.
Significance: This is the first study to determine survival of HuNoV surrogates on carpet under varying environmental conditions. Results indicate HuNoV surrogates can survive on carpet suggesting carpets could be an exposure source to HuNoV.