Purpose: The purpose of this project was to compare the persistence of HuNoV suspended in vomitus [using simulated gastric fluid (SGF), pH 2.5] to that suspended in phosphate buffered saline (PBS, pH 7.4).
Methods: A representative outbreak HuNoV strain (GII.4) was suspended in SFG or PBS, and the same solution inoculated on stainless steel coupons. The suspensions and coupons were held at room temperature for up to 42 days, with periodic recovery of virus inoculum. Viral RNA was extracted and quantified by RT-qPCR targeting the orf 1-orf 2 junction, with and without a prior RNase pre-treatment.
Results: There were no statistically significant differences (P > 0.05) between virus persistence over time when comparing RT-qPCR assays with and without prior RNase treatment except for when HuNoV was diluted in PBS and used in surface studies. In suspension assays, the genome copy number of HuNoV GII.4 suspended in SGF decreased by 1.0 log over 42 days, while that for the virus suspended in PBS dropped by 0.1 log. When inoculated on stainless steel coupons, the HuNoV GII.4 genome copy number decreased by 0.03 log in 42 days for inoculum diluted in SGF, while a decrease of 2.2 log was observed for the PBS inoculum. In both cases, there were statistically significant (P < 0.05) differences between virus persistence in SGF when compared to PBS.
Significance: This study demonstrates that HuNoV suspended in vomitus-like material can persist for long periods. Such environmental persistence likely contributes to foodborne transmission, as contaminated surfaces serve as a source of contamination to foods, especially during storage or preparation.