Chlorine Dioxide Gas for the Inactivation of Human Norovirus Genogroup II on Formica Coupons

Introduction: Human noroviruses (HuNoV), particularly genogroup II (GII), are predominant causes of non-bacterial gastroenteritis worldwide. Tulane virus (TV) is a cultivable HuNoV surrogate used to determine HuNoV inactivation methods. Chlorine dioxide (ClO₂) gas, a strong oxidizer, is being researched to determine antiviral effects against foodborne viruses.

Purpose: The objective of this study was to determine the ability of ClO₂ gas to inactivate HuNoV GII and TV on formica surfaces at room temperature.

Methods: HuNoV GII and TV preconditioned on formica coupons for 15 min were treated with 4 and 8 mg/L ClO₂ gas for 0, 1, 3, 5, and 8 min at 25°C and ~85% relative humidity. Viruses were recovered using Tris-glycine-beef extract buffer. HuNoV GII was detected by RNA heat-release and SYBR Green I-based RT-PCR with previously published MON primers and TV was detected by plaque assays. Each experiment was carried out in duplicate and replicated thrice.

Results: HuNoV GII, at initial 6 log RT-PCR units, was reduced by 1, 2, and 3 logs (based on end-point dilution) with 4 mg/L ClO₂ gas. TV showed reductions of 1.16 log after 1 min and to non-detectable levels (≥5 log) after 3 min with the higher 8 mg/L ClO₂ gas concentration.

Significance: ClO₂ gas treatments show promise in preventing HuNoV GII transmission and outbreaks.