Survivability of Norovirus Surrogate on Various Food-contact Surfaces

Introduction: Norovirus (NoV) is an environmental threat for humans causing foodborne and waterborne disease and spread easily from one infected person to another. NoV can survive on various environmental surfaces thus it can affect an incident of cross-contamination. However, there is lack of information about the survivability of NoV depending on variety types of food contact surfaces.

Purpose: The objective of this study was to investigate the survivability of NoV using a NoV surrogate, murine norovirus (MNV-1) on six different food-contact surfaces during the 28 days of storage. 10⁵PFU of MNV were inoculated on six different coupons and the contaminated coupons were kept for 28 days (4 weeks) at room temperature.

Methods: The prepared coupons (ceramic, rubber, wood, glass, plastic and stainless steel) were soaked in 70% ethanol for 1h and washed with distilled water. We inoculated 10⁵ PFU of MNV-1 on six different coupons and kept for 4 weeks (28 days) at room temperature. Each of coupons was taken out at the point of determined times, and 50 μl of elution buffer (0.05 M glycine-0.14 M NaCl buffer (pH 7.5)) was pipetted onto the coupons and left at room temperature for 10 minutes. The coupons were placed into 15 ml conical tubes with 200 μl of elution buffer and vortexed for 10 minutes to elute virus. Then, each eluted viral suspension was 10-fold serially diluted and analyzed by plaque assay. The value of d_R(time required to reduce virus by 90%) was determined by Weibull models.

Results: On the food-contact surfaces, the reduction of MNV was at maximum 2.28 log PFU/coupon on stainless steel, while at minimum 1.29 log PFU/coupon on wood. The highest reduction values were achieved on stainless steel, plastic, rubber, glass, ceramic, and wood, orderly on the virus. The values of D_R (time required to reduce virus by 90%) on the survival plots of MNV determined by modified Weibull model were 277.60 h (R²=0.99) on ceramic, 492.59 h (R²=0.98) on wood, 173.56 h on rubber (R²=0.98), 97.18 h (R²=0.94) on glass, 91.76 h (R²=0.97) on stainless steel, and 137.74 h (R²=0.97) on plastic. The infectivity of MNV on all food-contact surfaces was still active after 28 days.

Significance: This study shows that MNV-1 persists in an infective state on various food-contact surfaces for long periods of time. This study may provide valuable information to control the NoV on various food-contact surfaces for preventing foodborne disease.