Persistence and Disinfection profiles of Hypochlorite and Alcohols against Human Norovirus using Human Intestinal Enteroids

Geun Woo Park, Centers for Disease Control and Prevention

Kimberly Huynh, Verónica Costantini, Jan Vinjé. Division of Viral Diseases, Centers of Disease Control and Prevention, Atlanta, GA, USA

Prevention & Control (antivirals)

The potential of human intestinal enteroid (HIE) to assess the efficacy of disinfectants against human norovirus remains underexplored. We evaluated the surface persistence of human norovirus and the effectiveness of common active ingredients of disinfectants (ethanol, isopropanol, and sodium hypochlorite) against human norovirus using HIE. Ten µl of a clarified human norovirus stool specimen (GII.4 Sydney) was deposited on stainless steel coupons and dried up to 120 minutes to assess surface persistence. To assess the disinfection efficacy, virus-inoculated coupons were dried for 15 minutes, and then treated with 50 µl of different concentrations of sodium hypochlorite (5, 10, 25, 200 and 1000 ppm) or alcohols (ethanol or isopropanol) at 70% and 90% (v/v) for 5 min. The preparations were neutralized with 0.2% sodium thiosulfate for sodium hypochlorite-treated coupons or with 10% fetal bovine serum for alcohol-treated coupons, then inoculated on HIE monolayers and incubated for 1 and 72 hours at 37°C and 5% CO2. Infectious human norovirus titers were quantitatively calculated using the TCID50 method (improved Kärber). Persistence study showed that Viable human norovirus was detected up to 25 minutes post-inoculation but lost > 2.1 log after 60 minutes. Sodium hypochlorite as low as 10 ppm was effective against norovirus dried onto coupons by reducing the infectivity by more than 1.2 log. In contrast, both isopropanol and ethanol at 70% and 90% showed no reduction in human norovirus infectivity. Our data confirmed the utility of the HIE system in demonstrating the potential efficacy of commercially used disinfectants against human norovirus.