In Vitro Antiviral and Virucidal Activity of Ozone against Feline Calicivirus

Simple Summary Feline calicivirus (FCV) is a common pathogen of cats, displaying high contagiousness and resistance to many disinfectants. FCV infection can cause even fatal disease in cats. The virucidal efficacy of ozone (O3) has also been reported on naked viruses. In this study, the in vitro virucidal and antiviral activities of an ozone/oxygen (O3/O2) gaseous mixture were assessed against FCV. The antiviral activity of O3 was evaluated by exposing the virus to non-cytotoxic concentrations of the gaseous mixture. When confluent monolayers of CRFK cells were treated with the gas mixture after infection with FCV at a concentration of 50 mu g/mL for 90 s, significant antiviral activity was observed with a decrease in viral titer of 1.75 log10 TCID50/50 mu L. Virucidal activity was evaluated by exposing FCV to different concentrations (20, 35, and 50 mu g/mL) of the gaseous mixture at distinct contact times, and a reduction in the viral titer by up to 2.25 log10 TCID50/50 mu L was detected. The data obtained pave the way to the use of O3 as a disinfectant in cat environments at high risk of FCV transmission. Future studies will aim to assess the translational application of ozonation in disinfection of the food and beverage industry environments against human norovirus, which shares several biological similarities with FCV.Abstract The Caliciviridae family includes several viral pathogens of humans and animals, including norovirus (NoV), genus Norovirus, and feline calicivirus (FCV), genus Vesivirus. Due to their resistance in the environment, NoV and FCV may give rise to nosocomial infections, and indirect transmission plays a major role in their diffusion in susceptible populations. A pillar of the control of viruses resistant to an environment is the adoption of prophylaR1.6ctic measures, including disinfection. Since NoVs are not cultivatable in common cell cultures, FCV has been largely used as a surrogate of NoV for the assessment of effective disinfectants. Ozone (O3), a molecule with strong oxidizing properties, has shown strong microbicidal activity on bacteria, fungi, protozoa, and viruses. In this study, the virucidal and antiviral activities of an O3/O2 gas mixture containing O3 were tested at different concentrations (20, 35, and 50 mu g/mL) for distinct contact times against FCV. The O3/O2 gas mixture showed virucidal and antiviral activities against FCV in a dose- and contact time-dependent fashion. Ozonation could be considered as a valid strategy for the disinfection of environments at risk of contamination by FCV and NoV.