Inactivation of Tulane virus and feline calicivirus by aqueous ozone

Ongoing challenges with reproducible human norovirus cultivable assays necessitate the use of surrogates, such as feline calicivirus (FCV-F9) and Tulane virus (TV), during inactivation studies. Chlorine alternates used as control strategies include aqueous and gaseous ozone. This study aimed at determining the inactivation of FCV-F9 and TV by a portable ozone-generating device. FCV-F9 (similar to 8 log PFU/mL) orTV(similar to 6 log PFU/mL) in sterile-low-organic matter-containing-water was treated for 0-5 min, or in sterile-water containing newborn calf serum (high-organic matter/protein) for 0-38 min with similar to 1 ppm ozone (pH 7-6). Infectivity was determined from triplicate treatments using plaque assays. FCV-F9 titers significantly decreased by 6.07 log PFU/mL after 5 min in ozonated low-organic-matter- containing-water and was non-detectable (<= 2 log PFU/mL) after 36 min treatments in high-organic-matter-containing water (p < 0.05). TV titers decreased by 4.18 log PFU/mL after 4min in ozonated low- organic-matter water (non-detectable after 4.5min) and were non-detectable after 22.5 min treatments of high-organic-matter- containing water (p < 0.05). Overall, similar to 1 ppm aqueous ozone significantly decreased FCV-F9 by >6 log PFU/mL after 5min, TV to non-detectable levels (<= 2 log PFU/mL) after 4.5 min and required longer treatments (>32 and >20 min, respectively) for >= 4 log reduction in high-organic-mattercontaining water (p < 0.05). For ozone treatment of both viruses, the linear and Weibull models were similar for low-organic-load water, though the Weibull model was better for the high-organic load water. Prior filtration or organic load removal is recommended before ozonation for increased viral inactivation with decreased treatment-time.