Heat-denatured lysozyme could be a novel disinfectant for reducing hepatitis A virus and murine norovirus on berry fruit

Abstract

Hepatitis A virus (HAV) is well known worldwide as a causative virus of acute hepatitis. In recent years, numerous cases of HAV infection caused by HAV-contaminated berries have occurred around the world. Because berries are often consumed without prior heating, reliable disinfection of the raw fruit is important in order to prevent HAV outbreaks. Previous studies have found that murine norovirus strain 1 (MNV-1) and human norovirus GII.4 were inactivated in heat-denatured lysozyme solution. In this study, we investigated whether or not heat-denatured lysozyme is effective in inactivating HAV and whether it could be an effective disinfectant for berries contaminated with HAV or MNV-1.We examined the inactivating effect of heat-denatured lysozyme on three strains of HAV and found that it reduced the infectivity of all three strains. We then immersed blueberries and mixed berries into solutions of HAV or MNV-1, and disinfected them by soaking them in 1% heat-denatured lysozyme for 1min. Consequently, the infectious HAV and MNV-1 contaminating the berries were decreased by >3.1 log units in all samples.Our results demonstrate that heat-denatured lysozyme effectively inactivates HAV and suggest that heat-denatured lysozyme may be an effective disinfectant for berry fruit, which is a potential source of HAV food poisoning.