Detection of oxidative damages on viral capsid protein for evaluating structural integrity and infectivity of human norovirus

The infectivity evaluation of noncultivatable viruses, such as human norovirus, is crucial to address needs for ensuring the safety in usage of water and marine products. In this work, we tested a new approach to evaluate viral particle integrity, in which oxidatively produced carbonyl groups on viral capsid protein were quantitatively detected. As a result, the decrease in the infectivity of human astrovirus, a representative enteric virus, positively correlated with the amount of oxidative damage on viral particles. Furthermore, when human norovirus was treated by 1 ppm free chlorine for 15 min, 49.93% of virions were recovered as oxidatively damaged particles, which represents a 5-fold increase over those treated by 0.5 ppm free chlorine for 15 min. The detection of the carbonylated viral particles could be a powerful tool for the evaluation of the decrease in the infectivity of noncultivatable viruses.