Chlorine Dioxide Inactivation of Enterovirus 71 in Water and Its Impact on Genomic Targets

Abstract

To control the waterborne transmission of enterovirus 71­(EV71), which is associated with hand foot and mouth disease (HFMD), it is essential to know the inactivation effectiveness of disinfectants on EV71 in water. In this article, we present a comparative analysis of the effects on EV71 following exposure to chlorine dioxide (ClO₂) under different doses, pH, and temperature conditions. We show that the EV71 exhibited strong resistance to ClO₂ (more than the MS2 standard) and that <i>C_t</i> value ranges required for a 4-log reduction of EV71 in buffered, disinfectant demand-free water at pH 7.2 and 20 °C by ClO₂ were 4.24–6.62 mg/L·min according to the efficiency factor Hom model. ClO₂ inactivation of the virus was temperature- and pH-dependent. The virucidal efficiency was higher at pH 8.2 than at pH 5.6 and pH 7.2 and higher at 36 °C than at 4 and 20 °C. In addition, we also observed the impact of ClO₂ on the entire viral genome using RT-PCR, which indicated that the 5′ noncoding region (5′-NCR) within the EV71 genome, specifically the 1–118 nt region, was the most easily damaged by ClO₂ and correlated with viral infectivity. Our study has not only provided guidelines for EV71 disinfection strategies of waste and drinking water, but also confirmed the importance of the 5′-NCR for EV71 infectivity and may demonstrate a general inactivation by ClO₂ of enteric virus by damaging the 5′-NCR. Furthermore, 5′-NCR can be used as a target region for PCR to investigate infectious virus contamination in environmental water and evaluate the inactivation effects of ClO₂