Purpose: This study assessed pulsed light efficiency for the disinfection of liquid media contaminated with human norovirus surrogate (MNV-1) according to their composition. The mechanisms involved in the inactivation of MNV-1 were also investigated.
Methods: Viruses were exposed to pulsed light in several suspensions (PBS buffer, hard water, mineral water, turbid water and sewage treatment effluent) to different fluences (from 0.7 to 9.0 J.cm-2) in a Xenon SINTERON 500 device. The log reductions of infectious MNV-1 were determined by performing plaque assay. The mechanisms involved in the antiviral activity of pulsed light were elucidated by analyzing the morphology (electron microscopy), the viral proteins (SDS-PAGE) and the RNA integrity (Bioanalyzer, UPLC-MS/MS) of the treated MNV-1.
Results: The pulsed light device emitted a broadband spectrum (200–1000 nm) at a fluence of 0.7 J.cm-2 per pulse with 2 % UV at 8 cm beneath the lamp. Reductions in viral infectivity exceeded 3 log in less than 3 seconds (5 pulses, 3.5 J.cm-2) in clear suspensions. The presence of bentonite (turbidity) interfered significantly with viral inactivation (P < 0.05), leading to a reduction of 2.0 ± 0.4 log at the maximum turbidity (1000 NTU). Furthermore, pulsed light appeared to disrupt MNV-1 structure and degrade viral protein and RNA.
Significance: The results suggest that pulsed light technology could provide effective alternative means of inactivating noroviruses in wastewaters, in clear beverages or in drinking water, and so contribute to reduce the burden of norovirus illness.