title: Inactivation efficiency and mechanism of UV-TiO2photocatalysis against murine norovirus using a solidified agar matrix.
abstract: Human norovirus (HuNoV) is the primary cause of viral gastroenteritis worldwide. Fresh blueberries are among high risk foods associated with norovirus related outbreaks. Therefore, it is important to assess intervention strategies to reduce the risk of foodborne illness. The disinfection efficiency of decontamination methods is difficult to evaluate for fruits and vegetables due to an inconsistent degree of contamination and irregular surface characteristics. The inactivation efficiency and mechanism of murine norovirus 1 (MNV-1, a surrogate for HuNoV) was studied on an experimentally prepared solidified agar matrix (SAM) to simulate blueberries using different wavelengths (A, B, C) of UV light both with and without TiO2photocatalysis (TP). MNV-1 was inoculated on exterior and interior of SAM and inactivation efficiencies of different treatments were investigated using a number of assays. Initial inoculum levels of MNV-1 on the SAM surface and interior were 5.2logPFU/mL. UVC with TiO2(UVC-TP) achieved the highest level of viral reduction for both externally inoculated and internalized MNV-1. Externally inoculated MNV-1 was reduced to non-detectable levels after UVC-TP treatment for 5min while there was still a 0.9 log viral titer after UVC alone. For internalized MNV-1, 3.2 log and 2.7 log reductions were obtained with UVC-TP and UVC alone treatments for 10min, respectively. The Weibull model was applied to describe the inactivation behavior of MNV-1, and the model showed a good fit to the data. An excellent correlation between the steady-state concentration of OH radicals ([OH]ss) and viral inactivation was quantified using a para-chlorobenzoic acid (pCBA) probe compound, suggesting that OH radicals produced in the UV-TP reaction were the major species for MNV-1 inactivation. Transmission electron microscopy images showed that the structure of viral particles was completely disrupted with UVC-TP and UVC alone. SDS-PAGE analysis showed that the major capsid protein VP1 was degraded after UVC-TP and UVC alone. Real-time RT-qPCR analysis showed that UVC-TP and UVC alone caused a reduction in the level of viral genomic RNA. Propidium monoazide (PMA) pretreatment RT-qPCR analysis showed that UVC-TP caused damage to the viral capsid protein in addition to viral genomic RNA. UVC both with and without TiO2was more effective for MNV-1 inactivation than UVB and UVA. Thus, UVC-TP disinfection aimed to reduce levels of food-borne viruses can inactivate viruses present on the surface and internalized in the interior of blueberries.
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea.
authors.forename: Daseul
authors.initials: D
authors.lastname: Park
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea.
authors.forename: Hafiz Muhammad
authors.initials: HM
authors.lastname: Shahbaz
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea.
authors.forename: Sun-Hyoung
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea.
authors.forename: Mijin
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea.
authors.forename: Wooseong
authors.initials: W
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea.
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Oh
authors.affiliation: Department of Food Science and Technology, Chung-Ang University, Anseong 17546, South Korea.
authors.forename: Dong-Un
authors.initials: DU
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 03722, South Korea. Electronic address: foodpro@yonsei.ac.kr.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Park
mesh_terms: D000362:Agar; D000818:Animals; D001386:Azides; D029798:Blueberry Plants / Q000821:virology*; D036022:Capsid Proteins / Q000378:metabolism; D002723:Chlorobenzoates / Q000737:chemistry; D004203:Disinfection / Q000379:methods*; D004591:Electrophoresis, Polyacrylamide Gel; D005517:Foodborne Diseases / Q000517:prevention & control* / Q000821:virology; D005638:Fruit / Q000821:virology*; D005759:Gastroenteritis / Q000517:prevention & control / Q000821:virology; D006801:Humans; D051379:Mice; D046529:Microscopy, Electron, Transmission; D029322:Norovirus / Q000502:physiology / Q000528:radiation effects*; D011419:Propidium / Q000031:analogs & derivatives; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D038301:Virus Inactivation / Q000187:drug effects* / Q000528:radiation effects*
chemical_list: D001386:Azides; D036022:Capsid Proteins; D002723:Chlorobenzoates; C533957:propidium monoazide; C009495:titanium dioxide; D011419:Propidium; D000362:Agar; D014025:Titanium; C040768:4-chlorobenzoic acid
keywords: Murine norovirus; PMA-pretreatment RT-qPCR; SDS-PAGE; Solidified agar matrix; TEM; UV-assisted TiO(2) photocatalysis