Prediction of Photolysis Kinetics of Viral Genomes under UV254 Irradiation to Estimate Virus Infectivity Loss

UV254 irradiation disinfection is a commonly used method to inactivate pathogenic viruses in water and wastewater treatment. Model prediction method can serve as a pre-screening tool to quickly estimate the effectiveness of UV254 irradiation on emerging or unculturable viruses. In this study, an improved prediction model was applied to estimate UV254 photolysis kinetics of viral genomes (k(pred,genome)) based on the genome sequences and their photoreactivity and to correlate with the experimental virus infectivity loss kinetics (k(exp,infectivity)). The UV254 inactivation data of 102 viruses (including 2 dsRNA, 65 ssRNA, 33 dsDNA and 2 ssDNA viruses) were collected from the published experimental data with k(exp,infectivity) ranging from 0.016 to 3.49 cm(2) mJ(-1). The model had fairly good performance in predicting the virus susceptibility to UV 254 irradiation except dsRNA viruses (Pearson's correlation coefficient = 0.64) and 70% of k(pred,genome) fell in the range of 1/2 to 2 times of k(exp,infectivity). The positive deviation of the model often occurred for photoresistant viruses with low k(exp,infectivity) less than 0.20 cm(2) mJ(-1) (e.g., Adenovirus, Papovaviridae and Retroviridae). We also applied this model to predict the UV254 inactivation rate of SARS-CoV-2 (k(pred,genome) = 3.168 cm(2) mJ(-1)) and a UV dose of 3 mJ cm(-2) seemed to be able to achieve a 2-log removal by conservative calculation using 1/2k pred, genome value. This prediction method can be used as a prescreening tool to assess the effectiveness of UV254 irradiation for emerging/unculturable viruses in water or waste water treatment. (C) 2021 Elsevier Ltd. All rights reserved.