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Title:Inactivation mechanisms of adenovirus from exposure to polychromatic ultraviolet light irradiation
Author(s):Vazquez Bravo, Bernardo
Director of Research:Mariñas, Benito J.
Doctoral Committee Chair(s):Mariñas, Benito J.
Doctoral Committee Member(s):Shisler, Joanna L.; Nguyen, Thanh H.; Liu, Wen-Tso
Department / Program:Civil & Environmental Eng
Discipline:Environ Engr in Civil Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Ultraviolet Light
Inactivation Mechanisms
Abstract:Ultraviolet (UV) light is a drinking water treatment technology that has gained popularity as an alternative to control chlorine-resistant pathogens and comply with regulations on disinfection byproduct formation. Human adenovirus (HAdV) is found in water sources around the world and can cause respiratory, urinary, gastrointestinal, and eye infections. HAdV has emerged as a waterborne pathogen of concern due to its resilience against UV light inactivation. The ultraviolet disinfection guidance manual for the Long-Term 2 Enhanced Surface Water Treatment Rule in the United States has established a fluence (UV dose) of 186 mJ/cm2 to inactivate 99.99% of viruses based on adenovirus inactivation. There are different sources of UV light that are commercially available but the most commonly used are monochromatic low-pressure (LP) and polychromatic medium-pressure (MP) UV lamps. MP UV light is found more effective at inactivating human adenovirus than LP UV light. While LP UV disinfection has been largely studied, MP UV inactivation has been less investigated and the mechanisms by which MP UV inactivates adenovirus are not fully understood. The main goal of this research was to obtain a better understanding of the inactivation mechanisms that make MP UV light more effective than LP UV to control human adenovirus. In this research work the inactivation kinetics of human adenovirus type 2 (HAdV-2) after exposure to narrow wavelength bandwidths of polychromatic UV irradiation within the 200-300 nm range were characterized. Quantitative polymerase chain reaction (qPCR) and reverse transcriptase qPCR assays were used to elucidate stages in the adenovirus replication cycle that were disrupted after exposure to three UV wavelength ranges with peak emissions at 224, 254 and 280 nm. This research determined that association of HAdV-2 to the host cells was not inhibited by UV treatment at any of the wavelengths analyzed even after exposure to a fluence that would produce a reduction in virus infectivity greater than 99.99%. In contrast, early and late gene transcription, and viral DNA replication were inhibited to different extents by UV irradiation at all three peak emissions, which suggested that different mechanisms might be dominating such disruptions for each wavelength range. The findings of this work help to better understand the mechanisms by which polychromatic MP UV light inactivate human adenovirus and which components of the virus are affected by UV irradiation emitted at different wavelengths. This research provides valuable information that can be used to develop more effective and efficient treatment approaches that incorporate UV light technologies for water disinfection. Additionally, the presence of synergistic effects with the sequential application of polychromatic UV irradiation at different wavelength ranges, as well as the simultaneous application of monochromatic LP UV light and monochloramine were investigated. No explicit synergy was detected in any of the sequential configurations assessed. In contrast, the simultaneous application of LP UV light and monochloramine showed synergy between these two disinfectants; this aspect indicated potential for this configuration as an alternative to be further evaluated to control adenovirus in water treatment processes.
Issue Date:2018-04-17
Rights Information:Copyright 2018 Bernardo Vazquez Bravo
Date Available in IDEALS:2018-09-04
Date Deposited:2018-05

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