UVC Inactivation of dsDNA and ssRNA Viruses in Water: UV Fluences and a qPCR-Based Approach to Evaluate Decay on Viral Infectivity

Abstract

Disinfection by low-pressure monochromatic ultraviolet (UVC) radiation (253.7 nm) became an important technique to sanitize drinking water and also wastewater in tertiary treatments. In order to prevent the transmission of waterborne viral diseases, the analysis of the disinfection kinetics and the quantification of infectious viral pathogens and indicators are highly relevant and need to be addressed. The families Adenoviridae and Polyomaviridae comprise human and animal pathogenic viruses that have been also proposed as indicators of fecal contamination in water and as Microbial Source Tracking tools. While it has been previously suggested that dsDNA viruses may be highly resistant to UVC radiation compared to other viruses or bacteria, no information is available on the stability of polyomavirus toward UV irradiation. Here, the inactivation of dsDNA (HAdV2 and JCPyV) and ssRNA (MS2 bacteriophage) viruses was analyzed at increasing UVC fluences. A minor decay of 2-logs was achieved for both infectious JC polyomaviruses (JCPyV) and human adenoviruses 2 (HAdV2) exposed to a UVC fluence of 1,400 J/m(2), while a decay of 4-log was observed for MS2 bacteriophages (ssRNA). The present study reveals the high UVC resistance of dsDNA viruses, and the UV fluences needed to efficiently inactivate JCPyV and HAdV2 are predicted. Furthermore, we show that in conjunction with appropriate mathematical models, qPCR data may be used to accurately estimate virus infectivity.

Human enteric viruses in a wastewater treatment plant: evaluation of activated sludge combined with UV disinfection process reveals different removal performances for viruses with different features

“…Also indicates a differential treatment efficiency depending on the virus since those single stranded RNA viruses (HAstV and NoV GII) were easier to removal than HAdV (a DNA virus) or RVA (a segmented double stranded RNA virus), which is in agreement with previous studies (Meng and Gerba ; Calgua et al . ; Qiu et al . ).…”

Assessment of human virus removal during municipal wastewater treatment in Edmonton, Canada

“…The dose of UV is important for disinfection with dose–response curves shown for various viruses (Calgua et al . ). Other factors also affect the virucidal effect, for example, polychromatic medium pressure lamps inactivated AdV more effectively than low‐pressure lamps at the same UV dose (Linden and Sobsey ).…”

“…However, no further removal was observed after UV treat-ment. Since both are double-stranded DNA viruses, AdV and JCV are expected to be more resistant to heat and UV inactivation as compared to RNA viruses (Meng and Gerba 1996;Linden and Sobsey 2006;Calgua et al 2014). Based on the findings that JCV, a virus only infectious to humans, is stable and easy to detect, it is reasonable to use JCV as an indicator for human viral contamination in environmental waters and for the assessment of decontamination during wastewater treatment (Fong and Lipp 2005;Bofill-Mas et al 2006;Okoh et al 2010).…”

“…Using cell culture and ICC-qPCR in this study, UV treatment was shown to result in more than 50% reduction in virus infectivity compared to PS. The dose of UV is important for disinfection with dose-response curves shown for various viruses (Calgua et al 2014). Other factors also affect the virucidal effect, for example, polychromatic medium pressure lamps inactivated AdV more effectively than low-pressure lamps at the same UV dose (Linden and Sobsey 2006).…”

Progress in the study of virus detection methods: The possibility of alternative methods to validate virus inactivation

“…Jursch et al, 2002;Pecson et al, 2009Pecson et al, , 2011Richards, 1999). For other viruses, such as enterovirus, adenovirus, rotavirus, and most wild-type HAV strains, that cannot produce CPEs or need a long time (4-30 days) to produce CPEs (Calgua et al, 2014;Casas & Suñén, 2010;Chapron, Ballester, Fontaine, Frades, & Margolin, 2000;Reynolds, 2004), cell culture is not very practical due to the interference of cell apoptosis with CPE observation when the culture time is longer than 3 weeks (Ko, Cromeans, & Sobsey, 2005;Ryu, Cashdollar, Fout, Schrantz, & Samuel, 2015), and when the initial amount of virus used for inoculation is very low, longer incubation times and more lab costs are needed (Ryu et al, 2015). Meanwhile, there is no practical standard for handlers to precisely determine the appearance of CPEs; hence, there has always been human error during virus titration (Richards, 1999).…”