Comparing <i>Cryptosporidium</i> AND MS2 Bioassays—implications for UV Reactor validation

Mackey, Erin; Hargy, Thomas M.; Wright, Harold; Malley, James P.; Cushing, Robert S.

doi:10.1002/j.1551-8833.2002.tb09407.x

Cited by 18 publications

(9 citation statements)

References 6 publications

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“…As well as spores, viruses seem to be the pathogens that are the most resistant to UV radiation. In the present study, an MS-2 bacteriophage model was used to simulate viral contamination with a very stable viral strain [ 15 , 23 ]. MS-2 phages are commonly used as surrogates for stable viruses, e.g., adenoviruses, due to their similar size, shape, and genome composition [ 15 , 16 ].…”

Section: Discussionmentioning

confidence: 99%

UV-C Light-Based Surface Disinfection: Analysis of Its Virucidal Efficacy Using a Bacteriophage Model

Rudhart

Günther

Dapper

et al. 2022

IJERPH

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Background: The reprocessing of medical devices has become more complex due to increasing hygiene requirements. Previous studies showed satisfactory bactericidal disinfection effects of UV-C light in rigid and flexible endoscopes. Especially in the context of the current COVID-19 pandemic, virucidal properties are of high importance. In the present study, the virucidal efficacy of UV-C light surface disinfection was analyzed. Methods: MS-2 bacteriophages were applied to the test samples and irradiated by UV-C light using the UV Smart D25 device; unirradiated test samples were used as controls. A dilution series of the samples was mixed with 1 × 108 Escherichia coli and assayed. Results: 8.6 × 1012 pfu could be harvested from the unprocessed test samples. In the control group without UV-C exposure, a remaining contamination of 1.2 × 1012 pfu was detected, resulting in a procedural baseline reduction rate with a LOG10 reduction factor of 0.72. The LOG10 reduction factor was found to be 3.0 after 25 s of UV-C light exposure. After 50 and 75 s of UV-C radiation LOG10 reduction factors 4.2 and 5.9, respectively, were found, with all reductions being statistically significantly different to baseline. Conclusions: The tested UV system seems to provide a significant virucidal effect after a relatively short irradiation time.

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Section: Discussionmentioning

confidence: 99%

UV-C Light-Based Surface Disinfection: Analysis of Its Virucidal Efficacy Using a Bacteriophage Model

Rudhart

Günther

Dapper

et al. 2022

IJERPH

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“…MS2 is commonly used in the water treatment industry as a surrogate for enteroviruses because of its similar size, shape, and genome composition (9,14). It serves as a biodosimeter for UV disinfection studies (15) and for UV reactor validation in North America (14,16). For reactor validation, MS2 is also used as a surrogate for Cryptosporidium and adenovirus, despite the differences in UV sensitivity and spectral sensitivity between these microorganisms.…”

mentioning

confidence: 99%

Comparison of UV-Induced Inactivation and RNA Damage in MS2 Phage across the Germicidal UV Spectrum

Beck

Rodríguez

Hawkins

et al. 2016

Appl Environ Microbiol

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151

123

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c Polychromatic UV irradiation is a common method of pathogen inactivation in the water treatment industry. To improve its disinfection efficacy, more information on the mechanisms of UV inactivation on microorganisms at wavelengths throughout the germicidal UV spectrum, particularly at below 240 nm, is necessary. This work examined UV inactivation of bacteriophage MS2, a common surrogate for enteric pathogens, as a function of wavelength. The bacteriophage was exposed to monochromatic UV irradiation from a tunable laser at wavelengths of between 210 nm and 290 nm. To evaluate the mechanisms of UV inactivation throughout this wavelength range, RT-qPCR (reverse transcription-quantitative PCR) was performed to measure genomic damage for comparison with genomic damage at 253.7 nm. The results indicate that the rates of RNA damage closely mirror the loss of viral infectivity across the germicidal UV spectrum. This demonstrates that genomic damage is the dominant cause of MS2 inactivation from exposure to germicidal UV irradiation. These findings contrast those for adenovirus, for which MS2 is used as a viral surrogate for validating polychromatic UV reactors. UV irradiation is a common method of disinfection in the water treatment industry. UV light induces damage to the genomes of bacteria, protozoa, and viruses, breaking bonds and forming photodimeric lesions in nucleic acids, DNA, and RNA (1, 2). These lesions prevent both transcription and replication and ultimately lead to inactivation of the microorganisms (3, 4). Direct UV damage to nucleic acids occurs at the wavelengths absorbed by DNA and RNA, in the germicidal UV region between 200 and 300 nm (5, 6). In this wavelength range, however, UV light also damages other cellular and viral components, causing, for example, photochemical reactions in proteins and enzymes (7,8). For this reason, UV sources that emit polychromatic light, across the germicidal UV spectrum, are considered more effective at inactivating certain pathogens than sources that emit monochromatic light at 253.7 nm (9-12). As polychromatic sources become more common, more research is being undertaken to understand the mechanisms of inactivation occurring in pathogens exposed to polychromatic UV irradiation.Male-specific (MS2) coliphage is a single-stranded RNA virus. It infects strains of Escherichia coli that produce F ϩ pili, which serve as viral receptors. The virion consists of a short singlestranded RNA genome (3,569 bases) surrounded by an icosahedral protein capsid, 27 nm in diameter (13). MS2 is commonly used in the water treatment industry as a surrogate for enteroviruses because of its similar size, shape, and genome composition (9,14). It serves as a biodosimeter for UV disinfection studies (15) and for UV reactor validation in North America (14, 16). For reactor validation, MS2 is also used as a surrogate for Cryptosporidium and adenovirus, despite the differences in UV sensitivity and spectral sensitivity between these microorganisms. Recent interest has grown regarding microbial ...

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“…More recent investigations, using animal infectivity to assess oocyst survival, have shown UV to be an effective disinfectant of C. parvum oocysts, achieving 2‐log 10 inactivation at 2 mJ/cm 2 (Shin et al, 2001) and 4‐log 10 inactivation at 8 mJ/cm 2 (Clancy et al, 2000). Several other studies corroborated these findings that C. parvum is susceptible to inactivation by low doses of UV light (Mackey et al, 2002; Craik et al, 2001; Mofidi et al, 2001; Hargy et al, 2000; Bukhari et al, 1999). Each of these studies used Iowa strain oocysts.…”

Section: Uv Backgroundmentioning

confidence: 67%

Susceptibility of five strains of Cryptosporidium parvum oocysts to UV light

Clancy¹,

Marshall²,

Hargy³

et al. 2004

Journal AWWA

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Previous evaluations of the effect of ultraviolet (UV) light on Cryptosporidium parvum oocysts have been limited to a single strain—the Iowa strain. This study investigated the response of five strains of C. parvum to UV. A collimated beam apparatus was used to apply controlled doses of monochromatic (254 nm) UV to oocysts of the Iowa, Moredun, Texas A&M, Maine, and Glasgow strains. Irradiation was measured using a calibrated radiometer and sensor. Inactivation was quantified through animal infectivity by inoculation of cohorts of CD‐1 neonatal mice with UV‐treated and untreated control oocysts of each strain followed by examination of intestinal sections for infection using hemotoxylin and eosin staining. A UV light dose of 10 mJ/cm2 achieved at least 4‐log10 inactivation of all strains evaluated. All five strains of C. parvum were shown to be highly susceptible to low levels of UV light.

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Comparing Cryptosporidium AND MS2 Bioassays—implications for UV Reactor validation

Cited by 18 publications

References 6 publications

UV-C Light-Based Surface Disinfection: Analysis of Its Virucidal Efficacy Using a Bacteriophage Model

UV-C Light-Based Surface Disinfection: Analysis of Its Virucidal Efficacy Using a Bacteriophage Model

Comparison of UV-Induced Inactivation and RNA Damage in MS2 Phage across the Germicidal UV Spectrum

Susceptibility of five strains of Cryptosporidium parvum oocysts to UV light

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