Sunlight Inactivation of Human Norovirus and Bacteriophage MS2 Using a Genome-Wide PCR-Based Approach and Enzyme...

Area of Science:

• Environmental microbiology
• Virology
• Water quality analysis

Background:

• Human norovirus (hNoV) causes significant gastrointestinal illness and is waterborne.
• Current detection methods like RT-PCR cannot differentiate infectious from inactivated viruses.
• Understanding viral inactivation in water is crucial for public health.

Purpose of the Study:

• To investigate the impact of simulated sunlight on human norovirus (hNoV) infectivity in clear water.
• To compare the photoinactivation mechanisms of hNoV with MS2 coliphage, a common surrogate.
• To assess genome-wide damage and capsid integrity during sunlight exposure.

Main Methods:

• Utilized a multiple long-amplicon RT-qPCR extrapolation approach to assess genome-wide damage.
• Employed enzymatic pretreatment to evaluate capsid damage.
• Used MS2 coliphage as an internal control for comparison.
• Simulated sunlight exposure in clear, sensitizer-free water.

Main Results:

• The genome-wide damage assay overestimated sunlight inactivation for hNoV, indicating spectral differences compared to UV.
• hNoV genomic RNA showed higher susceptibility to simulated sunlight degradation than MS2 RNA.
• Enzymatic pretreatment revealed greater capsid damage in hNoV compared to MS2.
• Differences in inactivation mechanisms between hNoV and MS2 were observed.

Conclusions:

• Standard genome-wide damage assays may overestimate sunlight inactivation of hNoV due to spectral differences.
• hNoV is susceptible to both genomic RNA degradation and capsid damage from simulated sunlight.
• Findings provide mechanistic insights into hNoV inactivation, crucial for water safety and surrogate selection.