Sunlight Inactivation of Human Virus and Surrogates: Towards an Understanding of the Role of Viral Structure, Spectral Shape, Environmental Matrix, and Weather Conditions
Bibliographic record
Abstract
Sunlight is a known biocide, and photo-driven inactivation is an important avenue for controlling viruses in both natural and engineered systems.However, there remain significant unknowns regarding damage to viruses by sunlight, including the impact of wavelength and viral characteristics.Herein, a systematic review of the literature and meta-analysis was conducted to identify inactivation rate constants (k-values) when exposed to solar wavelengths (280 -700 nm) for common human viruses and surrogates in natural and synthetic matrices.We identified 457 kvalues, with 356 for non-enveloped viruses.Extracted rate constants were transformed into UV fluence-normalized k-values to isolate the most photobiologically relevant wavelengths in the solar spectrum and reported for the first time in terms of energy, rather than time, based units.Each spectral region was assessed independently, with UVB illumination reporting the highest inactivation rates, UVA contributing to inactivation both in the presence and absence of photosensitizers, and visible light demonstrating no biocidal activity.To further develop our understanding of the role of varying wavelength, experiments were performed to determine the biological weighting function (BWF) for two bacteriophages commonly used as surrogates for human viruses, phi6 and MS2, under simulated sunlight conditions to assess endogenous inactivation.Viral suspensions in buffer were exposed to simulated sunlight for 8 hours through one of five optical filters with a 50% cutoff wavelength ranging between 280 and 395 nm.Calculating the BWFs of MS2 and phi6 demonstrated their comparative sensitivity to endogenous photoinactivation, with phi6 demonstrating an increased sensitivity to longer wavelengths; the first BWF reported for an enveloped virus or surrogate.Furthermore, inactivation experiments with varying carbon concentrations (0, 5 10, 20 mg/L) of Suwannee River natural organic matter were conducted to compare the relative importance of the exogenous vs endogenous pathway.Laboratory studies were complemented with aquatic mesocosm experiments performed in a fresh water glacial lake, Lac Hertel near Mont-St-Hilaire, Québec.Specifically, phi6 and MS2 bacteriophages, along with wastewater samples, were diluted into lake water and enclosed in dialysis bags.These bags were subsequently fixed in mesocosm and exposed to natural sunlight for a duration of four days.The dialysis bags were strategically positioned at two different depths within the water column to evaluate the effects of light attenuation and varying light penetration XIV in the lake water.This setup allowed for a detailed examination of how sunlight exposure at different depths impacts pathogen viability.Additionally, meteorological data from a weather station located near the lake were collected and analyzed to assess the impact of cloud cover and other weather conditions on the inactivation process and rates.Based on the results, the linear mix model has been built and emphasized that the inactivation rate constants can be significantly affected by weather conditions, time of the day, water depth, humidity and viral types.Overall, this thesis aimed to model and predict the inactivation processes for viruses with variant structures from lab environment to natural environment.The findings indicate that enveloped viruses show increased sensitivity to sunlight and the matrix composition relative to nonenveloped viruses.Both endogenous and exogenous inactivation were identified as significant mechanisms affecting both types of viruses.Furthermore, the composition variations resulted in distinct absorbance spectra, highlighting the importance of considering and evaluating the differences between laboratory conditions and natural environments in future research.In summary, this comprehensive study further elucidates the differential photoinactivation mechanisms of various viruses under sunlight, providing valuable insights for future virus monitoring and inactivation strategies.XV
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.013 | 0.022 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.010 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".