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Factors affecting M13 bacteriophage inactivation by methylene blue photosensitization
H Abe1, S J Wagner, M Kuwabara
1Hokkaido Red Cross Blood Center, Sapporo, Japan.
Abstract:
We have investigated the factors that affect the virucidal activity of methylene blue (MB) photosensitization. The M13 bacteriophage was more rapidly inactivated at higher temperatures (6 degrees C < 24 degrees C < 38 degrees C). Rate constants for inactivation were 0.072, 0.139 and 0.260 (log10 inactivation)/ (J/cm2) at 6 degrees C, 24 degrees C and 38 degrees C, respectively. On the other hand, dye penetration into virus particles, which was monitored by the fluorescence of YOYO-1, was unchanged with incubation temperature. These data suggest that temperature dependency of M13 inactivation was due to factors other than dye permeability. The pH of the virus suspension also affected the rate of M13 inactivation by MB. The M13 bacteriophage was inactivated faster in basic suspensions and slower in acidic suspensions compared with neutral buffers. These results suggest that temperature and pH are factors that influence the extent of MB photosensitization, and hence, the control of these factors will be necessary for MB phototreatment of plasma products in transfusion medicine.
Insights
Higher temperatures and basic pH significantly enhance methylene blue (MB) photosensitization for inactivating M13 bacteriophage. Temperature affects inactivation rates more than dye permeability, suggesting other mechanisms are involved in MB phototreatment efficacy.
Area of Science:
- Photochemistry
- Virology
- Biophysics
Background:
- Methylene blue (MB) photosensitization is a promising virucidal method.
- Understanding factors influencing MB efficacy is crucial for applications like plasma product treatment.
Purpose of the Study:
- To investigate the impact of temperature and pH on the virucidal activity of MB photosensitization against M13 bacteriophage.
- To elucidate the mechanisms behind temperature-dependent inactivation rates.
Main Methods:
- M13 bacteriophage inactivation assays were performed at varying temperatures (6°C, 24°C, 38°C).
- Dye penetration into virus particles was monitored using YOYO-1 fluorescence.
- Inactivation rates were quantified at different pH levels (acidic, neutral, basic).
Main Results:
- M13 bacteriophage inactivation rate increased significantly with temperature (0.072, 0.139, 0.260 log10 inactivation/(J/cm²) at 6°C, 24°C, 38°C).
- Dye permeability into viral particles remained constant across tested temperatures.
- Inactivation was faster in basic suspensions and slower in acidic suspensions compared to neutral buffers.
Conclusions:
- Temperature and pH are critical factors influencing the virucidal effectiveness of MB photosensitization.
- Temperature-dependent inactivation is likely due to mechanisms beyond simple dye permeability.
- Precise control of temperature and pH is essential for optimizing MB phototreatment in transfusion medicine and other applications.