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Updated: Aug 24, 2026
In Vitro Analysis of Myd88-mediated Cellular Immune Response to West Nile Virus Mutant Strain Infection
Published on: November 27, 2014
West Nile virus in plasma is highly sensitive to methylene blue-light treatment
Harald Mohr1, Joseph Knüver-Hopf, Ute Gravemann
1Blood Center of the German Red Cross Chapters of NSTOB, Institute Springe, Germany. hmohr@bsd-nstob.de
Background:
The epidemic of West Nile virus (WNV) in the US resulted in cases of transfusion-transmitted WNV. Effective pathogen reduction methods could have removed this infectious agent from the blood supply We have evaluated the efficacy of photodynamic treatment of fresh frozen plasma (FFP) with methylene blue (MB), a decontamination method applied in several European countries.
Study Design And Methods:
FFP units (300 ml each) were spiked with WNV. MB was added, and the units were illuminated with white or monochromatic yellow light. WNV infectivity was determined by bioassay. WNV-RNA was quantitated by real-time PCR. The inactivation of WNV was investigated under standard and under suboptimal conditions, respectively. In addition, rechallenge experiments with multiple addition of WNV at maximal load (approx. 105 CFU/ml) and repeated illumination without replenishing MB were performed.
Results:
Complete inactivation of WNV was achieved by MB (0.8-1 mmol/l) and illumination with white light (30,000-45,000 Lux) within 2 min. White yellow light 20-40 J/cm(2) (2.5-5 min) were sufficient for inactivation by 5.75 log10-steps. The rechallenge experiments revealed the substantial reserve capacity of the procedure to inactivate WNV. Quantitative PCR indicated that the viral RNA was rapidly destroyed.
Conclusion:
All experimental data demonstrate the enormous potency of phototreatment with MB to inactivate WNV in plasma.
Insights
Photodynamic treatment with methylene blue effectively inactivates West Nile virus (WNV) in fresh frozen plasma (FFP). This study demonstrates the potent capability of this method to safeguard blood supplies from WNV transmission.
Area of Science:
- Blood safety research
- Virology
- Photochemistry
Background:
- West Nile virus (WNV) poses a risk of transfusion-transmitted infections in the US.
- Pathogen reduction technologies are crucial for blood supply safety.
- Photodynamic treatment with methylene blue (MB) is a potential decontamination method.
Purpose of the Study:
- To evaluate the efficacy of photodynamic treatment using methylene blue (MB) and light for inactivating West Nile virus (WNV) in fresh frozen plasma (FFP).
- To assess the robustness of the WNV inactivation process under various conditions.
Main Methods:
- Fresh frozen plasma (FFP) units were spiked with WNV.
- Methylene blue (MB) was added, followed by illumination with white or yellow light.
- WNV infectivity was assessed via bioassay, and WNV-RNA levels were quantified using real-time PCR.
- Rechallenge experiments were conducted to evaluate the method's capacity.
Main Results:
- Complete WNV inactivation was achieved within 2 minutes using MB and white light.
- Light exposure of 20-40 J/cm(2) resulted in a 5.75 log10-step reduction in WNV.
- Rechallenge experiments confirmed the method's substantial WNV inactivation capacity.
- Quantitative PCR showed rapid destruction of WNV-RNA.
Conclusions:
- Photodynamic treatment with MB demonstrates significant potency in inactivating WNV in plasma.
- This method offers a promising approach for pathogen reduction in blood products.
- The findings support the use of MB phototreatment for enhancing blood safety against WNV.
