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Photo-inactivation of viruses in therapeutical plasma
H Mohr1, B Lambrecht, H Schmitt
1German Red Cross Blood Transfusion Service Lower Saxony, Institute Springe.
Abstract:
Photodynamic virus inactivation of human fresh plasma is achieved by illuminating single units of plasma in their plastic containers with light from fluorescent tubes in the presence of the phenothiazine dye methylene blue. The effective dye concentration is 1 microM, i.e. approx. 300 micrograms per litre of plasma. Under the conditions used, all enveloped viruses tested so far have been sensitive to photodynamic treatment, although some had to be illuminated for a longer time than others. For example, under production conditions the infectivity of SFV-containing plasma was reduced by more than 7 log10 within five minutes, whereas 30 minutes were required to reduce the infectivity of plasma containing VSV by c. 5 log10. Among the non-enveloped viruses tested some were sensitive to photodynamic treatment (e.g. SV40 and calicivirus) and some were not (e.g. encephalomyocarditis and polioviruses). Using the optimized procedure, plasma proteins remain largely unaffected. Photodynamically treated fresh frozen plasma (FFP) has been routinely produced and distributed since February 1992. Requested reporting of adverse drug reactions indicates that the virus inactivated product is a well tolerated as conventional FFP.
Insights
Photodynamic inactivation using methylene blue dye effectively neutralizes enveloped viruses in fresh plasma. This method is well-tolerated and has been safely used in clinical settings since 1992.
Area of Science:
- Biomedical Science
- Virology
- Blood Product Safety
Background:
- Fresh frozen plasma (FFP) is a critical blood product.
- Viral contamination poses a significant risk to transfusion recipients.
- Existing viral inactivation methods may affect plasma protein function.
Purpose of the Study:
- To evaluate the efficacy of photodynamic virus inactivation (PVI) for human fresh plasma.
- To assess the impact of PVI on plasma protein integrity.
- To determine the safety and tolerability of PVI-treated plasma.
Main Methods:
- Illumination of plasma units with fluorescent light in the presence of 1 microM methylene blue dye.
- Testing inactivation efficacy against various enveloped and non-enveloped viruses (e.g., SFV, VSV, SV40, poliovirus).
- Assessing plasma protein integrity and monitoring adverse drug reactions.
Main Results:
- PVI effectively inactivated all tested enveloped viruses, with log10 reductions >7 for SFV and >5 for VSV.
- Some non-enveloped viruses showed sensitivity (SV40, calicivirus), while others did not (encephalomyocarditis, polioviruses).
- Optimized PVI procedures maintained plasma protein integrity, and treated FFP demonstrated comparable tolerability to conventional FFP.
Conclusions:
- Photodynamic virus inactivation is a highly effective method for neutralizing enveloped viruses in fresh plasma.
- The PVI process preserves the quality of plasma proteins.
- PVI-treated FFP is a safe and well-tolerated alternative to conventional FFP, enhancing blood product safety.