Photo-inactivation of viruses in therapeutical plasma.

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.