[Optimizing parameters in photodynamic virus inactivation of fresh frozen plasma].

Fresh plasma from single-blood donations is virus-inactivated by illuminating the plasma units in their respective plastic bags with visible light for 1 h in the presence of 1 microM of the photoactive dye methylene blue. For "soft" viruses, e.g. the togavirus Semliki Forest, 0.3 microM are sufficient to achieve complete inactivation within 5-10 min. The infectious titer is reduced by 5-6 log 10 steps. To achieve the same degree of reduction in infectivity for more resistant viruses, e.g. vesicular stomatitis virus or SV 40, the virus-containing plasma at a dye concentration of 1 microM has to be light-treated for 30-45 min. More time is required at lower dye concentrations. These findings determined the conditions chosen for photodynamic virus inactivation of fresh plasma from single-blood donations.