VIRAL INACTIVATION OF LABILE BLOOD PRODUCTS

Viral inactivation is one of the possibilities to reduce the residual risk of blood products. It is now applied to all plasma derived produc ts (PDP). Application of such techniques to labile blood products (LBP ) is difficult for two main reasons: any method should inactivate cell -associated viruses and should avoid any injury of the cells constitut ing the active ingredient. Physical techniques may reduce the viral co ntent of cellular BPL (leucodepletion, washing, gamma irradiation), bu t none of them is active enough to comply with the present requirement s for efficacy. An important work has been dedicated to the developmen t of virus photoinactivation techniques. They consist of the addition of a photoreagent followed by illumination at an appropriate wavelengt h which results in a photochemical reaction responsible for the viral inactivation. Treatment of platelet concentrates by psoralen derivativ es and UV-A illumination significantly inactivate in vitro enveloped a nd naked viruses, free and cell-associated viruses and also sequences integrated in the viral genome. Recent progresses have led to these re sults without detectable functional alteration of platelets and mutage nicity. Viral inactivation of red blood cells yet did not reach the sa me level because hemoglobin does not allow the use of the photoreagent compounds applicable to platelet concentrates. Viral decontamination of fresh frozen plasma by solvent and detergent, active on enveloped v iruses, has been used in France since 1992. Other techniques of compar able efficacy, have received an agreement in other countries. The rese arch on viral inactivation of LBP could prove to be of great importanc e in the near future in bringing additional safety to patients not onl y for the residual viral risk but maybe also for the residual bacteria l risk of LBP.