Thermal Inactivation of Human Immunodeficiency Virus in Lyophilised Blood Products Evaluated by ID50 Titrations

Inactivation of human immunodeficiency virus (HIV) in lyophilised small pool cryopree1p1tate, factor VIII concentrate, prothrombin complex and C1~esterase inhibitor concentrate by prolonged heat treatment (72 h, 60. C) was studied. Plasma products, inoculated prior to lyophilisation, had infectious titres ranging from I 07 to 1 QlO.s. Residual infectivity (TCID50) was assessed by multiple titrations on H9 cells in a macro system and subsequent detection of virus replication by de~ermining reverse .transcriptase activity. Kinetics of inactivation ·showed a biphasic pattern: during the first 8 ha variable TCID50 reduction up to 1 0 4·3 was observed, followed by an additional loss of 101-102.7 during the next 64 h. Heat treatment for 72 h resulted in a mean TCID5o reduction of 1 0 5. It is concluded that prolonged heat treatment may lead to the adequate prevention of HIV transmission by lyophilised plasma products.