Pierre Meulien

Two independent domains of Factor VIII co-expressed using recombinant vaccinia viruses have procoagulant activity

Using recombinant DNA technology, the NH2 and COOH terminal domains of the human Factor VIII molecule were co-expressed in baby hamster kidney 21 (BHK21) cells using the vaccinia virus system. Procoagulant activity was detectable in cell supernatants, thus suggesting that the central portion present in the FVIII protein (domain B) is not required for FVIII function.

Expression of Recombinant Factor VIII Molecules in Mammalian Cells

Factor VIII (FVIII) is an essential cofactor involved in blood clotting. It functions in the intrinsic pathway of coagulation in the step where the activated form of factor IX (FIXa) activates in its turn factor X to FXa. Lack or malfunction of FVIII results in the chromosome X-linked bleeding disorder haemophilia A. In blood, FVIII circulates as a complex with von Willebrand factor (VWF) which serves as carrier molecule stabilising FVIII procoagulant activity and may target FVIII to damaged sites. At present, haemophiliacs are treated by replacement therapy with plasma derived products which pose well documented problems associated with low purity and risk of contamination by viral agents such as those causing hepatitis A, B, non-A non-B and AIDS.