Mutagenesis in sequence encoding of human factor VII for gene therapy of hemophilia

Background: Current treatment of hemophilia which is one of the most common bleeding disorders, involves replacement therapy using concentrates of FVIII and FIX. However, these concentrates have been associated with viral infections and thromboembolic complications and development of antibodies. The use of recombinant human factor VII (rhFVII) is effective for the treatment of patients with hemophilia A or B, who develop antibodies (referred as inhibitors) against replacement therapy, because it induces coagulation independent of FVIII and FIX. However, its short half-life and high cost have limited its use. One potential solution to this problem may be the use of FVIIa gene transfer, which would attain continuing therapeutic levels of expression from a single injection. The aim of this study was to engineer a novel hFVII (human FVII) gene containing a cleavage site for the intracellular protease and furin, by PCR mutagenesis. Methods: The sequence encoding light and heavy chains of hFVII, were amplified by using hFVII/pTZ57R and specific primers, separately. The PCR products were cloned in pTZ57R vector. Results and discussion: Cloning was confirmed by restriction analysis or PCR amplification using specific primers and plasmid universal primers. Mutagenesis of sequence encoding light and heavy chain was confirmed by restriction enzyme. Conclusion: In the present study, it was provided recombinant plasmids based on mutant form of DNA encoding light and heavy chains. Joining mutant form of DNA encoding light chain with mutant heavy chain led to a new variant of hFVII. This variant can be activated by furin and an increase in the proportion of activated form of FVII. This mutant form of hFVII may be used for gene therapy of hemophilia.