EX-VIVO HEPATIC GENE-TRANSFER IN MOUSE USING A DEFECTIVE HERPES-SIMPLEX VIRUS-1 VECTOR

A defective amplicon herpes simplex virus-1 (HSV-1) vector, HSVlac, wa s used to transfer an E. coli lacZ reporter gene into primary hepatocy tes. The lacZ gene was driven by the HSV immediate early (IE) 4/5 prom oter, Use of the HSVlac vector resulted in highly efficient gene trans fer, Because difficulties in culturing primary hepatocytes impose Limi tations in ex vivo gene therapy, we sought to determine whether use of the HSVlac vector could simplify gene transfer, Therefore, we incubat ed HSVlac with primary hepatocytes in suspension and found that the la cZ gene was still transferred with great rapidity and efficiency, To e xamine lacZ expression in transduced hepatocytes in vivo we used a mou se hepatocyte transplantation system. In congeneic recipients of prima ry hepatocytes transduced with HSVlac in suspension, the lacZ gene was expressed in Liver and spleen up to 2 weeks. However, survival of tra nsplanted hepatocytes, as well as persistence of HSVlac genome in reci pient organs, was demonstrated for up to an 11-week duration of the ex periment, These findings suggest that in vivo regulation of the HSV IE 4/5 promoter was responsible for the short-term expression of lacZ, wh ich should be overcome by the use of Liver-specific promoters, Therefo re, our results indicate the feasibility of hepatic gene transfer with a defective HSV-1 vector.