Targeting a recombinant adenovirus vector to HCC cells using a bifunctional Fab-antibody conjugate

We developed a specific adenoviral gene delivery system with monoclonal ant ibody (mAb) AF-20 that binds to a 180 kDa antigen highly expressed on human hepatocellular carcinoma (HCC) cells. A bifunctional Fab-antibody conjugat e (2Hx-2-AF-20) was generated through AF-20 mAb crosslinkage to an anti-hex on antibody Fab fragment. Uptake of adenoviral particles and gene expressio n was examined in FOCUS HCC and NIH 3T3 cells by immunofluorescence; beta-g alactosidase expression levels were determined following competitive inhibi tion of adenoviral CAR receptor by excess fibre knob protein. The chimeric complex was rapidly internalized at 37 degrees C, and enhanced levels of re porter gene expression was observed in AF-20 antigen positive HCC cells, bu t not in AF-20 antigen negative NM 3T3 control cells. Targeting of recombin ant adenoviral vectors to a tumor associated antigen by a bifunctional Fab- antibody conjugate is a promising approach to enhance specificity and effic iency of gene delivery to HCC. (C) 2000 Academic Press.