Signaling antibodies complexed with adenovirus circumvent CAR and integrininteractions and improve gene delivery

Current adenoviral (Ad) vectors cannot be targeted to specific cell types d ue to the widespread distribution of the Ad receptor (CAR). Moreover, CAR a nd/or internalization receptors (alpha v integrins) are absent or present a t low levels on some cell types, rendering them resistant to Ad-mediated ge ne delivery. To address these problems, we have developed a novel vector ta rgeting approach that takes advantage of the common cell signaling pathways initiated by ligation of alpha v integrins and growth factor receptors. Re combinant growth factor/cytokines (TNF-alpha, IGF-1, EGF) which trigger pho sphatidylinositol-3-OH kinase (PI3K) activation, a signaling molecule invol ved in adenovirus internalization, were fused to a monoclonal antibody spec ific for the viral penton base. Ad vectors complexed with these bifunctiona l mAbs increased gene delivery 10 to 50-fold to human melanoma cells lackin g cry integrins. The bifunctional mAbs also enhanced gene delivery by fiber less adenovirus particles which cannot bind to CAR. Improved gene delivery correlated with increased virus internalization and attachment as well as P I3K activity. The use of bifunctional mAbs to trigger specific cell signali ng pathways offers a widely applicable method for bypassing the normal Ad r eceptors in gene delivery and potentially increasing the selectivity of gen e transfer.