The replication-defective (E1-deleted) HAdV5-based vectors expressing the green fluorescent protein (HAdV5-GFP) and the human PUMA−β protein (HAdV5-PUMA) under the control of the CMV immediate-early promoter were propagated in HEK293 cells. The HAdV5-null vector, harboring no transgene in the E1-deleted region of its genome, was purchased from GeneCust (Dudelange, Luxembourg). The vector stocks were prepared and purified by CsCl gradient ultracentrifugation according to conventional methods14, 22, 23. The recombinant baculovirus (BV) vector expressing CAR (BVCAR) was derived from the Autographa californica Multiple Nucleopolyhedrosis virus (AcMNPV) by inserting the human CAR-encoding sequence into the Nhe I and Kpn I cloning sites of pBlueBac (Life Technologies) under the control of the polyhedrin promoter14. The BV vector expressing GFP under the CMV promoter (BV-GFP) was a kind gift of Norman J. Maitland (University of York, UK). BV vectors were propagated by infection of Sf9 cells at a multiplicity of infection (MOI) of 1–514. The infected cell culture media were harvested at 48 h post-infection and clarified by centrifugation for 10 min at 2400 r.p.m. Concentrated stocks of BV vectors were prepared by ultracentrifugation of the infected cell supernatant through a 20% sucrose cushion at 30,000 r.p.m. for 1 h at 4 °C. The viral pellet was then resuspended in sterile phosphate-buffered saline (PBS) with gentle shaking overnight at 4 °C, and used for transduction assays.