FIG. 5.
CARex-VP22- or CARex-Tat-mediated adenoviral infection can be competed by recombinant CARex lacking a functional PTD and is effectively inhibited by negatively charged heparin and/or heparan sulfate. (A) To block fiber knobs of AdLacZ, the virus was treated for 15 min with various amounts of supernatant from 293 cells expressing CARex. Then, purified CARex-VP22 or CARex-Tat was added at a final concentration of 1 nM, and the mixture was subjected to SKLU-1 cells for an infection period of 30 min. Infected cells were maintained for 48 h and infection efficacy was determined by measuring β-galactosidase activity in cellular extracts. (B) U2-OS (top) and HT1080 (bottom) cells were covered with medium containing 2 nM purified CARex-PTD fusion proteins and increasing amounts of heparan sulfate or heparin, as indicated. AdLacZ (MOI, 5) was added, and infection was carried out for 30 min. Infected cells were maintained for 48 h, and infection efficacy was determined by β-galactosidase assays of cellular extracts.