Effect of ParAd41 on Ad41 attachment and postattachment step. ((a), (b)) Inhibition of Ad41 attachment. Ligands indicated above figures were allowed to interact with cells at 4°C. Different (a) or constant amounts (b) of Ad41 were allowed to attach to cells at 4°C and virus yield was assessed after one round of replication at 37°C, as described in the Section 2. (c) Postattachment cell entry of adenoviruses bearing different fiber proteins. The entry of Ad2Luc was compared to that of chimeric Ad5.LF40.Luc (Ad5:40-LF) and Ad5.SF40.Luc (Ad5:40-SF). Virus attachment was performed at 4°C for 2 h, and the luciferase expression was measured at one or three days after infection, respectively, for HeLa and Caco-2 cells.