Integrin α3β1 is an Alternative Cellular Receptor for Adenovirus Serotype 5

Many adenovirus serotypes enter cells by high-affinity binding to the coxsackievirus-adenovirus receptor (CAR) and integrin-mediated internalization. In the present study, we analyzed the possible receptor function of α3β1 for adenovirus serotype 5 (Ad5). We found that penton base and integrin α3β1 could interact in vitro. In vivo, both Ad5-cell binding and virus-mediated transduction were inhibited in the presence of anti-α3 and anti-β1 function-blocking antibodies, and this occurred in both CAR-positive and CAR-negative cell lines. Peptide library screenings and data from binding experiments with wild-type and mutant penton base proteins suggest that the Arg-Gly-Asp (RGD) in the penton base protein, the best known integrin binding motif, is only part of the binding interface with α3β1, which involved multiple additional contact sites.