Conservation of fiber structure and CD46 usage by subgroup B2 adenoviruses.

Most subgroup B2 adenoviruses use CD46 as their primary receptor. Recent structural and mutagenesis studies suggested that Ad11 and Ad35 likely engage this receptor in a very similar fashion. However, no comparative studies assessing the cell-associated CD46 binding efficiencies of different Ad fibers have been performed. We solved the crystal structure of Ad35 fiber knob and constructed a model of the fiber knob complexed with CD46. Comparison of our model with that of Ad11-CD46 showed that despite a larger CD46-interacting region in the IJ loop of Ad11, the buried surface area was very similar, suggesting that both fiber knobs might exhibit similar binding. In support of this, cell based competition studies demonstrated almost identical binding efficiencies of Ad11 and Ad35 fibers to cell surface CD46. These findings shed further light on CD46 association by Ad and could impact the selection of novel Ad types for gene transfer.