THE STRUCTURE OF INTACT HUMAN RHINOVIRUS 14 COMPLEXED WITH Fab17-IA. Thomas J. Smith, Elaine S. Chase, Timothy Schmidt, Norman H. Olson, Timothy S. Baker, Department of Biological Sciences, Purdue University, West Lafayette, IN 49707

Antibodies are a major component of the immune response to picornaviruses. It has long been contended that antibody neutralization is due to large structural changes in the capsid upon binding. To test this hypothesis, we have used crystallography and electron microscopy to determine the structure of intact human rhinovirus (HRV14) complexed with Fab17-IA. The atomic structures of Fab17-IA and HRV14 were first used to interpret the ~25Å resolution image reconstruction. This model was used to calculate initial phases to 8Å resolution for the data from a frozen Fab17-IA/HRV14 crystal. After phase extension to 4Å resolution, the structure clearly shows that the initial model was mis-positioned by up to 4Å in places, the HRV14 structure does not seem to change upon antibody binding, and that the CDR3 loop of the heavy chain moves to accommodate the epitope. This CDR3 movement had been predicted by molecular dynamics calculations.