Distinct cellular receptor interactions in poliovirus and rhinoviruses

Receptor binding to human poliovirus type 1 (PV1/M) and the major group of human rhinoviruses (HRV) was studied comparatively to uncover the evolution of receptor recognition in picornaviruses. Surface plasmon resonance showe d receptor binding to PV1/M with faster association and dissociation rates than to HRV3 and HRV16, two serotypes that have similar binding kinetics. T he faster rate for receptor association to PV1/M suggested a relatively mor e accessible binding site. Thermodynamics for receptor binding to the virus es and assays for receptor-mediated virus uncoating showed a more disruptiv e receptor interaction with PV1/M than with HRV3 or HRV16. Cryoelectron mic roscopy and image reconstruction of receptor-PV1/M complexes revealed recep tor binding to the 'wall' of surface protrusions surrounding the 'canyon', a depressive surface in the capsid where the rhinovirus receptor binds. The se data reveal more exposed receptor-binding sites in poliovirus than rhino viruses, which are less protected from immune surveillance but more suited for receptor-mediated virus uncoating and entry at the cell surface.