Enteroviruses, belonging to the group of Picornaviridae, are non-enveloped, positive-sense single-stranded RNA viruses. These animal and human pathogens cause variety of diseases ranging from mild respiratory illnesses to life-threatening meningitis. Human enterovirus 70 (EV70), which is transmitted by eye secretions, causes acute hemorrhagic conjunctivitis, a serious eye disease.
We used cryo-electron microscopy to determine the molecular structure of EV70 particles. EV70 was propagated in human hTERT-RPE1 cell line and purified by PEG precipitation and ultracentrifugation in CsCl gradient. Purified virus solution was vitrified on grids covered with holey carbon. Cryo-electron microscopy was done using an FEI Titan Krios transmission electron microscope equipped with Falcon II/III direct electron detector. The processed data resulted in near-atomic resolution electrostatic potential maps, suitable for building of the atomic structure of the EV70 capsid proteins.
After successful construction of the model of full and empty particle, we focused on the region of the capsid that might be occupied by a pocket factor, a small molecule that regulates genome release of the virus. This pocket factor might be replaced by artificial inhibitors that over-stabilize the virus and prevent its infection. Knowledge of the EV70 virion structure will allow development of specific capsid-binding inhibitors that may be used to treat the disease caused by this virus.