Preparation and Characterization of Inactivated Tick-Borne Encephalitis Virus Samples for Single Particle Imaging at European XFEL
X-ray imaging of virus particles at European XFEL could eventually allow solving their complete structure, potentially approaching resolution of other structural virology methods. To achieve this ambitious goal with todays technologies, several mL of purified virus suspension containing at least 1012 particles per mL are required. Such large amounts of concentrated suspension have never before been obtained for enveloped viruses. Tick-borne encephalitis virus (TBEV) represents an attractive model system for the development of enveloped virus purification and concentration protocols, given the availability of large amounts of inactivated virus material provided by vaccine manufacturing facilities. Here we present the development of a TBEV vaccine purification and concentration scheme combined with a quality control protocol allowing substantial amounts of highly concentrated non-aggregated suspension to be obtained. Preliminary single particle imaging experiments were performed for this sample at European XFEL, showing distinct diffraction patterns.