Spatiotemporal Corona virus binding dynamics and infection mechanism investigated with 100 Hz ROCS microscopy and thermal fluctuation analysis

• Applicant: Professor Dr. Alexander Rohrbach
• Subject Area: Biophysics ; Virology
• Term: from 2021 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458687324

Corona virus infection consists of several successive steps, among which the diffusion contact and binding are the first decisive processes before the virus entries the cell. However due to the extremely high dynamics of the only 0.1 micrometre small virus particles, observations and more detailed investigations of the first interaction steps before entry has not been possible with current measurement technology. The host virus interaction can become even more complicated because of rough cells surfaces, where filopodia are often involved in virus uptake.The goal of this research proposal is to unravel the highly dynamic, discontinuous binding process of viruses, which are governed by thermal fluctuations in position and orientation. This process can take up to 30 min until the virus enters the host. By using the novel label-free, super-resolution microscopy methods based on rotating coherent scattering (ROCS) of blue laser light, which was recently developed in our lab, we plan to monitor the decisive virus binding processes over 100,000 images at 100 Hz frame rate without loss in image quality. By automatic tracking and analysing the thermal position fluctuations of the viruses over seconds and minutes, we will calculate the temporal changes in binding strength of about 10-100 viruses per cell. With these novel measurement and analysis methods we want to quantify the on- and off- binding rate of pseudo-viruses (with SARS-COV-19 spikes) binding specifically to ACE-2 receptors - from the first contact to the uptake into the cell. By recording a large number of virus fluctuation trajectories will allow to analyze the contact binding behavior with high statistic confidence. In particular, we will investigate the spatiotemporal binding behavior to lung epithelial cells und lung macrophages expressing ACE-2 receptors. In a last step, we will test the influence of drugs such as ACE-2 receptor blockers on the virus dynamics with the goal to get further insights in posssible intervention mechanisms.

• DFG Programme: Research Grants