Researchers combine confocal and atomic force microscopy to better
understand this critical step of viral infections
Viruses cannot reproduce on their
own. They require the internal machinery of host cells for replication and
propagation. One of the challenges that successful viruses have overcome is
evolving complex, multi-step mechanisms to bind to host cell surfaces and then
transport themselves inside the cell.
Please broadly describe the research goals of your lab. How did this
publication fit into your overall research?
The ‘NanoBiophysics lab’ aims at better understanding the complex biological processes that take place on the cell surface under relevant physiological conditions. To this end we combine AFM and point scanning confocal microscopy to localize molecules, receptors and cells while mapping their nanomechanical properties or biophysical interactions between the AFM probe and the biological sample. We have been using force-distance based-AFM for several years already to study a variety of biological samples at both molecular and cellular levels to better understand how single-molecule interactions can drive biological processes.
Some key applications of my lab include, among others, imaging G-protein coupled receptors while quantifying their ligand-binding free-energy landscape, studying the first entry steps of viruses to animal cells (Reovirus, Rotavirus, Herpesvirus, Ebola virus-like particles) with a focus on the understanding of the dynamics of the interactions established at the surface of living cells.
Our recent publication perfectly fits into the main research’s axes of my lab. Since my postdoc stay at ETH Zürich (Basel, Switzerland), we further developed the combination of the latest generation of Bio-AFM with a high-resolution optical microscope. The ambition is to develop a new methodology in biophysics and virology to study virus entry at high-resolution, directly on living cells, and to provide quantitative information on the molecular details underlying the early steps of cell infection.
In our recent work, we combine the latest generations of confocal laser scanning microscope (CLSM) and AFM to follow the early steps of single virus entry. We also succeeded to describe these first steps in a quantitative manner and provided the kinetic and energetic parameters of the virus-receptors interactions.
Could you describe in layman’s terms how your combination of confocal and AFM technologies contributed to the findings in this publication?
Thanks to an atomic force microscope coupled to a confocal microscope, we investigated how reoviruses interact with mammalian cell surfaces in cell culture conditions. A very sharp tip is functionalized with a single virus and approached to the cell surface until soft contact, enabling it to interact with the cell surface component including glycans and receptors (Figure 1).