Cell membrane mimics and cell-based assays to probe virus-membrane interactions

Viruses are nanoscale particles that infect cells of all living organisms to replicate and spread. During the infection process, the plasma membrane plays a key role as it acts as a barrier that needs to be crossed both during viral entry and egress. It contains attachments factors and receptors that the virus exploits in order to bind to the cell surface and enter the cell. Understanding the mechanisms regulating these virus-cell membrane interactions is therefore of great interest in anti-viral research and an important step towards the development of new anti-viral drugs and vaccines.

A.   Cell membrane mimics to probe virus-membrane interactions


As a complement to traditional cell studies used in the field of virology, our group develops surface-based assays in combination with advanced microscopy techniques. These assays involve different types of cell membrane mimics: from simplified artificial supported-lipid bilayers that contain one cell receptor of choice(1, 2) (Figure 1A), to more complex native-like membranes in which we incorporate membrane material extracted from relevant cell lines(3) (Figure 1B). We probe binding kinetics and mobility of individual virions interacting with the surfaces and study how the composition of the membranes or the properties of the virions influence this interaction. Our current work focuses on the Herpes Simplex Virus, a very widespread human virus that affects about 90% of the population worldwide and which presents structural or functional similarities to a large number of other viruses, like HIV, Ebola, and Zika for example. Using our surface-based approaches we study the molecular and physical mechanisms modulating HSV binding and release from the cell surface (Figure 2). More specifically, we gain insight into the modulatory function of protein glycosylation(1, 2) and interrogate the role of GAG sulfation in the process(4).


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Figure 1: Cell membrane mimics to study virus-cell membrane interactions. A) Glycosaminoglycans serve as attachment factors for a large number of viruses. To mimic the presentations of these molecules in the extracellular matrix and close to the cell surface, we end-grafted the polysaccharide chains to the surface, using a supported lipid bilayer and a monolayer of streptavidin(1, 2). B) To increase the complexity of our model membrane and to study virus-cell membrane interactions in a more native-like environment, we incorporated membrane material extracted from relevant cell lines to the supported-lipid bilayers(3).

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Figure 2: Image of fluorescently labeled HSV-1 particles binding to end-grafted glycosaminoglycan chains, obtained with total-internal reflection fluorescence microscopy. Scale bar: 50 µm.

Major collaborations

Tomas Bergström, Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, Göteborg, Sweden

 

Stephan Block, Department of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany

 

B.   Cell-based assays to study virus uptake

In complement to the use of cell-membrane mimics, our group is developing and implementing experimental methods based on live cell microscopy to probe virus attachment to, diffusion on and uptake through the cell membrane on a single particle level. 


C.   Virus characterization on a single particle level

Virus particles are characterized by a high degree of heterogeneity in their composition and in their physical properties. To better understand what makes a virus infectious and to establish a relation between particle properties and the characteristics of their interaction with the cell surface, we are currently developing methods allowing for the characterization of virus particles on a single particle level. Along these lines we have recently presented a nanofluidic device, working as a nano flow cytometer to characterize one by one small biological particles (Figure 3). This device is compatible with standard epifluorescence microscopy, operates in multiple fluorescence channels and allows for the fluorescence-based detection of individual viruses and their quantification(5).


                                                                                                
Figure 3: A nanofluidic device working as a nano flow cytometer allows for the characterization of biological particles on a single particle level using fluorescence microscopy. The particles are flown through the nanochannels and kept in focus for imaging(5).

Major collaborations

Fredrik Westerlund, Department of Biology and Biological Engineering, Chalmers Univeresity of Technology, Göteborg, Sweden

 

Elin Esbjörner Department of Biology and Biological Engineering, Chalmers Univeresity of Technology, Göteborg, Sweden

 

D.   Selected references

 

1.        Altgärde, N., C. Eriksson, N. Peerboom, T. Phan-Xuan, S. Moeller, M. Schnabelrauch, S. Svedhem, E. Trybala, T. Bergström, and M. Bally. 2015. Mucin-like Region of Herpes Simplex Virus Type 1 Attachment Protein Glycoprotein C (gC) Modulates the Virus-Glycosaminoglycan Interaction. J. Biol. Chem. 290: 21473–21485.

2.        Peerboom, N., S. Block, N. Altgärde, O. Wahlsten, S. Möller, M. Schnabelrauch, E. Trybala, T. Bergström, and M. Bally. 2017. Binding Kinetics and Lateral Mobility of HSV-1 on End-Grafted Sulfated Glycosaminoglycans. Biophys. J. 113: 1–12.

3.        Peerboom, N., E. Schmidt, E. Trybala, T. Bergström, H. Pace, and M. Bally. In preparation. .

4.        Trybala, E., N. Peerboom, B. Adamiak, M. Krzyzowska, J.-Å. Liljeqvist, M. Bally, and T. Bergström. In preparation. .

5.        Friedrich, R., S. Block, M. Alizadehheidari, S. Heider, J. Fritzsche, E.K. Esbjörner, F. Westerlund, and M. Bally. 2017. A nano flow cytometer for single lipid vesicle analysis. Lab Chip. 17: 830–841.

 

E.   Project members

 

Marta Bally (Project leader)

 

Nadia Peerboom

Eneas Schmidt

Quentin Lubart

Noomi Altgärde

 

 


Published: Mon 20 Oct 2014. Modified: Mon 28 Aug 2017