Revealing in real-time a multistep assembly mechanism for SV40 virus-like particles

Many viruses use their genome as template for self-assembly into an infectious particle. However, this reaction remains elusive because of the transient nature of intermediate structures. To elucidate this process, optical tweezers and acoustic force spectroscopy are used to follow viral assembly in real time. Using Simian virus 40 (SV40) virus-like particles as model system, we reveal a multistep assembly mechanism. Initially, binding of VP1 pentamers to DNA leads to a significantly decreased persistence length. Moreover, the pentamers seem able to stabilize DNA loops. Next, formation of interpentamer interactions results in intermediate structures with reduced contour length. These structures stabilize into objects that permanently decrease the contour length to a degree consistent with DNA compaction in wild-type SV40. These data indicate that a multistep mechanism leads to fully assembled cross-linked SV40 particles. SV40 is studied as drug delivery system. Our insights can help optimize packaging of therapeutic agents in these particles

AFS_data_analyse_170323 -labview 2016

analyse softwar

AFS_tracking_array - 160816 -labview 2016

tracking softwar

AFS 1D model

<div>This software is divided in two parts: (i) an set of classes, methods and functions that allow for modelling the radiation force profile in a configuration of a transducer-resonator-flow cell, and (ii) a script that performs a massive automated sweep over some properties of this configuration, thus creating a parameter space for the radiation force. Both parts are equipped with a graphical user interface, the former for altering a configurations’ properties and analysing the effects in the model, the latter for exploring the plots of the parameter space, eg. in search for optimal configurations.</div

Single-molecule measurements using acoustic force spectroscopy (AFS)

Single-molecule force spectroscopy is a powerful tool to investigate the forces and motions related to interactions of biological molecules. Acoustic Force Spectroscopy (AFS) is a recently developed measurement tool to study single molecules making use of acoustic standing waves. AFS permits high experimental throughput, because many individual molecules can be manipulated and tracked in parallel. Moreover, a wide range of forces can be applied, as well as a force loading rate with range of six orders of magnitude. At the same time, AFS stands out because of its simplicity and the compactness of the experimental setup. Even though the AFS setup is simple, it can still be challenging to perform high-quality measurements. Here we describe, in detail, how to setup, perform, and analyze an AFS measurement

Single-Cell Measurements Using Acoustic Force Spectroscopy (AFS)

Single-molecule force spectroscopy is a powerful tool to investigate the forces and motions related to interactions of biological molecules. Acoustic force spectroscopy (AFS) is a developed measurement tool to study single molecules or cells making use of acoustic standing waves. AFS permits high experimental throughput because many individual molecules can be manipulated and tracked in parallel. Moreover, a wide range of forces can be applied as well as a force loading rate with range of six orders of magnitude. At the same time, AFS stands out because of its simplicity and the compactness of the experimental setup. Even though the AFS setup is simple, it can still be challenging to perform high-quality measurements. Here we describe, in detail, how to setup, perform, and analyze an AFS measurement to determine cell adhesion.</p