Electrostatics-driven inflation of elastic icosahedral shells as a model for radial swelling of virus-like particles

TL;DR

This paper presents a theoretical model explaining how electrostatic forces can cause virus-like particles to swell radially without conformational changes, aligning with experimental observations.

Contribution

It introduces an analytical framework coupling elastic and electrostatic effects to describe virus-like particle swelling.

Findings

Electrostatic interactions can induce about 10% swelling of capsids.

The model predicts swelling due to pH and ionic strength changes.

Analytical expressions enable quick estimation of swelling magnitudes.

Abstract

We develop a clear theoretical description of radial swelling in virus-like particles which delineates the importance of electrostatic contributions to swelling in absence of any conformational changes. The model couples the elastic parameters of the capsid -- represented as a continuous elastic shell -- to the electrostatic pressure acting on it. We show that different modifications of the electrostatic interactions brought about by, for instance, changes in $pH$ or solution ionic strength, are often sufficient to achieve the experimentally-observed swelling (about 10% of the capsid radius). Additionally, we derive analytical expressions for the electrostatics-driven radial swelling of virus-like particles, which enable one to quickly estimate the magnitudes of physical quantities involved.