What goes right and wrong during virus self-assembly?

Abstract

Self-assembly is a vital part of the RNA virus life cycle. The assembly of viral coat proteins around viral RNA occurs both in vivo and in vitro, suggesting that viral capsid assembly may be driven by minimization of free energy. To better understand this process, we study the assembly of bacteriophage MS2 virus-like particles (VLPs) as a function of coat-protein concentration, RNA concentration, ionic strength, temperature, and viscosity. We use dynamic light scattering, transmission electron microscopy, and gel electrophoresis to determine the size distribution, morphology, and composition of the assembled structures. We show how the morphology of MS2 VLPs varies with these conditions, and we relate these results to a model of assembly involving nucleation and growth.