Effects of RNA branching on the electrostatic stabilization of viruses

TL;DR

This study uses mean field theory to explore how RNA secondary structure and electrostatic interactions influence virus assembly efficiency and stability, revealing that branched RNA structures enhance packaging and virion stability.

Contribution

It introduces a theoretical framework linking RNA secondary structure to virus assembly and stability, highlighting the role of RNA branching in these processes.

Findings

Branched RNA can generate negative osmotic pressures.

Linear RNA tends to produce positive osmotic pressures.

RNA branching improves packaging efficiency and virion stability.

Abstract

Many single-stranded (ss) RNA viruses self assemble from capsid protein subunits and the nucleic acid to form an infectious virion. It is believed that the electrostatic interactions between the negatively charged RNA and the positively charged viral capsid proteins drive the encapsidation, although there is growing evidence that the sequence of the viral RNA also plays a role in packaging. In particular the sequence will determine the possible secondary structures that the ssRNA will take in solution. In this work, we use a mean field theory to investigate how the secondary structure of the RNA combined with electrostatic interactions affects the efficiency of assembly and stability of the assembled virions. We show that the secondary structure of RNA may result in negative osmotic pressures while a linear polymer causes positive osmotic pressures for the same conditions. This may suggest that the branched structure makes the RNA more effectively packaged and the virion more stable.