Self Consistent Field Theory of Virus Assembly

TL;DR

This paper uses self-consistent field theory to analyze RNA adsorption on viral shells, identifying when the ground state dominance approximation is valid and providing insights into genome distribution and persistence length.

Contribution

It introduces SCFT as a more reliable method than GSDA for certain virus assembly scenarios, especially with shorter or weakly interacting genomes.

Findings

GSDA works for long RNA or strong genome-shell interactions

SCFT reveals non-uniform genome distributions when GSDA fails

Genome persistence length is zero in GSDA but non-zero in SCFT

Abstract

The Ground State Dominance Approximation(GSDA) has been extensively used to study the assembly of viral shells. In this work we employ the self-consistent field theory (SCFT) to investigate the adsorption of RNA onto positively charged spherical viral shells and examine the conditions when GSDA does not apply and SCFT has to be used to obtain a reliable solution. We find that there are two regimes in which GSDA does work. First, when the genomic RNA length is long enough compared to the capsid radius, and second, when the interaction between the genome and capsid is so strong that the genome is basically localized next to the wall. We find that for the case in which RNA is more or less distributed uniformly in the shell, regardless of the length of RNA, GSDA is not a good approximation. We observe that as the polymer-shell interaction becomes stronger, the energy gap between the ground state and first excited state increases and thus GSDA becomes a better approximation. We also present our results corresponding to the genome persistence length obtained through the tangent-tangent correlation length and show that it is zero in case of GSDA but is equal to the inverse of the energy gap when using SCFT.