  We develop coarse-grained models that describe the dynamic encapsidation of
functionalized nanoparticles by viral capsid proteins. We find that some forms
of cooperative interactions between protein subunits and nanoparticles can
dramatically enhance rates and robustness of assembly, as compared to the
spontaneous assembly of subunits into empty capsids. For large core-subunit
interactions, subunits adsorb onto core surfaces en masse in a disordered
manner, and then undergo a cooperative rearrangement into an ordered capsid
structure. These assembly pathways are unlike any identified for empty capsid
formation. Our models can be directly applied to recent experiments in which
viral capsid proteins assemble around the functionalized inorganic
nanoparticles [Sun et al., Proc. Natl. Acad. Sci (2007) 104, 1354]. In
addition, we discuss broader implications for understanding the dynamic
encapsidation of single-stranded genomic molecules during viral replication and
for developing multicomponent nanostructured materials.
