  For many viruses assembly and budding occur simultaneously during virion
formation. Understanding the mechanisms underlying this process could promote
biomedical efforts to block viral propagation and enable use of capsids in
nanomaterials applications. To this end, we have performed molecular dynamics
simulations on a coarse-grained model that describes virus assembly on a
fluctuating lipid membrane. Our simulations show that the membrane can promote
association of adsorbed subunits through dimensional reduction, but also can
introduce barriers that inhibit complete assembly. We find several mechanisms,
including one not anticipated by equilibrium theories, by which membrane
microdomains, such as lipid rafts, can enhance assembly by reducing these
barriers. We show how this predicted mechanism can be experimentally tested.
Furthermore, the simulations demonstrate that assembly and budding depend
crucially on the system dynamics via multiple timescales related to membrane
deformation, protein diffusion, association, and adsorption onto the membrane.
