These structure extend to form a core sphere as the plasma membrane wraps around and eventually off the assembling particle. Release from the cells Release of enveloped viruses is intimately coupled with the budding process by which the envelope is acquired. Most of these viruses assemble at and bud from the plasma membrane. The final assembly reaction, fusion of the bud membrane, releases the newly formed virion into extracellular environment. When viruses acquire their envelope from intracellular membrane, the final step in assembly, budding, is also the first step in egress, which is followed by transport of particles to the cell surface.
Some enveloped viruses accumulate inside the cell and destroy the cell to facilitate release.
In natural infections, the host immune response to virus infection may destroys infected cell and may contribute to virus release.