Final answer:
The release phase is where enveloped viruses acquire a cell envelope and bud from the infected host cell, enabling the spread of new virions without immediate cell death.
Step-by-step explanation:
The viral replication phase that involves the acquisition of the cell envelope and eventual budding of the virion particle from an infected host cell is known as the release phase. During this phase, enveloped viruses such as influenza acquire a portion of the host cell's plasma membrane to form a protective envelope. This process allows the newly assembled virions to exit the host cell without immediately killing it, potentially enabling the virus to spread to adjacent cells and continue the cycle of infection. The virus's replication cycle consists of several steps: attachment, penetration, uncoating, replication, assembly, and release. As they assemble, enveloped viruses bud from the cell membrane, while non-enveloped viruses may cause cell lysis or apoptosis for release.