Final answer:
Mature animal viruses are released from host cells by either budding, which allows enveloped viruses to exit the cell without immediate destruction, or lysis/apoptosis, where non-enveloped viruses cause the host cell to burst open, releasing all virions and resulting in cell death.
Step-by-step explanation:
The two primary methods by which mature animal viruses are released into the host organism are budding and lysis or apoptosis. During the budding process, enveloped viruses acquire part of the host cell's plasma membrane and exit the cell one by one.
This method does not immediately kill the host cell but may leave it damaged. Conversely, non-enveloped viruses often accumulate within the host cell until they cause the cell to undergo lysis or induce apoptosis, leading to a simultaneous release of all virions, typically destroying the cell in the process.
Both of these release mechanisms are essential steps in the virus replication cycle after the virus has completed attachment, penetration, uncoating, replication, assembly, and is ready to spread to infect adjacent cells. The effectiveness of these release mechanisms can help to prevent further infection if the host cell is induced to undergo apoptosis before the virus completes its life cycle.