Final answer:
The fourth step in the life cycle of non-enveloped DNA animal viruses involves the assembly of new virions and their release upon host cell lysis or apoptosis, releasing the virions to infect other cells.
Step-by-step explanation:
Step Four of the Non-enveloped DNA Animal Virus Life Cycle
In the life cycle of non-enveloped DNA animal viruses, such as rhinoviruses, step four generally involves the assembly and subsequent release of newly formed virions. After the previous stages of attachment, penetration, uncoating, and replication, the newly synthesized viral components come together to form complete viral particles inside the host cell. In contrast to enveloped viruses like HIV, which utilize the process of budding to leave the host cell, non-enveloped viruses typically accumulate until the host cell receives a signal to undergo lysis (the cell membrane breaking down) or apoptosis (programmed cell death), leading to simultaneous release of all progeny virions.
Once the signal for lysis or apoptosis is triggered, the host cell releases the new viral particles into the surrounding environment, where they can infect adjacent cells and begin the replication cycle anew. Thus, the release stage marks the end of the replication cycle within a single cell but also sets the stage for further spread of the virus to additional host cells.