Why are monosomies rarely detected?

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.

Both of them have a nucleus, golgi apparatus, cell membrane, smooth and rough endoplasmic reticulum, lysosome, and ribosomes.