virus latches onto a cell

When a virus latches onto a cell that isn’t somehow protected from the virus,
the virus hijacks all that cell’s activities for the sole purpose of making more
viruses. Viruses reproduce this way because they aren’t really alive and have
no moving parts of their own to accomplish reproduction. Part of the virus’s
attack strategy involves integrating virus DNA into the host genome in order
to execute viral gene expression. The problem is that when a virus is good at
attacking a cell, it causes an infection that the patient’s immune system
fights. So the trick to using a virus as a vector is taming it.