Cytocidal infections are often associated with changes in cell morphology, physiology and are thus important for the complete viral replication and transformation.  Cytopathic Effects, often include a change in cells morphology such as fusion with adjacent cells to form polykaryocytes as well as the synthesis of nuclear and cytoplasmic inclusion bodies.  Physiological changes include the insufficient movement of ions, formation of secondary messengers, and activation of cellular cascades to continue cellular activity.  Biochemically, many viruses inhibit the synthesis of host DNA, RNA, proteins directly or even interfere with protein-protein, DNA-protein, RNA-protein interactions at the subcellular level.  Genotoxicity involves breaking, fragmenting, or rearranging chromosomes of the host.  Lastly, biologic effects include the viruses ability to affect the activity of antigens and immunologlobulins in the host cell.
There are two types of cytocidal infections, productive and abortive.  In productive infections, additional infectious viruses are produced.  Abortive infections do not produce infectious viruses.  One example of a productive cytocidal infection is the herpes virus.