<unk>  or cytopathogenic effect (abbreviated<unk>  refers to damage to host cells during virus invasion. This damage is measurable by obtaining viral titers. Degenerative changes in cells can also be studied in tissue culture.
When in tissue culture the spread of virus is restricted by an overlay of agar or other suitable substance. This barrier means the<unk>  may lead to the formation of a viral plaque. Thus identification of a viral infection can be made by examining the characteristic<unk>  produced on different cell sheets. This method however is relatively slow and not all viruses will grow on cell sheets. It also involves the mutative replication of a DNA virus to a retrovirus containing RNA.<unk> s have been shown in conjunction with non-viral infections as well, such as those changes seen in fibroblasts during the early lesion of periodontal disease.
Not all viruses cause a measurable<unk> . These include two human coronaviruses HCoV-229E and HCoV-OC43.
Cytopathic effect
Drug interaction
Steric effects
Cross-reactivity
Anaplerotic reactions
Opportunistic infection
Growth inhibition
Genotoxicity