What is the Cytopathic Effect?
When a virus invades a host cell, its structure changes. This is known as a cytopathic effect. This condition occurs when an infected cell excretes a host cell or when a cell dies due to its ability to reproduce. Viruses that cause morphological changes in host cells can be cytopathogenic.
The first sign of cytopathic action or viral infection is cell rounding. Inclusion bodies are seen in the cytoplasm and nucleus of host cells.
These can be detected by light microscopy or electron microscopy in blood smears from patients. Some viral infections cause syncytial formation. These are cytoplasmic giants formed by the fusion of infected cells. It is composed of many cores.
Types of Cytopathic Effects
- This is the most severe form of cytopathic effect. This is seen with enteroviruses. This causes all the cells in the layer to die.
- This is done by seeding cells on a glass surface to form a single layer of host cells. A viral infection is introduced into the cells and the cells are monitored. Within three days, all the cells shrink and come off the glass.
- Virus infection is induced by seeding a layer of host cells on the glass surface. Only a few particles separate from the glass surface over time. This type of CPE is caused by togavirus, picornavirus and paramyxovirus.
- This involves the direct transmission of the virus from one cell to another. Host cells are enlarged, rounded and smooth. After some time, the cells leave the surface. This type of cytopathic effect is exhibited by herpes viruses and influenza viruses.
- This is the adenovirus model. The cells swell and grow, join together, and then detach from the surface.
- Many large cytoplasmic vacuoles are formed. The host cell can be fixed and observed by staining. It is also found in retroviruses and flaviviruses.
Cytopathic Effect in Diagnostics
Cytopathological findings are used to diagnose viral infection. Under low-power optical microscopy, small cellular effects can be observed in non-stained, uncertain cells. while light microscopy reveals some cytopathological features such as inclusion bodies in stained fixed cells.
The cytopathological effects of some viruses are specific and therefore can be used to diagnose viral infections in humans and animals. The speed with which the cytopathological effect is observed is also used by virologists to diagnose the type of disease.
Key Points
- Cytopathological effects refer to structural changes in host cells caused by viral infection.
- Viral infection results in cell lysis.
- The disease also reduces the reproductive capacity of the cells, leading to cell death.
- Cytopathological effects lead to the formation of inclusion bodies or syncytia which helps in the diagnosis of viral infection.
