Describe several cytopathic effects of viruses. What causes thechanged appearance of the host cell, and how might it be used todiagnose viral infections?
Describe several cytopathic effects of viruses. What causes the
changed appearance of the host cell, and how might it be used to
diagnose viral infections?
When the host cell is invaded by a virus, its structure changes. This effect is known as cytopathic effects of viruses. This condition arises when the cells infecting causes lysis of the host cell or when the cells are unable to reproduce and die.
A virus that causes structural changes in the host cell is called as cytopathogenic.
Types of cytopathic effects :
- Total damage:
It is most severe type of effect and is seen with enteroviruses. The cells in the monolayer die.
This can be observed by putting the cells on a surface of glass and formation of single layer of host cell. After the viral infection is introduced and observed. All the cells shrinks and get detached from the glass, within 3 days.
- Subtotal damage:
In this case, only few cells will detach from glass after some time. Picornavirus, paramyxovirus, etc. causes this type of CPE.
- Focal degeneration:
Virus are directly transferred from one cells to another. The host cells rounded, enlarged and refractile. Cells detach from surface after some time. Pox virus and herpes virus exhibit this type of CPE.
- Clumping and swelling:
Cells swell and become enlarged, forms clump and eventually detach from surface.
- Foamy degeneration:
Large cytoplasmic vacuoles are formed.
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