Viruses in cell culture

An illustrated tutorial.

Laboratory diagnosis of viral infections frequently requires the isolation of the virus in cell cultures. Cell monolayers are inoculated with a suitable clinical specimen, and then observed for cytological changes that indicate virus growth.

Cytopathic changes

The term "cytopathic effect" (CPE) is frequently applied to virus-induced cellular changes that are visible by light microscopy. These changes include swelling or shrinkage of cells, the formation of multinucleated giant cells (syncytia), and the production of "inclusions" (made visible by staining) in the nucleus or cytoplasm of the infected cell.

The most efficient way to demonstrate cellular changes is by staining with chromatic dyes.
Cell monolayers are fixed and then exposed to basic and acidic dyes that accentuate the nature and location of the changes.

The use of haemotoxylin (basic dye) and eosin (acidic dye) is often referred to as
H&E staining.

The gross appearance of the cellular changes, and the location and nature of the "inclusions" - i.e. basophilic or eosinophilic - can in many instances be used as a diagnostic criterion to identify the causative virus. These will be illustrated for some of the viruses commonly isolated in cell culture:-

Adenovirus - example of basophilic intranuclear inclusions
Reovirus - example of eosinophilic intra-cytoplasmic inclusions

See also
Syncytia:	The herpes group of viruses:
Measles virus Respiratory syncytial virus Mumps virus	herpes simplex virus human cytomegalovirus varicella zoster virus

Adenovirus

Cells infected with adenovirus have an affinity for haematoxylin (a purplish-blue dye).
Infected cells become rounded and the cell sheet disintegrates. Dark basophilic inclusions within the nuclei represent accumulated viral proteins at the site of virus assembly.

Reovirus

Replication of reovirus particles occurs in the cytoplasm of the cell, and in the final stages of assembly the virus particles bud through the endoplasmic reticulum membrane.
Cytoplasmic sites of accumulated viral protein are stained with eosin (deep pink).

Go to:
Syncytia:
The herpes group of viruses:

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