Viral cytopathic effects

by Jason Wasserman MD PhD FRCPC
March 9, 2022


What are viral cytopathic effects?

Viral cytopathic effects are the changes that take place in a cell after it has been infected by a virus. These changes can only be seen after the tissue is examined under a microscope. These changes can involve the shape and size of the cell. They can also involve a part of the cell called the nucleus. The nucleus holds most of the genetic material inside a cell.

The changes that can be seen under the microscope include:

  • Inclusions – These are small spots or holes inside the cell or the nucleus of the cell. The inclusions can look clear or they can have a pink color.
  • Irregular nuclear membrane – The nucleus is surrounded by a thin capsule called the nuclear membrane. Normally the membrane is smooth but, in a cell infected by a virus, it can become wrinkled.
  • Chromatin changes – The genetic material inside the nucleus is called chromatin. After a cell becomes infected with a virus, the chromatin can start to look darker than normal or may move to the nuclear membrane.
  • Multi-nucleated cells – Most cells have only one nucleus. Cells infected by a virus can stick together so closely that they become a single large cell. This large cell will have more than one nucleus. Pathologists call this a multi-nucleated cell.

viral cytopathic effects

Viruses that cause viral cytopathic effects

The viral cytopathic effects described above can be caused by many different types of viruses. The most common types of viruses include:

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