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.
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:
- Cytomegalovirus (CMV).
- Epstein-Barr virus (EBV).
- Human papillomavirus (HPV).
- Herpes simplex virus types 1 and 2.