Viruses are a class of microorganisms that are extremely small in size and can only grow and proliferate in living cells through filters, and viral particles are generally in the range of 10-30 nm, mainly composed of nucleic acids and proteins. Ordinary light microscopy of some viral infected cells can be seen in varying sizes and numbers of round or irregular bodies, known as viral inclusion bodies, the material is located in the cytoplasm, acidic, such as the rabies virus inclusion bodies; some are located in the nucleus, alkaline, such as adenovirus nuclear inclusion bodies; some of the cytoplasm and also in the cell nucleus, such as the measles virus inclusion bodies; RNA viruses are often formed in the cytoplasm of the inclusion bodies, and DNA viruses are often formed in the nucleus, and the nucleus. RNA viruses often form cytoplasmic inclusion bodies, and DNA viruses mostly form intra-nuclear inclusion bodies.

Viral inclusion bodies are stained with Lenreum method, which is also known as fluorescent peach-tartaric yellow method, the nucleus is stained blue-gray, and the inclusion bodies are stained red. In viral infections, inclusion bodies may be the site of viral proliferation, but it should be noted that not all the inclusion bodies in the cell are viruses, and cell degeneration may also form inclusion bodies.