Orthopoxvirus inclusion bodies are aggregates of stainable protein produced by poxvirus virions in the cell nuclei and/or cytoplasm of epithelial cells in humans.
Type-A inclusion bodies are found only in certain poxviruses like cowpox.
[3] The Guarnieri bodies are found in all poxvirus infections and their presence is diagnostic.
[4] The diagnosis of an orthopoxvirus infection can also be made rapidly by electron microscopic examination of pustular fluid or scabs.
However, all orthopoxviruses exhibit identical brick-shaped virions by electron microscopy.