A viroplasm is an inclusion body

Inclusion bodies

Inclusion bodies are nuclear or cytoplasmic aggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication in a bacterium or a eukaryotic cell and usually consist of viral capsid proteins...

 in a cell where viral replication

Viral replication

Viral replication is the term used by virologists to describe the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. From the perspective of the virus, the purpose of viral replication is...

/assembly occurs. They may be thought of as viral factories in the cell. Very little is understood about the mechanism of viroplasm formation. These appear electron-dense under the electron microscope

Electron microscope

An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...

, most likely due to high amounts of viral RNA

RNA

Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

 in them.

Viroplasm has been found in the cauliflower mosaic virus

Cauliflower mosaic virus

Cauliflower mosaic virus is the type member of the caulimoviruses, one of the six genera in the Caulimoviridae family, pararetroviruses that infect plants...

, rotavirus

Rotavirus

Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...

, vaccinia virus

Vaccinia

Vaccinia virus is a large, complex, enveloped virus belonging to the poxvirus family. It has a linear, double-stranded DNA genome approximately 190 kbp in length, and which encodes for approximately 250 genes. The dimensions of the virion are roughly 360 × 270 × 250 nm, with a mass of...

 and the rice dwarf virus

Rice dwarf virus

Rice dwarf virus is a plant pathogenic virus of the family Reoviridae.-External links:**...

.