Cypoviruses or CPV, are a genus of viruses in the Reoviridae family. The virions structure is similar to other reoviruses with a genome composed of 10 segments of double-stranded RNA. The virions are embedded in a protein matrix in order to form structures referred to as polyhedra or occlusion bodies.

Cypoviruses have only been isolated from insects. They have more in common with the widely studied nucleopolyhedroviruses. CPVs are classified into 14 species based on the electrophoretic migration profiles of their genome segments. It has a single capsid shell similar to the orthoreovirus inner core.

When a susceptible insect consumes the polyhedra it is infected. This usually happens when the insect’s food is contaminated. The polyhedra dissolve in the digestive tract of the insect which releases the virus into the gut epithelial cells. The virus usually only replicates within these cells and thus spreads through feces. Spread of the virus is normally slow, although it is fatal.