Cytoplasmic polyhedrosis virus (CPV for short) belongs to the family Reoviridae and the genus Cypovirus. The polyhedrons are generally quadrilateral or hexagonal. shape, etc., and the size roughly varies in the range of 0.5 to 10 μm. Virus particles are spherical regular icosahedrons with protein inclusions that proliferate in the host cytoplasm. The viral nucleic acid is segmented double-stranded RNA with a molecular weight of 0.3 to 2.7 × 10 Daltons.