Abstract: A cytoplasmic polyhedrosis virus (CPV) isolated recently from the tobacco budworm Heliothis assulta was observed with EM and characterized biochemically. The polyhedral bodies of the CPV were pentagonal dodecahedron measured 0.8 to 4.6μm, and the virioas after release from the polyhedra were found with a hexagonal or spherical outline and a size of 62nm. The polyhedrin had a molecular weight of23,000 dalton and was not a glycoprotein because it was stained negatively by periodic acid-Schiff's reagent. Genes of the CPV were double-stranded with Dnase I resistance and considerable Rnase I resistance. The CPV genome consisted of ten segments of RNA. Their molecular weights range from 0.3-2.68 ×10⁶ dalton, with a total of 15.85×10⁶ dalton.

Key words: Heliothis assulta——cytoplasmic polyhedrosis virus——polyhed- ral.protein——double stranded RNA