Cypoviruses

Abstract

The genus cypovirus within the Reoviridae family comprises the cytoplasmic polyhedrosis viruses (CPVs) of insects (Holmes, 1991). Isolations of many CPVs from more than 250 insect species reared in a laboratory or collected from the field were so far recorded (Hukuhara and Bonami, 1992). These viruses are also very common pathogens found in insect colonies. As for the nuclear polyhedrosis (NPV) and granulosis viruses (GV), the incorporation during the disease progress of 70-nm viral particles into large (several microns) structures named polyhedra characterizes these viruses. The polyhedra located in the cytoplasm of insect cells are the result of the crystallization of a viral coded protein, called polyhedrin, late during the viral infection. It is assumed that one of the functions of these polyhedra is to protect the infectivity of the virions from hostile environmental conditions during the horizontal transmission of the disease.