The Cytopathology of Baculovirus Infections in Insects

Abstract

Baculoviruses are the most widely investigated of the viruses which infect insects. More than 320 of them have been isolated, mainly from insects and a few other arthropods such as mites and crustaceans. These viruses contain closed, circular, double-stranded DNA enclosed within rod-shaped, enveloped nucleocapsids. They are placed in the family Baculoviridae (Matthews, 1982) which is separated into two recognized subgroups: A, nuclear polyhedrosis viruses, and B, granulosis viruses. Two other subgroups have been proposed: C, nonoccluded, rod-shaped nuclear viruses, and D, nonoccluded nuclear viruses with a polydisperse DNA genome. In the nuclear polyhedrosis viruses (NPVs), numerous enveloped virions are occluded in occlusion bodies, called polyhedra, in the nuclei of infected cells (Figure 1), whereas in the granulosis viruses (GVs), the enveloped virions are occluded singly or rarely two or more in occlusion bodies called capsules which develop in the nucleus or cytoplasm (Figure 2). In subgroups C and D, the virions are not occluded in occlusion bodies.