High-voltage electron microscopy of insect capsule viruses
The High-Voltage Electron Microscope (HVEM) affords the researcher an opportunity to study insect virus inclusion bodies, intact, without resorting to physical thin-sectioning or chemical degradation procedures. In this manner polyhedral inclusion bodies, isolated from insects infected with nuclopolyhedrosis viruses (NPVs) were observed with the HVEM, and the numerous viruses lying internally, clearly delineated.In the present report we used the HVEM to study, in whole mount, another type of insect virus inclusion body, that from the capsule (granulosis) viruses of two hosts, the fall webworm, Hyphantria cunea (Drury) and the yellow wollybear, Diacrisia virginica (Fabricius). The insect capsule viruses, like the NPVs, are characterized by a crystalline protein matrix which occludes enveloped, rod-shaped virus particles. Whereas the inclusion bodies of NPVs contain a number of virus particles in each inclusion body, those of the capsule viruses contain, generally, only one virus particle in each capsule or granule.