Ultrastructure and formation of abnormal capsules in a granulosis virus of the moth Plodia interpunctella (Hbn.)

Abstract

An account is given of some mutant and aberrant capsules in the granulosis virus of Plodia interpunctella (Hbn.), the Indian meal moth. Several types of abnormal capsules have been found in the cells of this insect. One is a cubic (parallelepiped) “mutant” capsule in which crystallization and the occlusion of the virus rod are similar to these processes in the type virus. However, this form has a rectangular shape and the capsules are usually found arranged into orderly arrays within the infected cells. Giant capsules exhibiting more or less normal morphology but a several fold increase in volume were found associated with both the normal and cubic capsule forms. The following aberrant capsule types were found irregularly but with enough frequency to be characterized: elongate capsules are occasionally bent and consist of a long crystalline structure with a central channel; compound capsules also have a central channel but are made up of several component crystals; multiparticulate capsules are found with from 2 to 9 virus rods in a single capsule; agglomerated capsules consist of large irregular aggregations of crystalline capsular material but with only an occasional virus rod occluded in the structure. Additionally, crystals of non viral origin in the cells of both healthy and infected insects have been observed. The origin of these peculiar aberrant capsules is discussed especially in relation to the possible control of development in normal capsules.