ELECTRON-MICROSCOPY OF RABBIT EMBRYO FIBROBLASTS INFECTED WITH HERPESVIRUS ISOLATES FROM CLETHRIONOMYS-GLAREOLUS AND APODEMUS-FLAVICOLLIS

Abstract

EM of rabbit embryo fibroblasts (REF) infected with 5 herpesvirus isolates from rodents (C. glareolus and A. flavicollis) revealed morphological changes characterized by the formation of intranuclear vacuoles in which nucleocapsid envelopment took place. The herpesvirus nucleocapsids were formed in the vicinity of intranuclear granular inclusions. Margination of chromatin, disaggregation of nucleoli and, in some isolates, the occurrence of tubular structures with a diameter of 33-35 nm characterized the ultrastructural changes in the nuclei. In the cytoplasm, membraneous vacuoles, containing numerous naked nucleocapsids and, in some isolates, large electron-dense bodies, containing non-enveloped nucleocapsids, were formed. Extracellular spaces contained either enveloped virions which, besides nucleocapsids, contained in their envelope a part of the dense material from intracytoplasmic dense bodies, or viral envelope-like structures without nucleocapsids partially filled with dense material from intracytoplasmic dense bodies. Ultrastructural development of these isolates in REF resembled that of freshly isolated herpes simplex type 1 viruses, but some morphological changes resembled those characteristic of cytomegaloviruses.