Structure of pocks on the chorioallantoic membrane of fertile hens' eggs induced by herpes simplex virus types 1 and 2.

The fine structure of the chorioallantoic membrane of the fertile hen's egg infected with herpes simplex virus Types 1 and 2 was examined. Lesions induced by Type 1 virus were small, confined to the chorionic layer of the membrane and proliferative in nature with slight cellular infiltration into the mesoderm after incubation up to 7 days. With the Type 2 virus-induced pocks, reaction occurred throughout the thickness of the chorioallantoic membrane, and haemorrhages, necroses, ulceration and cellular infiltration of the mesoderm were prominent features. Inoculation of the membranes with Type 2 virus resulted in a large number of infected chorion cells compared with Type 1, whilst the cells of the mesoderm and blood vessels became infected with Type 2 virus but not Type 1. Two types of intranuclear granules, lattice structures in both nuclei and cytoplasm and virus particles with variously structured cores were found specifically in Type 2 infected cells.