ABSTRACT
Herpes simplex virus was the first animal virus to be studied by negative stain electron microscopy (EM). In micrographs of thin sections, a herpesvirus capsid measuring about 100 nm can be clearly resolved. The herpesviruses of importance in medicine are herpes simplex virus types 1 and 2, varicella zoster virus, Epstein-Barr virus, cytomegalovirus, human B cell lymphotropic virus, and herpes simiae. Herpesvirus enters the cell by a process similar to pinocytosis or by fusion with the cell. The exact process by which herpesvirus is released from the cell is not clear. However, particles appear to accumulate between the inner and outer lamella of the nuclear membrane or in the endoplasmic reticulum. EM has made an important contribution to the rapid diagnosis of herpesviruses from vesicular fluids, urine, and brain biopsy specimens. There is also some evidence that herpesviruses have a middle capsid layer just beneath the capsid and an inner capsid about 45 nm in diameter which encloses the core.
