[Virus propagation, virus replication and virus elimination in the human skin in zoster]

The purpose of this study was to investigate the spreading, the replication and the elimination of Varicella-Zoster-Virus (ZV) in human skin. Typical skin lesions of thoracic zoster in different stages of development and of exanthematic vesicles in ophthalmic zoster were examined under the electron microscope. We found that ZV may be detected in fully developed vesicular skin lesions only, whereas in immature lesions and in the surrounding non involved skin axonal alterations may be seen, with no ZV present. The replication of the virus in the skin takes place almost exclusively in the malpighian keratinocytes of the involved epidermis. Blister formation in zoster is basically a result of the acantholysis of the infected epidermal cells. Mature ZV are then extruded into the intercellar space and become phagocytised by mononuclear cells which infiltrate the epidermis and eliminate the virus in large phagolysosomes. Only few virions were found in the dermis extracellularly or in dermal macrophages. In some of these cells stages of ZV-replication were also seen. Other cell types (i.e. Langerhans cells) were rarely infected. The application of the periodic acid-silver methenamine technique (PASM) in zoster revealed that a glycoprotein-rich coat surrounds each mature virion, obviously originating from the plasma membrane of the infected keratinocytes. This coat may be reason for the ability of the ZV to adhere on the cell surface and to infect the cell.