Herpes simplex viral infection in human neonates: an immunohistochemical and electron microscopic study.

Specimens obtained at autopsy from six neonates with herpes simplex virus (HSV) infections were examined microscopically, electron microscopically, and immunohistochemically. Coagulative necrosis with inclusions was found in the livers and adrenal glands in all cases, as well as in various other organs, including the spleen, bone marrow, lungs, esophagus, tongue, and thymus, in some cases. Distinct hemorrhagic diathesis was found in three cases. No characteristic clinical findings, such as skin rashes or elevated titers of the antibody to HSV, were found, and clinical diagnosis was therefore difficult. In three cases isolation and typing of the causative virus were performed virologically, and type 1 HSV (HSV-1) was identified as the causative virus. Immunohistochemically, the type and distribution of the virus were evaluated in all cases with type-specific antisera to types 1 and 2 (HSV-2) antigens by the peroxidase-antiperoxidase method. In five cases the infections were found to be due to HSV-1 and in only one case to HSV-2. In the placenta in one case of HSV-2 infection, HSV antigen was demonstrated in the chorionic villi. Electron microscopic study confirmed the existence of viral particles in the placenta in that case and, thus, the possibility of a transplacental route of infection.