Herpes simplex encephalitis. A modified indirect immunoperoxidase technique for rapid diagnosis in paraffin-embedded tissue.

A modification of a reliable and simple method of the indirect immunoperoxidase technique was used to identify herpesvirus antigen in paraffin-embedded tissue of patients with herpes simplex encephalitis (HSE), as well as in rats and mice. So far we have studied five cases in humans and six in mice and rats. With preincubation, we increased antigenicity and accomplished high specificity. Brown reaction product was found mainly at the periphery of the areas of necrotizing encephalitis. Here it was present in different types of glial cells, as well as in neurons. In the animals, it was found in the leptomeninx in cells of the basal cortex and in the ependymal cells of the third ventricle and the cells around it. This method should be of great value for the study of human pathology because new drugs are available for treatment of HSE and a tissue diagnosis is necessary. It is also a useful technique for studying viral CNS infections in experimental animals.