Detection of herpes-simplex viral genome in brain tissue.

Herpes-simplex virus type (HSV-1) nucleic-acid sequences were detected by in-situ hybridisation in thin sections of brains from mice which had been inoculated 24 weeks previously with HSV-1. These mice were not ill, and infectious virus could not be recovered from them. HSV-1 sequences were also present in brain smears from 3 of 4 elderly patients who had died with chronic psychiatric illness and neuropathological changes but not in smears from 2 patients who had had acute psychotic episodes and minimum abnormal histology. Adenovirus type 7 nucleic-acid sequences were not detected in these human specimens.