Use of polymerase chain reaction for laboratory diagnosis of herpes simplex virus encephalitis.

Polymerase chain reaction was used to detect herpes simplex virus (HSV) specific deoxyribonucleic acid (DNA) sequences in acute and convalescent cerebrospinal fluid (CSF) and brain tissue of a 78-year-old man and in CSF of a neonate who died of complications owing to herpes simplex virus encephalitis (HSVE). Polymerase chain reaction (PCR) was carried out for 35 cycles with a set of primers that bracketed a 92 base pair segment unique to the HSV DNA polymerase gene. Amplified DNA was electrophoresed on 3 percent agarose gel, blotted onto a nylon membrane, and probed with 32p-labeled oligonucleotide internal to the primers. The HSV specific DNA sequences were detected in the specimens from both patients. No HSV specific DNA was detected in CSFs from 20 patients with suspected Lyme disease or neurosyphilis. Polymerase chain reaction is a rapid and noninvasive technique for the diagnosis of HSVE.