Detection of viral antigens in cerebrospinal fluid of patients with herpes simplex virus encephalitis

Abstract

Thirty‐two cerebrospinal fluid (CSF) samples from eighteen patients with confirmed herpes simplex encephalitis (HSE) were assayed by an indirect enzyme‐linked immunosorbent assay (ELISA) for the presence of viral antigens. The results are expressed as an antigen ratio distinguishing between herpes simplex virus (HSV) antigens containing samples and negative samples. Judged by this criterion a positive result was obtained in 33 % of the patients. Overall, 25% of the CSF samples from HSE patients were positive. In one out of 33 control patients with other neurological disorders a positive antigen ratio was found. Two or more CSF samples were available from eleven patients. In six of these, the second or later samples showed a decreased antigen ratio when compared to the first CSF sample. An increase of the anti‐HSV antibody titer was seen in the CSF of five of these six patients. Five out of six patients with a decreasing antigen ratio had an unfavorable outcome of their encephalitis, while a favorable outcome was seen in four of the five patients with an increasing or steady antigen ratio. A decrease of the antigen ratio in the course of HSE can be explained by the presence of immune complexes in CSF and may indicate a poor prognosis.