Serodiagnosis of herpes encephalitis by indirect enzyme-linked immunosorbent assay, experience from a Swedish antiviral trial

Analysis of IgM/IgG/IgA antibody class activity to herpes simplex (HSV), measles and varicella zoster (VZV) antigen by indirect enzyme-linked immunosorbent assays has been applied to the cerebrospinal fluid and serum from 127 cases of focal encephalitis - 39 patients with and 88 patients without biopsy/necropsy. Results indicative of herpes etiology were found in 53 cases. Intrathecal antibody production was found in all CSF samples taken beyond the tenth day after the onset of neurological illness with one exception - a boy treated with acyclovir for a primary infection within 20 hours after the onset of illness. Intrathecal HSV antibody response was of IgG class in 94%, IgM class in 70% and IgA in 94%. In primary infections, the HSV IgM CSF response was high and contributed to an early diagnosis; in recurrent infections it was often at a low level and late. HSV IgM persisted from 60 to 328 days, IgG and IgA during observation times to 678 days. Cross-reactivity with varicellae zoster was found to be restricted to IgG only.