Herpes simplex virus encephalitis: intrathecal synthesis of oligoclonal virus-specific IgG, IgA and IgM antibodies.

Paired specimens of serum and CSF from seven patients with acute herpes simplex virus encephalitis were examined during the acute illness or the convalescent stage or during both stages. Imprint immunofixation analyses of viral antibodies separated by agarose electrophoresis and by electrofocusing disclosed intrathecal production of herpes simplex virus IgG antibodies in all seven patients, and of IgA and IgM antibodies in six and three of six patients, respectively. Intrathecal production of herpes simplex virus-specific IgG and IgA was observed in two patients from whom samples were collected after 1 year, while intrathecal production of virus-specific IgM was not demonstrated later than 5 weeks after onset. The intrathecally synthesized IgG and IgM, and to a lesser extent IgA antibodies displayed oligoclonal characteristics. Oligoclonal bands of IgG were observed in the CSF of all patients. Evidence is presented to show that the bulk of the oligoclonal CSF IgG represents herpes simplex virus-specific antibodies. Intrathecally synthesized populations of herpes simplex virus antibodies cross-reacting with varicella-zoster virus were identified in three of the patients.