Kinetics of IgM and IgG responses to Japanese encephalitis virus in human serum and cerebrospinal fluid.

We measured levels of antibodies to Japanese encephalitis virus (JEV) in serum and in cerebrospinal fluid (CSF) specimens obtained from 32 patients with acute encephalitis by using "antibody-capture" solid-phase enzyme-linked immunoassays specific for IgM or IgG to JEV. The proportions of confirmed cases with IgM to JEV detectable in CSF were 68% (obtained on day 1), 100% (day 7), 96% (day 30), and 72% (day 180). For IgG in CSF the proportions were 47% (day 1), 89% (day 7), 100% (day 30), and 100% (day 180). Twenty-five CSF samples were obtained from control patients with other diseases with possible nervous system involvement (but none with a clinical diagnosis of viral encephalitis); none had detectable IgM to JEV. Five JEV-infected but asymptomatic siblings of patients with encephalitis were also examined; all had high levels of IgM to JEV in serum, but none had detectable IgM to JEV in CSF.