Neutralizing serum IgM antibodies in infections with Herpes simplex virus hominis

Forty-two patients with herpes simplex virus infections were tested for neutralizing serum IgM antibodies. A technique in which serum antibody fluorescein staining was combined with sucrose gradient centrifugation facilitated the isolation of the serum IgM fraction for the use in neutralization tests. In nearly all cases with primary infection, especially those presenting heavy clinical signs (encephalitis/meningitis) the IgM tests were positive. In one case we could detect the IgM antibodies for 11 weeks after the onset of the illness, in another case in cerebrospinal fluid samples for 6 weeks. In localized herpes infections, which were mostly due to reactivations, serum IgM antibodies could only rarely be demonstrated. Among the serologic tests used in this study (NT, CFT, IFT, ACIFT), only the CFT beside the NT (with certain reservations) can be applied for subtyping HSV serum antibodies.