Herpes simplex virus antibodies in patients with Parkinson's disease.

Sera from 40 patients with idiopathic Parkinson's disease and their age- and sex-matched controls were assayed for immunoglobulin G (IgG) antibodies against herpes simplex virus (HSV) type 1-induced cell surface antigens with the indirect immunofluorescent test. An increased level of HSV antibodies was found among the patients with Parkinson's disease when the distribution of titres (P less than 0.001), the mean titres (P less than 0.001), or the mean paired titre difference (P less than 0.001) was compared with the controls. This may suggest a part of HSV in the pathogenesis of Parkinson's disease. Alternatively, the increased HSV antibody response might be an epiphenomenon indirectly associated with Parkinson's disease.