鈥� Reassociation kinetics analyses with radioiodinated herpes simplex type 1 DNA and influenza A/NWS RNA were performed in the presence of tissue nucleic acids from defined loci of the brains of nine patients with idiopathic Parkinson's disease, one normal control brain, and the brains of uninfected mice or mice infected with either herpes simplex type 1 virus or influenza A/NWS virus. Herpes simplex type 1 DNA was detected by an increased reassociation rate in the herpes simplex type 1 virus-infected mouse brains. Influenza A/NWS RNA was detected by reassociation in the influenza A/NWS virus-infected mouse brains. Experimental limits for the detection of homologous nucleic acids are given for each separate experiment with human or mouse tissue. Within these detection limits, nucleic acids complementary to herpes simplex type 1 DNA or influenza A/NWS RNA were not detected in any of the brains of patients with idiopathic Parkinson's disease.