[1] Univ Calif San Francisco, Gladstone Inst Virol & Immunol, San Francisco, CA 94141 USA
[2] Univ Calif San Francisco, Dept Neurol, San Francisco, CA 94143 USA
[3] Frankfurt Univ Hosp, Dept Internal Med, Frankfurt, Germany
[4] Univ Calif San Diego, Dept Pathol, San Diego, CA 92103 USA
[5] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA USA
[6] Neurol Inst, Edinger Inst, Frankfurt, Germany