1 Departments of Neurology (D.G., T.W., M.A.N.) and Microbiology & Immunology (D.G.), University of Colorado School of Medicine, Aurora, CO; Departments of Neurology and Ophthalmology (S.L.G.), New York University School of Medicine, New York; and Department of Pathology and Laboratory Medicine (F.F.), University of Pennsylvania, Philadelphia, PA.