1. From the Division of Multiple Sclerosis (S.T., S.G., C.L., E.J.K., C.P., L.Z., L.D.Y., M.K.S., J.R.B., C.M., A.B.-O., R.F., R.B., A.A.P., D.A.J.), Hospital of the University of Pennsylvania and Perelman School of Medicine; Division of Infectious Diseases (C.C.), Department of Medicine; and Weill Institute for Neurosciences (M.R.W.), Department of Neurology, University of California, San Francisco.