1 Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany; First Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
2 Department of Virology, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany; German Center for Infection Research, Partner Site Hamburg-Lübeck-Borstel-Riems, Hamburg, Germany. Electronic address: [email protected].