1. Institute for Virology and Immunobiology, University of Würzburg, 97078 Würzburg, Germany.
2. Department of Dentistry and Oral and Maxillofacial Surgery, Mount Sinai School of Medicine, New York, NY 10029.
3. Institute for Gene and Cell Medicine and Brookdale Department of Molecular, Cell, and Developmental Biology, Mount Sinai School of Medicine, New York, NY 10029.