1Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
2Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
3Department of Pathology, Harvard Medical School, Molecular Pathology Research Unit, Massachusetts General Hospital, Boston, Massachusetts 02129
4Unité d’Immunologie Virale, Institute Pasteur, Paris 75724, France
5INRA, Villenave d’Ornon 33883, France
6Texas Children’s Cancer Center, Department of Pediatrics and Pathology, Baylor College of Medicine, Houston, Texas 77030
7Channing Laboratory, Harvard Medical School, Boston, Massachusetts 02115
8Department of Pathology, The Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115