1. Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, United States
2. Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, United States
3. National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, Massachusetts 02118, United States
4. Monogram Biosciences, South San Francisco, California 94080, United States