1. Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA.
2. Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, USA.
3. Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA, USA.
4. Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA.
5. University of Pittsburgh–Carnegie Mellon University Program in Computational Biology, Pittsburgh, PA, USA.
6. School of Computer Science and Engineering, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.