1. Center for Infectious Disease and Vaccine Research, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
2. Mytogen Inc., Charlestown, MA 02129, USA
3. Bioarray Consulting, Belmont, MA, USA
4. Electron Microscopy Core Facility, University of Massachusetts Medical School, Worcester, MA 01655, USA
5. Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA