1. Institute for Virology and Immunobiology, University of Wuerzburg, Versbacher Str. 7, D-97078 Wuerzburg, Germany
2. Centre for Cancer Research and Cell Biology, School of Biomedical Sciences, The Queen’s University of Belfast, Belfast BT9 7BL, Northern Ireland, UK
3. Department for Electron Microscopy, University Wuerzburg, Biocenter, D-97078 Wuerzburg, Germany