by Maureen Akinyi Obara, M.Sc. in Medical Microbiology/Medical Virology ; Hannover Medical School, International PhD program “Infection Biology” in Hannover Biomedical Research School (HBRS), Institute for Experimental Infection Research, Center for Experimental and Clinical Infection Research, TWINCORE, a joint venture between the Hannover Medical School and the Helmholtz Center for Infection Research ; Supervisor: Prof. Dr. Ulrich Kalinke, TWINCORE, Hannover; Co-Supervisors: Prof. Dr. Gisa Gerold, Medical University of Innsbruck; Dr. Simon E. Hufton, National Institute for Biosafety Standards (NIBSC) United Kingdom