Advanced light microscopy to resolve spatio temporal and spatio morphological infection processes in vitro and in vivo Virologie Mikroskopie Tollwutvirus SARS CoV 2 Coxiella burnetii Lichtscheibenmikroskopie Tissue Optical Clearing Lebendzellmikroskopie Nervensystem Atemwege Coxiella burnetii SARS CoV 2 light microscopy light sheet fluorescence microscopy live cell imaging nervous system rabies virus respiratory tract tissue optical clearing virology Technological advances in light microscopy have always gone hand in hand with unprecedented biological insight. For microbiology light microscopy even played a founding role in the conception of the entire discipline. The ability to observe pathogens that would otherwise evade human observation makes it a critical necessity and an indispensable tool to infectious disease research. Thus the aim of this thesis was to optimize extend and functionally apply advanced light microscopy techniques to elucidate spatio temporal and spatio morphological components of bacterial and viral infection in vitro and in vivo. Pathogens are in a constant arms race with the host’s immune system. By finding ways to circumvent host mediated immune responses they try to evade elimination and facilitate their own propagation. The first study (publication I) demonstrated that the obligate intracellular pathogen Coxiella burnetii is not just able to infect natural killer (NK) cells but is actually capable of surviving the harsh degradative conditions in the cytotoxic lymphocyte’s granules. Using live cell imaging of reporter expressing Coxiella burnetii the transient NK cell passage was closely monitored to provide detailed spatio temporal information on this dynamic process in support of a range of static analyses. Bacterial release from NK cells was pinpointed to a time frame between 24 to 48 hours post infection and the duration of release to about 15 minutes. The second approach ...