In subproject 3, the role of ticks as vectors for transmitting Q-fever will be investigated. The aim of these studies is to clarify the role of the sylvatic cycle (postulated by literature) for the epidemiology of Q-fever. To determine vector competence of ticks, an artificial tick feeding model will be developed and tested by means of Coxiella isolates of different origin. Furthermore, the subproject deals with isolate-specific differences in pathogeny and virulence. To confirm any observed isolate-specific virulence potential in these models, confirmatory tests on the proteome level will be performed and the data from genome analysis will be correlated. In addition, bacterial markers are intended to be identified which will contribute to the differentiation of circulating isolates and could enable the detection of especially virulent isolates. Both approaches will support the implementation of suitable counter measures.