Immune response is energetically demanding process and although an improper regulation of energetic metabolism during immune challenges leads to various complications in human patients it is largely unknown how is the energetic metabolism regulated during the immune response. Extracellular adenosine is a strong candidate for this type of regulation; nevertheless it has never been studied for such role. Our work using Drosophila as a model strongly supports the view of adenosine being the signal connecting energy reallocation with immune response. The regulation of extracellular-adenosine levels and its signaling are now well defined in flies and the model allows various manipulations with the adenosine system in vivo. Therefore the model is now perfectly suitable for a systematic analysis of the adenosine regulation of energetic metabolism during various infections which should lead to a better understanding of the energetic costs of mounting an immune response. Results of such analysis could greatly contribute to our knowledge of host-pathogen interactions and some highly important biomedical problems. Goal of this project is for the applicant to learn the complex methodology of Drosophila infections and use these obtained skills for the systematic analysis of the adenosine role during immune response.