SFB 900 Teilprojekt B1

Visualization of herpesviral infections and the immune response and modulation

The humane cytomegalovirus (HCMV) causes, in particular in immunosuppressed patients, significant clinical diseases which become manifest, i.a., as hepatitis, pneumonitis, retinitis and colitis. Since cytomegaloviruses are characterised by a pronounced species tropism, HCMV cannot be studied in the rodent model. The course of infection with the murine CMV (MCMV) in the mouse, however, shows many similarities to the HCMV infection in human beings. Although comprehensive infection experiments with MCMV were carried out, the exact processes during infection at a single-cell level are not sufficiently understood. The objective of this project is therefore to carry out comprehensive examinations regarding the spatial and temporal dissolution of infections with MCMV. We particularly intend to analyse the interaction of various cells of the immune system (macrophages, conventional dendritic cells, plasmacytoid dendritic cells, NK and T cells) as well as stroma cells during the induction of the immune response against MCMV within lymphoid organs, in particular within the primary draining lymph nodes, at a single-cell level. By using various recombinant MCMV virus mutants expressing Gaussia luciferase, a red fluorescent protein (mCherry) and a defined peptide sequence of ovalbumin (SIINFEKL) (so-called MCMV-3D), the temporal and spatial distribution of the infection, the virus dissemination and the resistance strategies in the natural host at a cellular level shall be represented with the help of in-vivo experiments using mice, i.a. by way of in-vivo two-photon microscopy. In our previous work we were able to demonstrate that the infection with MCMV induces a massive reduction of the expression of CCR7 on infected dendritic cells (DC). The viral genes responsible for this process shall therefore be identified and the cellular mechanisms mediating the reduced CCR7 expression shall be clarified. By using virus mutants which do not induce a down-regulation of CCR7 and mouse mutants in case of which the expression of CCR7 can be switched on or off specifically on DC, it shall be clarified how the CMV-mediated reduction of CCR7 expression influence the kind and scope of the antiviral immune response.