Intralesional host response within eschars in Mediterranean spotted fever

The host response within the eschar of inoculation during Mediterranean spotted fever (MSF) has been poorly studied. Our objective was to evaluate the host response by comparing transcriptional profiles of eschars to controls using a whole-genome microarray. Hierarchical clustering revealed a signature of eschars consisting of 698 genes. The genes included in this signature were mainly up-regulated and were predominantly associated with immune response and signalling. New molecules involved notably in microbicidal and innate immunity response have also been found up-regulated in eschars such as MMP1, Defensin β4, the proinflammatory S100A9, and the T cell attracting CCL-18. Genes down-regulated were mainly associated with biological regulation. We also observed that eschars from severe cases of MSF displayed a specific signature with notably difference in degree of modulation compared to eschars from non severe MSF cases. Some parameters identified in this work should be tested as biomarkers for prognostic assessment in future studies. To evaluate the host response by comparing transcriptional profiles of eschars to controls