R. conorii (Rickettsia conorii) causes Mediterranean Spotted Fever in humans, which is transmitted by brown dog ticks. Rickettsia are obligate intracellular bacteria normally living in arthropod cells. Rickettsia are true bacteria, small coccobacilli that are normally stained with Giemsa and poorly by the Gram stain. Its cell wall morphology is that of a Gram-negative bacillus. Phylogenetically R. conorii is a member of the Alpha-subgroup of Proteobacteria (Ref.1). The bacterium is closely related to R. prowazekii (Rickettsia prowazekii), which causes Typhus. R. conorii has a relatively small genome, in part because it tends to inactivate its own genes when it use of genes from its host. The R. conorii genome has 1.3 million base pairs and 1,374 genes, slightly more than [...]