Rickettsia felis, from Culture to Genome Sequencing

: Rickettsia felis has been recently cultured in XTC2 cells. This allows production of enough bacteria to create a genomic bank and to sequence it. The chromosome of R. felis is longer than that of previously sequenced rickettsiae and it possess 2 plasmids. Microscopically, this bacterium exhibits two forms of pili: one resembles a conjugative pilus and another forms hair‐like projections that may play a role in pathogenicity. R. felis also exhibits several copies of ankyrin‐repeat genes and tetratricopeptide encoding gene that are specifically linked to pathogenic host‐associated bacteria. It also contains toxin‐antitoxin system encoding genes that are extremely rare in intracellular bacteria and may be linked to plasmid maintenance.