Intradermal Infection of Mice with Orientia tsutsugamushi

Female six- to eight-week old CD-1 Swiss outbred mice (Charles River Laboratories, Wilmington, MA, USA) were housed in animal biosafety level (ABSL)-2 laboratories prior to inoculation. Two days prior to inoculation, they were relocated to an ABSL-3 laboratory to adapt to their new surroundings. The mice were intradermally inoculated with 10³ MuID₅₀ of O. tsutsugamushi Karp or Gilliam strains produced from liver-spleen homogenate of infected CD-1 mice into the dorsum of the right ear as previously described [67 (link)]. Sterile PBS was used as mock inoculum to inject negative control animals [67 (link)]. In some cases, Swiss CD-1 mice were intraperitoneally inoculated with 10³ MuID₅₀ of O. tsutsugamushi Karp. At various days post-infection, the mice were euthanized, and organs or blood were harvested for DNA isolation [68 (link)]. All animal research was performed under the approval of the Institutional Animal Care and Use Committee at the Naval Medical Research Center (Protocol Number: 11-IDD-26).