Cd 1 swiss outbred mice

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).

CD-1 Swiss outbred mice (female, 6–8 weeks of age) were purchased from Charles River Laboratories, Inc. (Wilmington, MA, USA). Mice were initially housed in animal biosafety level (ABSL)-2 laboratories and were transferred to an ABSL-3 laboratory for adaptation one week prior to challenge experiments. Mice were inoculated either intraperitoneally (IP) or intradermally (ID) with10³ MuID₅₀ of O. tsutsugamushi strain Karp (Papua New Guinea) or Woods (Australia) as previously described [34 (link)]. For all ID inoculations, mice were anesthetized using isofluorane (inhalation administration). ID injections of 10³ MuID₅₀ of O. tsutsugamushi were performed at the right ear dorsum at a single site (5 µL of pre-titrated liver-spleen homogenate) using a 0.3 mL insulin syringe (Becton Dickinson, NJ, USA). Negative control animals received an IP or ID inoculation of sterile PBS buffer. Following inoculation, the mice were observed for signs of systemic disease for 21 days. Mice (n = 3–8 per group/time point) were euthanized at 10, 14 (Karp IP only), and/or 21 days following infection. All animal experimentation was performed under the approval of the Institutional Animal Care and Use Committee at the Naval Medical Research Center, Silver Spring, MD (Protocol Number: 11-IDD-26).