Fig 1.
Pathophysiologic responses following infection with O. tsutsugamushi Karp strain.
A) A mean increase in body temperature was observed from 11–12 dpi, followed by hypothermia at 14 dpi. B) Weight loss was presented as the percentage of body weight change compared with 0 dpi. Weight loss was evident from 13–16 dpi, followed by a gradual recovery beginning around 17 dpi.
Fig 2.
Bacterial loads following infection with O. tsutsugamushi Karp strain (OtK).
A) Quantification of the OtK 47-kDa gene in the ear, draining lymph nodes (dLN), or B) in blood, lung, liver, spleen, and brain tissues. All data are presented as 47-kDa gene copies per 105 or 106 GAPDH for tissues, or per μl of blood. Representative data from one of two independent experiments are shown.
Fig 3.
Histopathologic changes in mouse liver after infection with O. tsutsugamushi.
A) Liver sections collected at 9 dpi, showed scattered intraparenchymal clusters of mononuclear inflammatory cells located randomly in the hepatic lobules (100X). B) Medium magnification shows lymphohistiocytic clusters between hepatic cords, (200X). C) Liver inflammatory index (inflammatory cluster per 10 medium-power fields x diameter of cluster, μm). Scores of infected groups were compared with sham controls, and statistically significant differences were observed from 9–56 dpi, respectively. *, p < 0.05, **, p < 0.01, *** p < 0.001.
Fig 4.
Location of O. tsutsugamushi Karp strain antigens in the lungs at 12 days following i.d. inoculation.
Low-power sections of the lungs revealed the presence of Orientia antigens (red) in alveolar septa (A) and an interstitial capillary (B) (100X, bars = 100 μm). High power magnification (400X) revealed the presence of Orientia in septal (C) and interstitial capillaries (D); bars = 20 μm.
Fig 5.
Histopathologic changes in mouse lung after infection with O. tsutsugamushi.
Lung tissues collected between 9 and 11 dpi were stained with H&E and scored from grades 1 to 4. A) Grade 1: widening of alveolar septa and scattered inflammatory cells. B) Grade 2: Diffuse widening of alveolar septal walls and mononuclear inflammatory cells around bronchovascular bundles (inset). C) Grade 3: Marked diffuse interstitial pneumonitis with mononuclear inflammatory cells and focal areas of alveolar collapse. D) Grade 4: Marked diffuse interstitial pneumonitis with mononuclear inflammatory cells and large areas of alveolar collapse. All images were taken at 40X, and insets were taken at 200X magnification. E) Histopathology scores of infected lungs were compared with uninfected controls and presented as Whiskers 5–95% percentile. *, p < 0.05, **, p < 0.01.
Fig 6.
Serum cytokine levels during infection with O. tsutsugamushi.
Serum samples were collected from sham controls (n = 3) and infected mice (n = 4) for measuring the indicated cytokines by using a BioPlex assay. Data (pg/ml) are presented as Whiskers 5–95% percentile. Infected samples were compared with sham controls. *, p < 0.05, **, p < 0.01, *** p < 0.001.
Fig 7.
Lung cytokine levels during infection with O. tsutsugamushi.
Lung samples were collected from sham controls (n = 3) and infected mice (n = 4) for measuring the indicated cytokines by using a BioPlex assay. Data (pg/ml) are presented as Whiskers 5–95% percentile. Infected samples were compared with sham controls. *, p < 0.05, **, p < 0.01.