Pulmonary tissue lesions caused by <i>O. tsutsugamushi</i>.

<p>Balb/c mice were infected with 5×10³<i>sfu</i> of <i>O. tsutsugamushi</i> or mock-infected with L929 cells via the hind footpad. A, Representative H&E-stained sections from lungs, taken on day 21 p.i. Upper panels: Overview of controls (left) and <i>O. tsutsugamushi</i>-infected (right) lungs, with rectangles specifying specific lesion areas (scale bar = 1 mm). B, Serial sections of lungs from <i>O. tsutsugamushi</i>-infected Balb/c mice (day 21 p.i.) were stained by HE and by immunohistochemistry for macrophages (IBA1), iNOS, neutrophils (Ly6G), B cells (B220) and T cells (CD3). Corresponding areas of the three characteristic localizations of infiltrates are shown (BALT, NIF, pleura). Scale bars: BALT, 100 µm; NIF and pleura, 50 µm. C, The IBA1- and iNOS-positive areas were quantified in BALT, NIF and pleura lesions and expressed in % of the total area and as iNOS/IBA1 ratio. Data are depicted as mean ± SD, ** p<0.01; *** p<0.001 by two-tailed t test (n = 10–14 areas from 2 animals).