Figure 4

N. meningitidis targets the thyroid gland and the nasal area of CD46 transgenic mice. (A) BLI of mice at 24 h after i.v. infection. Distinct bioluminescent signals are visible in the thyroid area (T) and oral-nasal region (N) of CD46 transgenic mice. (B) Ex vivo BLI imaging of a dissected thyroid. (C) Bacterial loads in blood and thyroid at 24 h post-infection. Significant difference between thyroid of CD46 transgenic mice and nontransgenic mice is indicated (P<0.001). Bars indicate mean ± SD. (D) Immuno-histochemical examination of thyroid gland tissue sections of mice infected for 24 h. Tissue sections were overlaid with antiserum against N. meningitidis, followed by a FITC-conjugated anti-rabbit IgG. Cell nuclei were counter-stained with DAPI (blue). Bacteria (shown in green) are detected in the cellular layer of thyroid follicles of CD46 transgenic mice (inset). Scale bar: 20 µm. (E) Thyroxine (T4) levels in mice. Sera were collected from CD46 transgenic (n = 6) and nontransgenic mice (n = 6) at indicated time points post-infection and T4 levels were determined by enzyme immunoassay (EIA). Uninfected CD46 transgenic mice had significantly less T4 than nontransgenic mice (P<0.05). Significant reductions of T4 compared with uninfected mice are indicated with asterisks (*, P<0.05).