FIG 1.

Burkholderia pseudomallei infects the trigeminal nerve via the nasal cavity. (A) Schematic drawing of a sagittal mouse brain section showing the locations of various panels: nasal cavity (NC), olfactory bulb (OB), cerebral cortex (CTX), midbrain (MB), cerebellum (C), brain stem (BST [blue]), spinal cord (S [blue]), and trigeminal nerve (red). (B and C) Tissue sections from mice infected with B. pseudomallei; nuclei are stained with DAPI. (B) Coronal view of a turbinate with widespread crenellation of the epithelium (fletched arrow) and exudate (arrow) within the nasal cavity. An asterisk shows the location of the image shown in panel D. (C) B. pseudomallei immunolabeling (green) within degraded olfactory epithelium (fletched arrow) and NC (arrow). (D) B. pseudomallei immunolabeling (green) within the lamina propria underlying the epithelium. (E) Sagittal view of the nasal region showing branches of the trigeminal nerve (red, S100β-DsRed; blue, DAPI); the boxed region is shown in panel F. (F) B. pseudomallei (arrow) near the trigeminal nerve, and associated particles immunoreactive for anti-B. pseudomallei antibodies (fletched arrows). (G to K) Whole-mount preparations of mouse heads. (G) Dorsal view of a whole-mount preparation of a mouse head, with the brain removed. The image is a merge of a bright-field image and a fluorescent image showing DsRed expression in the nasal cavity (NC), olfactory bulb (OB), and trigeminal nerves (Tg). (H) Fluorescent whole-mount image showing the structure of the trigeminal nerves while still present within the mouse head. (I) Trigeminal nerve after removal from the whole-mount mouse head and immunolabeled with anti-B. pseudomallei antibodies showing B. pseudomallei (arrows) within the nerve. (J) High-magnification view showing a B. pseudomallei rod within the whole-mount trigeminal nerve. (K) Same image shown in panel J with green fluorescence overexposed, revealing the presence of the associated particles. (Fletched arrows show some of the particles.) (L to P) Bacteria present throughout the trigeminal nerve in cryostat sections. (L) The olfactory mucosa consists of the olfactory epithelium (OE) and lamina propria (LP), olfactory nerve fascicles immunolabeled with anti-OMP antibodies (white [fletched arrow]), and a trigeminal nerve branch with Schwann cells that express DsRed with B. pseudomallei immunolabeling (arrows). (M) B. pseudomallei (arrow) within the trigeminal nerve midway (rostral-caudal) along the nerve. Associated particles can also be seen (fletched arrows). (N) B. pseudomallei present within the trigeminal nerve toward the caudal end of the nerve. (O) B. pseudomallei (arrow) and associated particles (fletched arrows) were localized to discrete patches within the trigeminal nerve. (P) B. pseudomallei Δcap rod (arrow) with a fluorescent particle (arrow with tail) within the caudal region of the trigeminal nerve. Scale bars are in micrometers.