Table 1.
Marmoset groups, identifiers, inoculating doses, clinical presentations, and bacterial loads in selected tissues.
Table 2.
Marmoset identifiers, groups, and cytology findings.
Fig 1.
Cytologic examination of liver, lung and spleen impression smears.
Tissue imprints from control and infected animals were made on glass slides, fixed with methanol, air-dried, stained with modified Wright-Giemsa, examined by light microscopy and photographed. Representative fields are shown. Panel A shows a liver sample from an uninfected control marmoset. The sample was high in cellularity and consisted of clumps of well-differentiated hepatocytes (black block arrows). Panel B shows a liver sample from marmoset D65, which was infected with a medium dose of B. mallei (2,500 CFU). The sample was high in cellularity and consisted of well-differentiated hepatocytes (black block arrows), admixed with increased numbers of small lymphocytes, plasma cells (green block arrow), and erythroid precursors (red arrows). Panel C shows a liver sample from marmoset F48, which was infected with a high dose of B. mallei (250,000 CFU). It consisted primarily of large numbers of degenerate neutrophils (blue block arrows) admixed with well-differentiated hepatocytes (black block arrows), some small lymphocytes (asterisk), extracellular bacilli (inset), and disrupted cellular debris. Panel D shows a splenic sample from an uninfected control marmoset. The sample was high in cellularity and consisted primarily of lymphoid cells (red block arrow) and erythroid precursors (red arrows) admixed with occasional heavily granulated band neutrophils (white block arrow) and segmented neutrophils (yellow block arrows). Panel E shows a splenic sample from marmoset D65, which was infected with a medium dose of B. mallei (2,500 CFU). The sample was high in cellularity and contained plasma cells (green block arrows), small lymphocytes (asterisk), and erythroid precursors (red arrows). Panel F shows a splenic sample from marmoset F48, which was infected with a high dose of B. mallei (250,000 CFU). The sample was high in cellularity and consisted of many degenerate neutrophils (blue block arrows), degranulated and vacuolated neutrophils (shaded block arrows), segmented neutrophils (yellow block arrow) and an increased number of erythroid precursors (red arrows). Panel G shows a lung sample from an uninfected control marmoset. The sample was high in cellularity and consisted of both individualized and clumped, well-differentiated, ciliated, columnar epithelial cells.
Table 3.
Marmoset identifiers, groups, and gross pathology, and histopathology findings.
Fig 2.
Histologic and immunofluorescence examination of nasopharyngeal tissues.
Tissue sections from control and infected animals were stained with H&E (panels A and D), DAPI (panels B and E), or convalescent serum from mice that survived acute infection with B. mallei and a goat anti-mouse antibody conjugated AlexaFluor 488 (panels C and F), examined by microscopy, and photographed. Representative fields are shown. Panel A shows tissue within normal limits from an uninfected control animal at a magnification of 20x. The tissue consisted of a mucosal surface composed of ciliated pseudostratified columnar epithelial cells and goblet cells (E), supported by underlying secretory glands (G) and smooth muscle (M). The asterisk indicates the area used to acquire the images shown in panels B and C. Panel B shows staining of nucleic acid from host cells (blue) at a magnification of 100x. Panel C shows the lack of reactivity of the anti-B. mallei serum with tissue from the uninfected control animal at a magnification of 100x. Panel D shows tissues from marmoset 109, which was infected with a medium-high dose of B. mallei (25,000 CFU), at a magnification of 20x. Mucopurulent exudate was present in the nasal cavity and the tissue exhibited extensive pyogranulomatous rhinitis with marked necrosis. The dotted lines show coalescing pyogranulomas that infiltrated and expanded the connective tissues underlying/supporting the nasal mucosa. The inset shows one of many multinucleated giant cells observed in pyogranulomas at a magnification of 100x. The asterisk indicates the area used to acquire the images shown in panels E and F. Panel E shows staining of nucleic acid from host cells and bacteria (blue) at a magnification of 100x. Panel F shows reactivity of the anti-B. mallei serum with intralesional bacilli (green) at a magnification of 100x.
Fig 3.
Histologic and immunofluorescence examination of lung tissues.
Tissue sections from control and infected animals were stained with H&E (panels A and E), a modified Gram stain method (panels B and F), DAPI (panels C and G), or convalescent serum from mice that survived acute infection with B. mallei and a goat anti-mouse antibody conjugated AlexaFluor 488 (panels D and H), examined by microscopy, and photographed. Representative fields are shown. Panel A and B show tissue within normal limits from an uninfected control animal at a magnification of 20x. The tissue contained numerous clear alveolar spaces (A), respiratory bronchioles (RB) and blood vessels (BV). The asterisk indicates the area used to acquire the images shown in panels C and D. Panel C shows staining of nucleic acid from host cells (blue) at a magnification of 100x. Panel D shows the lack of reactivity of the anti-B. mallei serum with tissue from the uninfected control animal at a magnification of 100x. Panel E and F shows tissues from marmoset 544, which was infected with a high dose of B. mallei (250,000 CFU), at a magnification of 20x. The dotted lines delineate a severe necropurulent granuloma surrounded by clear alveolar spaces as well as alveolar spaces filled with blood (B) and/or necrotic debris (D). The inset in Panel E shows an intralesional bacillus (white block arrow) at a magnification of 100x. The inset in Panel F shows intralesional Gram negative (dark pink-red) bacilli (red block arrow) at a magnification of 100x. The asterisk indicates the area used to acquire the images shown in panels G and H. Panel G shows staining of nucleic acid from host cells and bacteria (blue) at a magnification of 100x. Panel H shows reactivity of the anti-B. mallei serum with intralesional bacilli (green) at a magnification of 100x.
Fig 4.
Histologic and immunofluorescence examination of lymph node tissues.
Tissue sections from control and infected animals were stained with H&E (panels A and E), a modified Gram stain method (panels B and F), DAPI (panels C and G), or convalescent serum from mice that survived acute infection with B. mallei and a goat anti-mouse antibody conjugated AlexaFluor 488 (panels D and H), examined by microscopy, and photographed. Representative fields are shown. Panel A and B show tissue within normal limits from an uninfected control animal at a magnification of 20x. The solid line circle indicates a normal diffuse medullary lymphatic tissue. The asterisk indicates the area used to acquire the images shown in panels C and D. Panel C shows staining of nucleic acid from host cells (blue) at a magnification of 100x. Panel D shows the lack of reactivity of the anti-B. mallei serum with tissue from the uninfected control animal at a magnification of 100x. Panel E and F shows tissues from marmoset 544, which was infected with a high dose of B. mallei (250,000 CFU), at a magnification of 20x. The tissue contained necrotic and purulent areas (dashed lines) almost entirely effacing normal lymph node architecture (solid line circles). The inset in Panel E shows an intralesional bacillus (white block arrow) at a magnification of 100x. The inset in Panel F shows intralesional Gram negative (dark pink-red) bacilli (red block arrows) at a magnification of 100x. The asterisk indicates the area used to acquire the images shown in panels G and H. Panel G shows staining of nucleic acid from host cells and bacteria (blue) at a magnification of 100x. Panel H shows reactivity of the anti-B. mallei serum with intralesional bacilli (green) at a magnification of 100x.
Fig 5.
Histologic and immunofluorescence examination of liver tissues.
Tissue sections from control and infected animals were stained with H&E (panels A and E), a modified Gram stain method (panels B and F), DAPI (panels C and G), or convalescent serum from mice that survived acute infection with B. mallei and a goat anti-mouse antibody conjugated AlexaFluor 488 (panels D and H), examined by microscopy, and photographed. Representative fields are shown. Panel A and B show tissue within normal limits from an uninfected control animal at a magnification of 20x. The tissues consisted of closely packed rows of hepatocytes, portal tracts and blood vessels all radiating from a central vein (CV). No prominent liver sinusoid capillaries were present. The asterisk indicates the area used to acquire the images shown in panels C and D. Panel C shows staining of nucleic acid from host cells (blue) at a magnification of 100x. Panel D shows the lack of reactivity of the anti-B. mallei serum with tissue from the uninfected control animal at a magnification of 100x. Panel E and F shows tissues from marmoset 544, which was infected with a high dose of B. mallei (250,000 CFU), at a magnification of 20x. The dashed lines indicate foci with completely disrupted liver architecture consisting of necrotic hepatocytes and leukocytes debris surrounded by an enlarged and distorted central vein (CV) as well as numerous dilated liver sinusoid capillaries (SC). The inset in Panel E shows intralesional bacilli (white block arrow) at a magnification of 100x. The inset in Panel F shows an intralesional Gram negative (dark pink-red) bacillus (red block arrow) at a magnification of 100x. The asterisk indicates the area used to acquire the images shown in panels G and H. Panel G shows staining of nucleic acid from host cells and bacteria (blue) at a magnification of 100x. Panel H shows reactivity of the anti-B. mallei serum with intralesional bacilli (green) at a magnification of 100x.
Fig 6.
Histologic and immunofluorescence examination of spleen tissues.
Tissue sections from control and infected animals were stained with H&E (panels A and E), a modified Gram stain method (panels B and F), DAPI (panels C and G), or convalescent serum from mice that survived acute infection with B. mallei and a goat anti-mouse antibody conjugated AlexaFluor 488 (panels D and H), examined by microscopy, and photographed. Representative fields are shown. Panel A and B show tissue within normal limits from an uninfected control animal at a magnification of 20x. The tissues consisted of a meshwork of white pulp (WP) containing a large number of lymphoid cells admixed with red pulp (RP). The asterisk indicates the area used to acquire the images shown in panels C and D. Panel C shows staining of nucleic acid from host cells (blue) at a magnification of 100x. Panel D shows the lack of reactivity of the anti-B. mallei serum with tissue from the uninfected control animal at a magnification of 100x. Panel E and F shows tissues from marmoset 544, which was infected with a high dose of B. mallei (250,000 CFU), at a magnification of 20x. The dashed lines indicate necropurulent areas with complete loss of normal follicular structure surrounded by normal meshworks of white and red pulp. The inset in Panel E shows an intralesional bacillus (white block arrow) at a magnification of 100x. The inset in Panel F shows an intralesional Gram negative (dark pink-red) bacillus (red block arrow) at a magnification of 100x. The asterisk indicates the area used to acquire the images shown in panels G and H. Panel G shows staining of nucleic acid from host cells and bacteria (blue) at a magnification of 100x. Panel H shows reactivity of the anti-B. mallei serum with intralesional bacilli (green) at a magnification of 100x.