Table 1.
Summary of studies concerning biology of tissue cysts in rodents.
Table 2.
Summary of studies on size of tissue cysts in the brains of rodents inoculated with T. gondii.
Table 3.
Experimental toxoplasmosis in ratsa inoculated orally with oocysts of 11 strains of T. gondii of different genotypes.
Fig 1.
Acute toxoplasmosis and tissue cyst formation in cerebrum of Rat D6143 infected with the TgBbUS1 strain, 7 days p.i.
IHC staining with BAG1 T. gondii antibodies. (A) A focal area of necrosis, the genesis of a glial nodule, individual bradyzoites and small tissue cysts (arrow). Several tachyzoites are present in the lesion but are unstained. (B) Higher magnification of an area indicated by arrow in Fig 1A. Note individual bradyzoites (arrowheads) and small tissue cysts (arrows). (C) Necrosis (arrow) and two tissue cysts (arrowheads) in skeletal muscle.
Fig 2.
Focal inflammation in retina (a) of Rat D6143 infected with the TgBbUS1 strain, 7 days p.i.
(A) Necrosis, and inflammatory focus, primarily affecting the inner retinal layers, bulges into the vitreous chamber (arrows). The choroid (b) and sclera (c) are not affected. HE stain. (B) Higher magnification of Fig 2A with two tachyzoites (arrows). (C) A tachyzoite (arrow) in the inflammatory focus. IHC stain with polyclonal T. gondii antibodies. This tachyzoite is larger in size than the tachyzoites stained with HE in Fig 2B because tachyzoites swell during immunostaining.
Fig 3.
Tissue cysts in sections of brains of rats.
(A) A group of nine tissue cysts without host reaction. IHC staining with BAG1 T. gondii antibodies in Rat D6255 infected with the TgRabbitBr1 strain (B) Intraneuronal tissue cyst with thin PAS-negative cyst wall (arrow) enclosing numerous bradyzoites that are stained red. Rat D6249, Strain TgBbUS1. PASH stain.
Fig 4.
Tissue cyst distribution and pair wise comparison of the brain regions for infected rats.
(A) Box and whisker plot of tissue cyst densities for the regions in the mid-sagittal sections from the 108 rats (top). Table of statistics for comparison between pairs of regions using Mann-Whitney (bottom). SPSS Graph Builder (version 22) was used to draw the boxplot. (B) P-values for comparisons of tissue cyst densities in regions using the Mann-Whitney test. The Bonferroni corrected p-value cutoff for multiple testing is 0.0011 (0.05/45).
Table 4.
Measurements of tissue cysts from rat brains infected with different strains of T. gondii.
Fig 5.
Comparison of tissue cyst counts between strains of T. gondii.
(A) Box and whisker plot of tissue cyst number from the mid-sagittal sections for the 108 rats with eleven strains (n = 9–10 rats per strain). SPSS Graph Builder (Version 22) was used to create the boxplot. (B) Table of statistics for comparison between strains using Mann-Whitney test as Fig 4. Bonferroni multiple testing correction p-value cutoff is (0.05/55).
Table 5.
Summary of lesions in extra ocular tissues of rats inoculated orally with 11 strains of T. gondiia.
Fig 6.
Multiple necrotizing foci in cerebrum of Rat D6162 infected with the GT1 strain.
Two foci have degenerative tissue cysts (arrows). IHC staining with polyclonal T. gondii antibodies.
Fig 7.
(A) Meningoencephalitis in Rat D6157 infected with the TgCatCo3 strain. Note meningitis (a), perivascular infiltration of leukocytes (b), and a glial nodule with a degenerative tissue cyst (c). PASH stained. (B) A large inflammatory focus, probably resulting from the host reaction to degenerative tissue cysts in Rat D6162 infected with theGT1 strain and HE stained.
Fig 8.
Examples of encephalitis with intact and degenerative tissue cysts.
For Rat D6162 infected with the GT1 strain: (A) Vasculitis with five intact tissue cysts at the periphery of the lesion. IHC staining with T. gondii BAG1 antibodies and hematoxylin counterstain. (B) Several glial nodules, one with a degenerative tissue cyst (arrow). (C) Higher magnification of focus arrowed in Fig 8B. Note immunoreactive debris (arrows) in focus of necrosis focus. One intact tissue cyst (arrowhead) is at the periphery of the lesion. (D) The same lesion as in Fig 8B. An intact tissue cyst (arrowhead) is present at the periphery of glial nodule with central necrosis. There are no visible bradyzoites. PASH stain.
Fig 9.
Examples of degenerative tissue cysts in brains of rats.
(A) Higher magnification of the lesion in Fig 7D with Rat D6157 infected with strain TgCatCo3. The cyst wall (arrow) is visible but bradyzoites have degenerated. (B) Bradyzoites in different stages of degeneration in Rat D6163 infected with the TgCatCo3 strain. The tissue cyst wall is not visible. IHC staining with BAG1 T. gondii antibodies. (C) Intensely stained bradyzoites in Rat D6162 infected with the GT1 strain. IHC staining with polyclonal T. gondii antibodies. (D, E) Two tissue cysts in different stages of degeneration in Rat D6162 infected with the GT1 strain. The outline of the tissue cysts is visible in one (arrow) and not in the other (arrowheads). The bradyzoites (arrowheads) appear to be intact.
Table 6.
Ocular lesions in rats orally inoculated with T. gondii oocysts.
Fig 10.
(A) Inflammatory focus involving the entire width of the retina (a) and encroaching the choroid (b). The sclera (c) is unaffected. Rat D6185 infected with the VEG strain and HE stained. (B) A focally extensive area of inflammation (retinitis) composed of lymphocytes and few macrophages affecting primarily the inner layers of the retina. Rat D6243 infected with the TgBbUS1 strain and HE stained. (C) Four intact tissue cysts (arrows) and a probable degenerating tissue cyst (arrowhead) in retina. Rat D6186 infected with the VEG strain. (D) Tissue cyst (arrow) in retina without host reaction. Rat D6249 infected with the TgBbUS1 strain and HE stained.