• Korean Journal of Veterinary Research
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• v.28 no.2
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• pp.379-385
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• 1988

For the comparison of surface fine structures in the proliferative forms of two major protoroan parasites, Toxoplasma gondii and Sarcocystis species in mammalian hosts, isolated from the artificially infected mice and from the naturally infected cattle, respectively, an SEM(Hitachi S-570) was applied to the fixed, dried and coated with gold ion on the microslide glasses. The tachyzoites of T gondii from the peritoneal cavity of the mouse showed the crescent-like feature and measured as $5.57{\mu}m$ in length and $2.33{\mu}m$ in width, while the bradyzoites of Sarcocystis species from the heart muscle of slaughtered cattle was banana-shaped and measured as $14.18{\mu}m$ in length and $2.85{\mu}m$ in width. On the surface of Sarcocystis species bradyzoite, a distinct elliptical micropore was identified in the high magnification observation of 60,000X, and it measured as $0.35{\mu}m$ in length and $0.18{\mu}m$ in width.

• Parasites, Hosts and Diseases
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• v.35 no.1
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• pp.55-62
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• 1997

The molecular weight 30 kDa membrane protein of Toxoplusma Sondii (Toxoplasma 30 kDa) apparently conserved in most strains of T. gondii and sera of infected hosts. The present study aimed to elucidate Toxoplasmc 30 kDa as a useful diagnotic antigen for serodiagnisis of toxoplasmosis by ELISA and for induction of protective immunity. Murine spleen cells immunized with the membrane antigen of T. gondii were fused with mouse Sp2/0-Ag 14 myeloma cells. Out of 8 clones selected, five were IgG2b, the others belonged to IgG 1 and IgG2a. The 30 kDa antigen was distributed mainly on the surface membrane of tachyzoites by indirect fluorescence method. Murine peritoneal macrophages which were activated by 30 kDa antigen produced more amounts of NO2 compared with crude antigen-treated group, however there were no significant differences in toxoplamacidal activity between the two groups. Higher specificity of Toxoplosma 30 kDa antigen was recognized for serodiagnosis of toxoplasmosis than the crude antigen. From these results, ToxopLasmo 30 kDa antigen enhances the cytotoxic effect of macrophages as well as a more reliable means for the serodiagnosis of toxoplasmosis by ELISA. Key words: Toxoplosma gondii, 30 kDa antigen (p30), mouse, serodiagnosis, macrophage, cytotoxicity.

• Parasites, Hosts and Diseases
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• v.60 no.4
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• pp.241-246
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• 2022

Felids are the unique definitive host of Toxoplasma gondii. The intestine of felid is the only site for initiating Toxoplasma gondii sexual reproduction. T. gondii excretes millions of infectious oocysts from the intestine, which are the primary source of infection. There are many difficulties in developing vaccines and drugs to control oocyst excretion due to the lack of an appropriate experimental model. Here, we established an in vitro feline intestinal epithelial cell (IEC) infection system and an efficient animal model of T. gondii Chinese 1 genotype, Wh6 strain (TgCtwh6). The Kunming mice brain tissues containing TgCtwh6 cysts were harvested 42-day post-infection. The bradyzoites were co-cultured with cat IECs in vitro at a ratio of 1:10. Five 3-month-old domestic cats were orally inoculated with 600 cysts each. The oocysts were detected by daily observation of cat feces by microscopy and polymerase chain reaction. We found that the parasite adhered and invaded cat IECs in vitro, transformed into tachyzoites, and then divided to form rose-like structures. These parasites eventually destroyed host cells, escaped, and finished the asexual reproduction process. Schizonts associated with sexual reproduction have not been observed during development in vitro cultured cells. However, schizonts were detected in all infected cat intestinal epithelial cells, and oocysts were presented in all cat feces. Our study provides a feasible cell model and an efficient infection system for the following studies of T. gondii sexual reproduction, and also lays a foundation to develop drugs and vaccines for blocking excretion and transmission of oocysts.

• Journal of Life Science
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• v.20 no.10
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• pp.1556-1562
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• 2010

This study examined the histopathologic and electron microscopic findings of aborted fetuses from pregnant dairy cows naturally infected with Neospora caninum (N. caninum) at four farms in Gongju city and Yeonki gun of Choongnam province. Systemic subcutaneous edema was observed in the aborted fetuses. The necropsy revealed considerable serosanguinous fluid in the body cavity of the aborted fetuses. Light microscopy showed the infiltration of many inflammatory cells consisting of macrophages, lymphocytes and mononuclear cells, accompanied by congestion, hemorrhage and necrosis of myocardiac cells and hepatocytes in the liver and heart of the aborted fetuses. In the liver, clusters of tachyzoites were formed in the cytoplasm of hepatocytes and the interstitial tissue. In the brain, many tissue cysts of various sizes were observed in the nerve cells and their adjacent areas. Tissue cysts had a round shape and contained a large amount of bradyzoite. In addition, there was diffuse gliosis accompanied by congestion and hemorrhage and focal necrosis in the brain. Infiltration of microglial cells were observed at the periphery of the focal necrosis and perivascular area in the brain. Electron microscopy showed that the tissue cyst wall had a thickness of approximately 1 ${\mu}m$ with an irregular shape. On the interior side, more than 100 bradyzoites with lengths of 2-5 ${\mu}m$ and widths of 1-2 ${\mu}m$ were observed. The nucleus of in the bradyzoites was located approximately 1-1.5 ${\mu}m$ anterior to the posterior tip of the zoite. In the cytoplasm between the nucleus and the posterior tip, there were many amylopectin granules, electron-dense small-sized and electron-thin large-sized round granules, homogeneously electron-dense rhoptries and micronemes oriented perpendicularly to the zoite pellicle. To summarize, tissue cysts were identified on electron microscopy from the aborted fetus from N. caninum seropositive pregnant cow by the ELISA. This led to the confirmed presence of N. caninum.

• Parasites, Hosts and Diseases
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• v.32 no.4
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• pp.249-258
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• 1994

Recently, the importance of toxoplasmosis is raised as a complication in immunosuppressed or AIDS patients. Our study focused on the identification of a variety of Toxoplasma antigens by immunoblotting. Rabbits and BALB/c mice were immunized with Toxoplosmo Iysate (RH strain) , frozen tachyzoites (RH strain) or cysts (Beverly and Fukaya strain) . Blood were collected from ear vein, heart or orbital plexus for detecting the serum antibody levels. For excretory-secretory (E.S) antigens, T gondii (RH) tachyzoite were cultured in CHL (Chinese hamster lung) cells with MEM containing of 5% FCS. After 72hrs, culture supernatant was collected. BALB/c mice were inoculated with RH tachyzoite intraperitoneally and peritoneal fluids were extracted three days later. E.S antigens were detected in culture supernatant and infected mouse peritoneal fluid by EITB. Serum IgG levels in rabbit were 1 :512 of 10 days after primary immunization, 1 : 2,048 of 10 days after secondary immunization, 1: 1,024 of 20 days after secondary immunization by IFAT, respectively. Serum IgG levels of immunized mice were 1:128 after 7 weeks. Tachyzoite antigens of the RH strain were detected 25 protein bands ranging 10 kDa-220 kDa of molecular weights with Coomassie blue stain. Toxoplcsma major antigens corresponding to n of 24 kDa, 27 kDa,30 kDa, 35 kDa, 38 kDa were recognized by IgG and IgM antibodies. Excretory-secretory antigens present in culture supernatant with M. W. of 20, 30 kDa and in infected mouse peritoneal fluid with M.W. of 33 (P30), 45 kDa. When RH tachyzoite antigen was probed with different mice sera immunized with 2 strains of T gondii, the IgG antibody bud of Fukaya and Beverly strain (8 week-serum) is identical to those of RH strain. It is considered that the 30 kDa polypeptide detected in excretory- secretory materials and Iysate was important major antigen of T gondii (RH).

• Parasites, Hosts and Diseases
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• v.35 no.4
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• pp.251-258
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• 1997

Tachyzoite antigens of Toxoplosnc gondii (RH) were partially purified by immunoaffinity chromatography. The cultivated ToxopLusmc in uiuo (mouse) and in nitro (Hep-2 cell) and peritoneal fluid of T. Bondii infected mice were collected for antigen analy- sis. Tachyzoite antigens collected from infected mouse showed positive bands of 76 kDa, 70 kDa,64 kDa, 53 kDa, 46 kDa, 44 kDa, 41 kDa, 35 kDa, 25 kDa, 18 kDa, and 13 kDa on immunoblot with anti-Toxoplcsmn rabbit sera, and those from infected Hep-2 cells revealed reactive bands of 70 kDa,64 kDa,53 kDa,35 kDa,28 kDa, and 13-10 kDa. After applying to an IgG-Sepharose column, two elusion peaks, E-1 and I-2 fractions, were obtained from both soluble antigen of T. gondii and the peritoneal fluid of infected mice, respectively. Immunoblots of soluble antigen with immunized rabbit sera revealed positive bands of 97 kDa, 63 kDa, 53 kDa and 35 kDa from I-1 fraction and 53 kDa and 35 kDa from I-2. In the case of the eluted peaks from mice peritoneal fluid, E-1 showed protein bands of 84 kDa,76 kDa,53 kDa and 29 kDa bands and 53 kDa and 45 kDa from I-2 on immunoblots. Serum IgG antibody titer of mice immunized with T gonnii tachyzoites was increased on 1 week after booster immunization when analysed by ELISA using crude antigen, while it was elevated on 3 weeks after booster immunization by ELISA using puri- fied antigen.