• Parasites, Hosts and Diseases
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• v.28 no.2
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• pp.79-84
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• 1990

Metabolic inhibitors which act in the process of pyrimidine salvage influenced on the uracil incorporation into nucleic acids of Toxoplasma. Inhibitors of dihydrofolate reductase, pyrimethamine and methotrexate, and inhibitors of thymidylate synthase, fluoro-uridine, fluoro·dUMP and fluoro-uracil, diminished isotopic uracil uptake in dose-dependent manners. Azauridine which suppresses do novo pyrimidine biosynthesis did not affect the salvage even in a relatively high dose. These results suggested that the activation of uracil salvage should be closely related with the function of TMP biosynthetic enzymes. The pattern of thymidine uptake had no differences between control HL-60 cells and Toxoplasma infected cells, which did not reject the specific proliferation of Texoplasma. It can be exploited to characterize the elects of various compounds related with the proliferation of Toxoplasma, especially its DNA synthesis. Key words: Toxoplasma gondii, uracil salvage, dihydrofolate reductase, thymidylate synthase TMP biosynthesis.

• Korean Journal of Veterinary Research
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• v.33 no.2
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• pp.285-287
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• 1993

Toxoplasma gondii frozen by the method of very slow cooling ($-30^{\circ}C/3hrs.{\rightarrow}\;-60^{\circ}C/lhr.{\rightarrow}\;-196^{\circ}C$ of liquid nitrogen)were inoculated mice after storage in the liquid nitrogen for 5 years. The results obtained were as follows; 1. Toxoplasma gondii was detected in mice 4~5th day after intraperitoneal inoculation of organisms stored in the liquid nitrogen once a year for 5 years. 2. Toxoplasma gondii could be preserved longer than 5 years in liquid nitorgen being evidenced by the in vivo test.

• Parasites, Hosts and Diseases
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• v.51 no.5
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• pp.579-581
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• 2013

In recent years, worldwide surveys of Toxoplasma gondii infection in dogs have been reported. However, only limited surveys of T. gondii infection in police dogs have been available, including China. In the present study, we report the seroprevalence of T. gondii in police dogs in Shenyang, northeastern China. Sera from 291 police dogs were examined for T. gondii antibodies with the modified agglutination test (MAT), and 30.9% animals were tested seropositive. The results of the present study indicated a relatively high prevalence of T. gondii infection in police dogs in Shenyang, China.

• Parasites, Hosts and Diseases
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• v.59 no.6
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• pp.565-572
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• 2021

Toxoplasma gondii ME49 infections are typically diagnosed by serological tests. However, serological diagnosis of RH strain-induced toxoplasmosis remains unknown. In order to develop seradiagnosis of above 2 kinds of infections, we generated recombinant virus-like particles (VLPs) displaying the T. gondii rhoptry protein 4 (ROP4) and evaluated their potential in T. gondii ME49 or RH strain infection diagnostics. Mice were orally infected with either the tachyzoites of T. gondii (RH) or cysts of T. gondii (ME49) at various dosages, and sera were collected at regular intervals. ELISA-based serological tests were performed to assess IgG, IgM, and IgA antibody responses against ROP4 VLP antigen and tissue lysate antigen (TLA). Compared to TLA, IgG, IgM, and IgA levels to ROP4 VLP antigen were significantly higher in the sera of T. gondii RH-infected mice 1 and 2 week post-infection (PI). T. gondii-specific IgG antibody was detected at 1, 2, 4, and 8 week PI in the T. gondii ME49-infected mice with infection dose-dependent manner. These results indicated that the ROP4 VLP antigen was highly sensitive antigens detecting T. gondii RH and ME49 antibodies at an early stage.

• Korean Journal of Veterinary Service
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• v.35 no.1
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• pp.19-24
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• 2012

This study was performed to evaluate the prevalence rate of Toxoplasma gondii on 217 stray cats in Daejeon. The positive infection rate of T. gondii was 15.7% in enzyme-linked immunosorbent assay (ELISA), 12.4% in latex agglutination test (LAT), 14.7% in indirect immunofluorescent antibody test (IFA) and 0.5% in polymerase chain reaction (PCR) respectively. In districts, Yuseong-gu was shown the highest seropositive rate of T. gondii as 31.8% in ELISA, 22.7% in LAT and 31.8% in IFA. In gender, the seropositive rate of female cats was slightly higher than that of male cats as 17.2% in ELISA, 15.2% in LAT, 15.2% in IFA and 1.0% in PCR. Cats captured in National science museum, detached house and apartment was shown relatively high prevalence rate of T. gondii.

• Journal of Veterinary Science
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• v.23 no.1
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• pp.13.1-13.12
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• 2022

Background: Toxoplasma gondii can infect humans and most animals and has a very high infection rate worldwide, including in China. The number of people infected with T. gondii in China increases with the number of cats. Objectives: We investigated the seropositive rate of T. gondii in cats over the last five years and analyzed the risk factors via meta-analysis. Methods: We retrieved 20 studies, with a total of 5,158 cats, published between 2016 and 2020, used the DerSimonian-Laird model and calculated seroprevalence estimates with the variance stabilizing double arcsine transformation. Results: The overall seroprevalence rate after sinusoidal conversion was 19.9% (95% confidence interval [CI], 15.9-23.9; 966/5,158), lower than the domestic report from 1995 to 2015 (24.5%, 95% CI, 20.1-29.0). There was substantial heterogeneity among studies (χ² = 262.32; p < 0.001; I² = 64.6%). Regression analysis of possible heterogeneous causes and subgroup analysis showed that age and whether cats were stray or not have a significant effect on the seropositive rate. Conclusions: Articles published in recent five years suggest that the seroprevalence estimates of Toxoplasma gondii in cats has decreased. Cats, as the final host of T. gondii, are an important cause of the spread of the parasite, and this is an important concern for public health.

• Parasites, Hosts and Diseases
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• v.50 no.3
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• pp.233-238
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• 2012

The precise diagnosis of the acute toxoplasmosis in pregnant women and immunocompromsied patients has critical importance. Most of the commercially available assays use the whole Toxoplasma soluble extract as the antigen. However, the assays currently available for the detection of specific anti-Toxoplasma antibodies may vary in their abilities to detect serum immunoglobulins, due to the lack of a purified standardized antigen. The aim of this study was production and evaluation of the usefulness of the recombinant Toxoplasma gondii GRA7 antigen for the serodiagnosis of Toxoplasma gondii IgM and IgG by ELISA. A total of 70 T. gondii IgM positive sera, 74 T. gondii IgG positive sera, and 60 sera from subjects who were not infected with T. gondii were examined. These sera were shown different absorbance values in ELISA test. To control the specificity of the rGRA7 other parasitic diseases, for example, echinococcosis, malaria, leishmaniasis, fascioliasis, and strongyloidiasis were tested of which none showed positive results. Sensitivity and specificity of the generated recombinant IgG ELISA in comparison with commercial ELISA (com ELISA) were 89% and 90%, and the sensitivity and specificity of the generated recombinant IgM ELISA were 96% and 90%, respectively. The results obtained here show that this antigen is useful for diagnostic purposes.

• Journal of Veterinary Science
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• v.22 no.6
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• pp.88.1-88.6
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• 2021

Toxoplasma gondii consists of three genotypes, namely genotype I, II and III. Based on its virulence, T. gondii can be divided into virulent and avirulent strains. This study intends to evaluate an alternative method for predicting T. gondii virulence using hierarchical cluster analysis based on complete coding sequences (CDS) of sag1, gra7 and rop18 genes. Dendrogram was constructed using UPGMA with a Kimura 80 nucleotide distance measurement. The results showed that the prediction errors of T. gondii virulence using sag1, gra7 and rop18 were 7.41%, 6.89% and 9.1%, respectively. Analysis based on CDS of gra7 and rop18 was able to differentiate avirulent strains into genotypes II and III, whereas sag1 failed to differentiate.

• Parasites, Hosts and Diseases
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• v.53 no.4
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• pp.489-492
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• 2015

Although Toxoplasma gondii infection in primary school children has been investigated in many countries, limited surveys have been available in primary school children in China. In the present study, we report the seroprevalence of T. gondii infection in primary school children in Shandong province, China. Sera from 6,000 primary school children were evaluated for T. gondii antibodies with ELISA. The overall seroprevalence of T. gondii infection was 16.0% (961/6,000), of which 14.5% (870/6,000) were positive for anti-T. gondii IgG antibodies, 3.4% (206/6,000) positive for IgM, and 1.9% (115/6,000) were positive for both IgG and IgM. The results of the present investigation indicated a high seroprevalence of T. gondii infection in primary school children in Shandong province, China. Therefore, effective measures should be taken to prevent and control T. gondii infection in primary school children in this province. To the best of our knowledge, this is the first report of T. gondii seroprevalence in primary school children in Shandong province, China.

• Korean Journal of Veterinary Service
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• v.37 no.1
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• pp.29-33
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• 2014

This study aimed at finding a fast, sensitive, and efficient protocol for molecular identification of intracellular protozoa Toxoplasma (T.) gondii. For molecular detection of T. gondii, we developed a polymerase chain reaction coupled with dot blot hybridization assay (PCR/DBH). For DBH analysis, the amplified DNA of T. gondii tachyzoite was labeled by incorporation of digoxigenin. The DBH assay alone was capable of detecting down to $1{\times}10^4$ pg of T. gondii genomic DNA. The PCR alone was capable of detecting down to $1{\times}10^3$ pg of T. gondii genomic DNA, whereas the PCR/DBH assay was capable of detecting down to $1{\times}10^2$ pg of T. gondii genomic DNA, indicating that sensitivity of the PCR/DBH method was approximately 10 to 100 times higher than PCR or DBH alone. Our PCR/DBH assay will be useful for confirming the presence of T. gondii on the samples and differentiating T. gondii infection from other intracellular protozoa infections.