A New IgG Immunoblot Kit for Diagnosis of Toxoplasmosis in Pregnant Women

The determination of the accurate immune status of pregnant women is crucial in order to prevent congenital toxoplasmosis. Equivocal results with conventional serological techniques are not uncommon when IgG titers are close to the cut-off value of the test, so that a confirmatory technique is needed. For this purpose, we developed a homemade immunoblot (IB) using soluble extract of Toxoplasma gondii tachyzoites and assessed it by testing 154 positive, 100 negative, and 123 equivocal sera obtained from pregnant women. In order to select the more valuable bands in terms of sensitivity and specificity, we used the Youden Index (YI). The highest YIs were those given by the 32, 36, 98, 21, and 33 bands. The simultaneous presence on the same blot of at least 3 bands showed a much higher YI (0.964) and was adapted as the positivity criterion. The analysis of results showed that our homemade IB correlated well with the commercial LDBIO Toxo II IgG(R) kit recently recommended as a confirmatory test (96.7% of concordance).

Real-Time RT-PCR on SAG1 and BAG1 Gene Expression during Stage Conversion in Immunosuppressed Mice Infected with Toxoplasma gondii Tehran Strain

Toxoplasmic encephalitis is caused by reactivation of bradyzoites to rapidly dividing tachyzoites of the apicomplexan parasite Toxoplasma gondii in immunocompromised hosts. Diagnosis of this life-threatening disease is problematic, because it is difficult to discriminate between these 2 stages. Toxoplasma PCR assays using gDNA as a template have been unable to discriminate between an increase or decrease in SAG1 and BAG1 expression between the active tachyzoite stage and the latent bradyzoite stage. In the present study, real-time RT-PCR assay was used to detect the expression of bradyzoite (BAG1)- and tachyzoite-specific genes (SAG1) during bradyzoite/tachyzoite stage conversion in mice infected with T. gondii Tehran strain after dexamethasone sodium phosphate (DXM) administration. The conversion reaction was observed in the lungs and brain tissues of experimental mice, indicated by SAG1 expression at day 6 after DXM administration, and continued until day 14. Bradyzoites were also detected in both organs throughout the study; however, it decreased at day 14 significantly. It is suggested that during the reactivation period, bradyzoites not only escape from the cysts and reinvade neighboring cells as tachyzoites, but also converted to new bradyzoites. In summary, the real-time RT-PCR assay provided a reliable, fast, and quantitative way of detecting T. gondii reactivation in an animal model. Thus, this method may be useful for diagnosing stage conversion in clinical specimens of immunocompromised patients (HIV or transplant patients) for early identification of tachyzoite-bradyzoite stage conversion.

Anti-parasitic action and elimination of intracellular Toxoplasma gondii in the presence of novel thiosemicarbazone and its 4-thiazolidinone derivatives

Toxoplasma, which infects all eukaryotic cells, is considered to be a good system for the study of drug action and of the behavior of infected host cells. In the present study, we asked if thiosemicarbazone derivatives can be effective against tachyzoites and which morphological and ultrastructural features of host cells and parasites are associated with the destruction of Toxoplasma. The compounds were tested in infected Vero cell culture using concentration screens (0.1 to 20 mM). The final concentration of 1 mM was chosen for biological assay. The following results were obtained: 1) These new derivatives decreased T. gondii infection with an in vitro parasite IC50 percent of 0.2-0.7 mM, without a significant effect on host cells and the more efficient compounds were 2, 3 (thiosemicarbazone derivatives) and 4 (thiazolidinone derivative); 2) The main feature observed during parasite elimination was continuous morphological disorganization of the tachyzoite secretory system, progressive organelle vesiculation, and then complete disruption; 3) Ultrastructural assays also revealed that progressive vesiculation in the cytoplasm of treated parasites did not occur in the host cell; 4) Vesiculation inside the parasite resulted in death, but this feature occurred asynchronously in different intracellular tachyzoites; 5) The death and elimination of T. gondii was associated with features such as apoptosis-like stage, acidification and digestion of parasites into parasitophorous vacuoles. Our results suggest that these new chemical compounds are promising for the elimination of intracellular parasites by mainly affecting tachyzoite development at 1 mM concentration for 24 h of treatment.

Spontaneous stage differentiation of mouse-virulent Toxoplasma gondii RH parasites in skeletal muscle cells: an ultrastructural evaluation

Although the predilection for Toxoplasma gondii to form cysts in the nervous system and skeletal and heart muscles has been described for more than fifty years, skeletal muscle cells (SkMCs) have not been explored as a host cell type to study the Toxoplasma-host cell interaction and investigate the intracellular development of the parasite. Morphological aspects of the initial events in the Toxoplasma-SkMC interaction were analysed and suggest that there are different processes of protozoan adhesion and invasion and of the subsequent fate of the parasite inside the parasitophorous vacuole (PV). Using scanning electron microscopy,Toxoplasma tachyzoites from the mouse-virulent RH strain were found to be attached to SkMCs by the anterior or posterior region of the body, with or without expansion of the SkMC membrane. This suggests that different types of parasite internalization occurred. Asynchronous multiplication and differentiation of T. gondii were observed. Importantly, intracellular parasites were seen to display high amounts of amylopectin granules in their cytoplasm, indicating that tachyzoites of the RH strain were able to differentiate spontaneously into bradyzoites in SkMCs. This stage conversion occurred in approximately 3 percent of the PVs. This is particularly intriguing as tachyzoites of virulent Toxoplasma strains are not thought to be prone to cyst formation. We discuss whether biological differences in host cells are crucial to Toxoplasma stage conversion and suggest that important questions concerning the host cell type and its relevance in Toxoplasma differentiation are still unanswered.

Porcine abortion outbreak associated with Toxoplasma gondii in Jeju Island, Korea

This report deals with the acute onset of an abortion outbreak and high sow mortality in one pig herd consisted of 1,200 pigs and 120 sows on Jeju Island, Korea. Affected pregnant sows showed clinical signs, including high fever, gradual anorexia, vomiting, depression, recumbency, prostration, abortion, and a few deaths. Four dead sows, five aborted fetuses from the same litter, and 17 sera collected from sows infected or normal were submitted to the Pathology Division of the National Veterinary Research and Quarantine Service for diagnostic investigation. Grossly, hepatomegaly and splenomegaly were observed in sows. Multiple necrotic foci were scattered in the lungs, liver, spleen, and lymph nodes. Microscopically, multifocal necrotizing lesions and protozoan tachyzoites were present in the lesions. Tachyzoites of Toxoplasma (T.) gondii were detected immunohistochemically. Latex agglutination showed that the sera of 7 of 17 (41.2%) sows were positive for antibody to T. gondii. The disease outbreak in this herd was diagnosed as epizootic toxoplasmosis. To our knowledge, this is the first report of porcine toxoplasmosis with a high abortion rate and sow mortality in Korea.

Study on influence of Toxoplasma tachyzoites on human sperm motility parameters in vitro / 中国血吸虫病防治杂志

Objective To explore the influence of Toxoplasma tachyzoites infection on motility of human spermatozoa in vitro, and explain its possible mechanism. Methods Semen samples obtained from 10 healthy volunteers by masturbation were prepared by the swim-up technique. The samples were then inoculated at 37 ℃ with different concentrations of live Toxoplasma tachyzoites varying among 1?103/ml (Group A), 1?104/ml (Group B), 1?105/ml (Group C), 1?106/ml (Group D), 1?107/ml (Group E) and Group F containing Ham’s F-10 only as the negative control. Motion parameters were analysed by Computer-aided sperm analyzer(CASA) in 0 hour, 1 hour, 2 hours, 4 hours respectively. Modalities of spermatozoa and possible adherence and/or agglutination were observed under the light microscope. Results Distinct adhesion of spermatozoa to Toxoplasma tachyzoites and agglutination were noticed. In all the motion parameters, progressive motility was affected most and dependent upon the incubation time and tachyzoites concentration. Progressive motility showed a significant difference between Group E and the control (P

Analysis of Toxoplasma gondii Specific Antigens by Two Dimensional Electrophoresis and Western Blotting / 中国寄生虫学与寄生虫病杂志

The total protein of Toxoplasma gondii RH strain tachyzoites was separated by two-dimensional electrophoresis (2-DE), and Western blotting was performed to find out distinct antigens. 209 spots were detected through Coomassie brilliant blue-stained small gels (7?8 cm, pH 3-10). Western blotting showed 17 specific antigen spots with sera of the experimental group and two nonspecific spots with the control sera.

Dynamic Observation of Attachment and Invasion of Toxoplasma gondii Tachyzoites to Intestinal Mucosa in BALB/c Mice by Chromogenic In Situ Hybridization Targeting SAG2 mRNA / 中国寄生虫学与寄生虫病杂志

Objective To observe dynamically the location and time of attachment and invasion of Toxoplasma gondii tachyzoites to murine intestinal mucosa by chromogenic in situ hybridization targeting SAG2 mRNA. Methods Thirty 7- to 8-week-old BALB/c mice were randomly divided into experiment group(24 mice)and control group(6 mice). Each animal in the experiment group was given 2?104 tachyzoites of RH stain in 0.2 ml PBS by intragastric administration and that in the control group was given 0.2 ml PBS. Four mice in the experiment group and one in the control group were sacrificed at 15 min,30 min,1 h,2 h,4 h and 8 h after infection,respectively,and paraffin sections of duodenum,jejunum and ileum were prepared to perform the in situ hybridization with Dig-labeled oligonucleotide probe complementary to SAG2 mRNA of T. gondii. Results Tachyzoites were found on the striated border of small intestine epithelial cells (absorptive cells,goblet cells and endocrine cells),in or between two absorptive cells or in the lamina propria. At 15 min-2 h after infection,there was significant difference in the number of attachment on jejunum and ileum (P