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PubMed1989

[Epidemiological study on Toxoplasma infection in human beings and animals in Shandong Province].

A total of number of 6822 samples of human serum and 3093 samples of animal serum collected from 7 prefectures and cities were detected for the anti-toxoplasma antibodies by using the indirect hemagglutination (IHA) test in Shandong province. The positive rate of population was 4.06 +/- 0.24%. The antibody positive rates of swine, sheep, rabbits, chicken and ducks were 14.05%, 8.52%, 2.43%, 2.98% and 23.33% respectively. After the data were treated with groups analysis and stratified analysis, it was found that rearing cats and contacting with raw pork frequently were two important risk factors for human. The Relative Risk (RR) of the two factors were estimated to be 3.67 and 2.07 respectively. There was a very strong correlation between spontaneous abortion, stillbirth history and toxoplasma infection (RR = 7.44, P less than 0.001).

Adolescent↗
PubMed1989

[Detection of Toxoplasma antibodies using the c-ELISA method].

Sensitive and high capacity ELISA techniques introduced for the detection of toxoplasmatic antibodies so far do not correlate very well with standard serological examination systems used in common diagnosis of Toxoplasmosis. The most frequently used method in the CSSR - SFT using tween-ether soluble antigen extract, and displaying very satisfactory agreement with the Sabin-Feldman test, was compared with the system of direct ELISA, using the same antigen extract and the described c-ELISA method. The latter method uses for antibody detection whole non-disintegrated formol-treated trophozoites of Toxoplasma gondii and thus in the reaction in particular membrane antigens, incl. latent ones, are involved. Parallel examination of 160 sera of subjects with clinical suspicion of toxoplasma infection by the standard CFT, method and methods ELISA and c-ELISA revealed a better correlation between CFT and c-ELISA (r = 0.8031) than between CFT and ELISA with soluble antigen (r = 0.6016). Other positive specific features of the c-ELISA method are the use of commercially produced antigen for the immunofluorescence test, considerable elimination of selective adsorption of the polystyrene carrier and the perspective of the long-term preservation of plates with the fixed antigen.

Animals↗
PubMed1989

Susceptibility of Eimeria bovis and Toxoplasma gondii to oxygen intermediates and a new mathematical model for parasite killing.

Eimeria bovis and Toxoplasma gondii differ in their susceptibility to macrophages activated by lymphokines. Interferon-gamma can activate macrophages to totally inhibit E. bovis sporozoite development, whereas growth of T. gondii tachyzoites in macrophages is not totally affected. The susceptibility of these parasites to oxygen intermediates and their ability to evade the oxidative burst by macrophages were investigated in cell-free systems. Using a logistic model to assess growth inhibition, T. gondii growth was impaired by 50% at 10(-4.25) M (56 microM) H2O2, with 30 min as the optimum time for measuring inhibition. Preliminary results indicate that T. gondii follows mode-one and mode-two killing with relation to time after exposure to H2O2, implying a role for OH. and the induction of a DNA repair mechanism. The same model was used to assess inhibition of E. bovis growth that was more susceptible, being inhibited to 50% by 10(-5) M (10 microM) H2O2. Both parasites were susceptible to the effects of xanthine-xanthine oxidase that releases a full complement of oxygen intermediates (H2O2, OH., (1)O2, and O2-). Adding quenchers or scavengers to the system confirmed that T. gondii was susceptible to products of the interaction of O2- and H2O2 (OH. and (1)O2), and that E. bovis sporozoites were at least partially susceptible to H2O2 and O2-, but extremely susceptible to OH.. These data were supported by studies on scavenging enzymes present in the parasites. Toxoplasma gondii was rich in superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPO), and E. bovis had less catalase and SOD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Enzyme-linked immunosorbent assay for the detection of circulating antigens of Toxoplasma gondii in the serum of cats.

An ELISA was developed to detect circulating antigens of Toxoplasma gondii in the serum of cats. For the experiment, toxoplasmosis was induced in a group of cats by oral administration of bradyzoites. An ELISA that detects anti-Toxoplasma IgG, an ELISA to detect circulating antigens, and fecal examinations were performed on samples from each cat for 1 year after inoculation. When coupled with IgG-class antibody measurement, antigen detection can aid in the diagnosis of some cases of subclinical feline toxoplasmosis.

Animals↗
PubMed1989

Genetic regulation of early survival and cyst number after peroral Toxoplasma gondii infection of A x B/B x A recombinant inbred and B10 congenic mice.

Genetics of two traits, survival and brain cyst number after peroral Toxoplasma gondii infection, were studied by using recombinant inbred strains of mice derived from resistant A/J (A) and susceptible C57BL/6J (B) progenitors, F1 progeny of crosses between A/J and C57BL/6J mice, and congenic mice (B10 background). Analysis of strain distribution pattern of survival of A x B/B x A recombinant mice indicated that survival is regulated by a minimum of five genes. One of these genes appears to be linked to the H-2 complex and another is related to an as yet unmapped gene controlling resistance to Ectromelia virus. Associations of defined traits with resistance or susceptibility to Toxoplasma cyst formation were also analyzed. Cyst number is regulated by a locus on chromosome 17 within 0 to 4 centimorgans of the H-2 complex (p = 0.001). Mice with the H-2a haplotype are resistant and those with the H-2b haplotype are susceptible. This analysis also indicated that the Bcg locus on chromosome 1 may effect cyst number (map distance = 12 centimorgans, p = 0.05). Resistance to cyst formation is a dominant trait. To analyze relative roles of H-2 and Bcg loci on cyst numbers, C57BL10 (B10)-derived congenic strains of mice with known H-2 and Bcg type were studied. These studies indicated that the H-2 complex locus has the primary effect on cyst number.

Administration, Oral↗
PubMed1989

[Detection of circulating Toxoplasma gondii antigens by the dot-ELISA method].

Dot-immunobinding technique was used to detect circulating Toxoplasma antigens in the sera of men and animals. Serum samples were collected from mice and rabbits infected experimentally with parasites of the RH strain of T. gondii while human sera were obtained from persons suspected of having active toxoplasmosis. Circulating Toxoplasma antigens were detected in the samples of mice sera that had been collected since the 2-nd day of infection and in the sera of rabbits during 2 and 3 week of infection. From amongst 146 human sera, 35 (24%) gave positive reaction in the test while 14 (9,5%) produced doubtful results. The experiments proved the method to be sensitive, reproducible and easy to perform. It obviates the need of special equipment while most of the necessary reagents are commercially available. High percentage of doubtful results is the main drawback of the method.

Animals↗
PubMed1986

[A new ELISA method for the diagnosis of toxoplasmosis. Assay of serum IgM by immunocapture with an anti-Toxoplasma gondii monoclonal antibody].

The diagnosis of acute toxoplasmosis is based exclusively on the detection of IgM anti-Toxoplasma antibodies. The principal of the immunoenzymatic test reported here is the capture of serum IgM antibodies which are detected indirectly by the sequential addition of antigen and a monoclonal antibody directed against the immunodominant epitope at the surface of the tachyzoite. This test combines the sensitivity of enzyme-based assays and the specificity of monoclonal reagents and represents an important contribution to the diagnosis of Toxoplasma gondii infection.

Acute Disease↗
PubMed1988

[Incidence of antibodies to Toxoplasma gondii in cats from Brno and the surrounding area].

In the course of three years, 620 cats of all age categories were investigated for the occurrence of antibodies to Toxoplasma gondii. The serological examinations included the Sabin-Feldman reaction (SFR), complement-fixation reaction (CFR) and microprecipitation in agar gel (MPA), according to methods prescribed for use in Czechoslovakia. When the Sabin-Feldman reaction was used, 250 (40.3%) of the examined cats were found to be positive at the titre of 4-128. By the complement-fixation reaction, antibodies were demonstrated in 144 (23.2%) of the cats at the titre of 5-80. Microprecipitation in agar gel was positive in 106 animals, i.e. 17.1%. Antibodies to Toxoplasma gondii were demonstrated by one serological reaction in 150 (24.2%) cats; coincidence of two serological reactions occurred in 104 (16.8%) of the animals, and coincidence of all the three serological reactions was demonstrated in 48 (7.7%) cats. Specific antibodies were detected by minimally one serological reaction (which means one to three positive findings) in 302 (48.7%) of the examined cats. The diagnostic value of all serological reactions is discussed. It is recommended to repeat the examination after two to three weeks.

Animals↗
PubMed1988

[Clinical aspects of Toxoplasma primary infection in pregnancy].

Prevention of connatal toxoplasmosis is only possible by early diagnosis and treatment of toxoplasma-primoinfection in pregnancy. The authors describe the diagnostic approach and report on 110 pregnant women with toxoplasma-primoinfection. Treatment consisted in the application of pyrimethamine in combination with a sulfonamide or spiramycine. Side-effects of pyrimethamine are mentioned. The aim is an improvement of diagnosis and therapy.

Animals↗
PubMed1988

Toxoplasma gondii-induced abortion in sheep.

Twenty-nine of 200 (14.5%) ewes on a farm in Cobleskill, NY aborted or had dead lambs during the lambing seasons of 1985 and 1986. Thirteen of 15 ewes that aborted had high Toxoplasma gondii antibody titers (1,024), via the modified agglutination test, and T gondii was isolated from the tissues of 1 fetus. In the 1987 lambing season, 5 ewes aborted, but not because of T gondii infection. Toxoplasma gondii antibodies were detected in 73.8% of sera obtained from 592 ewes in January 1987, indicating enzootic toxoplasmosis on this farm. Seropositivity increased with age; 40.2% of 1-year-old ewes had detectable antibody vs 89.2% of 2-year-old ewes.

Abortion, Veterinary↗
PubMed1988

Dual regulation of resistance against Toxoplasma gondii infection by Lyt-2+ and Lyt-1+, L3T4+ T cells in mice.

Studies were performed to attempt to define the T cell subset responsible for resistance to Toxoplasma gondii. A temperature-sensitive mutant (ts-4) strain of T. gondii was used for immunization because it causes infection but does not persist in the host. Immunization with this strain induced marked resistance against lethal challenge infection with virulent strains of T. gondii in mice. The resistance could be transferred to normal recipient mice by i.v. injection of spleen cells from ts-4-immunized mice. Marked inhibition of cyst formation in the recipient mice was also noted. The protective activity of immune spleen cells was removed by pretreatment of the spleen cells with anti-Thy-1.2 and C, indicating that T cells are responsible for the observed protection. Pretreatment of immune spleen cells with anti-Lyt-2.2 and C completely ablated their protective effect; pretreatment with anti-Lyt-1.2 or anti-L3T4 and C had lesser effects on their ability to transfer resistance. The effect of anti-Lyt-1.2 was the same as that obtained with anti-L3T4. This suggested that one T cell subset that is partially responsible for protection has both Lyt-1.2 and L3T4 markers on the cell surface. These results indicate that there are substantial roles for both the Lyt-2+ and Lyt-1+, L3T4 T cell subsets in dual regulation of resistance against toxoplasma infection and that Lyt-2+ T cells are the principal mediator of the resistance.

Animals↗
PubMed1988

Membrane fluidity of Toxoplasma gondii: a fluorescence polarization study.

Toxoplasma gondii membrane fluidity was investigated by fluorescence polarization. We used 1,6-diphenyl 1,3,5-hexatriene (DPH) as a fluorescent hydrophobic probe. Fluorescence anisotropy (r) and degree of order (s) showed high fluidity properties. Chemical analysis was performed on this parasite. We found a low cholesterol/phospholipid ratio, many unsaturated fatty acids chains, and high phosphatidylcholine and low sphingomyelin amounts. These results were in good agreement with the observed high fluidity. This may be related to the great adaptability of Toxoplasma gondii in infesting a wide variety of host cells.

Animals↗
PubMed1987

[A new test for Toxoplasma gondii serology: carbon immunoassay].

Several tests with various sensitivities are available for sero-epidemiologic and diagnostic purposes in T. gondii serology. Carbon Immuno Assay test has been developed in recent years based on binding of carbon particles present in Indian ink by Toxoplasma-specific antibodies combined with Toxoplasma trophozoites. In this study, CIA test has been modified and compared with Sabin-Feldman Dye and ELISa Toxo-IgG tests.

Animals↗
PubMed1986

Activity of recombinant tumor necrosis factor on Toxoplasma gondii and Trypanosoma cruzi.

Activated macrophages produce tumor necrosis factor (TNF), a cytokine with anti-tumor and anti-plasmodia activities. This study revealed that recombinant TNF (rTNF) inhibits intracellular multiplication of blood trypomastigotes of Trypanosoma cruzi in murine peritoneal macrophages. rTNF did not have any apparent direct effect on the survival of extracellular T. cruzi or on its ability to infect mammalian cells. The degree of inhibition of the intracellular multiplication of T. cruzi was found to be a function of the time of exposure of the infected cells to rTNF. rTNF induced a comparable effect when different strains of the parasite were used. In contrast to its activity on T. cruzi, rTNF did not affect intracellular multiplication of Toxoplasma gondii tachyzoites or bradyzoites in normal murine peritoneal macrophages or in human fibroblasts. Killing of Toxoplasma tachyzoites by activated macrophages was not enhanced by rTNF.

Animals↗
PubMed1986

Toxoplasma antibodies in local domestic animals.

211 sera obtained from domestic animals generally used for human consumption in this area, were tested for Toxoplasma antibodies by the Indirect Haemagglutination Test (IHA). Goat (34.4%) and pig sera (26.6%) showed a higher prevalence as compared to cattle (16.6%) and sheep (7.4%). Obviously, proper precautions at every stage of the preparation of a meat dish are necessary to avoid Toxoplasma infection.

Animals↗
PubMed1987

Toxoplasma gondii cysts in placentas of experimentally infected sheep.

To determine the presence of tissue cysts in ovine placentas, 6 ewes were inoculated orally with 10,000 Toxoplasma gondii oocysts at 60 days of gestation. The ewes were euthanatized and necropsied 21, 52, 56, 57, 57, and 62 days after T gondii inoculation, and placental cotyledons from each ewe were collected and homogenized. To distinguish between the presence of tachyzoites that are killed by acid pepsin solution and bradyzoites (from cysts) unaffected by this solution, a portion of each homogenate was inoculated into mice and another portion was inoculated into mice after digestion in acid pepsin solution. Toxoplasma gondii was isolated in 26 of 34 (76.4%) of mice inoculated with nondigested placentas of all 6 ewes and in 16 of 34 (47%) mice inoculated with digested placenta of 5 of 6 ewes. Seemingly, cysts do occur in placental tissue, but the digestion method was inferior, compared with the nondigestion method for recovery of T gondii from placenta.

Animals↗
PubMed1978

[Toxoplasma infection of the liver (author's transl)].

Two months after a severe febrile attack a liver biopsy was performed in a 23 years old female patient with strongly elevated serological antibody levels of toxoplasma infection. The immunohistological investigation of the liver specimen showed the typical demonstration of Toxoplasma gondii in the liver parenchyma. Except a slightly elevated gamma-GT no signs of a "hepatitis" could be demonstrated.

Adult↗
PubMed1986

Rat macrophage activity against Toxoplasma gondii studied by electron microscopy.

An electron microscope model was used to study the effect of rat peritoneal macrophages on Toxoplasma gondii. 10(7) tachyzoites were injected i.p. in 30 days-old rats. After 1, 2, 4, 8 and 24 h peritoneal exudate was withdrawn and infected phagocytic cells were prepared for electronic microscope studies. Toxoplasma organisms inside of rat macrophages showed remarkable lesions such as vacuolization and organisms were totally lysed inside of macrophages of more than 8 h infection rats. The results confirm at molecular level, the importance of rat macrophages in the natural adaptation of this rodent to T. gondii.

Animals↗