Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TOXOPLASMA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed2001

Detection and localization of a Ca2+-ATPase activity in Toxoplasma gondii.

Toxoplasma gondii, the agent causing toxoplasmosis, is an obligate intracellular protozoan parasite. A calcium signal appears to be essential for intracellular transduction during the active process of host cell invasion. We have looked for a Ca2+-transport ATPase in tachyzoites and found Ca2+-ATPase activity (11-22 nmol Pi liberated/mg protein/min) in the tachyzoite membrane fraction. This ATP-dependent activity was stimulated by Ca2+ and Mg2+ ions and by calmodulin, and was inhibited by pump inhibitors (sodium orthovanadate or thapsigargin). We used cytochemistry and X-ray microanalysis of cerium phosphate precipitates and immunolabelling to find the Ca2+, Mg2+-ATPase. It was located mainly in the membrane complex, the conoid, nucleus, secretory organelles (rhoptries, dense granules) and in vesicles with a high calcium concentration. Thus, Toxoplasma gondii possesses Ca2+-pump ATPase (Ca2+, Mg2+-ATPase) as do eukaryotic cells.

Adenosine Triphosphate↗
PubMed1999

Interleukin-12, interferon-gamma and interleukin-4 gene expression in cats infected with Toxoplasma gondii.

Interleukin-12, Interferon-gamma and Interleukin-4 mRNA levels in cells of the spleen and mesenteric lymph nodes of cats following primary and secondary infection with Toxoplasma gondii were examined by a semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) method. Expression of Interleukin-12p40 mRNA and Interferon-gamma mRNA was observed after primary and secondary oral infection with Toxoplasma gondii. In contrast, no expression of IL-4 mRNA in the spleen and little expression in the mesenteric lymph nodes were observed after primary infection when the cats shed oocysts, however, the expression of IL-4 mRNA observed in the cats after secondary inoculation.

Animals↗
PubMed2001

Reduction of the infectivity of Toxoplasma gondii and Eimeria stiedai sporozoites by treatment with bovine lactoferricin.

Sporozoites of Toxoplasma gondii preincubated with lactoferricin showed decreased activity in penetration of mouse embryonal cells. Mice inoculated with 10(5) sporozoites preincubated with lactoferricin showed a higher survival rate than those inoculated with the same number of untreated sporozoites. Likewise, sporozoites of Eimeria stiedai preincubated with lactoferricin also showed decreased activity in penetration of rabbit hepatobiliary cells. Rabbits inoculated with 10(5) sporozoites preincubated with lactoferricin shed fewer oocysts than those inoculated with the same number of untreated sporozoites. These results indicate that lactoferricin is effective to reduce the infectivity of sporozoites of Toxoplasma gondii and Eimeria stiedai.

Animals↗
PubMed2006

PCR-based discrimination of Toxoplasma gondii from pigs at an abattoir in Okinawa, Japan.

To determine the prevalence of the 3 primary clonal lineages of Toxoplasma gondii (strain types I, II, and III) in pigs in Okinawa Prefecture, we analyzed lymph node samples that had been collected at an abattoir by PCR analysis using primers specific for the Toxoplasma gondii SAG2 locus. This study revealed the presence of this parasite in 57 out of 101 samples examined. Restriction fragment length polymorphism (RFLP) in PCR-amplified SAG2 products was used to group strains into one of the three genotypes of T. gondii. Genotypes I and II were equally predominant, accounting for 22 (44.9%) and 23 (46.9%) of 49 SAG2-positive samples, respectively, while the type III strain was found in only 4 (8.2%) of the 49 samples. The other 8 samples were indistinguishable by PCR-RFLP analysis. Polymorphisms for the 3 genotypes were confirmed at the sequence level for several samples using the sequences from the RH strain, the Beverley strain, and the C56 strain as references. On the other hand, the dihydropteroate synthase gene, which is responsible for sulfonamide resistance, was amplified in 40 of 54 SAG2-positive samples by PCR with the specific primers, and further RFLP and sequence analysis revealed that none of them carried the drug-resistant form of the dhps gene. This is the first report of genotyping of T. gondii distributed in Japan.

Abattoirs↗
PubMed2000

Cytologic detection of Toxoplasma gondii tachyzoites in cerebrospinal fluid.

We reviewed our case records to see how often Toxoplasma gondii organisms were identified by cytologic evaluation of cerebrospinal fluid (CSF). During a 12-year period, 6,090 CSF specimens were examined, and 2 cases (0.03%) showed tachyzoites. Both patients were immunocompromised. One patient underwent lumbar and ventricular taps, and the other underwent only ventricular tap. Organisms were identified in the ventricular specimens but not in the lumbar sample. Both patients were treated, and subsequent ventricular CSF samples were negative. Toxoplasma gondii can be identified by cytologic examination of CSF. Our results confirm prior observations that in patients with obstructive hydrocephalus, tachyzoites are more likely to be found in ventricular rather than lumbar specimens.

Adult↗
PubMed2006

Toxoplasma MIC2 is a major determinant of invasion and virulence.

Like its apicomplexan kin, the obligate intracellular protozoan Toxoplasma gondii actively invades mammalian cells and uses a unique form of gliding motility. The recent identification of several transmembrane adhesive complexes, potentially capable of gripping external receptors and the sub-membrane actinomyosin motor, suggests that the parasite has multiple options for host-cell recognition and invasion. To test whether the transmembrane adhesin MIC2, together with its partner protein M2AP, participates in a major invasion pathway, we utilized a conditional expression system to introduce an anhydrotetracycline-responsive mic2 construct, allowing us to then knockout the endogenous mic2 gene. Conditional suppression of MIC2 provided the first opportunity to directly determine the role of this protein in infection. Reduced MIC2 expression resulted in mistrafficking of M2AP, markedly defective host-cell attachment and invasion, the loss of helical gliding motility, and the inability to support lethal infection in a murine model of acute toxoplasmosis. Survival of mice infected with MIC2-deficient parasites correlated with lower parasite burden in infected tissues, an attenuated inflammatory immune response, and induction of long-term protective immunity. Our findings demonstrate that the MIC2 protein complex is a major virulence determinant for Toxoplasma infection and that MIC2-deficient parasites constitute an effective live-attenuated vaccine for experimental toxoplasmosis.

Animals↗
PubMed2025

Iron-mediated post-transcriptional regulation in Toxoplasma gondii.

Iron is required to support almost all life; however, levels must be carefully regulated to maintain homeostasis. Although the obligate parasite Toxoplasma gondii requires iron, how it responds upon iron limitation has not been investigated. Here, we show that iron depletion triggers significant transcriptional changes in the parasite, including in iron-dependent pathways. We find that a subset of T. gondii transcripts contain stem-loop structures, which have been associated with post-transcriptional iron-mediated regulation in other cellular systems. We validate one of these (found in the 3' UTR of TGME49_261720) using a reporter cell line. We show that the presence of the stem-loop-containing UTR is sufficient to confer accumulation at the transcript and protein levels under low iron. This response is dose and time-dependent and is specific for iron. The accumulation of transcript is likely driven by an increased reporter mRNA stability under low iron. Interestingly, we find iron-mediated changes in mRNA stability in around 400 genes. To examine the potential mechanism of this stability, we tested aconitase interaction with mRNA in low iron and found 43 enriched transcripts, but no specific interaction with our reporter UTR. However, the endogenous UTR led to maintenance of protein levels and increased survival of the parasite under low iron. Our data demonstrate the existence of iron-mediated post-transcriptional regulation in Toxoplasma for the first time; and suggests iron-mediated regulation may be important to the parasite in low iron environments.

Toxoplasma↗
PubMedDate not supplied

Usefulness of the detection of Toxoplasma gondii antigens in AIDS patients.

Toxoplasmic encephalitis (TE) is a mayor cause of central nervous system infection in patients with acquired immunodeficiency syndrome (AIDS). Toxoplasma antibodies were detected in 56 of 79 patients with AIDS (71%), in the present study. Fourteen out of 57 seropositive patients developed TF (25%) and had Toxoplasma gondii antigen detected in their urine. For this, most of them received an effective therapy, with the subsequent disappearance of the symptoms and discontinuity of excretion of the T. gondii antigens. Our results suggest that the monitoring of T. gondii antigen in the urine of AIDS patients may be useful to decide on the proper time for therapy, as well as to avoid the beginning of neurologic signs in these patients.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Detection of Toxoplasma gondii soluble antigen, SAG-1(p30), antibody and immune complex in the cerebrospinal fluid of HIV positive or negative individuals.

Active infection by T. gondii was evaluated by immunoassay for soluble SAG-1 (p30), the major surface antigen from T. gondii, specific antibodies and immune complexes in human cerebrospinal fluid (CSF) samples. A total of 263 samples of CSF were collected from hospitalized patients presenting neurological disorders and analyzed for antibodies to HIV. Patients were divided into two groups: HIV positive (n = 96) or HIV negative (n =167). The results of the assays showed that 45% of all samples were positive for soluble SAG-1. Toxoplasma Ag/Ab immune complexes were detected in 19% of the CSF samples and 62% were positive for T. gondii- specific IgG. A combination of these assays in the presence of clinical findings consistent with active Toxoplasma infection may predict the presence of toxoplasmic encephalitis. Moreover, detection of soluble SAG-1 in the CSF of these individuals appears consistent with active infection.

Animals↗
PubMed2003

Prevalence of IgG antibodies specific to Toxoplasma gondii among blood donors in Recife, Northeast Brazil.

A serological survey of Toxoplasma gondii infection in blood donors was carried out in order to identify seroprevalence in Recife, Brazil. Sera from 160 individuals (119 male and 41 female) were evaluated by using a Toxoplasma IgG-antibody enzyme immunoassay (Denka Seiken Co., LTD., Tokyo, Japan). The seropositive percentual for males (79.0%) showed to be higher (p < 0.05) than for females (63.4%). This percentage increases with age, ranging from 18.2% to 92.6% for individuals aging under 20 and 40-50 years old, respectively. For women of childbearing age (18-40 years) it was found a prevalence of 51.6%.

Adolescent↗
PubMedDate not supplied

[Eventual effect of artemisinine on the experimental infection of mice by Toxoplasma gondii].

Because of taxonomic similarities to previous data found in the literature, and with the aim of improving treatment of toxoplasmosis, we considered it of interest to assay artemisinin, an effective anti-malarial agent, for the treatment of experimental infection in mice by Toxoplasma gondii. Different amounts of the anti-parasitic agent were administered, including after previous contact in vitro with toxoplasma and stimulated macrophage production. With the methodology used artemisinin was not effective. Suggestions for further studies are made.

Animals↗
PubMedDate not supplied

Incidence of anti-Toxoplasma antibodies in women with high-risk pregnancy and habitual abortions.

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, an obligate intracellular parasite. In pregnant women on the worldwide scale, there are seroprevalences from 7% to 51.3% and in women with abnormal pregnancies and abortions the seroprevalences vary from 17.5% to 52.3%. In Mexico, seropositivity has been found to vary from 18.2% to 44.8% in women with abnormal deliveries or abortions. This study's aim was to determine the incidence of IgG and IgM anti-Toxoplasma antibodies in women at the Gineco-Obstetrics Hospital of the Western Medical Center of the Mexican Social Security Institute. Three hundred and fifty women with high-risk pregnancies were studied, and 122 (34.9%) were found to be IgG seropositive and 76 (20.7%) were IgM positive. In one group of women with habitual abortions there were 48 (44.9%) with the presence of IgG antibodies and 33 (33.3%) were IgM seropositive. Seropositivity was analyzed according to age, occupation, socio-economic level, eating raw or poorly cooked meat, and living with cats.

Abortion, Habitual↗
PubMedDate not supplied

Analysis of Toxoplasma gondii antigens with sera from toxoplasmosis patients.

Some proteins of the Toxoplasma gondii are recognized by IgG, IgM and IgA antibodies in patients with acute and chronic toxoplasmosis, depending on the strain and stage of the Toxoplasma. Sixty-nine sera from immunocompetent individuals were studied through the Western-Blot Test: 20 has an acute infection, 29 has a chronic toxoplasmosis infection and 20 were healthy (seronegatives). The protein analysis revealed by IgG and IgM antibodies were performed through the immunoplot method in order to know their recognition frequency (f) and be valued as infection markers. In the acute phase, the IgM antibodies showed a recognition frequency (f = 0.60) for the 60 kDa protein, and in the chronic phase the IgG antibodies showed a recognition frequency (f = 0.68) for the 12 kDa protein. Seronegatives revealed no type of band. The protein of 12 kDa can be a diagnostic marker of the chronic phase while protein 60 kDa of the acute phase of toxoplasmosis.

Acute Disease↗
PubMed2005

[Research on antibodies anti toxoplasma gondii in intraocular fluids (Aqueous and vitreous humor) from patients with ocular toxoplasmosis, in the City of Belém, Pará State].

Tests were performed for antibodies IgG, IgM and IgA anti-Toxoplasma gondii antibodies in serum and intraocular fluids (Aqueous and vitreous humor) from patients with ocular toxoplasmosis. By the results obtained, it was verified that intraocular IgG and IgA anti-Toxoplasma gondii antibodies can be important markers for the diagnosis of ocular toxoplasmosis.

Adult↗
PubMedDate not supplied

Technique for the detection of Toxoplasma gondii antigens in mouse urine.

A simple and rapid staphylococcal coagglutination test for the detection of Toxoplasma gondii antigens in mice urine is described. A suspension of protein-A containing Staphylococcus aureus coated with rabbit hyperimmune serum was used as reagent. The sensitivity of the antigen assay was found to be at least 118 ng of the antigen protein per ml. No coagglutination was observed when the reagent was challenged against antigenic solutions of other parasites. The suitability of the method for detecting antigens of T. gondii in urine samples was studied by experimental toxoplasma infection in mice. Before the staphylococcal test, the urine samples were double serially diluted in 0.1 M PBS. From the second day on all samples from infected mice were positive at 1/16 dilution. At this dilution, all samples from non infected mice were negative or did not produce coagglutination. This method might be used in the rapid etiological diagnosis also in human cases of acute toxoplasmosis.

Agglutination Tests↗
PubMedDate not supplied

Toxoplasma gondii: a rapid method for the isolation of pure tachyzoites. Preliminary characterization of its genome.

A rapid and simple technique for the purification of Toxoplasma gondii tachyzoites was developed. Highly purified parasites were obtained from the peritoneal exudates of infected mice by means of two consecutive discontinuous sucrose gradients run at low speed (10,000xg, 30 min). Parasites obtained by this method conserved its biological activity. Hybridization studies with DNA from healthy mice and from purified tachyzoites preparations demonstrated that Toxoplasma gondii tachyzoites DNA could be obtained with better than 90% purity. Preliminary studies with DNA endonucleases showed the presence in the tachyzoites genome of highly repetitive sequences.

Animals↗
PubMedDate not supplied

Experimental infection of Calomys callosus (Rodentia, Cricetidae) by Toxoplasma gondii.

Calomys callosus, Rengger 1830 (Rodentia, Cricetidae), a wild rodent found in Central Brazil, was studied to investigate its susceptibility to Toxoplasma gondii experimental infection and its humoral immune response against this protozoa. The electrophoretic profile of the serum proteins of C. callosus showed that IgG, which shows no affinity to Protein A, has higher cross reactivity with rat IgG than with IgG from other rodents. The susceptibility assay was performed by inoculation groups of animals with various suspensions of T. gondii tachyzoites from 10(2) to 10(6) parasites. All animals died between 3 and 9 days after infection and the kinetics of antibody synthesis was determined. Basically, they recognized predominantly the immunodominant antigen SAG-1 (P30). The immunohistochemistry assays revealed that the liver was the most heavily infected organ, followed by the spleen, lungs, intestine, brain and kidneys. It can be concluded that C. callosus is an excellent experimental model for acute phase of Toxoplasma infection.

Animals↗
PubMedDate not supplied

Frequency of specific anti-Toxoplasma gondii IgM, IgA and IgE in colombian patients with acute and chronic ocular toxoplasmosis.

We studied the frequency of specific anti-Toxoplasma IgM, IgA and IgE antibodies in serum of 28 immunocompetent Colombian patients, selected by ophthalmologists and with lesions that were compatible with ocular toxoplasmosis. Patients were classified in three groups: (i) group 1 consisted of ten patients with a first episode; (ii) group 2, with seven patients with a recurrence and (iii) group 3, consisted of eleven patients with chronic chorioretinal lesion without uveitis. We found that 10/28 (35%) of Colombian patients with ocular toxoplasmosis possessed at least one serological marker for Toxoplasma infection different from IgG. In group 1 (first episode), we found simultaneous presence of specific IgM plus IgA plus IgE in 1/10 (10%). In group 2 (recurrences) in 1/7 (14%) we found IgM and IgA test positives and in 1/7 (14%) we found IgM and IgE tests positives. In group 3 (toxoplasmic chorioretinal scar) the IgA serological test was positive in 2/11 (18%). These results show that serum IgM or IgA or IgE can be present during recurrences.

Acute Disease↗