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 631 records · Page 35Linked to original sources
PubMed1979

Simplified chromatographic separation of immunoglobulin M from G and its application to toxoplasma indirect immunofluorescence.

The indirect immunofluorescent (IIF) antibody technique for the detection of Toxoplasma gondii immunoglobulin M (IgM) often gives false negative results, probably due to the competition between IgG and IgM. We therefore adapted a gel filtration procedure for the separation of IgG and IgM to a routine diagnostic test capable handling at least 10 sera per day and requiring only 50 microliters of serum. The results from 108 sera having positive complement fixation titers for Toxoplasma showed that 17 were IgM positive when the whole serum was tested by IIF compared with 55 positive when the IgM fraction was used. Sera with antideoxyribonucleic acid titers do not give false positive results after fractionation, and the removal of IgG eliminates false positive results due to rheumatoid factor. A prospective study showed that Toxoplasma IgM may persist up to 9 months.

Antibodies↗
PubMed2000

Lytic cycle of Toxoplasma gondii.

Toxoplasma gondii is an obligate intracellular pathogen within the phylum Apicomplexa. This protozoan parasite is one of the most widespread, with a broad host range including many birds and mammals and a geographic range that is nearly worldwide. While infection of healthy adults is usually relatively mild, serious disease can result in utero or when the host is immunocompromised. This sophisticated eukaryote has many specialized features that make it well suited to its intracellular lifestyle. In this review, we describe the current knowledge of how the asexual tachyzoite stage of Toxoplasma attaches to, invades, replicates in, and exits the host cell. Since this process is closely analogous to the way in which viruses reproduce, we refer to it as the Toxoplasma "lytic cycle."

Animals↗
PubMed1997

Community study of toxoplasma antibodies in urban and rural schoolchildren aged 4 to 18 years.

To estimate the prevalence of toxoplasma antibodies in schoolchildren and their association with clinical and environmental data, antibody titres were measured in 1276 children aged 4 to 18 years attending primary and secondary schools. Environmental and clinical data were obtained by questionnaire. Altogether 12.8% (163/1276) of children had antibodies to Toxoplasma gondii with no difference between the sexes. Seroprevalence was higher in country children (16.6% (50/302)) than town children (10.2% (75/737)). The proportion testing positive increased with age in both town and country children. No association with cat ownership was found. Toxoplasma seropositivity was associated with a positive toxocara titre, having had a bitch whelp in the past two years, and having an unwormed dog at home. Lack of energy or tiredness in the last 12 months were the only clinical features associated with a positive titre.

Adolescent↗
PubMed1989

Assessment of immunoglobulin-M immunosorbent agglutination assay (ISAGA) for detecting toxoplasma specific IgM.

An immunoglobulin-M immunosorbent agglutination assay (ISAGA) was introduced to detect toxoplasma specific IgM. This assay incorporates mu chain capture and use of entire toxoplasma trophozoites as an antigen source. The performance of the ISAGA was compared with that of a double sandwich enzyme linked immunosorbent assay (DS-ELISA) currently used in the Public Health Laboratory Service Toxoplasma Reference Laboratories. The ISAGA was found to be more sensitive than DS-ELISA but there was no demonstrable difference in the specificity or reproducibility between the two assays. The ISAGA is suitable for the diagnosis of acute toxoplasmosis in immunocompetent patients and as a screening test for recent infection in pregnant women. The persistence of ISAGA reactivity, however, is such that additional serological assessment is required to define the risk of congenital infection.

Agglutination Tests↗
PubMed1989

Five commercial enzyme linked immunosorbent assay kits for toxoplasma specific IgM antibody.

Five commercially available enzyme linked immunosorbent assay (ELISA) kits for the detection of specific IgM against Toxoplasma gondii were evaluated in a three centre study and results compared with those of the Public Health Laboratory Service ELISA for Toxoplasma IgM (PHL IgM ELISA). Fifty selected sera were tested by all the methods (Toxo-M, Captia Toxo-M EIA, Toxo Enz M EIA, Toxonostika IgM EIA, Sopazyme Toxo IgM EIA) at the three reference centres in England and Wales and 177 routine sera by all the methods in one or other of the centres. Ten of the 50 selected sera contained autoimmune antibodies but no specific IgM and 29 had toxoplasma specific IgM detectable by the PHL IgM ELISA. The kits were assessed for their specificity and sensitivity compared with the PHL IgM ELISA, and the percentage coefficient of variation for binding to the solid phases was determined. They were also rated subjectively by the staff performing the assays and an overall impression of each kit was gained by allocating scores of several criteria. There was quite close agreement among the results obtained with all five commercial assays and the PHL IgM ELISA, although some of the sera pre-selected as being potentially problematic showed the limitations of some of the assays.

Animals↗
PubMed1992

Use of the polymerase chain reaction to detect Toxoplasma gondii in human blood samples.

AIMS: To assess the value of detecting Toxoplasma gondii in human blood samples using the polymerase chain reaction (PCR). METHODS: Blood samples in lithium heparin were examined from 34 patients with suspected toxoplasmosis, and six healthy volunteers with or without the addition of doubling dilutions of toxoplasma tachyzoites. Products of a nested PCR, using oligonucleotide primers of the B1 gene, were analysed by electrophoresis and stained by ethidium bromide. The primary product was 194 base pairs in length; the nested products were 160 or 97 base pairs. RESULTS: When toxoplasma tachyzoites were added to the leucocytes of six different volunteers, eight to 16 parasites were detected by nested PCR in one experiment and one to four parasites in eight experiments. All nine experiments were negative in samples without added tachyzoites. Of 34 patients, PCR was negative in 13 with recent lymphadenopathy; nine with persisting IgM, including two pregnant patients; four with reactivated infection due to immunodeficiency; and five with no evidence of active infection. Positive PCR results were found in three patients with reactivated infection. There was only one discrepancy between PCR and animal culture results; this was in an immunocompromised patient with a positive PCR and negative culture. CONCLUSIONS: The PCR technique was rapid, sensitive, and specific in human blood samples. Negative PCR results in patients with persisting IgM suggested that the fetus was not at risk, or that treatment was not indicated in myalgic encephalomyelitis-like illness. PCR results in immunocompromised patients permitted appropriate management--no treatment if negative, treatment if positive.

Animals↗
PubMed1992

Diagnosis of toxoplasma infection in cardiac transplant recipients using the polymerase chain reaction.

Cardiac biopsy samples taken from transplant recipients around the time of primary toxoplasma infection were investigated by conventional histology and amplification of the P30 gene of Toxoplasma gondii by the polymerase chain reaction (PCR). Toxoplasma was detected more frequently by PCR than histology which may reflect the enhanced sensitivity of the former technique. Further studies are required to determine the optimal amount of tissue which should be examined by each technique and to develop a PCR assay capable of distinguishing between quiescent infection and active toxoplasmosis.

Animals↗
PubMed1988

Titration of Toxoplasma gondii oocysts in non-pregnant sheep and the effects of subsequent challenge during pregnancy.

Fifty-nine ewes, seronegative to Toxoplasma gondii, were allocated to four groups which received 2000, 200, 20 or no M1 strain toxoplasma oocysts 56 days before mating. Fifty-one of them subsequently became pregnant and were challenged with 10,000 oocysts between 78 and 83 days of gestation. Infection with 2000 oocysts induced a pyrexia, seroconversion and protective immunity in all the recipient animals. Ewes that received either 20 or no oocysts before pregnancy were susceptible to subsequent challenge and severe fetal mortality occurred. In this study 200 oocysts was the threshold value for the induction of toxoplasma infection in sheep, although not all the ewes that seroconverted to this dose were protected against further challenge.

Animals↗
PubMed2004

Toxoplasma seropositivity and depression: a case report.

BACKGROUND: The association between toxoplasmosis and psychiatric disorders has been reported in a few anecdotal reports. CASE PRESENTATION: A case of depression with toxoplasma seropositivity is presented. The patient with depression showed poor response to antidepressants, for which he was investigated and was found positive on the serological test for the toxoplasma. The response to antidepressant treatment improved only after adequate treatment for toxoplasma. CONCLUSIONS: The case suggests a probable association between toxoplasmosis and depression.

Adult↗
PubMed2005

Seroprevalence and risk factors for toxoplasma infection among pregnant women in Aydin province, Turkey.

BACKGROUND: The aims of the present study were to determine the prevalence of toxoplasmosis in pregnant women at first trimester of their pregnancy and to follow up the seroconversion for next two trimesters, and to identify the risk factors and possible contamination routes in Aydin province, Turkey. METHOD: The sample size was calculated as 423 on a prevalence of 50%, d=0.05 at a confidence level of 95% with 10% addition. It was a cross-sectional study with multistage sampling. After a questionnaire applied to the pregnant women, anti-Toxoplasma IgG antibodies were studied with ELISA and IFA, values in conflict with DA test, where IgM antibodies were studied with ELISA and for borderline or positive values of IgM avidity test was used. RESULTS: The mean age of 389 (92.9%) of pregnant women in the study was 24.28+/-4.56 years, the seroprevalence of anti-Toxoplasma IgG antibodies for toxoplasmosis was 30.1%. Seroprevalence was increased with age (p=0.001) and with drinking water consumption other than bottled water (p=0.042). No significant relations were observed between anti-Toxoplasma IgG antibodies and education level, being native or migrant, abortion history, consumption of meat, vegetable and milk/milk products, personal or kitchen hygiene habits, cat owning at home of the pregnant women. No IgM antibody was detected. CONCLUSION: One of every three pregnant women in Aydin was at risk of toxoplasmosis at the first trimester of their pregnancy. Increased seroprevalance with age was a predictable result because of increasing time of exposure. Increased seroprevalence with consumption of municipal and uncontrolled water (well/spring water) supplies was similar with latest epidemiological findings.

Adolescent↗
PubMed1998

Growth inhibitory effect of bovine lactoferrin to Toxoplasma gondii tachyzoites in murine macrophages: tyrosine phosphorylation in murine macrophages induced by bovine lactoferrin.

Previous studies have shown that lactoferrin induces growth inhibitory effects in mouse macrophages against intracellular Toxoplasma gondii, and these effects were not mediated by the oxygen-dependent and inorganic nitrogen-dependent pathway. To clarify the mechanism of anti-Toxoplasma gondii activity induced by lactoferrin, we examined whether lactoferrin promoted the phosphorylation of tyrosine residues in macrophage proteins. In immunoblotting assays using anti-[phosphorylated tyrosine] monoclonal antibody, phosphorylation of tyrosine residues was detected in protein(s) of approximately 30 kDa in macrophages incubated with lactoferrin. Inhibition of the lactoferrin-induced tyrosine-phosphorylation by genistein led to loss of the lactoferrin-induced growth inhibitory effect against the parasites. These findings suggest that lactoferrin induces tyrosine-phosphorylation in macrophages, and the tyrosine-phosphorylation seems to be associated with the induction of the growth inhibitory activity exerted against intracellular Toxoplasma gondii.

Animals↗
PubMed2006

Acidification of the parasitophorous vacuole containing Toxoplasma gondii in the presence of hydroxyurea.

Toxoplasma gondii multiplies within parasitophorous vacuole that is not recognized by the primary no oxidative defense of host cells, mainly represented by the fusion with acidic organelles. Recent studies have already shown that hydroxyurea arrested the intracellular parasites leading to its destruction. In the present work we investigated the cellular mechanism involved in the destruction of intracellular Toxoplasma gondii. Fluorescent vital stains were used in order to observe possible acidification of parasitophorous vacuole-containing Toxoplasma gondii in presence of hydroxyurea. Vero cells infected with tachyzoites were treated with hydroxyurea for 12, 24 or 48 hours. Fluorescence, indicative of acidification, was observed in the parasitophorous vacuole when the cultures were incubated in presence of acridine orange. LysoTracker red was used in order to determine whether lysosomes were involved in the acidification process. An intense fluorescence was observed after 12 and 24 hours of incubation with hydroxyurea, achieving it is highly intensity after 48 hours of treatment. Ultrastructural cytochemistry for localization of the acid phosphatase lysosomal enzyme was realized. Treated infected cultures showed reaction product in vesicles fusing with vacuole or associated with intravacuolar parasites. These results suggest that fusion with lysosomes and acidification of parasitophorous vacuole leads to parasites destruction in the presence pf hydroxyurea.

Animals↗
PubMedDate not supplied

Toxoplasma gondii infection in Brazilian domestic outpatient cats.

The occurrence of Toxoplasma antibodies in domestic outpatient cats in the city of São Paulo was evaluated using the indirect immunofluorescence assay. A total of 248 blood samples obtained from male and female cats seen at the Veterinary Teaching Hospital at the University of São Paulo between February 1996 and January 1997 were tested. Of these, 17.7% were positive, with a 64 titer being detected in most animals. The frequence of Toxoplasma antibodies was significantly higher in older cats, those fed raw meat and those with free access to the outdoor environment. There was no significant difference in reactivity between males and females. We conclude that diet and free access to the outdoor environment were equally important as predisposing factors to the risk of Toxoplasma infection.

Age Distribution↗
PubMedDate not supplied

Protection against toxoplasmosis in mice immunized with different antigens of Toxoplasma gondii incorporated into liposomes.

Different toxoplasma antigens were entrapped within liposomes and evaluated, in this form, for their ability to protect Swiss mice against toxoplasma infection: soluble tachyzoite antigen (L/TAg), tissue cyst (L/CAg), tachyzoite plus tissue cyst (L/TCAg) or purified antigen of tachyzoite (L/pTAg). The protein used in L/pTAg was purified from tachyzoites using a stage-specific monoclonal antibody which reacted at a molecular weight of 32 kD in SDS PAGE and silver stain using reduced condition. To compare the immuno-adjuvant action of liposomes and of Freund's Complete Adjuvant (FCA), another group of mice was immunized with soluble tachyzoite antigen (STAg) emulsified in FCA (FCA/TAg). Control groups were inoculated with (STAg) alone, phosphate-buffered saline (PBS), FCA with PBS (FCA/PBS) and empty liposomes (L/PBS). Mice were inoculated subcutaneously with these antigens six, four and two weeks before a challenge with 80 tissue cysts of the P strain of Toxoplasma gondii orally. All mice immunized with or without adjuvant showed a humoral response, as measured by Elisa. However, no correlation was found between antibody titer and protection against the challenge. All mice immunized with L/pTAg or L/TCAg survived (100), whereas 80% and 90% of mice from groups which received respectively PBS or FCA/PBS and L/PBS died. All mice immunized with antigens entrapped within liposomes (L/TAg, L/CAg, L/TCAg and L/pTAg) showed low numbers of intracerebral cysts.

Animals↗
PubMed2001

Lack of evidence for superantigen activity of Toxoplasma gondii towards human T cells.

Toxoplasma gondii is an obligatory intracellular parasite whose life cycle may include man as an intermediate host. More than 500 million people are infected with this parasite worldwide. It has been previously reported that T. gondii contains a superantigen activity. The purpose of the present study was to determine if the putative superantigen activity of T. gondii would manifest towards human T cells. Peripheral blood mononuclear cells (PBMC) from individuals with no previous contact with the parasite were evaluated for proliferation as well as specific Vbeta expansion after exposure to Toxoplasma antigens. Likewise, PBMC from individuals with the congenital infection were evaluated for putative Vbeta family deletions in their T cell repertoire. We also evaluated, over a period of one year, the PBMC proliferation pattern in response to Toxoplasma antigens in patients with recently acquired infection. Some degree of proliferation in response to T. gondii was observed in the PBMC from individuals never exposed to the parasite, accompanied by specific Vbeta expansion, suggesting a superantigen effect. However, we found no specific deletion of Vbeta (or Valpha) families in the blood of congenitally infected individuals. Furthermore, PBMC from recently infected individuals followed up over a period of one year did not present a reduction of the Vbeta families that were originally expanded in response to the parasite antigens. Taken together, our data suggest that T. gondii does not have a strong superantigen activity on human T cells.

Adult↗
PubMed2004

Molecular and biologic characteristics of Toxoplasma gondii isolates from wildlife in the United States.

Toxoplasma gondii isolates can be grouped into 3 genetic lineages. Type I isolates are considered more virulent in outbred mice and have been isolated predominantly from clinical cases of human toxoplasmosis, whereas types II and III isolates are considered less virulent for mice and are found in humans and food animals. Little is known of genotypes of T. gondii isolates from wild animals. In the present report, genotypes of isolates of T. gondii from wildlife in the United States are described. Sera from wildlife were tested for antibodies to T. gondii with the modified agglutination test, and tissues from animals with titers of 1:25 (seropositive) were bioassayed in mice. Toxoplasma gondii was isolated from the hearts of 21 of 34 seropositive white-tailed deer (Odocoileus virginianus) from Mississippi and from 7 of 29 raccoons (Procyon lotor); 5 of 6 bobcats (Lynx rufus); and the gray fox (Urocyon cinereoargenteus), red fox (Vulpes vulpes), and coyote (Canis latrans) from Georgia. Toxoplasma gondii was also isolated from 7 of 10 seropositive black bears (Ursus americanus) from Pennsylvania by bioassay in cats. All 3 genotypes of T. gondii based on the SAG2 locus were circulating among wildlife.

Animals↗
PubMed2004

Efficacy of ponazuril in vitro and in preventing and treating Toxoplasma gondii infections in mice.

Toxoplasma gondii is an important apicomplexan parasite of humans and other warm-blooded animals. Ponazuril is a triazine anticoccidial recently approved for use in horses in the United States. We determined that ponazuril significantly inhibited T. gondii tachyzoite production (P < 0.05) at 5.0, 1.0, or 0.1 microg/ml in African green monkey kidney cells. We used outbred female CD-1 mice to determine the efficacy of ponazuril in preventing and treating acute toxoplasmosis. Each mouse was subcutaneously infected with 1,000 tachyzoites of the RH strain of T. gondii. Mice were weighed daily, and ponazuril was administered orally in a suspension. Mice given 10 or 20 mg/kg body weight ponazuril 1 day before infection and then daily for 10 days were completely protected against acute toxoplasmosis. Relapse did not occur after prophylactic treatments were stopped. Toxoplasma gondii DNA could not be detected in the brains of these mice using polymerase chain reaction (PCR). One hundred percent of mice treated with 10 or 20 mg/kg ponazuril at 3 days after infection and then daily for 10 days were protected from fatal toxoplasmosis. Sixty percent of mice treated with 10 mg/kg ponazuril at 6 days after infection and 100% of mice treated with 20 mg/kg or 50 mg ponazuril 6 days after infection and then daily for 10 days were protected from fatal toxoplasmosis. Relapse did not occur after treatments were stopped. Toxoplasma gondii DNA was detected in the brains of some, but not all, of these mice using PCR. The results demonstrate that ponazuril is effective in preventing and treating toxoplasmosis in mice. It should be further investigated as a safe and effective treatment for this disease in animals.

Acute Disease↗
PubMed2005

First biologic and genetic characterization of Toxoplasma gondii isolates from chickens from Africa (Democratic Republic of Congo, Mali, Burkina Faso, and Kenya).

The prevalence of Toxoplasma gondii in free-ranging chickens (Gallus domesticus) is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. In the present study, prevalence of T. gondii in chickens from Democratic Republic of Congo, Mali, Burkina Faso, and Kenya is reported. The prevalence of T. gondii antibodies in sera of 50 free-range chickens from Congo was 50% based on the modified agglutination test (MAT); antibody titers were 1:5 in 7, 1:10 in 7, 1:20 in 6, 1:40 in 1, and 1:160 or more in 4 chickens. Hearts, pectoral muscles, and brains of 11 chickens with titers of 1:20 or more were bioassayed individually in mice; T. gondii was isolated from 9, from the hearts of 9, brains of 3, and muscles of 3 chickens. Tissues of each of the 14 chickens with titers of 1:5 or 1:10 were pooled and bioassayed in mice; T. gondii was isolated from 1 chicken with a titer of 1:10. Tissues from the remaining 25 seronegative chickens were pooled and fed to 1 T. gondii-free cat. Feces of the cat were examined for oocysts, but none was seen. The results indicate that T. gondii localizes in the hearts more often than in other tissues of naturally infected chickens. Genotyping of these 10 isolates using the SAG2 locus indicated that 8 were isolates were type III, 1 was type II, and 1 was type I. Two isolates (1 type I and 1 type III) were virulent for mice. Toxoplasma gondii was isolated by mouse bioassay from a pool of brains and hearts of 5 of 48 chickens from Mali and 1 of 40 chickens from Burkina Faso; all 6 isolates were avirulent for mice. Genetically, 4 isolates were type III and 2 were type II. Sera were not available from chickens from Mali and Burkina Faso. Toxoplasma gondii antibodies (MAT 100 or more) were found in 4 of 30 chickens from Kenya, and T. gondii was isolated from the brain of 1 of 4 seropositive chickens; this strain was avirulent for mice and was type II. This is the first report on isolation and genotyping of T. gondii from any source from these 4 countries in Africa.

Agglutination Tests↗