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[Intrathecal synthesis of anti-Toxoplasma gondii antibodies during cerebral toxoplasmosis associated with African AIDS].

Thirty-four HIV-1-infected in-patients of the Hôpital Central des Forces Armées Congolaises, Brazzaville, Congo, hospitalized for suspected cerebral toxoplasmosis, have been evaluated for integrity of the blood-brain barrier, intrathecal synthesis of total IgG, toxoplasmic serology in blood and cerebrospinal fluid, and for intrathecal synthesis of IgG to Toxoplasma gondii. An empiric scale to gauge the possibility of clinical cerebral toxoplasmosis was used to classify the patients (+, +2, +3). Only an intrathecal synthesis of IgG to Toxoplasma gondii was found to be associated with suspected cerebral toxoplamosis: it was found in about 80% of patients, and more frequently in patients with a higher probability of disease. In contrast, alteration of the blood-brain barrier, intrathecal synthesis of total IgG and toxoplasmic serology in blood as well as in cerebrospinal fluid were not associated with suspected cerebral toxoplamosis. Taken together, these findings confirm that intrathecal synthesis of antitoxoplasmic antibodies of IgG isotype occurs in cerebral toxoplasmosis. Demonstration of intrathecal synthesis of antitoxoplasmic IgG antibodies could be used to confirm clinical diagnosis of cerebral toxoplamosis, especially in an African context, where sophisticated laboratory facilities are often lacking.

Acquired Immunodeficiency Syndrome↗

Infection and immunity with the RH strain of Toxoplasma gondii in rats and mice.

Infection and immunity to toxoplasmosis induced by the RH strain of Toxoplasma gondii was compared in Sprague-Dawley (SD) and Wistar rats and in outbred Swiss Webster mice. All rats injected with up to 1,000,000 RH-strain tachyzoites remained clinically normal, whereas mice injected with only 1 live tachyzoite died of acute toxoplasmosis. Rats could be infected with 1 tachyzoite of the RH strain as shown by antibody development and by bioassay in mice. However, after 8 days, RH-strain organisms were recovered only inconsistently from SD and Wistar rat brains. Contrary to a report of sterile immunity to T. gondii infection in rats after immunization with live RH tachyzoites, we found infection immunity after challenge with the VEG strain. Toxoplasma gondii tissue cysts of the VEG strain could be recovered from most SD and Wistar rats, first injected with live RH-strain tachyzoites and then challenged with oocysts of the VEG strain. Our RH strain, and probably many others, passed for 50+ yr as tachyzoites has lost not only the capacity to form oocysts, but also shows a marked reduction or absence of tissue cyst (bradyzoites) formation.

Animals↗

The CD28/B7 interaction is not required for resistance to Toxoplasma gondii in the brain but contributes to the development of immunopathology.

Infection of C57BL/6 mice with Toxoplasma gondii leads to chronic encephalitis characterized by infiltration into the brain of T cells that produce IFN-gamma and mediate resistance to the parasite. Our studies revealed that expression of B7.1 and B7.2 was up-regulated in brains of mice with toxoplasmic encephalitis (TE). Because CD28/B7-mediated costimulation is important for T cell activation, we assessed the contribution of this interaction to the production of IFN-gamma by T cells from brains and spleens of mice with TE. Stimulation of splenocytes with Toxoplasma Ag or anti-CD3 mAb resulted in production of IFN-gamma, which was inhibited by 90% in the presence of CTLA4-Ig, an antagonist of B7 stimulation. However, production of IFN-gamma by T cells from the brains of these mice was only slightly reduced (20%) by the addition of CTLA4-Ig. To address the role of the CD28/B7 interaction during TE, we compared the development of disease in C57BL/6 wild-type (wt) and CD28-/- mice. Although the parasite burden was similar in wt and CD28-/- mice, CD28-/- mice developed less severe encephalitis and survived longer than wt mice. Ex vivo recall responses revealed that mononuclear cells isolated from the brains of chronically infected CD28-/- mice produced less IFN-gamma than wt cells, and this correlated with reduced numbers of intracerebral CD4+ T cells in CD28-/- mice compared with wt mice. Taken together, our data show that resistance to T. gondii in the brain is independent of CD28 and suggest a role for CD28 in development of immune-mediated pathology during TE.

Animals↗

[Examination of cats for the elimination of Toxoplasma gondii oocysts].

Two hundred and two samples of excrements were investigated for the presence of Toxoplasma gondii oocysts. Fifty-two samples were taken from dead domestic cats and a hundred and fifty samples were obtained from wild cats living in various localities of the CSSR. The investigation was orientative and a flotation method with the Breza flotation solution of the specific weight of 1.300 was used. If the finding was positive, residues of the excrements were floated with a saccharose, solution of the specific weight of 1.150 and containing 0.8% of phenol. The oocysts were rinsed several times, then they were sporulated in Petri dishes with water with a 2.5% solution of potassium dichromate. The sporulated oocysts, after rinsing, were injected i. p. to mice. The excrements of the fifty-two domestic cats were negative. Out of a hundred and fifty samples of the excrements of wild cats, one sample with the oocysts of isospore type was found; a biological test with mice proved the oocysts of Toxoplasma gondii. It may be inferred from the results obtained that the elimination of oocysts by cats is the same as given in foreign literature, and the occurrence rate will be about 2%.

Animals↗

Baculovirus expression of the major surface antigen of Toxoplasma gondii and the immune response of mice injected with the recombinant P30.

The major surface antigen (P30) of the Toxoplasma gondii was expressed by an insect cell culture system infected with recombinant baculovirus. About 750 microg of purified (95% purity) P30 was obtained from a culture of 10(8) insect Sf21 cells. The recombinant P30 was used to immunize mice to induce immune response. Mice injected with the recombinant protein produced specific humoral and cellular immune responses. Immunization with P30 also prolonged the period of survival of mice infected by Toxoplasma. The average survival time of control group is 13.25+/-1.16 days, but are 16.13+/-2.1 days, 19.50+/-3.21 days, 20.38+/-3.38 days in different immunized groups, respectively.

Animals↗

[The occurrence of Toxoplasma gondii and Neospora caninum as regards meat hygiene].

Toxoplasma gondii and Neospora caninum are phenotypically and phylogenetically closely related cyst-forming coccidia, both of which may cause abortion in livestock animals. T. gondii exhibits also zoonotic potential by causing diaplacental infections in the human fetus and harmful infections in immunosuppressed individuals. Humans get infected either by consuming inappropriately prepared cyst-containing meat or by ingesting oocysts originating from cat feces. Therefore, in order to assess infection risk we need to have knowledge on the prevalence of the parasite in consumable meat and thus slaughtered animals. So far, no data indicate any zoonotic potential for N. caninum. Due to its high economic impact in the bovine production in Switzerland, we included this parasite in the present study as well. The prevalence of both parasite species were investigated by PCR in muscle and brain samples of slaughtered bovines, sheep, pigs and horses. Comparatively, a serum sample from each animal was simultaneously tested serologically by a Toxoplasma-P30-ELISA and a Neospora-SA-ELISA. The prevalences determined by the T. gondii-PCR were the followings: adult cows 3%, young bulls 2%, young cows prior to gravidity 6%, calves 1%, sheep 6%, horses and pigs each 0%. For N. caninum, the PCR-prevalence was 2% for adult cows and 0% for all other animal groups. Conversely, the seroprevalences were much higher for both parasite species and all animal groups, with the exception of the fattening pigs. However, as T. gondii was principally detectable in bovine (cows and calves) as well as in sheep meat, the consumption of this meat harbours a potential infection risk for humans. In contrast, the lack of any parasite detectability in fattening pig and horse meat allows to consider this infection source as neglectable when compared to bovine and ovine meat.

Animals↗

Toxoplasma gondii antibody in HIV-infected persons.

Toxoplasmosis in an immunocompromised host was not documented in Thailand until 1992 when HIV/AIDS infection became pandemic. Patients with toxoplasmic encephalitis and cerebral abscess were recorded, particularly from the northern part of the country. However, data on the prevalence of the disease in HIV/AIDS patients is not yet available. In this study the authors determine the prevalence of T. gondii antibody in HIV persons. During a two-year period 312 serum samples of which 190 were HIV positive and the remaining samples were negative for HIV were tested. In the HIV positive group, 44 samples (23.2%) were positive for toxoplasma IgG antibody, whilst in the HIV negative group 36 samples (29.5%) were positive. All antibody titres found were not higher than 1:64. There is no significant difference of toxoplasma IgG antibody in HIV positive and HIV negative persons (p = 0.25). Among the HIV positive and T. gondii antibody positive group, 19 out of 44 persons (43.2%) had symptoms and signs of acute toxoplasmosis involving the eye and/or the central nervous system. Due to the high reactivation rate, the authors propose that all HIV-infected persons should be tested for T. gondii antibody and prophylactic treatment of opportunistic infection from T. gondii should be considered in those with positive results.

AIDS-Related Opportunistic Infections↗

Seroprevalence of specific total immunoglobulin (Ig), IgG and IgM antibodies to Toxoplasma gondii in blood donors from Loei Province, Northeast Thailand.

A total samples from 345 healthy blood donors from Loei Province, Northeast Thailand were examined for anti-Toxoplasma gondii antibodies by ELISA. The seroprevalence of the anti-Toxoplasma gondii total Ig, IgG and IgM antibodies was 4.9%, 4.1% and 4.3%, respectively. Overall seropositive rate was 33 out of 345 individuals (9.6%). Among the seropositve cases, 5 (15.2%), 2 (6.1%) and 13 (39.4%) of the samples were determined by using each type of anti-T. gondii total Ig, IgG and IgM antibodies, respectively. The seropositive sera was also determined by combining of anti-T. gondii antibodies (anti-T. gondii total Ig with IgG and anti-T. gondii total Ig with IgM antibodies). These results were 10 (30.3%) and 2 (6.1%) cases, respectively. Only one (3%) sample had all types of anti-T. gondii antibodies. In addition, the frequency distribution curves of ELISA optical densities of anti-T. gondii total Ig, IgG and IgM antibodies in blood donor presented "unimodal" curves. The negative results were found in the age group that less than 20 years old and more than 51. The highest seropositive results were found in two age groups (21-30 and 31-40 years old), and males were significantly higher than female (p < 0.05). These results demonstrated that when using anti-T. gondii total Ig, IgG and IgM antibodies for determining the seroprevalence, the sensitivity was twice that with the anti-T. gondii, total Ig antibody alone.

Adolescent↗

[Polymerase chain reaction applied for detection of Toxoplasma gondii in lymph nodes].

In order to investigate the morbidity of toxoplasmic lymphadenitis, polymerase chain reaction (PCR) was used to detect DNA of Toxoplasma gondii within lymph nodes in 3 groups of 120 patients with different diseases. After extracting the DNA of each sample, PCR was employed to amplify toxoplasma DNA. The results showed that the amplification product of 210 bp was confirmed in 7 patients: 3 cases of Hodgkin's disease (HD), 2 cases of non-Hodgkin's lymphoma (NHL) and 2 cases of chronic lymphadenitis (CL). Each PCR product was then subjected to Southern blot hybridization. Besides the 7 cases proved by PCR, 1 case of CL was found positive. The positive percentages of HD, NHL and CL were 9.38% (3/32), 4.88% (2/41), and 6.38% (3/47), respectively. The total positive rate was 6.67% (8/120).

Animals↗

Prevalence of antibodies to Toxoplasma gondii among urban and rural residents in the Philippines.

A survey of antibodies to Toxoplasma gondii was carried out among residents in urban (Metro Manila) and rural (Mindoro and Leyte) areas in the Philippines. A total of 1,173 serum samples were examined for Toxoplasma antibody by an ELISA method. The overall seropositivity was 11.1% (n=904, 12.4% in males, 10.0% in females) in Metro Manila, 61.2% (n=152, 63.3% in males, 53.1% in females) in Mindoro, and 30.1% (n=113, 34.3% in males, 22.5% in females) in Leyte, indicating significantly higher (p<0.001) seropositivities in rural than urban settings. No significant differences in seropositivities were observed between males and females. In each group, seropositivity tended to increase with age of the subjects.

Adolescent↗

Toxoplasma antibodies in normal and complicated pregnancy.

A total of 70 women with complicated pregnancy and 20 ones with normal pregnancy were selected. They were all RH positive and free from syphilis, brucellosis and malignany. Both groups were subjected to detection of anti-Toxoplasma antibodies levels by the indirect haemagglutination tests (IHAT-IgG) and by ELISA (IgG and IgM). The results showed that all controls (normal pregnancy) were IHA-IgG and ELISA-IgM negative. However, two of the controls (10%) were ELISA. IgG positive. As to the women with complicated pregnancy 68/70 or 97.1% were IHAT positive. When using ELISA, 57/70 or 81.4% were IgG positive and 42/70 or 60% were IgM positive. The results revealed a significant difference between the complicated cases and controls. The diagnosis of abortion, stillbirth, premature labour, or neonatal death due to Toxoplasma infection needs careful and laborious evaluation. The use of ELISA (IgG & IgM) is a must, as it is more sensitive and specific than IHAT.

Abortion, Spontaneous↗

Immunity induced by DNA vaccine of plasmid encoding the rhoptry protein 1 gene combined with the genetic adjuvant of pcIFN-gamma against Toxoplasma gondii in mice.

OBJECTIVE: To construct the eukáryotic expression recombinant plasmid, pcIFN-gamma, as a genetic adjuvant and observe the immune responses elicited by pcDNA3-rhoptry protein 1 (pc-ROP1) combined with pcIFN-gamma against Toxoplasma gondii (T. gondii) infection in mice. METHODS: A fragment of the IFN-gamma gene was directly inserted into the pcDNA3 plasmid and identified by two restriction endonucleases digestion. pcIFN and pcROP1 DNA was injected into the left leg muscle of mice at a dosage of 100 micrograms, and a booster vaccination was given at the same dosage after two weeks. Control groups were injected with pcDNA3 blank plasmid or normal saline. At 30, 50 and 70 days after booster injection, kinetic tests were carried out: MTT assay for the proliferation response of T lymphocyte cells and the activity of NK cells, sandwich ABC-ELISA for the determination of IFN-gamma, IL-2 and IL-10; a serum enzymetic aassay for nitric oxide (NO) in sera and ELISA for the titer of IgG antibody in sera. RESULTS: The recombinant plasmid, pcIFN-gamma was constructed. The proliferation response of spleen T lymph cells, NK cell killing activity, and serum levels of IFN-gamma, IL-2 and NO in mice injected with pcROP1 and pcIFN-gamma were higher than in those injected with pcROP1 alone. There was no difference in IgG antibody levels between the two groups. CONCLUSION: The genetic adjuvant, pcIFN-gamma, could enhance the cellular immune response induced by DNA vaccine of pcROP1 in mice against Toxoplasma gondii infection.

Animals↗

[Isolation of Toxoplasma strains via the digestive method].

Tested was the effectiveness of the digestive method for the isolation of Toxoplasma strains. This method was used to study the musculature of the diaphragm in 80 sheep, 40 cattle, and 80 pigs. Isolated were one strain that was pathogenic and 3 apathogenic strains for albino mice. They were found only in the diaphragm of sheep. It is believed that the digestive method is effective for the isolation of Toxoplasma strains.

Animals↗

[Occurrence of Toxoplasma gondii antibodies in the population of Split-Dalmatia County].

The prevalence of antibodies reactive with Toxoplasma gondii in the population of the Split-Dalmatia county (southern Croatia) was investigated by enzyme linked immunosorbent assay (ELISA). Of a total of 1464 serum samples collected from persons aged 2-84 years 36.4% reacted with Toxoplasma gondii. The frequency of positive sera increased significantly with age (p < 0.001). Prevalence of specific antibodies to T. gondii does not vary significantly according to gender, except, among children younger than 10 years (boys 14.0%; girls 28.2%; p < 0.01). Of a total of 398 pregnant women tested 31.4% were seropositive. According to increase in seroprevalence among the pregnant women of different age the theoretical incidence of congenital toxoplasmosis was calculated.

Adolescent↗

[Serological studies on prevalence of Toxoplasma gondii in Awassi sheep in Syria].

Survey was conducted in 9 Syrian provinces on clinically healthy Awassi sheep. Serum samples were collected from several districts (more than 47 localities--31 villages and 20 herds). Animals were 1-5 years old. 458 samples were collected in spring 1997 and 352 samples were collected from November 1998 through February 1999. The result indicated that seroprevalence of Toxoplasma gondii ranged between 0-100% in the herds and 13.8-74.5% between the provinces. And the mean of sero-prevalence was 44.56% in all provinces. The following prevalence were found in as indicated: Idleb 74.46%, Hama 72.16%, Deraa 63.35%, Al-Hssakeh 51.11%, Suweida 46.98%, Homs 40%, area of Damascus 23.48%, Aleppo 17.02% and Deir Ezzor 13.79%. The serological titer was 1:4 for 37.67% to 1:64 for 78.93% of the positive samples. Results showed that there are 29 (8%) of the positive samples with 1:1.000, and only 5 (1.38%) with 1:4.000. It is concluded that the Toxoplasma-infections may be one of the main causes of sheep abortions and as the source of human infection in Syria. Therefore, it is suggested that further epidemical studies are needed.

Abortion, Veterinary↗

Experimental congenital infection of Toxoplasma gondii in Macaca arctoides.

Congenital toxoplasmosis was studied in Macaca arctoides as a model for primates. Time-mated female monkeys were assigned to 5 experimental groups and inoculated with 4 different strains of Toxoplasma gondii before pregnancy and during various stages of gestation. All monkeys showed a rise in indirect hemagglutination antibody (IHA) titers following infection, and some had demonstrable parasitemia. Of the 23 progeny, 2 were stillbirths and 2 died soon after birth, but only the one neonate born of a mother inoculated intrauterally succumbed to acute toxoplasmosis. No physical anomalies were observed in any of the progeny. The toxoplasms organism was not isolated from any of the placentas obtained nor from the cord blood. None of the tissues from the stillborn or infant monkeys that died were positive for toxoplasmosis by mouse inoculation. The live progeny were usually born with high IHA antibody titers which were usually soon lost, indicating presence of passively acquired maternal antibody. However, 2 babies, born of mothers infected with tissue cysts on day 79 and 149 of gestation, maintained moderate to high titers for about 8 and 19 months respectively, indicating that an active infection had taken place but no clinical disease was detected. Data obtained suggest that although certain developmental stages of the toxoplasma organism and of the fetus may favor the occurrence of congenital infection, very little neonatal disease results in this primate model.

Animals↗

Comparison between Toxoplasma gondii DNA and specific immunoglobulins during pregnancy.

Early diagnosis of toxoplasmosis in pregnant women can be of great help in early intervention and prevention of congenital disorders that usually lead to fetal death. The purpose of the present study was to evaluate nested PCR amplification of the B1 gene of Toxoplasma gondii before and after treatment and in comparison to serological follow-up during treatment. The efficiency of treatment on the bases of PCR detection of T. gondii DNA was statistically significant, while it was insignificant when anti-toxoplasma specific IgM and IgG antibodies were used. PCR detection of T. gondii DNA when performed on whole blood is a rapid, sensitive and specific diagnostic procedure and is a valuable tool for establishing the diagnosis of T. gondii infection in women before or during pregnancy.

Adult↗

[Toxoplasma gondii infection in the inhabitants of the city of Dresden].

After a description of modern knowledge of the biology and epidemiology of toxoplasma gondii the author enters into the affection in Dresden inhabitants. Males as well as females at the age of 16 to 60 years are infected on the average at 74%. The most frequently affected age groups are the 41-year-old to 50-year-old persons. IFAR-titres to 80 are very frequently to be found in clinically healthy probands and, as a rule, plead for the existence of a latent toxoplasma affection. Titre values of more than 80 should always give rise to repeated examinations.

Adolescent↗