Toxoplasma gondii infection in pregnant women in China

Infection with Toxoplasma gondii is common and usually asymptomatic, but it can have serious consequences in pregnant women if passed to the developing fetus. The aims of this study were to determine the prevalence of toxoplasmosis in pregnant women and to identify the possible risk factors associated with T. gondii infection in China. Of a sample of 235 pregnant women in Changchun, China, 25 (10.6%) were found by ELISA to be positive for IgG and none (0%) for IgM. Major risk factors were found by bivariate and multivariate analysis to include eating raw or undercooked meat, unwashed raw vegetables or fruit, contact with cats, living in rural areas, and low educational standards. In order to lower congenital infection, pregnant women need to be informed about the risk factors for toxoplasmosis.     

Effectiveness of a novel immunogenic nanoparticle platform for Toxoplasma peptide vaccine in HLA transgenic mice

We created and produced a novel self-assembling nanoparticle platform for delivery of peptide epitopes that induces CD8⁺ and CD4⁺T cells that are protective against Toxoplasma gondii infection. These self-assembling polypeptide nanoparticles (SAPNs) are composed of linear peptide (LP) monomers which contain two coiled-coil oligomerization domains, the dense granule 7 (GRA7_20–28 LPQFATAAT) peptide and a universal CD4⁺T cell epitope (derived from PADRE). Purified LPs assemble into nanoparticles with icosahedral symmetry, similar to the capsids of small viruses. These particles were evaluated for their efficacy in eliciting IFN-γ by splenocytes of HLA-B*0702 transgenic mice and for their ability to protect against subsequent T. gondii challenge. This work demonstrates the feasibility of using this platform approach with a CD8⁺ epitope that binds HLA-B7 and tests the biological activity of potentially protective peptides restricted by human major histocompatibility complex (HLA) class I molecules in HLA transgenic mice.     

Lack of technical specificity in the molecular diagnosis of toxoplasmosis

The polymerase chain reaction amplification of a fragment of the B1 gene of Toxoplasma gondii coupled to hybridization was performed in 42 patients from Rio de Janeiro, Brazil. The results showed 50% of positivity in the IgM positive toxoplasmosis group, and 12.5% in the positive IgG and negative IgM individuals. The data presented here revealed a lack of specificity of the molecular approach, clearly indicating that the primers used may co-amplify human sequences.     

Seroprevalence of Toxoplasma infection among pregnant women in Bahia, Brazil

Infection by Toxoplasma gondii represents a risk to fetal development during pregnancy. In this study, the serological profile of pregnant women from different regions of Bahia, Brazil, was determined. Tests were conducted at LACEN-BA (Salvador, Brazil). The mean age of the women was 24.5 years (±7.41 years) and 56.4% were positive for IgG and negative for IgM specific for T. gondii. Seronegative women represented 35.9% of the total (IgG- and IgM-negative) and inconclusive results comprised 4%. Differences were observed in distinct regions. Therefore, a preventive action must be reinforced in specific regions aimed at early diagnosis to minimise the risk of congenital toxoplasmosis development.     

Protective immunity against Toxoplasma challenge in mice by coadministration of T. gondii antigens and Eimeria profilin-like protein as an adjuvant

Toll-like receptor (TLR) ligands are attractive adjuvant candidates in vaccine development. Eimeria tenella profilin-like protein has recently been shown to be a potent agonist of the innate immune system through its recognition by Toll-like receptor-11. In this report, we studied the systemic and mucosal adjuvant activity of Eimeria profilin-like protein within a vaccinal strategy against Toxoplasma gondii in mice. Using intraperitoneal (i.p.) immunization, we observed that coadministration of the recombinant Eimeria antigen (rEA) with T. gondii antigen (TAg) effectively elevates plasma levels of IL-12p70 and consequently induced both enhanced specific humoral and Th1 cellular immune responses. The co-administration of TAg plus rEA by i.p route significantly enhanced the protection against T. gondii infection (62% brain cyst reduction) in comparison with control mice and with mice immunized with TAg alone (only 36% brain cyst reduction). After intranasal immunization, humoral and cellular responses were weak. However mice immunized nasally with TAg plus rEA were significantly protected with 50% of brain cyst reduction, conversely TAg immunized mice did not present any brain cyst reduction.These results indicate that Eimeria profilin-like protein would serve as an efficacious systemic and mucosal adjuvant inducing protective immune response against chronical stage of T. gondii infection through TLR11 activation.     

Serological screening and toxoplasmosis exposure factors among pregnant women in the Democratic Republic of Sao Tome and Principe

The seroprevalence of Toxoplasma gondii infection among pregnant women in the Democratic Republic of Sao Tome and Principe (DRSTP) from November 2003 to March 2004 was determined by detection of serum anti-T. gondii antibodies. A short questionnaire interview for pregnant women was performed to investigate risk factors associated with T. gondii infection, including consumption of raw meat or unwashed vegetables, drinking unboiled water and keeping pets (cats and dogs). The overall seroprevalence of T. gondii infection was high (75.2%; 375/499). The older age group of > or =35 years had a significantly higher seroprevalence (85.7%; 54/63) than that of the younger age group of 15-25 years (70.4%; 178/253) (odds ratio 2.5, 95% CI 1.2-5.4; P=0.01). No significant difference in the seroprevalence of T. gondii infection was found between the pregnant women with and without exposure to the risk factors studied. However, among pregnant women with high antibody titers of > or =1:1024, it seemed likely that continual contact with pets and consumption of oocyst-contaminated water or raw unwashed vegetables rather than tissue cysts in meat was the primary route of infection. The incidence of congenital toxoplasmosis in unborn babies should be intensively monitored in the DRSTP.     

Toxoplasma gondii microneme protein 6 (MIC6) is a potential vaccine candidate against toxoplasmosis in mice

Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. Microneme proteins which are responsible for adhesion and invasion have been implicated as vaccine candidates. In this study, we constructed a DNA vaccine expressing microneme protein 6 (MIC6) of T. gondii, and evaluated the immune response it induced in Kunming mice. The gene sequence encoding MIC6 was inserted into the eukaryotic expression vector pVAXI. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that the group immunized with pVAX-MIC6 developed a high level of specific antibody responses against T. gondii lysate antigen (TLA), a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production, compared with the other groups immunized with empty plasmid or phosphate-buffered saline, respectively. These results demonstrate that pVAX-MIC6 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-MIC6 showed an increased survival time (13.3 ± 1.2 days) compared with control mice died within 7 days of challenge. Our data demonstrate, for the first time, that MIC6 triggered a strong humoral and cellular response against T. gondii, and that the antigen is a potential vaccine candidate against toxoplasmosis, worth further development.     

上海市建卡孕妇弓形虫病健康教育效果评价

目的:探索在建卡孕妇中开展弓形虫病健康教育的可行性和近期效果。方法:随机抽取上海市12家医疗机构1 103名建卡孕妇,通过弓形虫病健康教育干预前后的该病相关知识、态度等信息的问卷调查结果,评价干预的近期效果。结果:建卡孕妇健康教育后人均弓形虫病相关知识评分较健康教育前有明显提高(t=17.549,P0.001);对弓形虫病症状与危害、传播途径和预防措施相关问题的答对率分别从干预前的51.0%、62.6%和80.7%提高至干预后的77.7%、75.0%和95.1%(P0.001)。孕前会主动要求做弓形虫检测的比例从干预前的59.7%提高至干预后的83.2%,并对检测阳性结果的重视度亦有显著提高(P0.001)。结论:在建卡孕妇中开展弓形虫病健康教育有效且可行。     

Protective effect against toxoplasmosis in mice induced by DNA immunization with gene encoding Toxoplasma gondii ROP18

Toxoplasma gondii is an obligate intracellular protozoan parasite infecting mammals and birds including humans. Rhoptry protein 18 has been implicated as an important virulence factor. In this study, we constructed a DNA vaccine expressing rhoptry protein 18 (ROP18) of T. gondii, and evaluated the immune response and protective immunity in Kunming mice. The gene sequence encoding ROP18 was inserted into the eukaryotic expression vector pVAX I. Intramuscular immunization of mice with pVAX-ROP18 elicited specific humoral responses and stimulated lymphoproliferation (P < 0.05). The cellular immune response was associated with the production of IFN-γ, indicating that a Th1 type response was elicited, which was confirmed by the production of large amounts of IgG2a (P < 0.05). By the expression of the CD69, an activation marker of CD4+ and CD8+ T cells, we found that pVAX-ROP18 enhanced the activation of CD4+ and CD8+ T cells in lymphoid in mice. After lethal challenge, the mice immunized with the pVAX-ROP18 showed a significantly increased survival time (27.9 ± 15.1 days) compared with control mice which died within 7 days of challenge (P < 0.05). Our results show for the first time, that a ROP18 vaccine construct can enhance the T. gondii-specific CTL. Th1 responses and increased survival suggested that ROP18 is a promising vaccine candidate against infection with T. gondii.     

Risk factors for infection by the Entamoeba histolytica/E. dispar complex: an epidemiological study conducted in outpatient clinics in the city of Manaus, Amazon Region, Brazil

An epidemiological study was conducted on a population attending outpatient clinics in Manaus, Amazon, Brazil to determine the prevalences of infection by the Entamoeba histolytica/E. dispar complex and by E. histolytica alone, as well as to identify the risk factors involved in transmission. The study was conducted in two phases: survey and case-control. Face-to-face interviews were carried out and faecal samples collected from 1578 individuals. Faeces were examined by optical microscopy and tested for the pathogenic E. histolytica specific antigen. Positivity to E. histolytica/E. dispar was 21.5% (340 cases). Cases were compared with 340 control samples, negative for the E. histolytica/E. dispar complex based on examination by optical microscopy. The analysis was conducted by logistic regression. The risk factors identified were: place of residence, age, ingestion of raw vegetables, quality of water consumed, number of rooms and bedrooms per house, and having other protozoan infections. Specific antigen detection tests identified 22 participants infected by E. histolytica (6.8%) among those positive for E. histolytica/E. dispar. There was a higher proportion of males among participants infected by E. histolytica than among those with E. dispar infections. The study population was asymptomatic or presented non-specific symptoms that could be attributed to amoebiasis.     

Protective immunity induced by a DNA vaccine expressing eIF4A of Toxoplasma gondii against acute toxoplasmosis in mice

Toxoplasma gondii is an obligate intracellular protozoan parasite infecting humans, mammals and birds. Eukaryotic translation initiation factor (eIF4A) is a newly identified protein associated with tachyzoite virulence. To evaluate the protective efficacy of T. gondii eIF4A, a DNA vaccine (pVAX-eIF4A) encoding T. gondii eIF4A (Tg-eIF4A) gene was constructed. The expression ability of this recombinant DNA plasmid was examined in Marc145 cells by IFA. Then, Kunming mice were intramuscularly immunized with pVAX-eIF4A and followed by challenge infection with the highly virulent T. gondii RH strain. The results showed that vaccination with pVAX-eIF4A elicited specific humoral responses, with high IgG antibody titers and specific lymphocyte proliferative responses. The cellular immune response was associated with significant production of IFN-γ, IL-2 in Kunming mice, and a mixed IgG1/IgG2a response with predominance of IgG2a production, indicating that a Th1 type response was elicited after immunization with pVAX-eIF4A. In addition, the increase of the percentage of CD8+ T cells in lymphoid in mice suggested the activation of MHC class I restricted antigen presentation pathways. After lethal challenge, the mice vaccinated with the pVAX-eIF4A showed a significantly prolonged survival time (23.0 ± 5.5 days) compared with control mice which died within 7 days of challenge (P < 0.05). These results demonstrate that pVAX-eIF4A could elicit strong humoral, Th1-type cellular immune responses and increase survival time of immunized mice, suggesting that eIF4A is a promising vaccine candidate against acute T. gondii infection in mice.     

Prevalence of toxoplasma gondii antibodies in gravidas and recently aborted women and study of risk factors

Two hundred seventeen parturients and eighty six recent aborters were screened for IgM and IgG toxoplasma antibodies. Age, profession, educational level, residence (urban/rural), presence of cat and other domestic animals were recorded for each subject. None of the subjects was IgM-positive. Prevalence of IgG positivity was 52.3% in the parturients and 50.2% in the recently aborted women. None of the personal or social characteristics investigated could be related to IgG positivity. However, the frequency of toxoplasma antibodies was found to be higher in recent aborters from rural areas where contact with soil is common regardless of whether cats are kept as pets or not.This study confirms other investigators' conclusion on the importance of soil contact as a risk factor for infection.     

Seroprevalence of Toxoplasma gondii in Pregnant Women and Bioassay of IgM Positive Cases in Zanjan,Northwest of Iran

Background

The aim of this study was to determine the Toxoplasma antibodies in pregnant women in Zanjan, by ELISA method.

Methods

Blood samples were taken from 500 pregnant women referred to the health centers of Zanjan City, North West Iran, IgM and IgG titers were primarily evaluated. The collected data were analyzed with SPSS 11.5 using Chi-Square test.

Results

Anti Toxoplasma IgM and IgG were positive in 1.4% and 37.2% respectively. Seropositive subjects were more frequently seen in those with >30 years old compared to younger women (<20 years old). No significant relationship was found between the seroprevalence of T. gondii infection and level of education, residence area, history of abortion and gestational age.

Conclusion

The rate of IgM positive was low; however, a large number of the studied population were IgG positive, indicative of having a latent infection due to the past exposure to Toxoplasma parasite in this region.     

Evaluation of protective effect of pVAX-TgMIC13 plasmid against acute and chronic Toxoplasma gondii infection in a murine model

Toxoplasma gondii is a significant zoonotic parasite which can cause congenital infection and abortion in warm-blooded animals and humans. Microneme protein 13 (MIC13) plays an important role in attachment and penetration of the host cell by T. gondii. In this study, a DNA vaccine expressing mic13 of T. gondii was constructed and its protective efficacy was evaluated in Kunming L615^H2k mice. Immunization with pVAX-TgMIC13 induced a strong immune responses demonstrated by significant lymphocyte proliferation, cytokine production and antibody responses. Immunized mice showed increased survival time (21.3 ± 11.3 days) and reduced number of cysts in brain of mice (57.14%) after challenge with tachyzoites of the virulent T. gondii RH strain and cysts of the T. gondii PRU strain, respectively, demonstrating that T. gondii MIC13 is a potential vaccine candidate, worth being included in future vaccine development against acute and chronic T. gondii infection.     

Seroprevalence of Toxoplasma gondii Infections in Pregnant Women in Gorgan City,Golestan Province,Northern Iran-2012

Background

Toxoplasma gondii is one of the most prevalent parasites of human and warm- blooded animals. Toxoplasmosis is important especially in two groups: pregnant women and immunocompromised patients. If women acquire the primary infection during the pregnancy, it would be life threatening or remains severe disorders for the fetus. This study was performed to evaluate the seroprevalence of T. gondii infection in pregnant women referred to Health Center in Gorgan City, Golestan Province, northern Iran.

Methods

Serum samples were collected from pregnant women referred to Health Center in Gorgan City, south eastern Caspian Sea. Anti- Toxoplasma IgG and IgM antibodies were determined by commercially ELISA kits and the relation of infection with socio-demographic and risk factors such as age, education, occupation, cat ownership, soil contact and some other factors was studied.

Results

From 555 tested sera of pregnant women referred to Health Center in Gorgan, 39.8% had IgG antibodies against T. gondii and 3.4% were positive for IgM antibodies. A significant correlation was seen between T. gondii infection with age and soil contact.

Conclusion

About 60% of pregnant women in Gorgan City are seronegative against T. gondii, so they should considered as at risk persons.     

早产影响因素的前瞻性队列研究

目的  分析中国早产的流行现状及危险因素,为早产的预防提供参考依据。 方法  本研究数据来源于中国孕产妇队列研究·协和项目(Chinese Pregnant Women Cohort Study, CPWCS),通过问卷调查和医院信息系统(hospital information system, HIS)收集孕妇基本情况和分娩结局。采用SPSS 26.0软件进行χ²检验和多因素Logistic回归分析模型分析。 结果  5 671名孕妇中发生早产的例数为295例,占5.2%,不同地区早产率差异无统计学意义(χ² =0.591, P=0.771)。多因素分析结果显示：高龄、糖尿病史、早产史、胎盘早剥、胎膜早破、胎儿宫内窘迫、妊娠期高血压以及双胎是早产的危险因素(均有P < 0.05),而在自然分娩的孕妇中,高龄(OR=2.90, 95% CI: 1.67~5.06, P < 0.001)、胎膜早破(OR=6.17, 95% CI: 4.21~9.06, P < 0.001)、双胎(OR=17.72, 95% CI: 3.23~97.25, P=0.001)是早产的主要危险因素。 结论  早产的影响因素较多,准确识别危险因素,为孕妇提供科学合理的健康教育和个性化的防治措施是预防早产的重要手段。     

Toxoplasma gondii immune mapped protein-1 (TgIMP1) is a novel vaccine candidate against toxoplasmosis

Immune mapped protein1 (IMP1) is a new protective protein in apicomplexan parasites, and exists in Toxoplasma gondii. In the present study, a DNA vaccine expressing IMP1 of T. gondii was constructed and the immune response induced in BALB/c mice was evaluated. The coding sequence of IMP1 was inserted into the eukaryotic expression vector pcDNA 3.1(+), resulting a recombinant plasmid pcDNA-IMP1, which was used to immunize BALB/c mice intramuscularly. After immunization, the immune response was evaluated using lymphoproliferative assay, and cytokine and antibody measurements. The mice were challenged with tachyzoites of the virulent T. gondii RH strain 14th day after the last immunization to observe the survival time. The results showed that the group immunized with pcDNA-IMP1 developed a high level of specific antibody responses against Escherichia coli expressed recombinant TgIMP1, with high IgG antibody titers, predominance of IgG2a production, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production compared with the control groups. These results demonstrate that pcDNA-IMP1 could elicit strong humoral and Th1 immune responses. Immunized mice showed a significantly (15.8 ± 6 days) prolonged survival time compared with control mice, which died within 7 days of challenge infection. These results suggest that IMP1 is a promising vaccine candidate against toxoplasmosis.     

The virulence-related rhoptry protein 5 (ROP5) of Toxoplasma Gondii is a novel vaccine candidate against toxoplasmosis in mice

Infections with the intracellular protozoan parasite Toxoplasma gondii pose a serious public health problem and are of great economic importance worldwide. The parasite rhoptry protein 5 (ROP5) has been implicated as a major virulence factor that reduces the accumulation of immunity-related GTPases (IRG) in parasitophorous vacuole membrane (PVM), which maintains PVM integrity and evades IFNγ-mediated killing by intracellular parasites. To study the immunoprotective value of ROP5, BALB/c mice were immunized with a recombinant form of the protein administered alone or in combination with another promising vaccine antigen, rSAG1. All mice vaccinated with the recombinant antigens developed a high level of specific antibody responses against soluble tachyzoite antigens (STAg), a statistically significant increase of the splenocyte proliferation response, and significant levels of IFN-γ and IL-2 production. In contrast to rSAG1, which only stimulated the release of IFN-γ and IL-2, rROP5 induced the specific production of IL-10, the Th2-type cytokine, in addition to IFN-γ and IL-2. These results demonstrated that rROP5 could induce significant cellular and humoral (Th1/Th2) immune responses. Moreover, mice immunized with rROP5 displayed a prolonged survival time against a lethal challenge with the T. gondii RH strain. Additionally, vaccination with the mixture of rROP5 + rSAG1 resulted in higher levels of T. gondii-specific IgG antibodies and lymphocyte proliferative responses and conferred more efficient protection against T. gondii challenge compared to immunization with rROP5 or rSAG1 alone. Our studies show that recombinant ROP5 antigen may be a promising vaccine candidate against toxoplasmosis. To our knowledge, this is the first report to evaluate the immunoprotective value of ROP5.     

Impact of drainage and sewerage on intestinal nematode infections in poor urban areas in Salvador, Brazil

This cross-sectional study was conducted in 1989 among children aged between 5 and 14 years old living in nine poor urban areas of the city of Salvador (pop. 2.44 million), capital of Bahia State, in Northeast Brazil. Three of these areas had benefited from both drainage and sewerage, 3 from improved drainage only, and 3 from neither. The children studied thus belonged to 3 exposure groups regarding their level of sanitation infrastructure. An extensive questionnaire was applied to collect information on each child and on the conditions of the household, and stool examinations of the children 5-14 years old were performed to measure nematode infection. Comparison of the sewerage group with the drainage-only group and the latter with the control (no sewerage or drainage) group showed that, when the level of community sanitation was better, the prevalence of infection among children was less, but risk factors identified for infection were more numerous and more significant. Intensity of infection with Trichuris, but not with Ascaris or hookworm, was also less. The results suggest that sewerage and drainage can have a significant effect on intestinal nematode infections, by reducing transmission occurring in the public domain.