IgG Avidity Test for the Diagnosis of Acute Toxoplasma gondii Infection in Early Pregnancy

Background: Toxoplasmosis is well known as an important infection in pregnant women. Although many serologic methods are available, diagnosis of early Toxoplasmosis may be extremely difficult. Objective: To detect the Toxoplasma IgG antibodies developed at the early stage of infection in pregnant women. Methods: 225 pregnant women, who were in the 2nd to 4th month of their pregnancy, enrolled in this study. Anti-toxoplasma IgG, IgM and IgG avidity were evaluated by ELISA method. Results: The patients were categorized into three groups as follows: Group A, 124 cases; IgG+, IgM+, 55.1%; group B, 99 cases; IgG+, IgM-, 44%; and group C, 2 cases; IgG -, IgM +, 0.9%. Fifty five percent of the pregnant women had positive IgG and IgM among which 7.1% had low avidity which revealed an active infection in the pregnant women. In the current study, 44% of pregnant women had positive IgG and negative IgM, all of which had high avidity, which is an indication that in our population the level of toxoplasmosis infection is high and most women have had contacts with this parasite before pregnancy. Conclusion: In this study, the low avidity test was 7.1% showing that the occurrence of toxoplasmosis infection is still a serious issue. Observation of 45.8% high avidity among group A suggests that either IgM has a high half-life or there is a false positive IgM as a result of rheumatologic disorders. Therefore, avidity test is important in predicting maternal toxoplasmosis which is of value in disease treatment.     

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%.     

石家庄市大学生献血者弓形虫感染调查

目的 了解石家庄市大学生献血者弓形虫感染情况。 方法 2012年3-10月采集石家庄市4所大学大学生献血者和健康体检成人血清标本, 采用酶联免疫吸附试验 （ELISA） 检测弓形虫感染情况。 结果 共检测石家庄市4所大学864 例大学生献血者和95例健康成人, 弓形虫IgG阳性率分别为5.1%和7.4%, 差异有统计学意义 （P ＜ 0.05）。男性和女性大学生献血者弓形虫IgG阳性率分别为5.0%和5.2%, 差异无统计学意义 （P ＞ 0.05）; 不同大学的大学生献血者弓形虫IgG阳性率差异无统计学意义 （P＞0.05）。结论 大学生献血人群中部分感染弓形虫, 有必要加强弓形虫病防控工作。     

刚地弓形虫感染致小鼠生殖细胞DNA损伤的作用

目的 探讨刚地弓形虫感染对小鼠睾丸细胞DNA的损伤作用.方法 选用9～10周龄雄性BALB/c小鼠20只,随机分为4组,每组5只,分为正常对照组(CG)和3个染虫组(G1,G2,G3).采用腹腔注射法建立小鼠刚地弓形虫感染的动物模型,CG组每只注射PBS 0.2 ml;染虫G1,G2,G3组注射纯化的刚地弓形虫速殖子悬液,每只注射刚地弓形虫速殖子的量依次为2.5×10 3、5×10 3、1×10 4,注射体积均为0.2 ml,应用单细胞凝胶电泳检测睾丸细胞DNA的损伤. 结果 正常对照组和染虫组的尾距分别为10.94±7.57、40.37±6.25、69.76±3.97、79.16±6.36,olive尾距分别为10.57±6.72、31.39±4.59、48.66±4.60、53.87±6.55,G1-G3组与CG组比较,差异具有统计学意义(P＜0.01).结论 弓形虫感染可导致小鼠睾丸生殖细胞DNA不同程度的损伤.     

刚地弓形虫感染致小鼠睾丸细胞DNA的损伤作用

目的探讨刚地弓形虫感染对小鼠睾丸细胞DNA的损伤作用。方法选用9～10周龄雄性BALB/c小鼠20只,随机分为对照组(CG)和3个染虫组(G1、G2和G3)。采用腹腔注射法建立小鼠刚地弓形虫感染的动物模型,CG组注射PBS 0.2 ml/只,染虫G1、G2和G3组各注射纯化刚地弓形虫速殖子悬液0.2 ml,剂量分别为2.5×10~3个、5×10~3个和1×10~4个。应用单细胞凝胶电泳(彗星实验)检测睾丸细胞DNA的损伤。结果对照组和3个染虫组的彗星实验尾矩分别为10.94±7.57、40.37±6.25、69.76±3.97和79.16±6.36;Olive尾矩分别为10.57±6.72、31.39±4.59、48.66±4.60和53.87±6.55,对照组和实验组彗星尾矩和Olive尾矩差异有统计学意义(P<0.01)。结论弓形虫感染可致小鼠睾丸细胞DNA不同程度的损伤。对小鼠有生殖遗传毒性。     

Infection with cytomegalovirus during pregnancy: specific IgM antibodies as a marker of recent primary infection

Specific IgM antibodies that persisted for up to four months were detected by radioimmunoassay (RIA) in the sera of 16 (55%) of 29 women with primary infections due to cytomegalovirus (CMV). The RIA for IgM detected primary infections in six (86%) of seven sera obtained within four months of seroconversion. In contrast, IgM antibodies were never detected by RIA in 104 serum samples from 18 women with recurrent infections due to CMV, irrespective of whether intrauterine transmission of virus had occurred. Specific IgM antibodies were also detected in the earliest samples during pregnancy of serum from three (14%) of 21 women whose type of infection with CMV was unknown but who had been delivered of congenitally infected infants. All of these results show that primary infection with CMV in the first trimester of pregnancy can be diagnosed by testing a single serum sample by RIA for IgM antibodies. Attempts to measure IgM antibodies by immunofluorescence gave a high frequency (19 [18%] of 104) of false-positive reactions.     

Cellular immunopathogenesis in primary Toxoplasma gondii infection during pregnancy

Congenital toxoplasmosis is caused by the vertical transmission of infection from mother to foetus through the placenta when a pregnant woman is infected with Toxoplasma gondii (T. gondii). Congenital infection can have serious consequences, such as intrauterine abortion, foetal death and severe neurological, ocular or other organ damage in the foetus. In this review, we focus on recent publications investigating vertical transmission of T. gondii infection, cellular immunopathogenesis and protective immunity in primary toxoplasmosis during pregnancy.     

Detection of Toxoplasma gondii DNA and specific antibodies in high-risk pregnant women

Primary maternal infection with toxoplasmosis during pregnancy is frequently associated with transplacental transmission to the fetus. This study was conducted to test the utility of a polymerase chain reaction (PCR) assay to detect recent infections with Toxoplasma in pregnant women. One hundred forty-eight women with high-risk pregnancies who had abnormal pregnancy outcomes (cases) and 100 with normal pregnancies (controls) were tested for the presence of Toxoplasma DNA in their blood by a nested PCR and specific antibodies to Toxoplasma by an enzyme-linked immunosorbent assay. The IgG results of the cases differed significantly from those of the controls (54% and 12%, respectively; P < 0.02). Four (2.7%) of the cases were IgM positive, but none of the controls were positive. Detection of Toxoplasma DNA in 20 (8.1%) of the IgG-positive cases suggests a recent infection. The risk factors associated with the infection were eating raw meat and contact with soil. The diagnostic serology of recent infection in early pregnancy could be confirmed by a positive Toxoplasma-specific PCR result in blood samples collected in the first half of pregnancy, even in the presence of serologic results difficult to interpret due to the lack of sequential follow-up during pregnancy.     

弓形虫感染者血清IgM和IgG抗体免疫印迹谱分析

目的探索近期和慢性弓形虫感染的免疫诊断标志物。方法采用无毒灵敏的TMB为底物的酶联免疫印迹技术,分析弓形虫感染者IgM或IgG抗体阳性血清与弓形虫速殖子可溶性抗原的免疫反应谱。结果IgM抗体对p35、p38和p22的识别比例达80%以上,且反应带出现率较其它抗原组分高,而p32、p30与IgG抗体的反应带出现率和识别比例也分别高达40%和80%以上。其中,反应最强烈最具代表性的分别属p35(出现率81.5%,P<0.0001)和p32(出现率57.1%,P<0.0001)。结论p35、p38、p22可能为近期弓形虫感染的诊断标志物,p32和p30则可能是慢性弓形虫感染的诊断标志物。     

Identification of Toxoplasma gondii antigens recognized by specific T lymphocytes

The paper presents chosen experimental strategies for identifying of Toxoplasma gondii antigens recognized by specific T lymphocytes.     

抗弓形虫单克隆抗体免疫筛选弓形虫速殖子cDNA文库

目的　探讨自制的抗弓形虫单克隆抗体 (McAb)相应抗原的分子结构机制 ,为弓形虫疫苗的研制寻找有效抗原提供依据。方法　用自制的抗弓形虫速殖子的McAb免疫筛选弓形虫速殖子cDNA文库 ,对阳性克隆cDNA插入片段进行PCR鉴定并测序分析。结果　 2个McAb第一轮分别获得 6个和 3个阳性克隆。分别进行第 2轮筛选 ,选取其中持续阳性最强的2个进行体外剪切 ,提取质粒DNA并进行PCR扩增和序列测定 ,经核苷酸同源性比较 ,可能为 2个新基因 ,其中 7C3-C3筛选的基因命名为WX2 (GenBank登录号为 :AY2 38892 ) ,2B9-G1筛选的基因命名为WX(GenBank登录号为 :AY2 0 8994 ) ,并用蛋白质分析软件对新基因编码的蛋白质结构和功能进行预测。结论　自制的具有一定保护性效果的McAb免疫筛选获得的阳性克隆插入基因片断的表达产物 ,可能具有抵抗弓形虫感染的作用 ,值得进一步深入研究。     

IL-10 mediates immunosuppression following primary infection with Toxoplasma gondii in mice

Suppression of the host immune response by Toxoplasma gondii has been observed in both human and experimental murine infection. In this study, inbred mice were infected with T. gondii. At day 7 post-infection, the lymphoproli-ferative response to both mitogen and superantigen as well as parasite antigen were found to be significantly depressed. Using a transwell system, it was determined that the reduced proliferative response was due to soluble factor (s) being expressed by splenocytes from the infected mice. Isolation of the splenocytes into an adherent and nonadherent population suggested that both macrophages and T cells were able to produce at least one soluble factor. Tissue culture supernatant derived from the splenocytes of the infected mice contain increased levels of IL-10, whereas measurable IL-2 levels could not be quantitated. At day 7 post-infection, both a biologic assay for IFN-γ in culture supernatant and the expression of IFN-γ mRNA in the splenocytes were reduced. Antibody to IL-10 was able to partially neutralize (almost 50%) the in vitro immune downregulation of the tissue culture supernatant. Anti-IL-10 in combination with a nitric oxide (NO) antagonist was able to reverse the inhibitory activity of the culture supernatant by 85%. Since IL-10 is a potent antagonist of IFN-γ, it may represent a critical cytokine involved in mediating T. gondii induced immunosuppression in the infected host.     

Control of Toxoplasma gondii infection by athymic LEW-Whn rnu rats

In immunocompetent rats and humans infection with Toxoplasma gondii remains mostly without overt clinical symptoms, but can be fatal, if the T-cell response is impaired. For a better understanding of the lack of control of T. gondii infection under immunosuppressed conditions , congenitally athymic rats were used as the experimental model. Whereas athymic F344- Whn^rnu (F344 nude) rats die from a generalized infection during the first 3 weeks after peritoneal inoculation with 10⁶ tachyzoites of T. gondii strain NTE, LEW- Whn^rnu (LEW nude) rats and euthymic LEW rats infected with a 10-fold higher number of parasites developed chronic infection. To identify underlying mechanisms of LEW rats resistance to T. gondii infection and to investigate a possible contribution of residual T-cells to LEW- Whn^rnu rat resistance, we characterized the immune response of LEW rats by determination of cellularity and composition of lymphocyte population, antigen-specific IgG2b response as well as assays of antigen-specific proliferation and production of IL-2, IFN-γ and TNF-α. As only euthymic LEW rats developed production of antigen-specific IgG and cellular in vitro responses, these results strongly suggest that the genetic background of LEW rats permits a control of the infection independent of an adaptive immune response.     

Avidity determination of Borrelia burgdorferi-specific IgG antibodies in Lyme disease.

The avidity indices of Borrelia burgdorferi-specific IgG antibodies were estimated using ELISA in sera from patients with different stages of Lyme disease. In addition, sera from healthy students with proof of borrelial-specific IgG antibodies from standard serology were tested. Low avidity indices were detected predominantly in sera from patients with early-stage Lyme disease [erythema migrans (EM); n = 25]. High avidity indices were found in healthy students (n = 72) and in most of the patients with neuroborreliosis (NB; n = 44) and chronic late-stage Lyme disease [acrodermatitis chronica atrophicans (ACA); n = 36]. In conclusion, early-stage Lyme disease (EM) could be differentiated from advanced and chronic stages (NB, ACA) and from "seropositive" healthy persons using avidity determination in the majority of patients in this study.     

刚地弓形虫感染致Th1/Th2细胞因子变化对大鼠生精细胞的影响

目的 研究弓形虫感染后雄性大鼠Th1、Th2细胞因子IFN-γ、IL-4及一氧化氮(NO)水平的变化,探讨其对雄性睾丸生精细胞损伤的影响.方法 选用9～10周龄雄性SD大鼠132只,按随机数字表法分为3组:正常对照组、低剂量感染组(1×102个速殖子)、高剂量感染组(1×104个速殖子),感染后第0、3、6、9、……30天,感染组和对照组分别取4只大鼠,检测大鼠血清IFN-γ、IL-4及NO的水平,并且做睾丸的病理学检查和精子计数.结果 弓形虫感染组大鼠血清IFN-γ显著升高,低剂量组及高剂量组在第6天达峰值,分别为(286.3±45.3) pg/ml和(506.6±34.3) pg/ml;血清NO亦显著升高,高剂量组第9天达峰值(77.7±7.0) μmol/L,低剂量组第12天达峰值(59.5±5.3) μmol/L,之后均迅速降低;感染组大鼠血清IL-4逐渐升高,低剂量组及高剂量组于第15天达峰值(233.3±36.9) pg/ml、(366.7±52.4) pg/ml后逐渐降低.以上指标至实验末期均未恢复正常水平.病理检查显示,正常对照组大鼠生精小管层次清晰,细胞丰富,精子计数为175.7±23.7,感染组大鼠生精小管层次混乱,精母细胞、精子细胞明显减少,低剂量组及高剂量组至第15天达谷值84.5.23.5、47.3±14.7,至实验末期无明显恢复.结论 弓形虫感染导致的早期Th1细胞因子IFN-γ极化及NO显著升高,随后引起Th2细胞因子IL-4反应性增高,并介导以精母细胞为主的生精细胞损伤及生精障碍.