[Establishment and diagnostic performance of biotin-avidin complex enzyme linked immunosorbent assay of detecting specific IgG4 of clonorchiasis].

OBJECTIVE: To explore the performance of the biotin-avidin complex enzyme linked immunosorbent assay of detecting specific IgG4 for the diagnosis of clonorchiasis. METHODS: The avidin-biotin complex enzyme linked immunosorbent assay of detecting specific IgG4 (IgG4-ABC-ELISA)against Clonorchis sinensis was established, and used to detect the serum samples of patients with clonorchiosis sinensis, schistosomiasis japonica, paragonimiasis, toxoplasmosis, echinococcosis, cysticercosis and sparganosis mansoni. At the same time, these sera were analyzed by the ELISA of detecting IgG4 (IgG4-ELISA) and ELISA of detecting the total IgG (IgG-ELISA) as controls. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and the respective diagnostic performance of the three methods were compared. RESULTS: The IgG4-ABC-ELISA for diagnosis of clonorchiasis was established successfully. The sensitivity and specificity of the IgG4-ABC-ELISA for detecting clonorchiasis were 90.0% and 98.2% respectively, and PPV and NPV were 93.8% and 97.0% respectively. Its diagnostic performance was 96.3%. The sensitivity and specificity of the IgG4-ELISA for detecting clonorchiasis were 86.0% and 98.2% respectively, and PPV and NPV were 93.5% and 95.9% respectively. Its diagnostic performance was 95.4%. The sensitivity and specificity of the IgG-ELISA for detecting clonorchiasis were 94.0% and 88.1% respectively, and PPV and NPV were 70.1% and 98.0% respectively. Its diagnostic performance was 89.4%. The sensitivity of IgG4-ABC-ELISA was higher than that of IgG4-ELISA (P < 0.05), and the specificity of IgG4-ABC-ELISA was higher than that of IgG-ELISA (P < 0.05). CONCLUSIONS: IgG4-ABC-ELISA of detecting specific antibody IgG4 against Clonorchis sinensis has high sensitivity and specificity. Therefore, it has a good application value in the diagnosis of clonorchiasis.

[Effect of Toxoplasma gondii Infection in Female Mice on Dopamine Level in the Brain of the Male Offspring].

OBJECTIVE: To investigate the effect of Toxoplasma gondii infection in female mice on dopamine level in the brain of male offspring. METHODS: Thirty-six ICR female mice were randomly divided into control group and infection group, 18 mice in each group. Each mouse in infection group was orally infected with 10 cysts of T. gondii Prugniaud strain. On the 90th day after infection, the infected female mice were mated with normal male ICR mice at 1:1 ratio. On the 20th day of pregnancy, 2 mice in each group were delivered for fetal mice by cesarean section, and the brain of male fetal mice (n = 6) in each group were collected. On the 14th and 63rd day after birth, 6 male offspring mice in each group were sacrificed, and the brain were collected. Dopamine levels in the cortex, cerebellum, hippocampus, and striatum were analyzed by high-performance liquid chromatography-electrochemical detection (HPLC-ECD). RESULTS: Three mice in infection group died during the experiment, and 6 out of 15 female mice mated successfully. The number of fetal mice and F1 generation mice in infection group was 12 (male: 7) and 21 (male: 15), respectively. All the mice in control group mated successfully. The number of fetal mice and F1 generation mice was 23 (male: 12) and 179 (male: 92), respectively. The dopamine level in the cerebellum of fetal mice of infection group and control group was (413.25 ± 21.78) ng/g and (346.30 ± 51.83) ng/g, respectively (P < 0.01). No significant difference was found in dopamine content in the cortex between the two groups (P > 0.05). Compared with the control group, on the 14th day and 63rd day after birth, the dopamine content in cortical areas [(462.50 ± 24.80) ng/g and (1215.77 ± 113.64) ng/g], cerebellum area [(271.55 ± 26.19) ng/g and (1328.82 ± 39.62) ng/g], hippocampus area [(225.78 ± 24.17) ng/g and (1322.70 ± 58.34) ng/g], and striatum area [(455.23 ± 61.53) ng/g and (991.32 ± 54.31) ng/g] of the male offspring in infection group were significantly higher than that of the control (P < 0.05, P < 0.01). CONCLUSION: T. gondii infection in female mice causes an increase of dopamine level in the brain of F1 generation male mice.

Stem cell therapy for the treatment of parasitic infections: is it far away?

Stem cell therapy is an interventional treatment that introduces new cells into damaged tissues, which help in treating many diseases and injuries. It has been proved that stem cell therapy is effective for the treatment of cancers, diabetes mellitus, Parkinson's disease, Huntington's disease, cardiovascular diseases, neurological disorders, and many other diseases. Recently, stem cell therapy has been introduced to treat parasitic infections. The culture supernatant of mesenchymal stem cells (MSCs) is found to inhibit activation and proliferation of macrophages induced by the soluble egg antigen of Schistosoma japonicum, and MSC treatment relieves S. japonicum-induced liver injury and fibrosis in mouse models. In addition, transplantation of MSCs into naïve mice is able to confer host resistance against malaria, and MSCs are reported to play an important role in host protective immune responses against malaria by modulating regulatory T cells. In mouse models of Chagas disease, bone marrow mononuclear cell has been shown effective in reducing inflammation and fibrosis in mice infected with Trypanosoma cruzi, and transplantation of the bone marrow mononuclear cells prevents and reverses the right ventricular dilatation induced by T. cruzi infection in mice. Preliminary clinical trials demonstrate that transplantation of bone marrow derived-cells may become an important therapeutic modality in the management of end-stage heart diseases associated with Chagas disease. Based on these exciting results, it is considered by stating that it is firmly believed that, within the next few years, we will be able to find the best animal models and the appropriate stem cell type, stem cell number, injection route, and disease state that will result in possible benefits for the patients with parasitic infections, and stem cell therapy, although at an initial stage currently, will become a real therapeutic option for parasitic diseases.

[Effect of latent asymptomatic toxoplasmosis on glucose metabolism in brain of mice].

OBJECTIVE: To explore the effect of latent asymptomatic Toxoplasma gondii infection on glucose metabolism in brain of mice. METHODS: Twenty mice were randomly divided into two groups: a Toxoplasma infected group and normal control group. The mice in the Toxoplasma infected group were inoculated with 0.3 ml of brain suspension in saline containing ten Toxoplasma gondii tissue cysts, avirulent Toxoplasma gondii Prugniaud (PRU, a Type II strain). The mice in the control group received 0.3 ml of saline orally. Six monthes after the infection, the glucose metabolism changes in the mouse brain were evaluated by MicroPET, then all the mice were sacrificed and the brain tissues were observed histopathologically. RESULTS: Compared with the normal controls, the infected mice demonstrated profound and widespread brain pathology, and MicroPET indicated a significant glucose metabolism reduction in the brain of asymptomatic Toxoplasma gondii infected mice. CONCLUSION: Chronic Toxoplasma gondii infection maybe results in the glucose metabolism reduction in the brain of mice.

Effect of praziquantel prolonged administration on granuloma formation around Schistosoma japonicum eggs in lung of sensitized mice.

Schistosomiasis remains a major public health problem and it is an immune disease. The schistosome egg is the primary parasite factor responsible for the overt disease. The eggs release the soluble antigen, which induces intensive tissue reaction, a granulomatous reaction to the eggs. If granuloma formation could be suppressed, overt disease might not develop. Praziquantel is an effective antischistosomal drug especially for adult worms. However, whether praziquantel has a suppressing effect on granuloma formation around schistosome eggs directly remains unclear. The purpose of the present study was to investigate the effect of praziquantel, especially administered persistently, on granuloma formation around Schistosoma japonicum eggs in the lung of sensitized mice. Thirty-six mice were divided into three groups averagely. Group A was a control group. First, the mice were injected with schistosomal eggs hypodermically in abdomen, and 10 days later injected with schistosomal eggs intravenously via a tail vein. Group B was a praziquantel short administration group. In addition to the injections of schistosomal eggs as the same of Group A, the mice were administered with praziquantel in a daily dose of 300 mg/kg for 3 days, from 1 day before the intravenous injection of the eggs. Group C was a praziquantel prolonged administration group. In addition to the injections of schistosomal eggs as the same of Group A, the mice were administered with praziquantel in a daily dose of 150 mg/kg for 5 days weekly until the mice were sacrificed. Three mice of each group were sacrificed on days 7, 14, 28, and 56, respectively after the intravenous injection of the eggs, and the lung tissues were fixed with formalin and the slices were HE stained. The granulomas containing eggs in their centers were selected, and 25-30 granulomas from the animals of each group were measured at each time period. The mean areas of egg granulomas of each group were calculated, and the neutrophilic granulocytes, eosinocytes, lymphocytes, fibroblasts, and macrophages within the egg granulomas were counted. The mean numbers of them of each group were calculated. All the data of each group were analyzed and compared statistically. On day 56 after the intravenous injection of the eggs, the mean area of schistosomal egg granulomas in group B was (227.4 ± 728.0) × 10(3) µm(2), less than that of [(297.9 ± 153.3) × 10(3) µm(2)] in group A, and the suppression rate was 23.7% (P < 0.05). On days 7, 14, 28, and 56, the mean areas of schistosomal egg granulomas in group C were (575.8 ± 155.6) × 10(3) µm(2), (310.5 ± 854.0) × 10(3) µm(2), (267.7 ± 513.3) × 10(3) µm(2), and (214.9 ± 446.4) × 10(3) µm(2), respectively, significantly less than those of [(692.7 ± 232.6) × 10(3) µm(2), (439.4 ± 165.0) × 10(3) µm(2), (385.7 ± 129.3) × 10(3) µm(2), and (297.9 ± 153.3) × 10(3) µm(2)] in group A. The suppression rates were 16.9%, 29.3%, 30.6%, and 27.9%, respectively (P values <0.05). On day 56, the mean numbers of neutrophilic granulocytes were 11.4 ± 5.0 in group A and 5.2 ± 3.1 in group C, respectively, with the suppression rate of 54.4% in group C (P < 0.05). On day 56, the mean numbers of eosinocytes within the egg granulomas were 2.3 ± 2.0, 0.1 ± 0.3, and 0.3 ± 0.6 in groups A, B, and C, respectively, with the suppression rate of 95.7% in group B and 87.0% in group C (P values <0.05). On day 56, the mean numbers of macrophages within egg granulomas were 14.3 ± 6.9 in group C, compared with 18.6 ± 8.2 in group A, the suppression rate was 23.1% (P < 0.05). On day 56, the mean numbers of fibroblasts within the egg granulomas were 6.6 ± 4.4 and 5.8 ± 2.6 in groups B and C, respectively, and compared with 14.3 ± 7.8 in group A, the increasing extents decreased by 53.8% and 59.4%, respectively (P values <0.05). Therefore, the administration of praziquantel, especially the prolonged administration, can suppress the formation of schistosomal egg granulomas, including reduction in the areas of granulomas and suppression of the inflammatory cells and the hyperplasia of fibroblasts within granulomas.

Kinetics of circulating antigen 14-3-3 in sera of rabbits firstly infected with Schistosoma japonicum and treated with/without praziquantel.

A sandwich ELISA was developed for the detection of circulating antigen 14-3-3 in the sera of rabbits. Rabbits that were infected with 500 cercariae of Schistosoma japonicum were grouped and the kinetics of 14-3-3 was observed. For the treated group, the 14-3-3 protein could be detected as early as 2-4 weeks postinfection and then its levels rose rapidly and reached a peak at around 6 weeks. The 14-3-3 levels in the sera significantly decreased after the infected rabbits were treated with praziquantel at 6 weeks postinfection and declined to the initial level about 8 weeks posttreatment. While in the untreated group, 14-3-3 levels reached a peak in 8 weeks postinfection and then remained at plateau level for about 6 weeks. Our findings showed that detection of S. japonicum 14-3-3 has an important value for diagnosis of acute infection of S. japonicum and evaluation of chemotherapy.

[Impairment of learning and memory ability in mice with latent infection of Toxoplasma gondii].

OBJECTIVE: To detect the learning and memory ability in mice model of latent Toxoplasma gondii infection with object recognition test and Morris water maze test. METHODS: Thirty-six Kunming mice were divided into control group, infection group with 6 cysts each mouse (low infection group), and infection group with 12 cysts each mouse (high infection group) averaged. Mice in the two infection groups were orally infected with T. gondii Prugniaud (PRU) low virulence strain. Object recognition test was conducted at the 63rd day after infection. After the first day of adaptation and the second day of familiarization in the test, the time expended on exploring new and familiar objects was recorded on the third day and the discrimination index (DI) was calculated. Morris water maze test was conducted at the 66th day. The ability of spatial learning, spatial memory retention and working memory capacity was evaluated by place navigation test, spatial probe test, and working memory test, respectively. The mice were sacrificed at the 74th day after infection. The left cerebral hemisphere of mice was fixed, sliced, and stained with eosin-hematoxylin for pathological examination. The right hemisphere was used to detect the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) content. RESULTS: The results of object recognition test showed that the discrimination index of high infection group and low infection group was (14.3 +/- 5.2)% and (17.5 +/- 5.6)%, respectively, significantly lower than the control [(28.9 +/- 7.1)%] (P < 0.01). In the place navigation test, the latency to find the platform in the two infection groups was longer than the control, with significant difference on the second and third day (P<0.05). In the spatial probe test, the percentage of the distance across the platform quadrant in the total swimming distance of high infection group and low infection group were (19.9 +/- 5.0)% and (23.9 +/- 6.8)%, respectively, significantly lower than the control [(27.4 +/- 3.6)%] (P < 0.05). In the working memory test, at the fourth day of test the latency of high infection group and low infection group [(365 +/- 14.2) s and (35.3 +/- 13.7) s] was significantly longer than the control [(30.4 +/- 12.5) s] (P<0.05). In all the tests, there was no statistical significance between low infection group and high infection group (P > 0.05). The brain sections of two infection groups showed cysts of T. gondii, proliferation of glial cells, widened gap around small blood vessels, and a phenomenon of "vascular cuff". The activity of SOD in the mice brains of two infection groups was significantly lower than the control, while MDA level was significantly higher (P < 0.05). SOD and MDA showed no significant difference between two infection groups (P > 0.05). CONCLUSION: Latent infection of T. gondii may lead to learning and memory impairment in mice.

[Fusion expression and antigenicity analysis of miracidial antigen from eggs of Schistosoma japonicum].

OBJECTIVES: To express the miracidial antigen from eggs of Schistosoma japonicum (Chinese mainland strain) (SjMP10), and investigate the role of the miracidial antigen during the hepatic granuloma formation of schistosomiasis. METHODS: A pair of specific primers was designed and synthesized according to the nucleotide sequence of the open reading frame of the miracidial antigen gene. The open reading frame of the miracidial antigen gene was amplified, digested by restrictive enzyme (BamHI, SolI), and cloned directly into the expression plasmid pGEX-4T-3 to construct the recombinant plasmid. The recombinant plasmids were transformed into E. coli BL21(DE3), and induced by IPTG to express the fusion protein of GST-SjMP10. The expressed fusion protein was purified by electric elution method, and its antigenicity was examined by Western blotting and lymphocyte proliferation test. RESULTS: The gene of miracidial antigen was cloned into the expression plasmid pGEX-4T-3. After induced by IPTG, the recombinant expressed a fusion protein of GST-SjMP10, with a molecular weight of 39 000 approximately. The purified fusion protein showed proper antigenicity that could be recognized by the sera of rabbits heavily infected by Schistosoma japonicum and could stimulate the proliferation of splenic lymphocytes of infected BALB/c mice. CONCLUSION: The miracidial antigen from eggs of Schistosoma japonicum was expressed successfully.