Exacerbation of allergic asthma by somatic antigen of Echinococcus granulosus in allergic airway inflammation in BALB/c mice

BACKGROUND

There is ample evidence demonstrating a reverse relationship between helminth infection and immune-mediated diseases. Accordingly, several studies have shown that Echinococcus granulosus infection and hydatid cyst compounds are able to suppress immune responses in allergic airway inflammation. Previous studies have documented the ability of hydatid cysts to suppress aberrant Th2 immune response in a mouse model of allergic asthma. However, there is a paucity of research on the effects of protoscoleces on allergic asthma. Thus, this study was designed to evaluate the effects of somatic antigens of protoscoleces in a murine model of allergic airway inflammation.

METHODS

Ovalbumin (OVA)/aluminum hydroxide (alum) was injected intraperitoneally to sensitize BALB/c mice over a period of 0 to 7 days, followed by challenge with 1% OVA. The treatment group received somatic antigens of protoscoleces emulsified with PBS on these days in each sensitization before being challenged with 1% OVA on days 14, 15, and 16. The effects of somatic antigens of protoscoleces on allergic airway inflammation were evaluated by examining histopathological changes, the recruitment of inflammatory cells in the bronchoalveolar lavage, cytokine production in the homogenized lung tissue (IL-4, IL-5, IL-10, IL-17, and IFN-γ), and total antioxidant capacity in serum.

RESULTS

Overall, administration of somatic antigens of protoscoleces exacerbated allergic airway inflammation via increased Th2 cytokine levels in the lung homogenate, recruitment of eosinophils into bronchoalveolar lavage fluid, and pathological changes. In addition, total antioxidant capacity and IFN-γ levels declined following the administration of somatic antigens.

CONCLUSIONS

The results revealed that the co-administration of somatic products of protoscoleces with OVA/alum contributed to the exacerbation of allergic airway inflammation in BALB/c mice. Currently, the main cause of allergic-type inflammation exacerbation is unknown, and further research is needed to understand the mechanism of these interactions.

Multiple-bead assay for the differential serodiagnosis of neglected human cestodiases: Neurocysticercosis and cystic echinococcosis

BACKGROUND

Neurocysticercosis (NCC), and cystic echinococcosis (CE) are two neglected diseases caused by cestodes, co-endemic in many areas of the world. Imaging studies and serological tests are used in the diagnosis of both parasitic diseases, but cross-reactions may confound the results of the latter. The novel multiplex bead-based assay with recombinant antigens has been reported to increases the diagnostic accuracy of serological techniques.

METHODOLOGY

We set-up an immunoassay based on the multiplex bead-based platform (MBA), using the rT24H (against Cysticercus cellulosae, causing cysticercosis) and r2B2t (against Echinococcus granulosus sensu lato, causing CE) recombinant antigens, for simultaneous and differential diagnosis of these infections. The antigens were tested on 356 sera from 151 patients with CE, 126 patients with NCC, and 79 individuals negative for both diseases. Specificity was calculated including sera from healthy donors, other neurological diseases and the respective NCC or CE sera counterpart. The diagnostic accuracy of this assay was compared with two commercial ELISA tests, Novalisa and Ridascreen, widely used in the routine diagnosis of cysticercosis and CE, respectively.

MAIN FINDINGS

For the diagnosis of NCC, sensitivity ranged from 57.94-63.49% for the rT24H-MBA, and 40.48-46.03% for Novalisa ELISA depending on exclusion or inclusion of sera having equivocal results on ELISA from the analysis; specificities ranged from 90.87-91.30% and 70.43-76.96%, respectively. AUC values of the ROC curve were 0.783 (rT24H) and 0.619 (Novalisa) (p-value < 0.001). For the diagnosis of CE, the sensitivity of the r2B2t-MBA ranged from 68.87-69.77% and of Ridascreen ELISA from 50.00-57.62%; specificities from 92.47-92.68% and from 74.15-80.98%, respectively. AUC values were 0.717 and 0.760, respectively.

CONCLUSIONS/SIGNIFICANCE

Overall, the recombinant antigens tested with the bead-based technology showed better diagnostic accuracy than the commercial assays, particularly for the diagnosis of NCC. The possibility of testing the same serum sample simultaneously for the presence of antibodies against both antigens is an added value particularly in seroprevalence studies for cysticercosis linked to control programs in endemic areas where these two parasites coexist.

Molecular characterization and immune protection of the 3-hydroxyacyl-CoA dehydrogenase gene in Echinococcus granulosus

BACKGROUND

Cystic echinococcosis (CE) is a serious parasitic zoonosis caused by the larvae of the tapeworm Echinococcus granulosus. The development of an effective vaccine is one of the most promising strategies for controlling CE.

METHODS

The E. granulosus 3-hydroxyacyl-CoA dehydrogenase (EgHCDH) gene was cloned and expressed in Escherichia coli. The distribution of EgHCDH in protoscoleces (PSCs) and adult worms was analyzed using immunofluorescence. The transcript levels of EgHCDH in PSCs and adult worms were analyzed using quantitative real-time reverse transcription PCR (RT-qPCR). The immune protective effects of the rEgHCDH were evaluated.

RESULTS

The 924-bp open reading frame sequence of EgHCDH, which encodes a protein of approximately 34 kDa, was obtained. RT-qPCR analysis revealed that EgHCDH was expressed in both the PSCs and adult worms of E. granulosus. Immunofluorescence analysis showed that EgHCDH was mainly localized in the tegument of PSCs and adult worms. Western blot analysis showed that the recombinant protein was recognized by E. granulosus-infected dog sera. Animal challenge experiments demonstrated that dogs immunized with recombinant (r)EgHCDH had significantly higher serum IgG, interferon gamma and interleukin-4 concentrations than the phosphate-buffered saline (PBS) control group. The rEgHCDH vaccine was able to significantly reduce the number of E. granulosus and inhibit the segmental development of E. granulosus compared to the PBS control group.

CONCLUSIONS

The results suggest that rEgHCDH can induce partial immune protection against infection with E. granulosus and could be an effective candidate for the development of new vaccines.

Design of a Novel Multi-Epitope Vaccine Against Echinococcus granulosus in Immunoinformatics

All the time, echinococcosis is a global zoonotic disease which seriously endangers public health all over the world. In order to speed up the development process of anti-Echinococcus granulosus vaccine, at the same time, it can also save economic cost. In this study, immunoinformatics tools and molecular docking methods were used to predict and screen the antigen epitopes of Echinococcus granulosus, to design a multi-epitope vaccine containing B- and T-cell epitopes. The multi-epitope vaccine could activate B lymphocytes to produce specific antibodies theoretically, which could protect the human body against Echinococcus granulosus infection. It also could activate T lymphocytes and clear the infected parasites in the body. In this study, four CD8+ T-cell epitopes, three CD4+ T-cell epitopes and four B-cell epitopes of Protein EgTeg were identified by immunoinformatics methods. Meanwhile, three CD8+ T-cell epitopes, two CD4+ T-cell epitopes and four B-cell epitopes of Protein EgFABP1 were identified. We constructed the multi-epitope vaccine using linker proteins. The study based on the traditional methods of antigen epitope prediction, further optimized the prediction results combined with molecular docking technology and improved the precision and accuracy of the results. Finally, in vivo and in vitro experiments had verified that the vaccine designed in this study had good antigenicity and immunogenicity.

Evaluation of fecal immunoassays for canine Echinococcus infection in China

Human echinococcosis is present worldwide but it is in China that disease prevalence is the highest. In western China, especially in the Tibetan Plateau, the burden of echinococcosis is the most important. Dogs are a major definitive host of Echinococcus and monitoring the presence of Echinococcus worms in dogs is therefore essential to efficiently control the disease. Detection kits based on three different technologies including sandwich ELISA, (indirect) ELISA, and gold immunodiffusion, are currently marketed and used in China. The objective of this work was to assess the efficacy of these kits, in particular with respect to sensitivity and specificity. Four fecal antigen detection kits for canine infection reflecting the three technologies were obtained from companies and tested in parallel on 220 fecal samples. The results indicate that the performance is lower than expected, in particular in terms of sensitivity. The best results were obtained with the sandwich ELISA technology. The gold immunofiltration yielded the poorest results. In all cases, further development is needed to improve the performance of these kits which are key components for the control of echinococcosis.

Although present worldwide, human echinococcosis is at its highest prevalence in western China and particularly in the Tibetan Plateau. Controlling echinococcosis is a national priority and routine monitoring must be established. Dogs are the main infection source in China and surveying Echinococcus worms in dogs is therefore a research priority. Commercial detection kits are currently in use in China to monitor the presence of Echinococcus in dogs. The kits are based on three different technologies including sandwich ELISA with two monoclonal antibodies, (indirect) ELISA, and gold immunodiffusion. National survey programmes are essential for the control of echinococcosis and it is thus very important to assess the efficacy of these kits for the programmes. This work was therefore undertaken to assess efficacy of the kits, in particular with respect to sensitivity and specificity. Four fecal antigen detection kits for canine infection reflecting the three technologies were obtained from companies and tested in parallel on 220 fecal samples. The performance was lower than expected, in particular for their sensitivity which ranged between 51.5% and 83.9% with only two samples displaying a worm burden lower than 100. Three out of four kits showed non-specific cross-reactions with other parasites. The best results were obtained with the sandwich ELISA technology, whereas gold immunofiltration yielded the poorest results. However, in all cases, further development is strongly needed to improve the performance of these kits which are key components for the control of echinococcosis.

Immunohistological detection of small particles of Echinococcus multilocularis and Echinococcus granulosus in lymph nodes is associated with enlarged lymph nodes in alveolar and cystic echinococcosis

BACKGROUND

Alveolar (AE) and cystic echinococcosis (CE) in humans are caused by the metacestode of the tapeworms Echinococcus multilocularis and Echinococcus granulosus sensu lato (s.l.). Immunohistochemistry with the monoclonal antibodies (mAb) Em2G11, specific for AE, and the mAb EmG3, specific for AE and CE, is an important pillar of the histological diagnosis of these two infections. Our aim was to further evaluate mAb EmG3 in a diagnostic setting and to analyze in detail the localization, distribution, and impact of small particles of Echinococcus multilocularis (spems) and small particles of Echinococcus granulosus s.l. (spegs) on lymph nodes.

METHODOLOGY/PRINCIPAL FINDINGS

We evaluated the mAb EmG3 in a cohort of formalin-fixed, paraffin embedded (FFPE) specimens of AE (n = 360) and CE (n = 178). These samples originated from 156 AE-patients and 77 CE-patients. mAb EmG3 showed a specific staining of the metacestode stadium of E. multilocularis and E. granulosus s.l. and had a higher sensitivity for spems than mAb Em2G11. Furthermore, we detected spegs in the surrounding host tissue and in almost all tested lymph nodes (39/41) of infected patients. 38/47 lymph nodes of AE showed a positive reaction for spems with mAb EmG3, whereas 29/47 tested positive when stained with mAb Em2G11. Spegs were detected in the germinal centers, co-located with CD23-positive follicular dendritic cells, and were present in the sinuses. Likewise, lymph nodes with spems and spegs in AE and CE were significantly enlarged in size in comparison to the control group.

CONCLUSIONS/SIGNIFICANCE

mAb EmG3 is specific for AE and CE and is a valuable tool in the histological diagnosis of echinococcosis. Based on the observed staining patterns, we hypothesize that the interaction between parasite and host is not restricted to the main lesion since spegs are detected in lymph nodes. Moreover, in AE the number of spems-affected lymph nodes is higher than previously assumed. The enlargement of lymph nodes with spems and spegs points to an immunological interaction with the small immunogenic particles (spems and spegs) of Echinococcus spp.

Evaluation of the sensitivity and specificity of GST-tagged recombinant antigens 2B2t, Ag5t and DIPOL in ELISA for the diagnosis and follow up of patients with cystic echinococcosis

Cystic echinococcosis (CE) is a neglected zoonotic disease caused by Echinococcus granulosus sensu lato. Diagnosis and monitoring of CE rely primarily on imaging while serology is used as a confirmatory test. However, imaging is not always conclusive and currently available serological assays have suboptimal sensitivity and specificity, lack standardization, and are not useful for patients´ follow-up. Seroassays for CE are usually based on hydatid fluid (HF), a complex, variable antigenic mixture, and cross-reactivity exists especially with alveolar echinococcosis. Recombinant proteins based on immunogenic antigens most abundant in HF, such as AgB1, AgB2 and Ag5, have been used to overcome these limitations. None of them so far showed potential to replace HF; however, their performance have been largely tested on a limited number of samples, and comparison of different antigens using the same cohort has been rarely performed. The combination of several immunogenic epitopes in a single recombinant protein could enhance test sensitivity. For the diagnosis and follow-up of patients with CE, we compared the performance of the crude HF, previously described recombinant 2B2t antigen, and GST-tagged version of 2B2t, and novel designed recombinants (GST-Ag5t and the GST-DIPOL chimera containing AgB1, AgBB2 and Ag5 epitopes) by IgG-ELISA format. Samples belong to a retrospective cohort of 253 well-characterized patients with CE, previously described for the evaluation of the 2B2t antigen, 92 patients with alveolar echinococcosis, and 82 healthy donors. The reference standard for CE diagnosis was the presence of a CE lesion as diagnosed by ultrasonography. The highest sensitivity was obtained with HF [86.7%, 95% confidence interval (CI): 81.2–91.0], followed by GST-2B2t (70.0%, 95% CI: 63.1–76.2), 2B2t (65.5%, 95% CI: 58.5–72.0), GST-Ag5t (64.5%, 95% CI: 57.5–71.1) and GST-DIPOL (63.1%, 95% CI: 56.0–69.7). The GST-2B2t had the best specificity (95.8%, 95% CI: 88.3–99.1) and the lowest cross-reactivity (38.7%, 95% CI: 27.6–50.6). Good response to treatment also correlated to negative test results in the GST-2B2t ELISA. While none of the tested recombinant antigen appears suitable to replace HF for the diagnosis of CE, GST-2B2t should be further explored as a confirmation test, based on its high specificity and low cross-reactivity, and for the follow-up after treatment in those patients with positive serology for this antigen.

Cystic echinococcosis (CE) is a neglected parasitic zoonosis. Its diagnosis and follow-up require evaluation with imaging. Currently available serological tests are applied to confirm the diagnosis in doubtful cases, although having limitations in diagnostic accuracy, and they are not useful for patients’ follow-up. Seroassays for CE are usually based on hydatid fluid (HF) obtained from infected animals, with consequent problems of heterogeneity and low specificity. The use of semi-purified HF derivatives or recombinant antigens has been attempted to improve these aspects, but with an unacceptable loss in sensitivity. Most newly developed antigens have been tested on a limited number of samples, not always well characterized, and have been rarely compared using the same samples cohort. Here, we tested and compared three recombinant antigens (2B2t, GST-2B2t and GST-Ag5t), and a recombinant chimeric antigen (DIPOL) based on three highly immunogenic components of HF (B1, B2 and Ag5), in an attempt to increase the sensitivity of recombinant antigen-based seroassays for the diagnosis and follow-up of patients with CE. We found that GST-2B2t had higher sensitivity than the other antigenic preparations, but still not as high as HF, and that GST-2B2t and GST-DIPOL had statistically higher specificity than any of the other tested antigens. GST-2B2t also showed potential for the follow-up of patients with CE after drug treatment.

Effects of Allium sativum on IFN-γ and IL4 concentrations in mice with cystic echinococcosis

The aim of the current investigation was to assess the impacts of methanolic extract of Allium sativum (MEAS) on IL-4 (a cytokine derived from Th2 cells) and IFN-ɣ (a cytokine derived from Th1 cells) levels in mice infected with Echinococcus granulosus. Sixty healthy BALB/c female mice were used in this study. Each animal was intraperitoneally injected with 1500 protoscoleces. The infected animals were randomly divided into six groups: albendazole (100 mg/kg), MEAS 10 (10 mg/kg), MEAS 20 (20 mg/kg), MEAS 40 (40 mg/kg), MEAS 80 (80 mg/kg) and control group with no treatment. The studied animals received albendazole and/or MEAS through drinking water for 30 days. Serum IFN-γ concentration significantly increased in the MEAS 20 and 80 groups in comparison to the control, albendazole and MEAS 10 groups (P < 0.05). The serum IL-4 level showed no significant difference between the trial groups. The findings of this study showed that MEAS at 20 and 80 mg/kg concentrations enhanced Th1 cell response in mice with cystic echinococcosis.

Cattle co-infection of Echinococcus granulosus and Fasciola hepatica results in a different systemic cytokine profile than single parasite infection

E. granulosus is a cestode that causes Cystic Echinococcosis (CE), a zoonotic disease with worldwide presence. The immune response generated by the host against the metacestode induces a permissive Th2 response, as opposed to pro-inflammatory Th1 response. In this view, mixed Th2 and regulatory responses allow parasite survival. Overall, larval Echinococcus infections induce strong regulatory responses. Fasciola hepatica, another common helminth parasite, represents a major infection in cattle. Co-infection with different parasite species in the same host, polyparasitism, is a common occurrence involving E. granulosus and F. hepatica in cattle. ‘While it is known that infection with F. hepatica also triggers a polarized Th2/Treg immune response, little is reported regarding effects on the systemic immune response of this example of polyparasitism. F. hepatica also triggers immune responses polarized to the Th2/ Treg spectrum. Serum samples from 107 animals were analyzed, and were divided according to their infection status and Echinococcal cysts fertility. Cytokines were measured utilizing a Milliplex Magnetic Bead Panel to detect IFN-γ, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12 and IL-18. Cattle infected only with F. hepatica had the highest concentration of every cytokine analyzed, with both 4.24 and 3.34-fold increases in IL-10 and IL-4, respectively, compared to control animals, followed by E. granulosus and F. hepatica co-infected animals with two-fold increase in IL-10 and IL-4, compared to control animals, suggesting that E. granulosus co-infection dampens the cattle Th2/Treg immune response against F. hepatica. When considering Echinococcal cyst fertility and systemic cytokine concentrations, fertile cysts had higher IFN-γ, IL-6 and IL-18 concentrations, while infertile cysts had higher IL-10 concentrations. These results show that E. granulosus co-infection lowers Th1 and Th2 cytokine serological concentration when compared to F. hepatica infection alone. E. granulosus infections show no difference in IFN-γ, IL-1, IL-2, IL-6 and IL-18 levels compared with control animals, highlighting the immune evasion mechanisms of this cestode.

Hepatic Cystic Echinococcosis (Hydatid Cyst) in a Six Year Old

Presentation To describe a case of cystic echinococcosis (CE) in a previously healthy child and review epidemiology of CE in Ireland. Diagnosis A previously healthy 6 year old girl was found to have a cystic lesion in the right lobe of her liver. Serology for Echinococcus granulosus was positive, and radiological features were suggestive of CE. Treatment The patient was pre-treated with anti-helminthic medications before undergoing a liver segmentectomy to remove the cyst, and received further treatment with albendazole after surgery. Histological findings were consistent with CE due to E. granulosus, likely acquired during travel to continental Europe. Conclusion CE should be considered in the differential of children with asymptomatic cysts in the liver and/or lung, and a travel history elucidated in such cases.

In vitro evaluations on canine monocyte-derived dendritic cells of a nanoparticles delivery system for vaccine antigen against Echinococcus granulosus

Since dogs play a central role in the contamination of humans and livestock with Echinococcus granulosus, the development of an effective vaccine for dogs is essential to control the disease caused by this parasite. For this purpose, a formulation based on biodegradable polymeric nanoparticles (NPs) as delivery system of recombinant Echinococcus granulosus antigen (tropomyosin EgTrp) adjuved with monophosphoryl lipid A (MPLA) has been developed. The obtained nanoparticles had a size of approximately 200 nm in diameter into which the antigen was correctly preserved and encapsulated. The efficiency of this system to deliver the antigen was evaluated in vitro on canine monocyte-derived dendritic cells (cMoDCs) generated from peripheral blood monocytes. After 48 h of contact between the formulations and cMoDCs, we observed no toxic effect on the cells but a strong internalization of the NPs, probably through different pathways depending on the presence or not of MPLA. An evaluation of cMoDCs activation by flow cytometry showed a stronger expression of CD80, CD86, CD40 and MHCII by cells treated with any of the tested formulations or with LPS (positive control) in comparison to cells treated with PBS (negative control). A higher activation was observed for cells challenged with EgTrp-NPs-MPLA compared to EgTrp alone. Formulations with MPLA, even at low ratio of MPLA, give better results than formulations without MPLA, proving the importance of the adjuvant in the nanoparticles structure. Moreover, autologous T CD4+ cell proliferation observed in presence of cMoDCs challenged with EgTrp-NPs-MPLA was higher than those observed after challenged with EgTrp alone (p<0.05). These first results suggest that our formulation could be used as an antigen delivery system to targeting canine dendritic cells in the course of Echinococcus granulosus vaccine development.

Variability of the EG95 antigen-coding gene of Echinococcus granulosus in animal and human origin: implications for vaccine development

In the present study, the genetic variability of the EG95 protein-coding gene in several animal and human isolates of Echinococcus granulosus was investigated. A total of 24 isolates collected from cattle, buffalo, sheep, goat, dog and man were amplified by Eg95-coding gene-specific primers. From the generated sequence information, a conceptual amino acid sequence was deduced. Phylogenetically, the Eg95 coding gene belongs to the Eg95-1/Eg95-2/Eg95-3/Eg95-4 cluster. Further confirmation on the maximum composite likelihood analysis revealed that the overall transition/transversion bias was 2.913. This finding indicated thatthere is bias towards transitional and transversional substitution. Using artificial neural networks, a B-cell epitope was predicted on primary sequence information. Stretches of amino acid residues varied between animal and human isolates when hydrophobicity was considered. Flexibility also varied between larval and adult stages of the organism. This observation is important to develop vaccines. However, cytotoxic T-lymphocyte epitopes on primary sequence data remained constant in all isolates. In this study, agretope identification started with hydrophobic amino acids. Amino acids with the same physico-chemical properties were present in the middle. The conformational propensity of the Eg95-coding gene of 156 amino acid residues had α-turns and β-turns, and α-amphipathic regions up to 129, 138-156 and 151-155 residues, respectively. The results indicated potential T-cell antigenic sites. The overall Tajima's D value was negative (-2.404165), indicative of negative selection pressure.

Expression and purification of truncated recombinant B8/1 protein of Echinococcus granulosus for diagnosis of hydatid infection in human

Hydatidosis is one of the most important diseases common between animals and human beings. Caused by Echinococcus granulosus tapeworm, the disease has a global epidemic. The serological diagnostic tests that are now utilized to confirm the imaging approaches have some drawbacks such as low sensitivity and cross-reaction with the serum of the patients infected with other parasites. The application of recombinant and synthetic antigens has proven improvement in the functionality of serological diagnostic tests. The purpose of this study was to demonstrate the expression and purification of truncated recombinant B8/1 (trB8/1) antigen and its application in ELISA for diagnosis of hydatid infection in human. The tEgB8/1 was colonized in the expression vector pET28b (+) and expressed in different strains of E. coli. This protein was purified by Ni²⁺-NTA chromatography. The antigenicity of the protein was evaluated by Western blotting and ELISA. In the test, 50 positive serum samples from hydatid infected patients, 50 samples from healthy people, and 30 serum samples from patients with other parasitic diseases were used to determine the sensitivity and the specificity of this antigen. The measured sensitivity and specificity of this antigen were identified to be 75.75% and 96.38% respectively. The P value of <0.0001 by using ROC curve, confirmed that this antigen is able to differentiate between healthy and hydatid-infected individuals. Considering the excellent specificity of this antigen and in order to enhance the sensitivity, it is recommended to use a combination of this antigen with other antigens (e.g., EgB8/2-8/5).

Effect of hydatid cyst antigens on inhibition of melanoma cancer growth in mouse model

Cancer is the main cause of death in the developed countries. There are some scientific evidences indicating that parasitic infections induce antitumor activity against certain types of cancers. Hydatid cyst is the larval stage of Echinococcus granulosus, which causes hydatidosis in human and livestock. We have already shown that vaccination of mice with hydatid cyst crude antigens and subsequently challenge them with cancer cells, causes inhibition of melanoma cancer growth. In this study, therapeutic effects of hydatid cyst antigens on C57/black mice that had already been challenged with melanoma tumor were investigated. In this experimental study, 6 groups of C57 black mice were subcutaneously inoculated with melanoma cancer cells (line B16F10) in PBS inside their chest site. After 2 weeks case groups were injected with hydatid cyst fluid, a fraction of cyst fluid, live protoscolices or BCG.  control groups were injected with alum alone and other control group was left intact without any intervention. The size of each tumor was measured in all mice. Blood samples were also taken to estimate Interleukin-2 (IL-2), Tumor necrosis factor alpha (TNF-α), Interferon gamma (IFN-γ) and Interleukin-4 (IL-4) levels. Treatment of mice bearing melanoma cancer with hydatid cyst antigens resulted in inhibition of tumor growth and the difference between mean size of tumor in case and control groups was statistically significant. Also, according to our results mean level of measured cytokines between case and control groups was statistically different. Hydatid cyst antigens have anti-melanoma activities and this effect may be related to immune response to parasite antigens.

Evaluation of the recombinant antigens B2t and 2B2t, compared with hydatid fluid, in IgG-ELISA and immunostrips for the diagnosis and follow up of CE patients

Cystic echinococcosis (CE) is one of the most widespread helminthic zoonoses and is caused by the tapeworm Echinococcus granulosus complex. CE diagnosis and monitoring primarily rely on imaging techniques, complemented by serology. This is usually approached by the detection of IgG antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture results in a variable percentage of false positive and negative results, and has shown to be useless for follow-up due to the long persistence of anti-HF antibodies in cured patients. To improve test performances and standardization, a number of recombinant antigens mainly derived from HF have been described, among them the B2t and 2B2t antigens. The performance of these antigens in the diagnosis and follow up of patients with CE has been so far evaluated on a limited number of samples. Here, we evaluated the performances of tests based on B2t and 2B2t recombinant antigens compared to HF in IgG-ELISA and immunochromatography (IC) for the diagnosis and follow-up of patients with CE in a retrospective cohort study. A total of 721 serum samples were collected: 587 from 253 patients with CE diagnosed by ultrasonography (US), 42 from patients with alveolar echinococcosis and 92 from healthy donors from Salamanca (Spain). The highest overall sensitivity was obtained with HF in ELISA (85.5%), followed by IC containing HF and 2B2t-HF (83.0% and 78.2%, respectively). The lowest sensitivity was obtained with B2t and 2B2t in ELISA (51.8%). The highest specificity was obtained with IC containing 2B2t-HF (100%), and the lowest with HF-ELISA (78.0%). The lowest cross-reactivity with sera from patients with alveolar echinococcosis was detected with the recombinant antigens in ELISA (9.5% - 16.7%) and the highest with the HF-IC (64.3%). The results of B2t and 2B2t-ELISA were influenced by cyst stage, as classified by US according to the WHO-Informal Working Group on Echinococcosis (WHO-IWGE), with low sensitivity for inactive (CE4 and CE5) cysts, and by the drug treatment, with higher sensitivity in patients after drug treatment compared with patients not subjected to drug treatment. The two recombinant antigens in ELISA provided promising results for monitoring patients in follow-up, although their use is limited to patients with positive serology against them at the beginning of the follow-up. Potential biological reasons behind the low sensitivity of the recombinant antigens and possible strategies to enhance the performance of CE serology are discussed.

Cystic echinococcosis (CE) is a helminthic zoonosis caused by Echinococcus granulosus sensu lato. CE diagnosis and monitoring is of paramount importance for the clinical management of patients and primarily rely on imaging techniques, complemented by serology. CE serology is usually based on the detection of antibodies against hydatid fluid (HF), but the use of this heterogeneous antigenic mixture shows several drawbacks, including false positive and negative results, unsatisfied predictive values, and long persistence of detectable antibody levels in cured patients. As an alternative, to improve test performances and standardization, several recombinant antigens have been described, but these have been so far evaluated only on a limited number of samples. Here, two recombinant antigens derived from one of the immunodominant HF antigens (antigen B2) have been tested in enzyme-linked immunosorbent assay (ELISA) and in immunochromatographic strips (IC) against 721 serum samples. Although more specific than the HF, the recombinant antigens in ELISA showed low sensitivity for patients with inactive (CE4 and CE5) cysts and for patients not subjected to drug treatment. This limited their use for follow-up, although promising, to those patients with positive serology at the beginning of the follow-up period. These results will aid in the future development of a serological test with enhanced performance in the diagnosis and follow-up of patients with CE.

Identification of emu-TegP11, an EF-hand domain-containing tegumental protein of Echinococcus multilocularis

Tegumental proteins (TegPs) are a group of proteins that coat on the surface of worms, mainly being involved in ion uptake and immune evasion. Echinococcus species have many TegPs, but none of them have been characterized and their role remains unclear. The genome-wide analysis revealed that there were at least 14 tegp genes (tegp1 - 14) in Echinococcus species, the majority of which were found to contain an EF-hand domain or a dynein light chain-like domain or both. Despite low identity, all TegP11 proteins from 25 flatworms were conserved in structure. Echinococcus multilocularis TegP11 (emu-TegP11) was verified to be secreted by extracellular vesicles and to be localized in different spatiotemporal patterns in protoscoleces. Moreover, emu-TegP11 was also shown to have weak or no Ca²⁺-binding capacity. In treated macrophages, emu-TegP11 interfered with the small RNA-induced silencing pathway via inducing ectopic expression of some key component genes. Additionally, emu-TegP11 remarkably promoted NO secretion possibly by upregulation of inos gene expression (p < 0.05). It was further shown that emu-TegP11 acted as a suppressor of inflammation, with il-12B and il-1β being significantly down-regulated (p < 0.01), and il-10 and il-4 being significantly upregulated (p < 0.05). The study demonstrates a regulatory role of emu-TegP11, likely acting as a immunomodulator to be involved in regulation of host immune system during Echinococcus infection.

Improved experimental model of hepatic cystic hydatid disease resembling natural infection route with stable growing dynamics and immune reaction

AIM

To investigate a safer way to set up the disease model of cystic echinococcosis without contamination risk and develop a novel experimental murine model of hepatic cystic echinococcosis.

METHODS

C57B/6 mice were injected with human protoscolices of three different concentrations via the portal vein. The mice were followed for 10 mo by ultrasound, gross anatomy, and pathological and immunological examinations. The protoscolex migration in the portal vein, hydatid cyst growth, host immune reaction, and hepatic histopathology were examined periodically.

RESULTS

The infection rates in the mice in the high, medium, and low concentration groups were 90%, 100%, and 63.6%, respectively. The protoscolices migrated in the portal vein with blood flow, settled in the liver, and developed into orthotopic hepatic hydatid cysts, resembling the natural infection route and course.

CONCLUSION

We have established an improved experimental model of hepatic cystic echinococcosis with low biohazard risk but stable growing dynamics and immune reaction. It is especially useful for new anti-parasite medication trials against hydatid disease.

Knowledge, attitudes, and practices regarding cystic echinococcosis and sheep herding in Peru: a mixed-methods approach

BACKGROUND

The parasitic disease, cystic echinococcosis (CE), is prevalent in low-income, livestock-raising communities and 2000 new people will be diagnosed this year in South America alone. The disease usually passes from livestock to dogs to humans, making it a zoonotic disease and part of the One Health Initiative. Control of CE has been infamously difficult; no endemic areas of South America have succeeded in maintaining sustainable eradication of the parasite. For the current study, we aimed to gain a better understanding of the knowledge, attitudes, and practices of rural sheep farmers and other community leaders regarding their sheep herding practices and perspectives about a control program for CE. We also hope to identify potential barriers and opportunities that could occur in a control program. The authors conducted Knowledge, Attitude and Practices (KAP) surveys and semi-structured interviews in rural communities in the highlands of Peru. The KAP surveys were administered to 51 local shepherds, and the semi-structured interviews were administered to 40 individuals, including shepherds, community leaders, and health care providers.

RESULTS

We found that the shepherds already deworm their sheep at a median of 2 times per year (N = 49, range 2-4) and have a mean willingness-to-pay of U.S. $ 0.60 for dog dewormer medication (N = 20, range = 0.00- $2.00 USD). We were not able to learn the deworming agent or agents that were being used, for neither sheep nor dogs. Additionally, 90% of shepherds slaughter their own sheep (N = 49). We also learned that the main barriers to an effective control program include: lack of education about the cause and control options for CE, accessibility to the distant communities and sparse grazing pastures, and a lack of economic incentive.

CONCLUSIONS

Findings suggest it may be feasible to develop an effective CE control program which can be used to create an improved protocol to control CE in the region.

Comparative proteome profiling of hydatid fluid from Algerian patients reveals cyst location-related variation in Echinococcus granulosus

Human cystic echinococcosis, an endemic zoonosis in Algeria, is caused by larvae of the cestode Echinococcus granulosus. Parasitic modulation of the immune response allows E. granulosus to persist in intermediate hosts. Previous in vitro and in vivo immunological studies have shown differences in host immune responses according to the status and location of the hydatid cysts in the body. In this study, a proteomic analysis of human hydatid fluids was performed to identify the proteins in hydatid cyst fluids. Hydatid fluid was obtained after cystic surgical removal from three patients with these cysts. The study was conducted on fertile hydatid fluids from lungs, vertebra, and infertile paravertebral fluids. Comparisons of the protein compositions of these fluids revealed differences in their protein profiles. These differences are probably related to the cyst location and fertility status of the parasite. Notably, our analysis identified new proteins from the parasite and human host. The identification of host proteins in hydatid fluids indicates that the hydatid walls are permeable allowing a high protein exchange rate between the metacestode and the affected tissue. Interestingly, our study also revealed that parasite antigenic protein expression variations reflect the differences observed in host immunostimulation.

Impairment of Macrophage Presenting Ability and Viability by Echinococcus granulosus Antigens

BACKGROUND

Despite advances toward an improved understanding of the evasive mechanisms leading to the establishment of cystic echinococcosis, the discovery of specific immunosuppressive mechanisms and related factors are of great interest in the development of an immunotherapeutic approach.

OBJECTIVE

To elucidate immunosuppressive effects of bioactive factors contained in chromatographic fractions from hydatid cystic fluid (HCF) of Echinococcus granulosus.

METHODS

Hydatid cystic fluid was fractionated by reverse phase chromatography. Non-specific Concanavalin A-driven proliferation of spleen cells was used to determine specific inhibitory fractions. Trypan blue exclusion test and flowcytometry analysis were performed to check whether highly inhibitory fractions of HCF have apoptotic effect on peritoneal macrophages. Western blot analysis was used to determine proteolytic effects of parasitic antigens on major histocompatibility complex (MHC) class II (I-a) contained in membrane proteins extract from macrophages.

RESULTS

High concentrations of HCF and few of chromatographic fractions suppressed spleen cells proliferation. Fractions 7 and 35 were the highest inhibitory fractions. Specifically fraction 35 and to a lesser extent HCF induced apoptosis in peritoneal naive macrophages. However, HCF and the fraction 7 proteolytically altered the expression of MHC class II molecules on peritoneal macrophages. The proteolytic molecule was identified to be a serine protease. Macrophages taken at the chronic and end phase from cystic echinococcosis-infected mice were able to uptake and process C-Ovalbumine-FITC. These cells expressed a drastically reduced level of (I-a) molecules.

CONCLUSION

Our study present new aspects of immune suppression function of E. granulosus. Further molecular characterization of apoptotic and proteolytic factors might be useful to develop immunotherapeutic procedure to break down their inhibitory effects.

Heterologous expression of antigenic peptides in Bacillus subtilis biofilms

BACKGROUND

Numerous strategies have been developed for the display of heterologous proteins in the surface of live bacterial carriers, which can be used as vaccines, immune-modulators, cancer therapy or bioremediation. Bacterial biofilms have emerged as an interesting approach for the expression of proteins of interest. Bacillus subtilis is a well-described, endospore-forming organism that is able to form biofilms and also used as a probiotic, thus making it a suitable candidate for the display of heterologous proteins within the biofilm. Here, we describe the use of TasA, an important structural component of the biofilms formed by B. subtilis, as a genetic tool for the display of heterologous proteins.

RESULTS

We first engineered the fusion protein TasA-mCherry and showed that was widely deployed within the B. subtilis biofilms. A significant enhancement of the expression of TasA-mCherry within the biofilm was obtained when depleting both tasA and sinR genes. We subsequently engineered fusion proteins of TasA to antigenic peptides of the E. granulosus parasite, paramyosin and tropomyosin. Our results show that the antigens were well expressed within the biofilm as denoted by macrostructure complementation and by the detection of the fusion protein in both immunoblot and immunohistochemistry. In addition, we show that the recombinant endospores of B. subtilis preserve their biophysical and morphological properties.

CONCLUSIONS

In this work we provide strong evidence pointing that TasA is a suitable candidate for the display of heterologous peptides, such as antigens, cytokines, enzymes or antibodies, in the B. subtilis biofilms. Finally, our data portray that the recombinant endospores preserve their morphological and biophysical properties and could be an excellent tool to facilitate the transport and the administration.

DOT-ELISA AS A FIELD TEST FOR HYDATID DIAGNOSIS

Cystic hydatid disease (Hydatidosis) is one of the most important parasitic zoonoses and remains a public health and economic problem all over the world. Cyst fluid was obtained from hepatic and pulmonary cysts for demonstration of protoscolices and hooklets. Therefore, a standardized and approachable diagnostic tool for the serodiagnosis of CE is still needed. Dot-ELISA is a solid phase diagnostic method for detection of antigen or antibody that is used widely for diagnosis of protozoan and metazoan diseases of human and animals. In the present study, E. granulosus protoscolex antigen was early detected in patient sera using Dot-ELISA, PAb was prepared from anti-rabbit sera and used for coating and as conjugate in Dot-ELISA technique. 48 patients out of 50 were positive to E. spp. with sensitivity and specificity 96% and 94%, respectively. The PPV was 94% and NPV was 90%. Finally, the present results showed that the Dot-ELISA was easy to perform, not expensive, safe, and with good sensitivity and specificity.

Diagnostic value of semi-purified antigens of hydatid cyst fluid in human cystic echinococcosis

Cystic Echinococcosis (CE) is an infection caused by the larval stage of Echinococcus granulosus. The diagnosis of this disease has been problematic. Serological tests detecting antibodies against E. granulosus are the most popular and mainly use the crude Hydatid Cyst Fluid (HCF) or its components, Ag 5 and B. However, the diagnostic value of these tests is limited by the problems of specificity and/or sensitivity. The use of purified HCF antigens could be more helpful in the serodiagnosis of CE compared to the whole HCF. In the present study, we have evaluated the diagnostic value of semi-purified antigens using ELISA tests. Our results have shown that the 53 KDa antigen gave the best specificity (97.5%) and sensitivity (80%). We have also used Western Blot technique to analyze the serological profile against HCF. The results have confirmed that the most immunogenic component of HCF is the Ag 5.

Serological survey of Echinococcus granulosus in nomads of southwest Iran using the ELISA method during 2014-15

Echinococcosis is one of the diseases common to humans and animals worldwide and its metacestode form Echinococcus granulosus is the cause of disease. Diagnosis based on clinical symptoms is a problem. However, using serological methods such as ELISA, specific antibodies can be determined. Based on the medical and economic importance of the disease, this study aimed to undertake a serological survey of human echinococcosis in Behbahan nomads using the ELISA method during 2014-15. In a descriptive study, 180 blood samples were collected and analysed from the tribes in the four geographic regions of Behbahan city. The obtained sera were assessed for the presence of IgG antibodies against hydatid cyst. Demographic data were collected using a questionnaire and the results were analysed by SPSS software. In all, 175 persons (97.2%) tested negative while five (2.8%) were positive. The most frequent was in people over 50 years with three persons (1.7%). In the 40-50 years age group, two subjects (1.1%) tested positive. 62 (34.4%) of the subjects were female and 118 (65.6%) were male, among which four men (2.2%) and one woman (0.6%) were infected. Overall, the most infected were men. Of the infected persons, three lived in the East, one in the South and one in the West of the city. All subjects had a history of contact with dogs. According to the results of this study, the prevalence was high in the area and therefore disease control programmes are recommended.

Polyfunctional Specific Response to Echinococcus Granulosus Associates to the Biological Activity of the Cysts

BACKGROUND

Cystic echinococcosis (CE) is a complex disease caused by Echinococcus granulosus (E.granulosus), and its immunophatogenesis is still not clearly defined. A peculiar feature of chronic CE is the coexistence of Th1 and Th2 responses. It has been suggested that Th1 cytokines are related to disease resistance, whereas Th2 cytokines are related to disease susceptibility and chronicity. The aim of this study was to evaluate, by multi-parametric flow cytometry (FACS), the presence of CE specific immune signatures.

METHODOLOGY/PRINCIPAL FINDINGS

We enrolled 54 subjects with suspected CE; 42 of them had a confirmed diagnosis, whereas 12 were classified as NO-CE. Based on the ultrasonography images, CE patients were further categorized as being in "active stages" (25) and "inactive stages" (17). The ability of CD4+ T-cells to produce IFN-γ, IL-2, TNF-α, Th2 cytokines or IL-10 was assessed by FACS on antigen-specific T-cells after overnight stimulation with Antigen B (AgB) of E.granulosus. Cytokine profiles were evaluated in all the enrolled subjects. The results show that none of the NO-CE subjects had a detectable AgB-specific response. Among the CE patients, the frequency and proportions of AgB-specific CD4+ T-cells producing IL-2+TNF-α+Th2+ or TNF-α+Th2+ were significantly increased in the "active stages" group compared to the "inactive stages" group. Moreover, an increased proportion of the total polyfunctional subsets, as triple-and double-functional CD4 T-cells, was found in CE patients with active disease. The response to the mitogen, used as a control stimulus to evaluate the immune competence status, was characterized by the same cytokine subsets in all the subjects enrolled, independent of CE.

CONCLUSIONS

We demonstrate, for the first time to our knowledge, that polyfunctional T-cell subsets as IL-2+TNF-α+Th2+ triple-positive and TNF-α+Th2+ double-positive specific T-cells associate with cyst biological activity. These results contribute to increase knowledge of CE immunophatogenesis and the disease outcome in terms of control and persistence.

Pilot Field Trial of the EG95 Vaccine Against Ovine Cystic Echinococcosis in Rio Negro, Argentina: Second Study of Impact

Background

Cystic echinococcosis (CE) is an important zoonotic disease caused by the cestode parasite Echinococcus granulosus. It occurs in many parts of the world where pastoral activities predominate, including the Rio Negro province of Argentina. Although CE control activities have been undertaken in the western regions of Rio Negro for more than two decades, the disease continues to remain prevalent in both the human and livestock animal populations. Vaccination of animal intermediate hosts of CE with the EG95 vaccine may provide a new opportunity to improve the effectiveness of CE control measures, although data are lacking about field application of the vaccine.

Aims

Evaluate the impact of EG95 vaccination in sheep on the transmission of Echinococcus granulosus in a field environment.

Methodology

Two trial sites were established in western Rio Negro province within indigenous communities. Vaccination of lambs born into one trial site was introduced and continued for 6 years. Prior to initiation of the trial, and at the end of the trial, the prevalence of CE in sheep was determined by necropsy. Weaned lambs received two injections of EG95 vaccine, approximately one month apart, and a single booster injection one year later. Vaccination was not implemented at the second trial site. A total of 2725 animals were vaccinated in the first year. Animals from this cohort as well as age-matched sheep from the control area were evaluated by necropsy.

Key results

Introduction of the vaccine led to a statistically significant in the number and size of hydatid cysts in comparison to the situation prior to the introduction of the vaccine, or compared to CE prevalence in the control area where the vaccine was not applied. The prevalence of infection in the vaccinated area was also significantly reduced by 62% compared to the re-intervention level, being lower than the prevalence seen in the control area, although the difference from the control area after the intervention was not significant possibly due to limitations in the numbers of animals available for necropsy.

Conclusions

Vaccination of sheep with the EG95 vaccine provides a valuable new tool which improves the effectiveness of CE control activities. Vaccination was effective even in a difficult, remote environment where only approximately half the lambs born into the communities were fully vaccinated.

Hydatid disease, otherwise known as cystic echinococcosis (CE), is caused by Echinococcus granulosus. The disease is common in many pastoral areas, including parts of the Rio Negro province of Argentina, and is formally recognised by the WHO as a Neglected Tropical Disease. We undertook the first scientific evaluation of the EG95 vaccine against transmission of hydatid disease in a field situation. Sheep in remote indigenous communities of Rio Negro were vaccinated over a six year period. Young lambs received two injections of vaccine and a single booster injection as one year old sheep. A similar region acted as a control where vaccination was not implemented. Evaluation of the outcomes of vaccination revealed a significant, 62% decrease in the prevalence of hydatid infection in 6 year old sheep. Our study provides a template for the application of vaccination in future efforts to control transmission of E. granulosus and reduce the burden of human disease caused by the parasite.

Evaluation of reactivity to Echinococcus spp. among rural inhabitants in Poland

A group of 172 rural inhabitants from eastern Poland (68 males and 104 females, mean age 49.0 ± 12.0 years) was examined for the presence of antibodies against Echinococcus granulosus and Echinococcus multilocularis. A population of 38 healthy urban dwellers from the city of Lublin (17 males and 21 females, mean age 36.2 ± 9.6 years) were examined as a control group. Sera of 22 rural inhabitants (12.8%) reacted positively to Echinococcus granulosus hydatid fluid antigen in the screening test. A cross-reactivity was observed with two serum samples that tested positive in ELISA for E. granulosus. Three serum samples were tested positive for E. multilocularis using the Em2plus ELISA assay and also positive for Western blot. None of the members of control group showed the presence of a seropositive reaction to Echinococcus spp. The reactivity to Echinococcus spp. among rural inhabitants decreased with age and this correlation was statistically significant (R = -0.197151, p = 0.009535). The percentage of positive findings was the highest (50.0%) in the youngest age group (14-20). No significant correlations were found between responses to interview questions (possession of domestic and farm animals, contact with wild animals, eating unwashed berries, drinking unboiled water) and the presence of seropositive reactions to Echinococcus spp. The presented results seem to indicate that echinococcosis is still a current problem in Poland that should not be neglected and, moreover, indicates the need for improvement in the routine laboratory diagnostics of Echinococcus spp. by standardizing the ELISA and Western blot tests.

[Cystic Echinococcosis Seropositivity in the Blood Samples Sent to Parasitology Laboratory of Yüzüncü Yıl University Medical Faculty between 2005 and 2013: Retrospective Assessment]

OBJECTIVE

This study was performed in order to contribute the data on the prevalence of cystic echinococcosis (CE) in Turkey and to reveal this parasitosis problem in Van province.

METHODS

Blood samples of 2642 patients (1214 men, 1428 women; 506 of them 0-13 age, 2136 of them 14 and over age group), which were sent with suspected CE to Parasitology Laboratory from various policlinics of Yüzüncü Yıl University Medical Faculty, between the dates of 01.09.2005 and 01.09.2013, were evaluated for CE by using Enzyme-Linked Immunosorbent Assay (ELISA) (R-Biopharm, Germany; IgG) method.

RESULTS

801 (30.3%) of examined blood samples of these patients were found positive for this parasitosis. Seropositivity was found 31.9% of men, 29% of women; 33.4% of 0-13 age group, 29.6% of 14 and over age group in the study. Cysts, which were obtained from operated seropositive patients, were confirmed that unilocular cysts as pathological.

CONCLUSION

As a result, it was seen that CE is continued to be a major public health problem in Van province and it was appear that comprehensive protection and control programs should be carry out to struggle this disease.

[Hydatidosis: epidemiological, clinical, diagnostic and therapeutic aspects]

Hydatidosis or cystic echinococcosis (CE) is a parasitic zoonosis caused by Echinococcus granulosus. Its life cycle involves dogs, sheep and sometimes other animals. CE has a worldwide distribution, with greater prevalence in temperate zones. In Spain, Castile and León, La Rioja, Navarre, Aragón, and the Mediterranean coast are the areas where it is most commonly diagnosed, although there have also been published cases in other regions, such as Cantabria. Clinical signs and symptoms of EC may be related to the mass effect of the cyst, its superinfection or anaphylactic reactions secondary to its rupture. Because of its slow growth, diagnosis is usually made in adulthood by combining clinical symptoms with imaging and serological tests. There is no universal consensus on the management of CE. Treatment is based mainly on three pillars: medical treatment (mainly albendazole), surgery, and percutaneous drainage. The choice of the most appropriate approach is based on the patient's symptoms and the characteristics of the cysts.

Evaluation of immunochromatographic test for the detection of antibodies against Echinococcosis granulosus

BACKGROUND

Echinococcosis in humans is a disease caused by the larvae of Echinococcus granulosus (E. granulosus) and Echinococcus multilocularis (E. multilocularis). Serological tests are valuable, especially in the clarification of unexplained clinical findings and imaging methods. For this reason, indirect hemagglutination (IHA), latex agglutination, immunoelectrophoresis, immunoblotting, immuno-enzymatic tests, indirect fluorescence antibody test (IFAT), and enzyme-linked immunosorbent assay (ELISA) are used. The purpose of this study was to investigate the value of an immunochromatographic test (ICT) specific for E. granulosus antibodies in the diagnosis of echinococcosis.

MATERIAL/METHODS

ICT evaluated 102 cases of cystic echinococcosis, 38 cases of other parasitic diseases, and 50 healthy individuals. ELISA (DRG, Germany) that detects IgG antibodies specific for E. granulosus was used as the reference method.

RESULTS

The sensitivity, specificity, and positive and negative predictive values of ICT were 96.8%, 87.5%, 98.9%, and 70%, respectively. Diagnostic value was 96.1%. No significant differences and high degrees of agreement were found between ELISA and immunochromatographic test for cystic echinococcosis. Serum samples included 4 taeniasis, 2 leishmaniasis, and 2 healthy individuals were diagnosed to be positive with immunochromatographic test.

CONCLUSIONS

The ability of test to give fast results without need for equipment, devices, and specific storage conditions is an advantage. This test may be used due to its advantages in endemic regions for screening and diagnostic purposes.

[Construction and immunogenicity analysis of the attenuated recombinant Salmonella typhimurium strains expressing Echinococcus granulosus Eg95 antigen]

OBJECTIVE

To study the feasibility of using attenuated Salmonella typhimurium as carrier for oral immunization of Eg95 antigen of Echinococcus granulosus.

METHODS

The recombinant plasmid pYA3341-Eg95 was constructed by inserting the Eg95 gene into expression vector pYA3341, and identified by the methods of PCR and enzyme digestion. The recombinant plasmid pYA3341-Eg95 was electro-transformed into attenuated S. typhimurium strains X3730 and X4550 one by one to construct the recombinant strain St-Eg95. The expression of recombinant Eg95 protein in the recombinant strains St-Eg95 was analyzed by Western blotting. The strains of St-Eg95 were passaged 10 times in vitro and the recombinant plasmids were extracted at one generation interval. The genetic stability of recombinant plasmids was identified by PCR. BALB/c mice were randomly divided into six groups (five mice per group) and inoculated orally with St-Eg95, 100 µl/mouse, at dosage of 1 x 10(9), 1 x 10(10), 1 x 10(11), and 1 x 10(12) cfu/ml, wild-type S. typhimurium strain(l x l0(7)cfu/ml), and PBS, respectively. The survival rate was monitored daily for 30 days. Another 15 mice were divided into three groups and inoculated orally with St-Eg95(5 x 10(5) cfu/ml), X4550(pYA3341)(5 x 10(5) cfu/ml), and PBS, respectively, for 2 times, 0.5 ml/mouse/time, at biweekly intervals. On weeks 0, 2, 4, and 6 after the second immunization, sera were collected and tested for the presence of Eg95 antibody titers using commercially Eg antibody detection ELISA kit. The splenic lymphocyte proliferation was detected by MTT assay at 6 weeks after the second immunization.

RESULTS

The constructed recombinant plasmid pYA3341-Eg95 was identified by enzyme digestion and PCR identification. The Eg95 protein (M, 18000) was expressed in the recombinant strains St-Eg95. After the recombinant strains St-Eg95 were passaged 10 times, the Eg95 gene (about 486 bp) was still amplified from St-Eg95. Safety results showed that mice inoculated orally with the St-Eg95 or PBS were all survival on the 30th day after immunization. However, all mice taking wild virulent S. typhimurium strain diedr within 4 days. The Eg95-specific antibodies examined by indirect ELISA were significantly higher in mice immunized with St-Eg95 than that of mice immunized with X4550 (pYA3341) or PBS at 2 weeks after the second immunization (P<0.05). The average Eg95-specific antibody titers reached up to the highest value of 1:1700 in mice immunized with St-Eg95 at 4 weeks after the second immunization. The lymphocyte proliferation test showed that the stimulation index value was significantly higher(P<0.05) in mice immunized with the St-Eg95(reached up to 1.94±0.15) than that in mice immunized with X4550 (pYA3341) or PBS at 6 weeks after the second immunization.

CONCLUSION

The recombinant oral attenuated S. typhimurium St-Eg95 was successfully constructed, and has a good safety and immunogenicity profile in mouse.

Identification, expression and phylogenetic analysis of EgG1Y162 from Echinococcus granulosus

OBJECTIVE

This study was to clone, identify and analyze the characteristics of egG1Y162 gene from Echinococcus granulosus.

METHODS

Genomic DNA and total RNAs were extracted from four different developmental stages of protoscolex, germinal layer, adult and egg of Echinococcus granulosus, respectively. Fluorescent quantitative PCR was used for analyzing the expression of egG1Y162 gene. Prokaryotic expression plasmid of pET41a-EgG1Y162 was constructed to express recombinant His-EgG1Y162 antigen. Western blot analysis was performed to detect antigenicity of EgG1Y162 antigen. Gene sequence, amino acid alignment and phylogenetic tree of EgG1Y162 were analyzed by BLAST, online Spidey and MEGA4 software, respectively.

RESULTS

EgG1Y162 gene was expressed in four developmental stages of Echinococcus granulosus. And, egG1Y162 gene expression was the highest in the adult stage, with the relative value of 19.526, significantly higher than other three stages. Additionally, Western blot analysis revealed that EgG1Y162 recombinant protein had good reaction with serum samples from Echinococcus granulosus infected human and dog. Moreover, EgG1Y162 antigen was phylogenetically closest to EmY162 antigen, with the similarity over 90%.

CONCLUSION

Our study identified EgG1Y162 antigen in Echinococcus granulosus for the first time. EgG1Y162 antigen had a high similarity with EmY162 antigen, with the genetic differences mainly existing in the intron region. And, EgG1Y162 recombinant protein showed good antigenicity.

An easy and efficient method for native and immunoreactive Echinococcus granulosus antigen 5 enrichment from hydatid cyst fluid

Background

Currently, the serodiagnosis of cystic echinococcosis relies mostly on crude Echinococcus granulosus hydatid cyst fluid as the antigen. Consequently, available immunodiagnostic tests lack standardization of the target antigen and, in turn, this is reflected on poor sensitivity and specificity of the serological diagnosis.

Methodology/Principal Findings

Here, a chromatographic method enabling the generation of highly enriched Antigen 5 (Ag5) is described. The procedure is very easy, efficient and reproducible, since different hydatid cyst fluid (HCF) sources produced very similar chromatograms, notwithstanding the clearly evident and extreme heterogeneity of the starting material. In addition, the performance of the antigen preparation in immunological assays was preliminarily assessed by western immunoblotting and ELISA on a limited panel of cystic echinococcosis patients and healthy controls. Following western immunoblotting and ELISA experiments, a high reactivity of patient sera was seen, with unambiguous and highly specific results.

Conclusions/Significance

The methods and results reported open interesting perspectives for the development of sensitive diagnostic tools to enable the timely and unambiguous detection of cystic echinococcosis antibodies in patient sera.

Echinococcus P29 antigen: molecular characterization and implication on post-surgery follow-up of CE patients infected with different species of the Echinococcus granulosus complex

The protein P29 is a potential serological marker for post-treatment monitoring of cystic echinococcosis (CE) especially in young patients. We now have demonstrated that P29 is encoded in the Echinococcus genus by a single gene consisting of 7 exons spanning 1.2 kb of DNA. Variability of the p29 gene at inter- and intra-species level was assessed with 50 cDNA and 280 genomic DNA clones isolated from different E. granulosus s.l. isolates (E. granulosus sensu stricto (G1), E. equinus (G4), E. ortleppi (G5), E. canadensis (G6), E. canadensis (G7) and E. canadensis (G10)) as well as four E. multilocularis isolates. Scarce interspecies polymorphism at the p29 locus was observed and affected predominantly E. granulosus s.s. (G1), where we identified two alleles (A1 and A2) coding for identical P29 proteins and yielding in three genotypes (A1/A1, A2/A2 and A1/A2). Genotypic frequencies expected under Hardy-Weinberg equilibrium revealed a high rate of heterozygosity (47%) that strongly supports the hypothesis that E. granulosus s.s. (G1) is predominantly outbreeding. Comparative sequence analyses of the complete p29 gene showed that phylogenetic relationships within the genus Echinococcus were in agreement with those of previous nuclear gene studies. At the protein level, the deduced P29 amino acid (AA) sequences exhibited a high level of conservation, ranging from 97.9% AA sequence identity among the whole E. granulosus s.l. group to 99.58% identity among E. multilocularis isolates. We showed that P29 proteins of these two species differ by three AA substitutions without implication for antigenicity. In Western-blot analyses, serum antibodies from a human CE patient infected with E. canadensis (G6) strongly reacted with recombinant P29 from E. granulosus s.s. (G1) (recEg(G1)P29). In the same line, human anti-Eg(G1)P29 antibodies bound to recEcnd(G6)P29. Thus, minor AA sequence variations appear not to impair the prognostic serological use of P29.

[Diagnostic potential of five natural antigens from Echinococcus granulosus in the patients of cystic echinococcosis with different clinical status]

OBJECTIVE

To analyze the characteristics of serum antibody reactivity of cystic echinococcosis (CE) patients with different clinical status towards five native antigens obtained from Echinococcus granulosus (Eg).

METHODS

The protoscolex somatic soluble antigen (EgPS), crude hydatid cyst fluid antigen (EgHF), partially purified hydatid fluid antigen (Burstein's antigen, EgBu), adult somatic soluble antigen (EgAs) and the native antigen B (EgAgB) were pre- pared. 369 serum samples from CE patients and 281 sera samples from healthy individuals were examined for the antibodies against 5 native antigens with indirect ELISA. The serologic results were classified according to clinical status, and the statistical analyses were carried out to understand the relationship between the results of different antigen-ELISA and the clinical status of patients.

RESULTS

The results of EgBu, EgAS and EgAgB-ELISA showed that the antibody positive rate in hepatic CE patients [74.1% (212/286), 73.4% (210/286), 63.6% (182/286)] was significantly higher than that of other groups (including renal CE and pelvic CE, 1/8, 2/8, 1/8) (P < 0.05). Except EgAS, the S/N value of other groups examined by the rest four antigen-ELISA (EgPS: 3.10, EgHF: 2.40, EgBu: 1.60, EgAgB: 2.38) was also significantly lower than that of hepatic CE patients (3.73, 3.65, 4.40, and 3.61) (P < 0.05). EgBu, EgAS and EgAgB-ELISA results showed that the antibody positive rate in sera of recurrent CE patients [82.4% (150/182), 86.3% (157/182), 70.9% (129/182)] and the S/N value (5.54, 3.23, 3.75) were significantly higher than that of primary patients [positive rate: 67.4% (126/187); 63.6% (119/187); 57.2% (107/187); S/N value: 4.20, 2.70, 3.75] (P < 0.05). The S/N value detected by EgPS-ELISA and the positive rate examined by EgAgB-ELISA significantly increased with the increasing of the number of operations (P < 0.05), reached 4.23 and 91.7% (11/12), respectively, in the patients with > or = 4 times of operations. The positive rate and S/N value of EgAS-ELISA and EgAgB-ELISA increased with the number of hydatid cysts in patients (P < 0.05), reached 90.5% (19/21), 76.2% (16/21), and 3.97, 4.42, respectively, in patients with at least 4 cysts. Among the five antigen-ELISA, the positive rate increased with the cyst diameter (P > 0.05). The S/N value of EgHF-ELISA and EgAS-ELISA increased significantly with the cyst diameter (P < 0.05), reached 3.66 and 3.69, respectively, when the cyst diameter was > or = 15.1 cm. ROC analysis result showed that among the 5 native antigen-ELISA, the AUC(ROC) was highest in patients with cysts at CE2 stage (EgPS: 0.988 +/- 0.009, EgHF: 0.957 +/- 0.013, EgBu: 0.969 +/- 0.011, EgAs: 0.910 +/- 0.024, EgAgB: 0.894 +/- 0.021), EgAgB-ELISA presented the lowest AUC(RCO) of 0.267 +/- 0.031 in patients with cysts at CE5 stage. Except EgAgB, the positive rate of another 4 antigen-ELISA in detection of patients with cysts at CE 2 stage [EgPS: 97.2% (69/71), EgHF: 93.0% (66/71), EgBu: 88.7% (63/71), EgAs: 85.9% (61/71)] was slightly higher than that of the patients with cysts at CE1 stage, and then promptly reduced in patients with cysts at CE5 stage (EgPS: 56.3%, EgHF: 43.8%, EgBu: 12.5%, EgAs: 12.5%). In the patients with cysts at CE5 stage, the S/N value of the five antigen-ELISA was lowest (EgPS: 2.29, EgHF: 1.50, EgBu: 1.11, EgAs: 0.78, and EgAgB: 1.11).

CONCLUSION

Compared with the other three antigens, the EgPS and EgAgB antigens have higher antigenicity, sensitivity, and specificity. The sera of hepatic CE patients are more reactive to the five native antigens than the other clinical types.

[Serodiagnosis of the recombinant multi-epitope antigens from antigen B subunits of Echinococcus granulosus]

OBJECTIVE

To evaluate the diagnostic value of six recombinant multi-epitope antigens and three AgB subunit antigens from antigen B subunit of Echinococcus granulosus.

METHODS

A linker sequence was inserted into the sequence of MEA-26 to make it an MEA-49. I-TASSER on-line server was used to analyze protein structure. The reactivity of two multi-epitope recombinant antigens with the same target sequence but in different tertiary structure was compared. The reactivity of six multi-epitope antigens (MEA-8, MEA-20, MEA-26, MEA-36, MEA-49, and MEA-52), 3 subunit antigens (AgB1, AgB2, and AgB4), and 2 control antigens (Trx and linker) was determined by indirect ELISA. The assays were performed on 232 serum samples separated as follows: 112 sera from patients with cystic echinococcosis, 35 sera from individuals with alveolar echinococcosis, 43 sera from patients with cysticercosis and 42 sera from healthy individuals. Their diagnostic performance was assessed by receiver operating characteristic (ROC) curve analysis.

RESULTS

Tertiary structure prediction showed that the epitope regions of MEA-26 were closer to each other and aligned in parallel, while that in MEA-49 were farther apart from each other and formed two independent domains. Serological analysis revealed that the mean P/N value (2.88 +/- 2.02), sensitivity (92%) and diagnostic efficiency (89%) of MEA49 were higher than that of MEA-26 (2.54 +/- 2.02, 78% and 82%). MEA-20 (2.24 +/- 1.31), MEA-26 (2.54 +/- 2.02), MEA-36 (2.44 +/- 1.51), MEA-49 (2.88 +/- 2.02) and MEA-52 (2.50 +/- 1.37) showed a high reactivity to the sera from patients with cystic echinococcosis, which was superior to that of AgB1 (2.15 +/- 1.26). There was no significant difference in the reactivity to sera from individuals with alveolar echinococcosis between multi-epitope antigens and AgB1 (P > 0.05). MEA-52 showed a high diagnostic sensitivity in cysticercosis cases (1.27 +/- 0.70), superior to that of AgB1 (0.95 +/- 0.13) (P < 0.01). The reactivity of MEA-8 (1.04 +/- 0.15) to sera from healthy individuals was significantly higher than that of AgB1 (0.89 +/- 0.07) (P < 0.01). ROC analysis showed in the cases of cystic echinococcosis, the diagnostic sensitivity accomplished with AgB1, AgB2, and AgB4 was 77%, 55%, and 66%, respectively; the multi-epitope antigens of MEA-49 (92%), MEA-36 (92%), MEA-52 (87%), and MEA-26(78%) revealed a higher sensitivity than AgB1.

CONCLUSION

The reactivity of multi-epitope antigens is superior to that of AgB subunit antigens. The reactivity of MEA-49 is higher than that of MEA-26 which has the same target sequence but in different tertiary structure.

[Preliminary evaluation on the diagnostic performance of five native antigens from Echinococcus granulosus]

OBJECTIVE

To evaluate the diagnostic potential of 5 native antigens obtained from Echinococcus granulosus.

METHODS

The cyst fluid and protoscoleces were collected from infected livers of slaughtered sheep near Urumqi. The protoscolex somatic soluble antigen (EgPS), crude hydatid cyst fluid antigen (EgHF), partially purified hydatid fluid antigen (Burstein's antigen, EgBu) and the native antigen B (EgAgB) were prepared. Echinococcus granulosus adult worms were collected from experimentally infected dogs, and then used to prepare adult somatic soluble antigen (EgAS). Serum samples from patients with cystic echinococcosis (369 cases), alveolar echinococcosis (14 cases), cysticercosis (20 cases), schistosomiasis (50 cases), paragonimiasis westermani (10 cases), visceral leishmaniasis (5 cases), and healthy individuals (366 cases) were examined for the antibodies against 5 native antigens with indirect ELISA. A ROC analysis was performed to determine a cut-off value for each native antigen.

RESULTS

EgPS presented the highest AUC(BOC) (0.958 +/- 0.067), sensitivity (88.7%), positive predictive value (0.96), positive likelihood ratio (16.61), diagnostic efficiency (91.7%), and odds ratio (138.475). The specificity of EgBu (96.1%) was the highest, followed by EgAgB (95.7%), EgPS (94.7%), EgAS (89.0%), and EgHF (80.4%). The Youden index was ranked in order of EgPS>EgBu>EgHF>EgAS>EgAgB. The antibody reactive intensity of EgBu-ELISA was highest (4.055 +/- 1.365) and the EgAS-ELISA was lowest (2.947 +/- 1.276), and there was no significant difference between them (P > 0.05). The five native antigens presented high cross-reactivity with sera from alveolar echinococcosis (9/14-12/14) and from cysticercosis (8/20-16/20).

CONCLUSION

There are significant differences among the five native antigen-ELISA. The EgPS antigen has the best diagnostic performance , which is followed by EgBu and EgAgB.

Canine echinococcosis in Turkana (north–western Kenya): a coproantigen survey in the previous hydatid-control area and an analysis of risk factors

A study of Echinococcus granulosus infection in dogs, with risk-factor analysis, was carried out in the endemic area of northern Turkana district, Kenya, using necropsy on 42 strays and a coproantigen-ELISA survey of 161 owned animals. During the post-mortem examinations, 14 (33%) of the necropsied dogs were found infected with E. granulosus, with a mean burden of 540 worms (range=two to 4080 worms). The 26 necropsied dogs that came from the north-western Lokichoggio division--an area where, from 1983 to 1997, there had been a continuous programme of hydatid control--showed a similar prevalence of infection to the other dogs (34.6%) but a significantly lower mean burden, of 53 worms (range=two to 300). Forty-two (26%) of the animals tested for Echinococcus coproantigen were found positive. Although the dogs from the Lokichoggio division were more likely to be coproantigen-positive (29%) than those from the central Kakuma division (20%) or the north-eastern division (18%), the differences were not statistically significant. In questionnaire-based interviews, the owners of the dogs tested for coproantigens were asked about possible risk factors for canine infection with E. granulosus. Women were found to have twice the level of contact with dogs as men. The results of a univariate analysis of the dog-owners' responses revealed six factors that appeared to be significantly associated with a coproantigen-positive dog: non-restraint of the dog (P<0.001); dog fed on raw offal (P<0.001); the improper disposal of slaughter offal (P<0.001); the dog-owner's lack of knowledge about the transmission of echinococcosis (P=0.001); the dog not receiving anthelmintic treatment (P=0.003); and dog age < or =5 years (P=0.01). The results of a multivariate analysis confirmed that lack of dog restraint, access to raw offal, and young age of the dog (< or =5 years) each significantly increased the risk of coproantigen positivity (P, 0.005). Dogs that scavenged from cooking pots, were used to clean babies, had access to the inside of houses, and/or slept indoors appeared, however, to be at no increased risk of coproantigen positivity. The present results are discussed in relation both to older information on the epidemiology and role of human behaviour in the transmission of E. granulosus in Turkana, and the effects of the hydatid-control programme that ran continuously in the north-western division of Turkana between 1983 and 1997.

[Effect comparison between two ELISA kits in IgG antibody detection of Echinococcus granulosus]

OBJECTIVE

To compare the effects of two ELISA kits on IgG antibody detection of human Echinococcus granulosus.

METHODS

A Total of 134 sera of patients with echinococcosis, paragonimiasis westermani, clonorchiasis sinensis, schistosomiasis japonica, and cysticercosis cellulosae, and normal persons were detected by two IgG ELISA kits produced by different companies. Furthermore, the specificity, sensitivity and cross reactivity were counted and analyzed statistically.

RESULTS

The sensitivity and specificity were extremely high of the two kits as 100.00%. The cross-reactivity rates were 25.00% (paragonimiasis westermani), 26.09% (clonorchiasis sinensis), 10.00% (schistosomiasis japonica), and 87.5% (cysticercosis), respectively, by using the kit produced by the Combined Company in Shenzhen; the cross-reactivity rates were 5.00% (paragonimiasis westermani), 13.04% (clonorchiasis sinensis), 20.00% (schistosomiasis japonica), and 93.75% (cysticercosis) respectively, by using the kit produced by Haitai Company in Zhuhai. In addition, there was a significant difference of Paragonimus westermani detection (P < 0.05), but the rests had no statistically significant differences (all P > 0.05) between the two kits.

CONCLUSION

Both ELISA kits on IgG antibody detection of human Echinococcus granulosus have the advantages of a high sensitivity, specificity, convenience and high-speed. However, it is also in urgent need to further solve the cross-reactivity of Echinococcus granulosus with other parasites, in order to improve the accuracy of early diagnosis.

[Position analysis of three recombinant proteins of Echinococcus granulosus protoscolex with two-dimensional electrophoresis]

OBJECTIVE

To obtain specific antibodies of the three recombinant antigens obtained previously, rEgZW-5, rEg14-3-3 and rEgP-29, for identifying the corresponding proteins in two-dimensional electrophoretogram of Echinococcus granulosus protoscolex.

METHODS

The distribution of proteins from E. granulosus protoscoleces was judged by SDS-PAGE previously. Two-dimensional electrophoresis was used to separate proteins from E. granulosus protoscoleces, and the result was scanned and analyzed by the PDquest software to get the information about the quantity of proteins as well as their isoelectric point (IP) and relative molecular mass (MA,). Rabbits were immunized with the 3 recombinant antigens and antibodies were purified from antisera. Western blotting was used to identify the protein as marker in two-dimensional electrophoretogram of protoscolex.

RESULTS

SDS-PAGE displayed that the proteins separated from Echinococcus granulosus protoscoleces mainly distributed in the M, region of 18,000-90,000. 240 proteins were obtained by two-dimensional electrophoresis with M, 15,790-117,050 and IP 4.0-9.5, and 85.8% (206/241) of the proteins showed the IP ranged from 5 to 9. Western blotting showed that the specific antibody of rEg14-3-3 identified the 14-3-3 protein in two-dimensional electrophoretogram of protoscolex with Mr 33 000 and IP 4.86, the specific antibody of rEgZW-5 identified the ZW-5 protein with Mr 23,000 and IP 4.98, and the specific antibody of rEg P-29 identified the P-29 protein with Mr 29,000 and IP 5.65.

CONCLUSION

The antibodies against the three recombinant proteins from Echinococcus granulosus protoscoleces can identify corresponding proteins in the two-dimensional electrophoregrams.

[Different Echinococcus granulosus antigens induced indoleamine 2,3-dioxygenase expression in dendritic cells]

OBJECTIVE

To observe the expression of indoleamine 2, 3-dioxygenase (IDO) in dendritic cells (DCs) via different Echinococcus granulosus antigens in vitro.

METHODS

Bone Marrow DCs generated from bone marrow precursor cells of C57BL/6 mice and cultured in the presence of recombinant mouse GM-CSF (rmGM-CSF). Then, DCs were induced with 15 microg/ml recombinant antigen B (rAgB), 5 mg/ml mouse hydatid fluid (MHF), 1,000 U/ml IFN-gamma (as positive control), and RPMI 1640 complete medium (as negative control), respectively. Meanwhile, the treated DCs and cell supernatants were collected at 18, 24 and 48 h after induction. The positive expressions of D40, CD80, CD86 and I- A/I-E on DCs were determined by flow cytometry. By real-time fluorescent quantitative reverse-transcription polymerase chain reaction (FQ-RT-PCR), the expression level of IDO mRNA in DCs was measured. Concentrations of tryptophan (Try) were tested by high-performance liquid chromatography (HPLC) assay in cell supernatant.

RESULTS

The data from flow cytometry showed that the positive expressions of CD40, CD80, CD86, I-A/I-E were decreased after stimulated by rAgB and MHF. At 24 h after induction, there was significant difference in the level of CD40, CD86 and I-A/I-E among rAgB-treated group [(22.60 +/- 2.69)%, (35.50 +/- 4.38)%, (57.30 +/- 4.38)%], MHF-treated group [(38.00 +/- 3.54)%, (53.00 +/- 3.39)%, (77.10 +/- 1.70)%] and negative control [(37.95 +/- 3.61)%, (19.55 +/- 1.06)% and (85.45 +/-1.63)%] (P < 0.05). At 18, 24 and 48 h after induction, the levels of IDO mRNA in rAgB-treated group [(9.20 +/- 0.01), (29.44 +/- 0.02), (16.48 +/- 0.04)] and MHF-treated group [(9.67 +/- 0.02), (17.52 +/- 0.01), (16.81 +/- 0.01)] was higher than that of negative control group [(2.46 +/- 0.01), (7.77 +/- 0.01), and (10.56 +/- 0.01)] (P < 0.01). And significant difference was found between rAgB-treated group and MHF-treated group (P < 0.05). At 18, 24 and 48 h after induction, the concentrations of Try were lowest in rAgB-treated group [(23.65 +/- 0.64), (13.95 +/- +1.06), (19.0 +/- 00.64) micro.mol/L]. At 24h after induction, Try concentration in negative control group (22.9 +/- 0.14) was higher than that of MHF-treated group (20.65 +/- 0.34) ( P < 0.05).

CONCLUSION

Under in vitro condition, rAgB and MHF can up-regulate IDO expression. The ability of rAgB to up-regulate IDO activity was stronger than that of MHF at 24 h after induction.

IgG4 detection of Echinococcus granulosus paramyosin is a useful diagnostic test for human hydatidosis

Hydatidosis is a public health problem in many parts of the world, and improvement in diagnosis of the disease is still being pursued. Protoscoleces of Echinococcus granulosus were isolated from hydatid cysts collected from naturally infected sheep slaughtered in abattoirs in Iran. Sonicated extract of protoscolex was subjected to two-dimensional gel electrophoresis and Western blot analysis. Primary antibodies were from serum samples from 130 hydatidosis patients, 38 individuals infected with other parasitic infections, and 30 healthy people, whereas peroxidase (HRP)-conjugated anti-human IgG and IgG4 were used as secondary antibodies. The recombinant form of the identified protein was produced and tested for its sensitivity and specificity for the detection of human hydatidosis. An antigenic band of ∼60 kDa was found to be sensitive (82%) and specific (100%) for the detection of hydatidosis when probed with anti-human IgG4-HRP, while the sensitivity and specificity were 33 and 100%, respectively, with anti-human IgG-HRP. By mass spectrometry, the band was identified as protoscolex tegument paramyosin. The sensitivity and specificity of full-length paramyosin-recombinant protein in IgG4 blots were found to be 86 and 98%, respectively. In conclusion, IgG4 detection of Echinococcus granulosus paramyosin was found to be useful for the diagnosis of human hydatidosis.

[Construction and expression of the Echinococcus granulosus recombinant BCG-EgG1Y162]

OBJECTIVE

To construct and express Echinococcus granulosus recombinant bacille Calmette-Guerin (BCG) strain rBCG-EgG1Y162.

METHODS

The encoding gene of the antigen EgG1Y162 of E. granulosus was recombined with E. coli-Mycobacterium shuttle expression plasmid vector pMV361 by genetic engineering technique, and transformed into E. coli for amplification. The recombinant plasmid rpMV-EgG1Y162 was identified by PCR, double digestion with restriction enzymes, and sequence analysis. The confirmed rpMV-EgG1Y162 was transformed into BCG strain via electroporation technique to construct the recombinant rBCG-EgG1Y162. After identification by PCR and double digestion with restriction enzymes, the recombinant strain was cultured for about 2 weeks. In order to induce the expression of target protein, the rBCG was placed in 45 degrees C for 30 min. SDS-PAGE and Western blotting were used to analyze the expressive protein.

RESULTS

The product of recombinant plasmid rpMV-EgG1Y162 was approximately 360 bp by PCR amplification and double digestion with restriction enzymes, consistent with the expected fragment length. Sequencing results showed that the inserted sequence was correct. The rBCG-EgG1Y162 grew well and the identification of PCR and enzyme digestion revealed accuracy. The results of SDS-PAGE and Western blotting showed that the relative molecular weight (M(r)) of the protein was about 71 000.

CONCLUSION

The E. granulosus rBCG-EgG1Y162 strain is constructed and expressed.

Clinical and demographic characteristics of patients with urinary tract hydatid disease

Background

Human cystic echinococcosis (CE) is caused by flatworm larvae of Echinococcus granulosus and is endemic in many parts of the world. In humans, CE cysts primarily affect the liver and pulmonary system, but can also affect the renal system. However, the clinical manifestations of renal CE can be subtle, so healthcare professionals often overlook renal CE in differential diagnosis. In this study, we examined the clinical and demographic characteristics of patients with urinary tract CE and analyzed the diagnosis and treatment procedures for this disease.

Methods

The records of 19 consecutive renal CE patients who were admitted to the First Affiliated Hospital of Xinjiang Medical University from January 1983 to April 2011 were retrospectively reviewed. In all cases, CE of the urinary tract was confirmed by pathological examination and visual inspection during surgery.

Results

Fifteen patients were males and 4 were females. The most common symptoms were non-specific lower back pain and percussion tenderness on the kidney region. All patients were followed up for 9–180 months after surgery. None of the patients experienced a recurrence of renal CE, but 4 patients experienced non-renal recurrence of hydatid disease.

Conclusions

Hydatid cysts from E. granulosus are structurally similar in the liver and urinary tract. Thus, the treatment regimen for liver CE developed by the World Health Organization/Informal Working Group on Echinococcosis (WHO/IWGE) could also be used for urinary tract CE. In our patients, the use of ultrasound, computed tomography, serology, and clinical characteristics provided a diagnostic accuracy of 66.7% to 92.3%.

[Study on immune response in ICR mice by immunization with recombinant myophilin vaccine against Echinococcus granulosus]

OBJECTIVE

To investigate the immune response and the protection in mice induced by the recombinant myophilin protein of Echinococcus granulosus.

METHODS

Thirty-six male ICR mice of 6-8 weeks old were randomly divided into groups A, B and C each with 12. The mice in the 3 groups were subcutaneously immunized with Eg myophilin protein, blank plasmid protein or PBS, respectively, by 3 times and challenged with protoscoleces of E. granulosus 2wk after the last vaccination. Mice were sacrificed 20wk after the infection, the hydatid cysts were collected for measuring the weight reduction. Spleens were obtained and the splenocytes were separated and cultured in vitro with EgAg or ConA stimulus for 4-5 h. The subsets of CD4+ and CD8+ T cells were measured by FACsort. The proliferation of splenocytes was determined by MTT method with blank plasmid and PBS as control.

RESULTS

The average weight of the hydatid cysts in the immunized group decreased by 69.1% in comparison to the blank plasmid and PBS groups. The CD4+ subset [(29.7 +/- 0.9)%] and CD84+ subset [(9.7 +/- 0.8)%] in group A increased significantly than group C, [(11.6 +/- 1.4)%] and [(7.8 +/- 0.2)%] respectively (P < 0.01 or < 0.05). The ratio of CD4+/CD8+ subsets in group A (3.061 +/- 0.015) was also higher than group C (1.487 +/- 0.106) (P < 0.01). Without stimulation, the proliferation of T lymphocytes in group A(0.237 +/- 0.009) was higher than group C (0.159 +/- 0.005) (P < 0.01), with EgAg or ConA stimulus, it was also higher in group A than that of group C (P < 0.01).

CONCLUSION

The recombinant myophilin protein of E. granulosus can induce the proliferation of splenocytes and Th1 response in mice, and the CD4+ T cells subset may bear a part in the induced protection against the challenge of protoscoleces.

[Cloning, expression and immunodiagnostic evaluation of enolase from Echinococcus granulosus]

OBJECTIVE

To clone and express EgEno gene of Echinococcus granulosus, and to investigate the immunogenicity and diagnostic value of recombinant EgEno.

METHODS

Total RNAS of E. granulosus was extracted and reversedly transcripted to cDNA. EgEno gene was amplified from cDNA and inserted into vector pET28a. The recombinant plasmid pET28a-EgEno was transformed into E. coli BL21 (DE3) for expression under the induction of IPTG. The expressed product was identified by SDS-PAGE and Western blotting. The purified recombinant EgEno protein was detected by ELISA with the sera of cystic echinococcosis patients, healthy persons and other patients.

RESULTS

The EgEno gene was successfully amplified from cDNA of E. granulosus and a fusion protein was expressed in E. coli BL21 (DE3). The molecular weight of the expressed protein was around 50 kDa. The result of Western blotting indicated that the antigenicity of the protein was specific. The sensitivity of diagnosis by ELISA for cystic echinococcosis was 81.25%.

CONCLUSION

EgEno of E. granulosus is cloned and expressed in E. coli BL21 (DE3) successfully, which might be used as a candidate antigen of immunodiagnosis for cystic echinococcosis.

[Epitope structure prediction of antigen B of Echinococcus granulosus and construction of multi-epitope recombinant antigen]

OBJECTIVE

To improve the reactivity of Echinococcus granulosus antigen B (EgAgB) multi-epitope antigens using the gene fragment from 3 subunits, EgAgB1, EgAgB2, and EgAgB4.

METHODS

Discovery Studio Visualizer software and I-TASSER on-line server were used to predict protein structure gene sequence of the 3 subunits and their combinations in different way. The epitope or subunit combination higher prediction scores was selected for gene recombination. The target sequence was amplified with primers and by using overlap extension PCR technology. The target sequence was then cloned to pET32a constructing expression plasmid and expressing recombinant proteins. The expressed products were served recombinant antigens after purification. The immuno-response of the recombinant multi-epitope antigens were Western blotting analysis.

RESULTS

Structure prediction showed that all the three subunits EgAgB1, EgAgB4 are in a "Z" word structure. The epitope region is located in the central part of the sequence. For from the three subunits and four reactive epitopes (KK36, RK30, B4-2, and B4-3), 57 different combinations tried for structure prediction. Six of them were selected for recombination and expression. Western blotting six multi-epitope antigens (MEA-8, MEA-20, MEA-26, MEA-36, MEA-49, and MEA-52) suggested reactivity of multi-epitope antigen was much stronger than AgB subunit antigens when the positive echinococcosis were used.

CONCLUSION

By using protein tertiary structural prediction and screening the higher prediction score of combinations, six multi-epitope recombinant antigens were constructed. Western blotting shows that the hand reactivity of multi-epitope antigen is much stronger than that of AgB subunit antigens.