Diagnostic Accuracy of Antigen 5-Based ELISAs for Human Cystic Echinococcosis

Evaluation of the Local and Peripheral Immune Responses in Patients with Cystic Echinococcosis

BACKGROUND

Cystic echinococcosis (CE) cysts may persist for decades because of immune modulation mechanisms. Here, we characterize the cysts and the blood immune responses in patients with CE.

METHODS

We enrolled 61 patients with CE and 19 control subjects. We received tissue samples from seven patients with CE and a control subject requiring liver cystectomy. The immunohistochemistry evaluation of the immune cell subtypes and cytokines in the pericysts and surrounding liver and the antigen B (AgB)-specific response analysis of whole blood were performed.

RESULTS

In CE, the pericyst and the surrounding liver parenchyma showed aggregates of CD3+ T lymphocytes, mainly CD4+. B lymphocyte aggregates were present in the liver tissue. Monocytes/granulocytes were rarely observed. Th2 cytokine expression was scarce, whereas IFN-γ expression was present in the CE tissues. The control subject did not show an inflammatory infiltrate. The IL-4-specific response to AgB was increased in the patients with CE compared to the control, and this result was confirmed in a larger cohort (p = 0.003), whereas the IFN-γ-response was similar between the two groups (p = 0.5570).

CONCLUSION

In patients with CE, CD4+ lymphocytes infiltrate the pericyst and the surrounding liver tissue with a low IL-4/IL-13 expression level and a moderate IFN-γ expression level; moreover, an IL-4 parasite-specific response is detected in the periphery. These results support adventitia involvement in CE immunopathogenesis.

Advances in Detecting Cystic Echinococcosis in Intermediate Hosts and New Diagnostic Tools: A Literature Review

Cystic echinococcosis (CE) is a zoonotic disease affecting humans and animals. Despite a lack of clarity about many details of parasite-intermediate host interactions, the nature of the immune responses triggered by hydatid infection has revealed new perspectives. This study discusses the latest advances in elucidating the immunologic mechanism of echinococcosis and its detection and potential approaches to enhance serodiagnosis accuracy. Moreover, nanobiosensors have been evaluated according to their potential to improve treatment efficiency and aid in an early diagnosis of cystic echinococcosis. The serum of an intermediate host can diagnose CE by analyzing antibodies induced by Echinococcus granulosus. Among the most notable features of this method are its noninvasive ability and high sensitivity, both of which make it an excellent tool for clinical diagnosis. Several serological tests, including ELISAs and immunoblotting, can detect these antibodies to assess the disease's state and determine the treatment outcome. A thorough understanding of what cross-reactivity means and the stage of the disease are crucial to interpreting serological results. Nanobiosensors have also proven better than conventional biosensors in detecting hydatid cysts. Additionally, they are highly sensitive and versatile when detecting specific biomarkers, improving diagnostic accuracy. These immunomodulatory molecules, induced by E. granulosus, are a good candidate for diagnosing cystic echinococcosis because they alter intermediate host immune responses. Hydatid cyst detection is also enhanced through nanobiosensors, which provide better accuracy.

Proteomics investigation of human sera for determination of postoperative indicators of pulmonary cystic echinococcosis

BACKGROUND

Cystic echinococcosis (CE)/hydatidosis is an important zoonotic parasitic disease caused by the larval stage of Echinococcus granulosus. The disease is a major health problem all over the world. Finding specific and sensitive biomarkers for follow-up of CE in patients after surgery is essential. Using proteomics methods, the present study aimed to evaluate post-surgical treatment by finding probable biomarker/s in the serum of human lungs CE.

METHODS

A total of 24 human sera were tested. These sera included eight confirmed lung/s CE patients sera before surgery (BS), eight sera 12 months post-surgery (12MPS) as well as eight control sera from healthy people. Proteomics methods including 2DE and LC-MS/MS were performed on the specimens followed by bioinformatics analysis. Differentially expressed proteins (DEP) were detected and, separately integrated with protein-protein interaction (PPI) data to construct the PPI network.

RESULTS

A total of 171 protein spots were detected in three groups including BS, 12MPS, and control groups; of which a total of 106 DEP have been expressed based on fold changes > = 2 and p-value < 0.05. More analysis was performed and a total of 10 protein spots were selected for identification by mass spectrometry showing the following proteins: APOA1, BGN, SPP2, EAF1, ACOXL, MRPL55, MCTP2, SEPTIN1, B4GALNT1, and ZNF843. Based on centrality parameters of the PPI network (degree and betweenness) five Hub-bottlenecks proteins with significant centrality values were found including APOA1, BGN, SPP2, EAF1, and ACOXL.

CONCLUSION

This study showed five proteins as hub-bottleneck proteins; of which APOA1 was more prominent. It can be concluded that a change in expression of this protein in patients' sera could be used as an indicator tool for the achievement of lungs CE surgical therapy.

Evaluation of Potential Inflammatory Markers for Cystic Echinococcosis: P-selectin and Resistin

OBJECTIVE

Cystic echinococcosis (CE) is one of the most common zoonotic diseases worldwide. Diagnosis of CE is predominantly based on imaging techniques and serological tests are used in cases of non-characteristic imaging findings as diagnostic reference. However, serological test results cannot be completely reliable as they are affected by multi-factors. P-selectin and resistin are inflammatory markers that are altered during the acute stages of infection. In this purpose, inflammatory markers as P-selectin and resistin have been investigated for a potential diagnostic reference for CE diagnosis.

METHODS

A total of 60 patients who were diagnosed with CE and twenty-five healthy individuals were included in this study. Blood samples were obtained from all participants. Obtained sera were evaluated using the P-selectin and resistin ELISA kits for protein levels. Additionally, the relative expression of SELP (P-selectin) and RETN (resistin) genes were determined using the comparative CT (ΔΔCT) method between groups as CE patients with active and inactive cysts, CE patients and healthy controls.

RESULTS

SELP (13.9-fold change, p<0.05) and RETN (8.1-fold change, p<0.05) were differentially expressed in CE patients compared in the control group. Whereas resistin protein levels were significantly higher in CE patients than the healthy controls (p<0.001), the difference in P-selectin protein levels was not significant (p>0.05). There was no difference between active and inactive CE patients in terms of P-selectin and resistin in gene and protein levels (p>0.05).

CONCLUSION

Although there was no difference between the active and inactive CE patients, the good differentiation between the healthy controls and the CE patients suggested that resistin is a potential inflammatory diagnostic reference.

Proteomic characterization of Echinococcus granulosus sensu stricto, Taenia hydatigena and Taenia multiceps metacestode cyst fluids

Cystic echinococcosis (CE) diagnosis by means of serological assays is hampered by the presence of parasites closely related to Echinococcus granulosus sensu lato (s.l.), responsible of the zoonotic disease and with which share cross-reacting antigens. Thus, improvements on the characterization of Echinococcus specific antigens expressed in the larval stage are required, in order to provide useful information for the development of immunological assays for the serodiagnosis of CE in sheep. Here, the proteome of the hydatid cyst fluids (HFs) of Echinococcus granulosus (hydatid fluid, EgHF) and other ovine parasites cyst fluids (CFs), Taenia hydatigena (ThCF) and Taenia multiceps (TmCF) were analyzed by a shotgun proteomic approach. Parasite and host protein profiles in the three types of cyst fluids were characterized and compared. Among the identified proteins, differential parasitic markers with serodiagnostic potential, due to their well-known immunoreactivity in human, included Ag5, AgB proteins, 8-kDa glycoproteins, hydatid disease diagnostic antigen P29 and major egg antigen P40. In particular, seven proteoforms of AgB and 8-kDa glycoprotein resulted to be the most promising diagnostic biomarkers, as they might predict CE in ovine and discriminate between different types of parasites.

Comparison of the multi-epitope recombinant antigen DIPOL and hydatid fluid for the diagnosis of patients with cystic echinococcosis

The use of serological tests containing multiple immunodominant antigens rather than single antigens have the potential to improve the diagnostic performance in Cystic Echinococcoses (CE) as a complement tool to clear the inconclusive imaging data. Here, we comparatively evaluated the diagnostic value of Hydatid Fluid (HF) and the recently described recombinant multi-epitope antigen DIPOL in IgG-ELISA in a clinically defined cohort of CE patients. The serum samples from 149 CE patients were collected just before surgical or Percutaneous- Aspiration- Injection- Reaspiration (PAIR) procedures. Additionally, serum samples of patients with other parasitic infections (n=49) and healthy individuals (n=21) were also included in the study as controls. To investigate the association between the genotype of the parasite and DIPOL, cyst materials from 20 CE patients were sequenced. In terms of overall sensitivity, HF was higher than DIPOL (82.55%,78.52%, respectively). However, while the sensitivity of HF was higher than DIPOL in patients with active and transitional cysts (83.3%, 75.4%, respectively), sensitivity of DIPOL in inactive cysts was higher compared to HF (95.6%, 78.3%, respectively). The sensitivity of DIPOL depending on cyst stage was statistically significant (P= 0.041). In terms of specificity, DIPOL was found to be better than HF (97.71%, 91.43%, respectively). By genotyping, the majority of 20 patients showed G1 genotype (80%). All patients harboring G3 and G1/G3 cyst genotypes were positive with both antigens, while 87.5% of patients with G1 genotype were seropositive with HF and 75% with DIPOL. The overall sensitivity and high specificity of DIPOL suggest that this recombinant protein containing immunodominant epitopes is a potential substitute for the HF by serological tests for the diagnosis of CE.

Total Splenectomy for a Giant Isolated Splenic Hydatid Cyst Compressing the Abdominal Viscera: A Case Report

Patient: Female, 49-year-old

Final Diagnosis: Echinococcus infection

Symptoms: Left upper quadrant abdominal pain

Medication:—

Clinical Procedure: —

Specialty: Surgery

Th1/Th2/Th17 cytokine profile in hepatic cystic Echinococcosis patients with different cyst stages

AIMS

The study aimed to investigate possible correlation between expression level of Th1/Th2/Th17-type profile and cyst viability in the systemic and local immunity of hepatic cystic Echinococcosis (CE) patients.

METHODS AND RESULTS

Expression of Th1-type interleukin (IL)-2, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, Th2-type IL-4, IL-6, IL-10 and Th17-type IL-17A was examined in the serum and liver samples of hepatic CE patients with different cyst stages. Compared with healthy controls, Th1/Th2/Th17-type cytokines were significantly increased in the serum of hepatic CE patients. Moreover, expression of these cytokines was also at higher level in the inflammatory cell band of peri-lesion liver (PL) tissues than that in the adjacent normal (AN) liver tissues. Interestingly, elevation of Th1-type and Th17-type cytokines was more evident in PL tissues of patients with inactive cysts. Relatively, Th2-type cytokines were predominant in PL tissues of patients with active cysts.

CONCLUSION

Our findings provide new insights that Th1/Th2/Th2-type cytokine profile was associated with cyst stages. In hepatic CE patients with inactive cysts, Th1 and Th17-type cytokines were predominant. Comparatively, Th2-type cytokines were more evident in hepatic CE patients with active cysts, which may provide basis for the immune response diversity in hepatic CE patients with different cyst stages.

Following up of Surgical Treated Human Liver Cystic Echinococcosis: A Proteomics Approach

Background:

Cystic echinococcosis (CE) is one of the most important parasitic zoonosis in the world. Post-surgery follow up in CE patients is an important non-solved problem up to now. Therefore, the investigations on this problematic issue would be very applicable in the view of CE clinical treatment.

Methods:

A total of 24 confirmed liver CE patients sera including eight sera before surgery (BS), eight sera three months post-surgery (3MPS), and eight sera six months post-surgery (6MPS) were used in the present study. Proteomics methods including 2DE and LC-MS/MS were performed on the specimens followed by bioinformatics analysis such as Gene Ontology (GO) and Protein-Protein Interaction (PPI) network analysis.

Results:

A total of 235 proteins were detected of which 12 differentially expressed proteins (DEP) were identified by LC-MS/MS in all sera. The proteins were presented in BS and suppressed after surgery as follows: HPX, SERPINA1, SERPINC1, CP, HBD, and HBA2. Comparisons of the protein expression in sera of patients BS, 3MPS, and 6MPS revealed that GC, IGJ, AHSG, CD5L, FGG, and APOC3 have been overexpressed in 3MPS and 6MPS. PPI network analysis demonstrated that SERPINC1 and AHSG with more connection in the network could be considered as hub proteins and potential prognostic biomarkers in response to surgical treatment of liver CE.

Conclusion:

Application of proteomics methods on patient’s sera could be used as a novel biomarker tool for following-up liver CE patients. In this regards, proteomics and, application of bioinformatics analysis including GO and PPI showed that SERPINC1, AHSG and HPX are of more value as a potential follow up biomarkers in response to surgical treatment.

Immunological detection of human and camel cystic echinococcosis using different antigens of hydatid cyst fluid, protoscoleces, and germinal layers

BACKGROUND AND AIM

Cystic echinococcosis (CE)/hydatidosis is one of the most prevalent neglected zoonotic diseases. It is initially asymptomatic and does not produce any clinical signs until the cyst becomes enlarged, causing localized pressure on internal organs and tissues. Therefore, the detection of Echinococcus granulosus antibodies is highly essential. This study evaluated the antigens of hydatid cyst fluid, protoscoleces, and germinal layers for efficient immunological diagnosis of CE in humans and camels.

MATERIALS AND METHODS

Hydatid cyst fluid (FLc), protoscoleces (Psc), and the germinal layer (GLc) antigens were prepared from camel-lung hydatid cysts. In the same way, hydatid cyst fluid (FLh) and protoscoleces (Psh) antigens from human-liver cyst aspirate were produced. The comparative immunodiagnostic efficacy of the prepared antigens was verified using indirect enzyme-linked immunosorbent assay (ELISA), SDS-PAGE, and immunoblotting.

RESULTS

ELISA proves that FLc and GLc antigens were higher than FLh and Psh antigens. This shows that binding reactivity in naturally infected human sera, camel sera, and Psc is the most potent, exhibiting 100% sensitivity with 78.26% and 76.47% specificity in camel and human sera, respectively. The CE prevalence using diagnostic Psc was 54.79% and 61.32% in tested human and camel sera, respectively. The electrophoretic profiles of all shared antigens showed similarities at 52, 41, and 22 kDa. Immunoblotting demonstrated common immune-reactive bands in all antigen types at 52 and 41 kDa against positive human and camel sera.

CONCLUSION

This immunological study introduces camel hydatid cyst Psc as a potent diagnostic antigen and new immune-reactive fractions of 52 and 41 kDa for diagnosing hydatidosis in humans and camels.

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.

A case of human cystic echinococcosis acquired in Ireland

Cystic echinococcosis (CE) is caused by the cestodes of the Echinococcus granulosus sensu lato complex and, in the majority of cases, is associated with hepatic or pulmonary involvement. Human CE is not thought to be endemic in Ireland. We describe the first reported case of human CE possibly acquired in Ireland.

Cystic Echinococcosis: Clinical, Immunological, and Biomolecular Evaluation of Patients from Sardinia (Italy)

Cystic echinococcosis (CE), a zoonotic disease caused by the larval stage of the tapeworm Echinococcus granulosus sensu lato (s.l.), is a worldwide public health problem. Echinococcus granulosus sensu stricto (s.s.), associated with G1 and G3 genotypes, is endemic with high prevalence in the Mediterranean basin. The parasite's life cycle comprises definitive hosts (canids) and intermediate hosts (ruminants) and can occasionally involve humans. The main aim of this research was to confirm the diagnosis of 13 patients suspected of CE who presented different complications and needed the surgical removal of the cysts. We also wanted to understand and clarify more the diagnosis of echinococcosis in humans. For this purpose, the patients first underwent cyst evaluation by ultrasound (US), immunological analysis, and then total pericystectomy, followed by parasitological, histopathological, and molecular biology examinations of the cysts. US stadiated one CE1, one CE2, eight CE3b, one CE4, and two CE5; immunology evidenced nine positives; histopathology confirmed 11 CE cysts, of which 8 fertile presenting protoscoleces were identified as E. granulosus s.s. by molecular biology, genotyped as three G1 and four G3 by neighbor-joining (NJ) phylogenetic tree. In conclusion, the results showed that 11 patients were affected by E. granulosus s.s. G1 orG3, and 2 cystic neoformations were of non-parasitic origin.

A Comparative Study of Different Immunoassays to Detect Specific Antibodies to Echinococcus Spp. in Human Sera

Human echinococcosis, one of the most serious of parasitic zoonoses, is caused by the larval stages of taeniid cestodes of the genus Echinococcus. The study aimed to assess the reliability of the detection of specific antibodies to E. multilocularis and E. granulosus s.l. in human sera and to compare their diagnostic potential for their utilization in the practice. In the study, the somatic antigen of E. multilocularis (AgEm), antigen B (AgB), and the hydatid fluid antigen of E. granulosus and two commercial ELISA kits – Echinococcus granulosus (Bordier Affinity Products, Crissier, Switzerland) and NovaLisa^TMEchinococcus IgG (NovaTec Immunodiagnostica, Germany) – were compared. Sera of patients with alveolar and cystic echinococcosis, and with different parasitic/other infections were used to evaluate the sensitivity, specificity and cross-reactivity of in-house and commercial ELISA methods. AgEm presented the highest values regarding the diagnostic indicators, showing 100 % specificity and 90.0 % sensitivity. The tests for serological diagnostics of cystic echinococcosis were less sensitive and specific. The Echinococcus granulosus kit had 83.8 % specificity and 88.2 % sensitivity, while AgB and AgHF showed 85.0 % and 86.3 % specificity, and 76.5 % and 100 % sensitivity, respectively. NovaLisa^TMEchinococcus IgG proved to have 95.7 % specificity and 77.8 % sensitivity. The results point out that the combination of different serological tests and approaches in accordance with clinical and imaging findings is still essential to prove the correct diagnosis in suspected patients.

Seroprevalence of Echinococcus spp. and Toxocara spp. in Invasive Non-native American Mink

Invasive non-native species can become reservoirs of zoonotic pathogens and cause their spread during colonization, increasing the risk of zoonoses transmission to both wild hosts and humans. American mink (Neovison vison) are considered an important invasive mammal species responsible for carrying endoparasites. The aim of our study was to evaluate the role of feral American mink as a possible transmission vector of Echinococcus spp. and Toxocara spp. in wildlife. We analysed the frequency of American mink exposure to both parasites, the spatial distribution in Poland, and the variability over time on the basis of specific antibody presence using ELISA and Western blot. Alimentary tract analyses revealed that American mink do not serve as definitive hosts for these parasites. Altogether, 1100 American mink were examined. The average seropositivity for American mink was 14.2% for echinococcosis and 21.7% for toxocarosis; dual-seropositivity was detected in only 6.0%. Seroprevalence of both parasites differed between study sites and significantly increased over time in Toxocara spp. Thus, our study revealed that free-living American mink are exposed to parasites and likely to be involved in the maintenance of both Echinococcus spp. and Toxocara spp. in the wild as paratenic hosts.

A simple and efficient purification method of native immunoreactive antigen for diagnosis of camel hydatidosis

BACKGROUND

Cystic echinococcosis (CE), a zoonotic disease that affects animal and human health, is of increasing economic importance due to high morbidity rates and high economic losses in the livestock industry.

AIM

The present study was conducted to purify the antigen from hydatid cyst fluid (HCF) with high diagnostic efficacy of camel hydatidosis using indirect enzyme-linked immunosorbent assay (ELISA).

MATERIALS AND METHODS

The HCF antigen was purified using Sephacryl S-300 column chromatography. Characterization of fractions was performed using reducing and non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. Further, antibodies against Echinococcus granulosus cysts in camel serum were detected using indirect ELISA.

RESULTS

The purification process resulted in three fractions of antigens: FI, FII, and FIII. Indirect ELISA showed that higher diagnostic efficacy was observed in FI than in FII and FIII. Indirect ELISA, in which FI was utilized, showed 88% sensitivity and 91.7% specificity. Non-reducing SDS-PAGE showed that FI had two bands of molecular weights 120 and 60 kDa. Western blot analysis of FI demonstrated that 60, 38, and 22 kDa were antigenic bands when reacted with naturally infected camel sera with E. granulosus cysts. Using indirect ELISA, F1 recorded an infection percentage of 81.7% in randomly collected camel serum samples.

CONCLUSION

FI is a promising antigen for accurate diagnosis of camel CE using indirect ELISA.

Structural and Immunodiagnostic Characterization of Synthetic Antigen B Subunits From Echinococcus granulosus and Their Evaluation as Target Antigens for Cyst Viability Assessment

Background

Several tools have been proposed for serodiagnosis of cystic echinococcosis (CE), but none seems promising for cyst viability assessment. Antigens with stage-specific diagnostic value have been described, but few studies with well-characterized antigens and human serum samples have been performed. Antigen B (AgB) proteoforms hold promise as markers of viability, due to their differential stage-related expression and immunoreactivity.

Methods

Four AgB subunits (AgB1, AgB2, AgB3, AgB4) were synthesized and structurally characterized. Based on the preliminary evaluation of the subunits by western immunoblotting and enzyme-linked immunosorbent assay (ELISA), AgB1 and AgB2 were further tested in two ELISA setups and extensively validated on 422 human serum samples.

Results

All subunits showed a high degree of spontaneous oligomerization. Interacting residues within oligomers were identified, showing that both the N-terminal and C-terminal of each subunit are involved in homo-oligomer contact interfaces. No hetero-oligomer was identified. AgB1 and AgB2 ELISAs revealed different sensitivities relative to cyst stage. Of note, besides high specificity (97.2%), AgB1 revealed a higher sensitivity for active-transitional cysts (100% for CE1, 77.8% for CE2, 81.5% for CE3a, and 86.3% for CE3b) than for inactive cysts (41.7% for CE4 and 11.1% for CE5) and postsurgical patients (44%). Interestingly, 19 of 20 patients with spontaneously inactive cysts and 6 of 9 treated with albendazole >5 years earlier were negative on the AgB1 assay.

Conclusions

The structural characterization of subunits provides insights into the synthetic antigen conformation. The stage-related sensitivity of synthetic AgB1 holds promise as part of a multiantigen setting and deserves further longitudinal evaluation as marker of cyst viability.

Detection of Echinococcus granulosus sensu lato infection by using extracts derived from a protoscoleces G1 cell line

Cystic echinococcosis (CE) can be diagnosed by means of several serological approaches, but their results vary among laboratories due to the molecular characteristics of the reference antigens used. Thus, this study aimed to address both the relevance of an EGPE cell line previously obtained from Echinococcus granulosus protoscoleces G1 and the complexity of the immune response by using two different in vitro growth stages as separate sources of parasite antigens. The serum reactivity was investigated by western blotting (WB) in 21 CE patients from an endemic area in a matched case-control design and also in seven experimentally infected sheep and five healthy control sheep. EGPE-antigen-human serum sensitivity by WB was higher than that of hydatid fluid (HF) WB, ELISA and DD5 (P < .05, Chi-square test). EGPE protein extract was immunogenic in mice and hyperimmune plasma reacted with HF proteins, and AgB2 expression was detected by molecular analysis. Proteins of 37 to 60 kDa were recognized by 95.24% of the CE patients' sera but, with poor specificity. Statistically significant differences were found between serum protein extract recognition at 7 and 20 days of cell growth. The EGPE cell line is a laboratory source of antigens for improvement of CE serological diagnosis.

Zataria Multiflora bois as an auspicious therapeutic approach against Echinococcus granulosus: Current status and future perspectives

Hydatidosis caused by Echinococcus granulosus is a major zoonotic diseases. In addition to imposing heavy economic losses, the disease is a public health problem worldwide. The larval stage of the parasite (hydatid cyst) is formed in a wide range of domestic, wild and human beings as intermediate hosts. On the other, its recurrence has been reported anywhere as a reemerging disease. Although the cysts have some evading mechanisms, both human TH1 and TH2 cells subsets are stimulated. Because of increasing resistance and adverse effects of medications such as abnormalities of liver and other organs functions and abdominal pain, seeking alternative therapeutic approaches to be inexpensive, easy available, with low side effects and toxicity seems essential. However, the lack of information on the social and economic welfares of herbal medicines for the industrial scale application is a limitation. Zataria Multiflora bois (ZMB) has exhibited huge advantages and tremendous protoscolicidal effects as demonstrated by numerous studies and its combination therapies with anti-parasitic drugs have exerted desirable outcomes in vitro and in vivo. Noticeably, the compound confers negligible side effects or toxicity even at high concentrations. ZMB has exhibited promising inhibitory effects against hydatid cyst, particularly when combined with chemical drugs and in formulations of nanoemulsions. Its immunomodulatory effects include increase of nitric oxide production (NO) and protection of hepatic cells (Kupffer cells, fat-storing cells, and endothelial cells), enhancement of macrophages and T cells and increase of cytokines production. This study aimed at assessment of ZMB traits for application against hydatid cyst protoscolices.

Echinococcosis: Advances in the 21st Century

Echinococcosis is a zoonosis caused by cestodes of the genus Echinococcus (family Taeniidae). This serious and near-cosmopolitan disease continues to be a significant public health issue, with western China being the area of highest endemicity for both the cystic (CE) and alveolar (AE) forms of echinococcosis. Considerable advances have been made in the 21st century on the genetics, genomics, and molecular epidemiology of the causative parasites, on diagnostic tools, and on treatment techniques and control strategies, including the development and deployment of vaccines. In terms of surgery, new procedures have superseded traditional techniques, and total cystectomy in CE, ex vivo resection with autotransplantation in AE, and percutaneous and perendoscopic procedures in both diseases have improved treatment efficacy and the quality of life of patients. In this review, we summarize recent progress on the biology, epidemiology, diagnosis, management, control, and prevention of CE and AE. Currently there is no alternative drug to albendazole to treat echinococcosis, and new compounds are required urgently. Recently acquired genomic and proteomic information can provide a platform for improving diagnosis and for finding new drug and vaccine targets, with direct impact in the future on the control of echinococcosis, which continues to be a global challenge.

Extracellular vesicles from Echinococcus granulosus larval stage: Isolation, characterization and uptake by dendritic cells

The secretion of extracellular vesicles (EVs) in helminth parasites is a constitutive mechanism that promotes survival by improving their colonization and adaptation in the host tissue. In the present study, we analyzed the production of EVs from supernatants of cultures of Echinococcus granulosus protoscoleces and metacestodes and their interaction with dendritic cells, which have the ability to efficiently uptake and process microbial antigens, activating T lymphocytes. To experimentally increase the release of EVs, we used loperamide, a calcium channel blocker that increases the cytosolic calcium level in protoscoleces and EV secretion. An exosome-like enriched EV fraction isolated from the parasite culture medium was characterized by dynamic light scattering, transmission electron microscopy, proteomic analysis and immunoblot. This allowed identifying many proteins including: small EV markers such as TSG101, SDCBP, ALIX, tetraspanins and 14-3-3 proteins; proteins involved in vesicle-related transport; orthologs of mammalian proteins involved in the immune response, such as basigin, Bp29 and maspardin; and parasite antigens such as antigen 5, P29 and endophilin-1, which are of special interest due to their role in the parasite-host relationship. Finally, studies on the EVs-host cell interaction demonstrated that E. granulosus exosome-like vesicles were internalized by murine dendritic cells, inducing their maturation with increase of CD86 and with a slight down-regulation in the expression of MHCII molecules. These data suggest that E. granulosus EVs could interfere with the antigen presentation pathway of murine dendritic cells inducing immunoregulation in the host. Further studies are needed to better understand the role of these vesicles in parasite survival and as diagnostic markers and new vaccines.

Human cystic echinococcosis, caused by chronic infection with the larval stage of Echinococcus granulosus, affects over 1 million people worldwide. This helminth parasite secretes numerous excretory/secretory products that are in contact with host tissues where it establishes hydatid cysts. In this study, we comprehensively characterized extracellular vesicles (EVs) from E. granulosus protoscoleces and metacestodes, and demonstrated for the first time that the exosome-like vesicles from helminths can interact with host dendritic cells and carry several immunoregulatory proteins. This study provides valuable data on cestode-host immune communication. Nevertheless, further research on EVs is needed to fully understand their role in the parasite-host interface and obtain new data concerning their function as therapeutic markers and diagnostic tools.

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.

Performance of the commercially available SERION ELISA classic Echinococcus IgG test for the detection of cystic echinococcosis in clinical practice

Diagnosis of cystic echinococcosis (CE) is at present mainly based on imaging techniques. Serology has a complementary role, partly due to the small number of standardized and commercially available assays. Therefore we examined the clinical performance of the SERION ELISA classic Echinococcus IgG test. Using 10 U/ml as a cut-off point, and serum samples from 50 CE patients and 105 healthy controls, the sensitivity and specificity were 98.0% and 96.2%, respectively. If patients with other infectious diseases were used as negative controls, the specificity decreased to 76.9%, which causes poor positive predictive values. However, if results between 10 and 15 U/ml are classified as indecisive, the specificity of positive results (≥15 U/ml) increased to 92.5% without greatly affecting the sensitivity (92.0%). Using this approach in combination with imaging studies, the SERION ELISA classic Echinococcosis IgG test can be a useful aid in the diagnosis of CE.

Expression of Echinococcus granulosus recombinant EgAg5-38 sub-unit and P-29 antigens and evaluation of their diagnostic potential for cystic echinococcosis in buffaloes

There are no routine, reliable diagnostic methods for detection of Echinococcus granulosus infection, the causative agent of cystic echinococcosis in human and domestic animals. Two recombinant proteins EgAg5-38 sub-unit and P-29 of E. granulosus were expressed in prokaryotic expression vectors. The diagnostic potential of these two recombinant proteins was evaluated in the detection of cystic echinococcosis in buffaloes in IgG-ELISA. TheEgAg5-38 sub-unit and P-29 recombinant protein reacted fairly with the hydatid infected buffaloes with EgAg5-38 sub-unit showing sensitivity and specificity of 67.9 and 78.8%, respectively. However, the recombinant P-29 protein showed a higher sensitivity of 82.1% but a low specificity of 43.9% in the detection of hydatid infection in buffaloes. Cross-reactivity of these recombinant antigens in buffaloes naturally infected with several gastrointestinal trematodes and Sarcocystis was studied. The results showed that both these antigens cross-reacted with most of these parasites of buffaloes. Present study is the first report on the evaluation of diagnostic potential of E. granulosus recombinant EgAg5-38 sub-unit and P-29 antigens in buffaloes.