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PubMed2004

Echinococcus granulosus-specific T-cell lines derived from patients at various clinical stages of cystic echinococcosis.

To investigate the role of T lymphocytes in the immune response to Echinococcus granulosus, using sheep hydatid fluid (SHF) and antigen B (AgB), we generated T-cell lines from patients with active, transitional and inactive hydatid cysts. We established 16 T-cell lines, eight specific to SHF and eight specific to AgB. At surface phenotyping 88-98% of cells displayed the helper/inducer CD4 antigen. In all patients, at all clinical stages of hydatid cyst disease, T-cell stimulation with SHF and AgB invariably amplified a large number of almost identical Vbeta subfamily fragments. Irrespective of antigen-specificity, the two cell lines from the patient with an inactive cyst had a Th1 profile, because they exclusively expressed and produced IFN-gamma. Conversely, the T-cell lines derived from the seven patients with active and transitional hydatid cysts had mixed Th1/Th2 and Th0 clones. The functional characteristics of the 16 T-cell lines differed markedly in the various clinical stages of cystic echinococcosis, thus providing new in vitro evidence that Th1 lymphocytes contribute decisively to the inactive stage of hydatid disease, Th2 lymphocytes in the active and transitional stages. The parasite-specific T-cell lines, especially the two Th1 lines from the patient with an inactive cyst, may help identify Th1 protective epitopes on SHF and AgB.

Adolescent↗
PubMed1990

Echinococcus granulosus: the potential use of specific radiolabelled antibodies in diagnosis by immunoscintigraphy.

Diagnosis of hydatid disease in man is frequently dependent on the imaging of cysts in situ by techniques such as ultrasonography and CAT scans. Such methods are useful but are not specific and can lead to errors in diagnosis. The present work reports preliminary experiments on the development of a specific imaging technique for hydatid cysts using radiolabelled antibodies. A purified preparation of antigen B of hydatid fluid was used to raise polyclonal antisera in rabbits and the resulting affinity-purified IgG labelled with 131I. Gerbils with an established Echinococcus granulosus infection were injected intraperitoneally with the labelled antibody and imaged 48 h later with a gamma camera. Hydatid cysts could be identified within the peritoneal cavity and post-mortem assessment of activity showed the cysts to contain approximately four times as much activity as the surrounding organs thereby indicating successful targeting of the antibody to the cysts.

Animals↗
PubMed2005

Screening of an Echinococcus granulosus cDNA library with IgG4 from patients with cystic echinococcosis identifies a new tegumental protein involved in the immune escape.

The worldwide problem of chronic Echinococcus granulosus disease calls for new parasite-derived immunomodulatory molecules. By screening an E. granulosus cDNA library with IgG4 from patients with active cystic echinococcosis, we identified a cDNA that encodes a predicted partial protein that immunofluorescence studies localized in the protoscolex tegument and on the germinal layer of cyst wall. We named this protein EgTeg because the 105 amino acid sequence scored highest against a family of Schistosoma tegumental proteins. Evaluating the role of EgTeg in the human early inflammatory response we found that EgTeg significantly inhibited polymorphonuclear cell (PMN) chemotaxis. Cytometric analysis of intracellular cytokines disclosed a significantly higher percentage of cells producing IL-4 than IFN-gamma (P = 0.001, Student's t-test) in T lymphocytes from patients with cystic echinococcosis stimulated with EgTeg. EgTeg induced weak Th1-dependent proliferation in 42% of patients' peripheral blood mononuclear cells. In immunoblotting (IB) analysis of total IgG and IgG subclass responses to EgTeg in patients with cystic echinococcosis, patients with other parasitoses, patients with cystic lesions and healthy controls, total IgG specific to EgTeg yielded high sensitivity (73%) but low specificity (44%) precluding its use in immunodiagnosis. Conversely, IgG4 specific to EgTeg gave acceptable sensitivity (65%) and high specificity (89%) suggesting its use in immunodiagnosis to confirm ultrasound documented cysts suggestive of E. granulosus. Because the new tegumental antigen EgTeg inhibits chemotaxis, induces IL-4-positive T lymphocytes and noncomplement fixing antibodies (IgG4) it is an immunomodulatory molecule associated with chronic infection.

Amino Acid Sequence↗
PubMed2006

Echinococcus multilocularis metacestodes modulate cellular cytokine and chemokine release by peripheral blood mononuclear cells in alveolar echinococcosis patients.

Infection with the cestode Echinococcus multilocularis causes human alveolar echinococcosis (AE), a life-threatening disease affecting primarily the liver. Despite the severity of AE, clinical symptoms often develop only many years after infection, which suggests that E. multilocularis has developed mechanisms which depress anti-parasite immune response, thus favouring immune evasion. In this study we examined the production of cytokines, chemokines and the expression of CD molecules on peripheral blood mononuclear cells (PBMC) from AE patients and healthy controls in response to E. multilocularis metacestode culture supernatant, viable E. multilocularis vesicles and E. multilocularis vesicle fluid antigen in vitro. After 48 h of co-culture, E. multilocularis metacestode culture supernatant and E. multilocularis vesicles depressed the release of the proinflammatory cytokine interleukin (IL)-12 by PBMC. This effect was dose-dependent and a suppression of tumour necrosis factor (TNF)-alpha and IL-12 was observed even when PBMC were activated with lipopolysaccharide (LPS). Comparing proinflammatory cytokine release by AE patients and controls showed that the release of IL-12 and TNF-alpha was reduced in AE patients, which was accompanied by an increased number of CD4+ CD25+ cells and a reduced release of the Th2 type chemokine CCL17 (thymus and activation regulated chemokine, TARC), suggesting an anti-inflammatory response to E. multilocularis metacestode in AE patients. Instead the production of interferon (IFN)-gamma and the expression of CD28 on CD4+ T cells were increased in PBMC from AE patients when compared to controls. This was accompanied by a higher release of the Th2-type chemokine CCL22 (macrophage derived chemokine, MDC) supporting that E. multilocularis also generates proinflammatory immune responses. These results indicate that E. multilocularis antigens modulated both regulatory and inflammatory Th1 and Th2 cytokines and chemokines. Such a mixed profile might be required for limiting parasite growth but also for reducing periparasitic tissue and organ damage in the host.

Adolescent↗
PubMed1982

Immune recognition of Echinococcus granulosus. 1. Parasite-activated, primary transformation by normal murine lymph node cells.

Culture of murine lymph node cells together with living protoscolices of Echinococcus granulosus is described. The presence of the parasite induced potent blastic transformation in lymphocytes of unimmunized mice as indicated by tritiated thymidine incorporation. The response was markedly reduced by killing the parasite immediately prior to culture. No blastogenic activity was detectable in supernatants from living parasites cultured alone. Protoscolices from artificially infected syngeneic mice were effective stimuli, as were protoscolices from naturally infected horse and sheep. Stimulation was not detectably reduced by maintenance of the parasite in vitro for 72 h at 37 degrees C or for 46 days at 4 degrees C prior to culture. It is concluded that unprimed lymphocytes are stimulated to transform by surface contact with a stimulator synthesized, but not secreted, by the parasite. The biological significance of the reaction and its possible contribution to immunosuppression are discussed.

Animals↗
PubMed1985

Purification and characterization of a specific antigen from Echinococcus multilocularis.

A polypeptide (Em2a) purified by affinity chromatography from the Echinococcus multilocularis metacestode showed a high degree of purity as assayed by SDS-PAGE and analytical isoelectrical focusing. A minor contamination with host albumin was revealed. Estimation of relative mol. mass gave a value of 54,000. The isoelectric point was found to be 4.8. Antigenic activity of the polypeptide was demonstrated by immunoprecipitation and western blotting. In these assays the protein was recognized only by homologous sera from patients infected with larval E. multilocularis. This antigen (Em2a) did not react in the ELISA with sera from patients infected with heterologous helminths; these sera were highly cross-reacting with antigen from E. granulosus hydatid fluid. Seventy-three (94%) from 78 investigated patients (alveolar echinococcosis) showed a seropositive reaction with the polypeptide Em2a.

Animals↗
PubMed1989

Identification of protein components of Echinococcus granulosus protoscolex antigens for specific serodiagnosis of E. granulosus infection in dogs.

Proteins of Echinococcus granulosus protoscolex excretory/secretory or deoxycholate solubilized somatic antigens were radiolabelled with 125I and immunoprecipitated with sera from dogs naturally or experimentally infected with E. granulosus and various control dog sera. Analysis of immunoprecipitates was performed using one- and two-dimensional gel electrophoresis to identify antigenic protein components specific for E. granulosus. Using both electrophoretic techniques, a basic component of Mr 27,000 and an acidic component of Mr 94,000 were defined in both excretory/secretory and somatic protoscolex antigens, and were specifically identified by 95% and 62% of 21 sera from E. granulosus-infected dogs, respectively. An abundant component of Mr 35,000 was identified by 100% of these dogs, parts of which were E. granulosus specific. Results of this study should allow identification of specific recombinant antigens for routine serodiagnosis of E. granulosus infection in dogs.

Animals↗
PubMed1990

Humoral and cellular immune response in mice and dogs induced by a recombinant Echinococcus multilocularis antigen produced by a Salmonella typhimurium vaccine strain.

A gene fragment (II/3-10) from the cestode Echinococcus multilocularis coding for a species-specific antigen was expressed in the live attenuated Salmonella typhimurium vaccine strain LT2 M1C. The recombinant vaccine (S. typhimurium + pVM II/3-10) was assessed for its potential to induce both a humoral and cell-mediated immune response in mice and dogs. Both subcutaneous and peroral administration of the vaccine resulted in antibody synthesis and lymphocyte priming of C57BL/6J mice against S. typhimurium antigens as well as against the recombinant E. multilocularis antigen. Two vaccinated (subcutaneous and peroral) dogs showed a strong humoral immune response to S. typhimurium antigens and to the recombinant E. multilocularis antigen, but proliferation of peripheral blood lymphocytes was not detectable against the bacterial S. typhimurium antigens. Regarding the recombinant E. multilocularis antigen, borderline lymphocyte proliferation was demonstrated following subcutaneous and none following peroral administration of the recombinant vaccine to dogs.

Animals↗
PubMed1991

Detection of antibodies against glycolipids of Echinococcus multilocularis metacestodes in sera of patients with alveolar hydatid disease.

Glycosphingolipids extracted from Echinococcus multilocularis metacestodes were tested against sera from patients with alveolar hydatid disease (AHD). The tests were performed first by ELISA then by immunostaining on thin layer chromatography. A binding between the parasite glycolipids and antibodies of AHD human sera was observed by ELISA. The glycolipids related to this binding were specifically parasite neutral glycosphingolipids. No reaction was observed with parasite acid glycolipids nor with neutral glycolipid extracts from human or mongolian gerbil erythrocytes. Comparison between absorbance values of 25 AHD sera and 20 control sera showed significant differences. Similar results were obtained with sera from hydatid cyst patients. Sera from patients with other parasitoses (schistosomiasis, strongyloidosis or paludism) were also tested. The reactive fractions were identified by immunostaining on thin layer chromatography with AHD sera, they were neutral glycosphingolipids containing at least two carbohydrate residues. These results were compared with chromatograms obtained with hydatid cyst human sera and discussed.

Animals↗
PubMed1993

Arginine-dependent generation of reactive nitrogen intermediates is instrumental in the in vitro killing of protoscoleces of Echinococcus multilocularis by activated macrophages.

The interaction between protoscoleces of Echinococcus multilocularis and activated murine macrophages was examined in this study. Marked protoscolicidal activity was displayed by peritoneal macrophages (PM) activated with interferon-gamma (IFN-gamma), or IFN-gamma plus lipopolysaccharide. Pretreatment of the parasites with heat-inactivated specific murine infection serum, but not with normal serum rendered them more susceptible to PM killing. NG-monomethyl-L-arginine, a competitive inhibitor of L-arginine completely inhibited the killing activity of activated PM, while reconstitution of arginine-free medium with L-arginine restored the killing properties of the activated PM. The results show that activated PM have the ability to kill E. multilocularis protoscoleces in vitro and suggest that reactive nitrogen intermediates (RNI) play an important role in the mechanism. An oxygen-mediated mechanism did not appear to play a role because scavengers of reactive oxygen species did not reduce the killing activity. The arginine-dependent killing mechanism was enhanced by superoxide dismutase (SOD), probably because SOD might prolong the effect of nitric oxide. Secretion of RNI by activated macrophages may be capable of a significant role in preventing of the dissemination of E. multilocularis infection in vivo.

Animals↗
PubMed1993

Chromatographic and antigenic properties of Echinococcus granulosus hydatid cyst-derived glycolipids.

The neutral and acidic fraction glycolipids of Echinococcus granulosus metacestode tissue compartments were isolated, defined by their chromatographic and antigenic properties, and assessed as to their efficacy as antigens in the serodiagnosis of human hepatic cystic and alveolar echinococcosis, and other helminthiases. Analyses were accomplished by thin-layer chromatography immunostaining and ELISA. The neutral glycolipid fraction's major carbohydrate epitope was the same as or very similar to that of Taenia crassiceps neutral glyco(sphingo)lipids, as represented by the 'neogala'-series core structure. The blood group-active, carbohydrate epitope P1 was expressed by a number of neutral fraction glycolipid component bands. The reverse-phase, thin-layer chromatography-isolated neutral fraction glycolipid component, designated Ag1, was efficient in the serological discrimination of cystic echinococcosis medium to high-titred sera. Ag1 did not specifically discriminate low-titred sera, i.e., other human helminthiases. The detected sialic acid residues of the acidic fraction glycolipids, on enzymatic cleavage, were identified as N-acylneuraminic acid and terminal. The acidic fraction glycolipids exhibited the paradox of only chemically minor components being antigenic towards cystic and alveolar echinococcosis infection sera. The combined acidic fraction glycolipid components Ra and Rx were capable of serological discrimination between cystic echinococcosis, alveolar echinococcosis and other helminthiases.

Animals↗
PubMed1993

Ultrastructural localization of major hydatid fluid antigens in brood capsules and protoscoleces of Echinococcus granulosus of human origin.

Monospecific rabbit antisera obtained through experimental immunization with previously purified proteins were used in the ultrastructural localization of two hydatid fluid antigens, in brood capsules and protoscoleces of Echinococcus granulosus of human origin. The antigen-antibody reaction was revealed by a colloidal gold based method. Reaction was evident in the connective region of the germinal membrane and in the parenchyma of the protoscoleces. Both antigen 5 and antigen B were located in the interstitial material between the parenchymal cells and precisely associated with disorganized areas. The brood capsule wall and the brood capsule contents, the tegument of the protoscoleces, the parenchymal cells, the muscle cells, the calcareous corpuscles and the hooks did not contain antigen 5 or antigen B. Label was not observed in the lumen of the collecting ducts or in the flame cells, although antigen 5 was evident in the periluminal cytoplasm. The origin of the antigens and their release are discussed.

Animals↗
PubMed1994

Identification and diagnostic value of a major antibody epitope on the 12 kDa antigen from Echinococcus granulosus (hydatid disease) cyst fluid.

An IgG1 monoclonal antibody (MoAb), designated C9E7H8, has been produced against an epitope on the 12 kDa antigen of Echinococcus granulosus cyst fluid, believed to represent the smallest subunit of antigen B. This MoAb, raised against purified 12 kDa antigen eluted from a reducing SDS-PAGE gel, demonstrated strong binding to native sheep cyst fluid in ELISA and recognition of all three subunits of antigen B (at 12, 16, 23 kDa) by immunoblot under both reducing and non-reducing conditions. Immunoblot analysis also indicated that the complementary epitope is conserved amongst cyst fluids from different intermediate hosts of E. granulosus, including fluids from cysts of two distinct strains, and is present in cyst fluid from E. multilocularis. The monoclonal displays binding to a cDNA clone, EgPS-3, which we have previously shown expresses part of the 12 kDa molecule. EgPS-3, expressed as a glutathione-S-transferase fusion protein, was successful in positive detection of 74% of cystic hydatid patients, although cross-reactions were observed with 25% of sera from alveolar hydatid and 22% of sera from schistosomiasis japonica patients. Three peptides, based on the predicted amino acid sequence of EgPS-3, showed increased specificity but slightly reduced sensitivity in the detection of antibody from E. granulosus patients. The predominant epitope recognized by human antibody occurs in the N-terminal 27 amino acids (peptide 65) of EgPS-3 which also correlates with the location of the monoclonal antibody epitope.

Amino Acid Sequence↗
PubMed1995

Further characterization of the 38 kDa antigen from Echinococcus granulosus (hydatid disease) cyst fluid: evidence for antigenic heterogeneity and reactivity with anti-P1 antibodies.

A panel of 5 IgM and 6 IgG1 monoclonal antibodies (MoAbs) was produced against a band, eluted from a reducing SDS-PAGE gel, containing the 38 kDa subunit of antigen 5 (Ag 5) from Echinococcus granulosus cyst fluid; seven of the MoAbs were shown subsequently to bind epitopes on Ag 5 but none recognized phosphorylcholine or periodate-sensitive carbohydrate epitopes. Differences in the fine specificity of the MoAbs were apparent and, upon reduction, heterogeneity in 38 kDa components from hydatid cyst fluids of different intermediate host origin was revealed by peptide fingerprinting and immunoblotting using the MoAbs. One of the IgG1 MoAbs (ED9) was able to distinguish a reduced 38 kDa molecule in cyst fluids from two distinct genotypes--the horse/dog and sheep/dog strains--of E. granulosus and this may have implications for hydatid serology, immunoepidemiology and strain typing. Furthermore, epitopes on this 38 kDa component or on a different molecule with the same or similar M(r) are reactive with anti-P1 blood group antigen antibodies and this could result in false-positive reactions where sera from P2 patients with suspected hydatid disease are tested by immunoblot or immunoprecipitation analysis.

Animals↗
PubMed1995

Study of the in vitro activation of the complement alternative pathway by Echinococcus granulosus hydatid cyst fluid.

In the present study we have investigated the fluid phase activation of the complement (C) alternative pathway by Echinococcus granulosus sheep hydatid cyst fluid (SHCF) and its higher molecular weight fraction (SHCF-I) by quantitating the formation of both the terminal C intermediary C5b6 complex and the terminal C complex (TCC). Our results show that in vitro C activation progresses beyond the C5 step suggesting that potentially lytic complexes may be generated in vivo. In addition, SHCF and SHCF-I glucidic moieties are probably involved in C activation since 80% and 86% of SHCF and SHCF-I activity respectively was destroyed by periodate oxidation. Furthermore, partial deglycosylation with Peptide N-Glycosidase F of SHCF-I which had been digested with Pronase E, released an active fraction (MW < 14 KDa) which bound to Soybean agglutinin, suggesting that N-linked oligosaccharides containing alpha- or beta-linked N-acetyl galactosamine play a role in C activation by SHCF.

Acetylgalactosamine↗
PubMed1996

Characterization of T-cell immune responses of Echinococcus multilocularis-infected C57BL/6J mice.

Specific and non-specific parasite-induced changes in lymphocyte responses were analysed in C57/BL/6J mice after intrahepatic infection with Echinococcus multilocularis. Spleen cells harvested at selected times after infection were in vitro stimulated with mitogens or a crude soluble parasite extract (EmAg) at an optimized dose. Cell proliferative responses to Con-A were not modified by the infection over the first 22 weeks. In contrast, LPS-induced responses were decreased from the 13th week. A strong CD4+ proliferative T-cell response to the parasitic extract of infected mouse spleen cells was observed at the early stage of infection. This response then progressively decreased but remained significantly higher than that of control mice until the 19th week of infection. Cytokine production was investigated after in vitro EmAg stimulation of spleen cells. IFN-gamma, IL-2, IL-5 were produced within the first weeks after infection whereas the detection of IL-10 was slightly delayed. Thus, the promotion of the disease does not appear associated with the expansion of one rather than another T-cell subset in C57BL/6J mice. A general immunosuppression affecting both mitogenic and parasite-specific T-cell responses was observed at the end of the infection.

Animals↗
PubMed2003

The Echinococcus granulosus antigen EgA31: localization during development and immunogenic properties.

EgA31 is a fibrillar protein from Echinococcus granulosus that behaves as a potent antigen during infestation of dogs. The localization of this antigen during development of the parasite was investigated by immunohistochemistry in optical and electron microscopy. The protein is mostly abundant in the microtriches and subtegumental cells of the adult, whereas it is absent from protoscolex microtriches. Eggs, the periphery of calcareous corpuscles, and the germinal layer were other sites of accumulation. Immunogenicity of different domains of the protein was assessed during experimental infection of dogs. It was shown that the polypeptide encoded by the Pst I-Hind III fragment of the complete cDNA is the most antigenic during the infection. The uses of such polypeptide for infection diagnosis and as a candidate vaccine protein are discussed.

Animals↗
PubMed1991

Serological (Em2-ELISA) and parasitological examinations of fox populations for Echinococcus multilocularis infections.

Serum or body fluid samples of 1,006 foxes were investigated in an ELISA for antibodies against a highly sensitive and specific antigen (Em2-antigen) of Echinococcus multilocularis. Parasitological examinations of the intestines and simultaneous serological examinations were carried out in 505 foxes: A group of 98 blue foxes (Alopex lagopus) from Norwegian fox farms did not contain intestinal stages of E. multilocularis and was clearly sero-negative in Em2-ELISA. On the other hand in red foxes (Vulpes vulpes) originating from European areas known to be endemic for E. multilocularis the following average prevalence rates were found: 244 foxes from Southern Germany, E. multilocularis prevalence 55% and sero-prevalence 60%; 139 foxes from Austria, E. multilocularis prevalence 4% and sero-prevalence 12%. Serological identification of individual foxes with or without intestinal E. multilocularis infection was not possible. Only serological (no parasitological) examination in 402 foxes originating from endemic areas in Switzerland resulted in a sero-prevalence rate of 37%. Sero-prevalence was only 6% and 4% in 54 and 26 other foxes, respectively, originating from Swiss and German areas where E. multilocularis has not yet been reported. Negative control Norwegian (farmed) silver foxes (n = 43) were all sero-negative. The specificity of the Em2-ELISA was confirmed by negative Em2-serologies with sera from dogs infected with intestinal and tissue dwelling helminth species (with the exception of two from 24 dogs infected with E. granulosus).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗