Host serum protein levels in cysts of human hydatidosis

Application and evaluation of native antigen B from Echinococcus granulosus sensu stricto and E. canadensis alone or mixture for serodiagnosis of human G1-G3 and G6/G7 genotypes cystic echinococcosis sera, using ELISA and Western blotting

Cystic echinococcosis (CE) is one of the most important helminthic diseases in the world with different genotypes distribution. The application of specific genotype antigens together with sera from patients with specific cyst genotypes have not been reported, so far. The present study aimed to apply and evaluate native AgB from Echinococcus granulosus sensu stricto (Eg) and Echinococcus canadensis (Ec) alone or mixture for serodiagnosis of human G1-G3 and G6/G7 genotypes cystic echinococcosis sera, using ELISA and Western blotting. A total of 47 human sera along with 47 human CE cysts were collected. CE genotypes were determined. Native AgB were prepared from E. granulosus s.s and E. canadensis genotypes. ELISA and Western blot were performed on human specific G1-G3 and G6/G7 genotypes sera. Species specific native AgB were used alone or mixed. The sensitivity of ELISA using alone and mixed 1Eg-1Ec, 1Eg-2Ec, and 2Eg-1Ec of native AgB from E. granulosus s.s and E. canadensis genotypes for human G1-G3 sera were 92.10, 89.47, 97.37, 100, and 100%, respectively; while using AgBs, alone and mixed for human G6/G7 sera were 100%. The sensitivity of Western blotting using native AgB of E. granulosus s.s and E. canadensis genotypes alone and mixed 2Eg-1Ec were 78.95% and 100% for human G1-G3 and G6/G7 genotypes sera, respectively. The mixture of AgB from Echinoccus granulosus sensu stricto and Echinococcus canadensis genotypes increased ELISA sensitivity for the diagnosis of human CE. Preparation and application of native AgB from specific and prevalent genotypes of CE in endemic regions is recommended.

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.

Proteomic characterisation of Echinococcus granulosus hydatid cyst fluid from sheep, cattle and humans

The hydatid cyst fluid (HCF) of Echinococcus granulosus is a complex biological mixture containing a wide range of proteins of both parasite and host origin. Using a combination of in- and off-gel protein fractionation techniques and tandem mass spectrometry 130 HCF proteins were identified from fertile cysts of sheep and human origin and infertile cysts from cattle. Forty-eight proteins were of parasite origin including Antigen 5 and Antigen B--the most abundant parasite proteins, thioredoxin, low-density lipoprotein receptors, cyclophilin and ferritin. Across the three host species the identified HCF proteins were broadly similar although, based on spectral counts, three proteins, including an antigen B isoform, were more abundant in sheep HCF compared with the fluids of cattle and human origin. Eighty-two host proteins were identified in HCF from the three species. Host plasma proteins were the most abundant, although approximately thirty of the host proteins that were identified are not considered constituents of plasma. The identification of parasite heat shock proteins and annexin A13 exclusively in infertile cysts, along with an increased spectral count for cathepsin B, supports the hypothesis of increased cellular stress and apoptosis as the cause of their infertility.

Eosinophil cationic protein damages protoscoleces in vitro and is present in the hydatid cyst

Eosinophils are locally recruited during the establishment and chronic phases of cystic hydatidosis. This study provides evidence that eosinophil cationic protein (ECP), one of the major components of eosinophil granules, can damage Echinococcus granulosus protoscoleces (PSC). The toxicity of ECP was investigated in vitro by following parasite viability in the presence of this protein. ECP was found to damage PSC at micromolar concentrations; the effect was blocked by specific antibodies and heparin, and was more severe than the one caused by similar concentrations of RNase A, suggesting that the cationic nature of ECP, and not its ribonuclease activity, is involved in toxicity. This observation may highlight the capacity of eosinophils to control secondary hydatidosis, derived from PSC leakage from a primary cyst. To further assess the relevance of the previous result during infection, the presence of eosinophil proteins was investigated in human hydatid cysts. ECP was found to be strongly associated with the laminated layer of the cyst wall, and present at micromolar concentrations in the hydatid fluid. Overall, these results demonstrate that eosinophils degranulate in vivo at the host-parasite interface, and that the released ECP reaches concentrations that could be harmful for the parasite.

Usefulness of hydatid cyst fluid of Echinococcus granulosus developed in mice with secondary infection for serodiagnosis of cystic Echinococcosis in humans

The aim of this work was to assess the usefulness of hydatid cyst fluid (HCF) of Echinococcus granulosus, obtained from mice experimentally infected with hydatid cyst tissue homogenates, for the serodiagnosis of cystic echinococcosis (CE) in humans. The sensitivity and specificity of HCF obtained from mice for the detection of immunoglobulin G (IgG) antibodies in the sera of CE patients were compared with those of HCF from sheep and/or from a human CE patient by using immunoblotting (IB) and an enzyme-linked immunosorbent assay (ELISA). HCFs obtained from three different host species all were highly useful for immunoblotting, and sera from 19 (95%) of 20 CE patients equally recognized the antigen B subunit (approximately 8 kDa). HCF from mice showed a cross-reaction with 9 of 20 alveolar echinococcosis (AE) sera (45%), whereas HCFs from two other host species cross-reacted with 14 of the AE sera (70%). Although 2 (10%) of 20 sera from neurocysticercosis (NCC) patients were false positive with HCF from both sheep and humans, none of these sera showed a positive reaction with HCF from mouse origin. ELISAs with HCFs from both mouse and sheep origins detected all 20 CE and AE sera; however, these ELISAs showed 45% (9 of 20) and 60% (12 of 20) false-positive reactions with 20 NCC sera, respectively. The presence of nonspecific human IgG in HCF obtained from a CE patient prevented us from applying it to the ELISA. HCF of E. granulosus, obtained from laboratory mice with a secondary infection with hydatid cyst tissue homogenates, appears to be highly useful for the serodiagnosis of CE in humans and may be useful in domestic animals.

In-vitro susceptibility of hydatid cysts of Echinococcus granulosus to nitric oxide and the effect of the laminated layer on nitric oxide production

Murine hydatid cysts of Echinococcus granulosus were incubated in vitro in the presence of nitric oxide produced from S-nitroso-N-acetylpenicillamine (SNAP) or interferon-gamma activated peritoneal macrophages. In both situations, evidence of cyst damage and death was observed by microscopy in over 77% of cysts after 3 days, indicating that intact hydatid cysts could be susceptible to a Th1 driven macrophage attack. A crude extract of the laminated layer from cysts was found to be able to reduce the production of nitric oxide from activated macrophages in vitro and in vivo and this may have been due to phagocytosis of laminated layer fragments by the macrophages. The results indicate that, although cysts may be susceptible to the effects of nitric oxide, the laminated layer may be involved in downregulating nitric oxide production.

Characterization and optimization of bovine Echinococcus granulosus cyst fluid to be used in immunodiagnosis of hydatid disease by ELISA

The aim of this work was to assess the influence in the diagnostic value for human hydatid disease of the composition of bovine hydatid cyst fluid (BHCF) obtained from fertile (FC) and non-fertile cysts (NFC). Eight batches from FC and 5 from NFC were prepared and analysed with respect to chemical composition: total protein, host-derived protein, carbohydrate and lipid contents. No differences were observed in the first two parameters but carbohydrate and lipid contents were shown to be higher in batches from FC than in those from NFC. Bands of 38 and 116 kD in SDS-PAGE profiles were observed to be present in BHCF from FC only. Two pools were prepared from BHCF batches obtained from FC (PFC) and NFC (PNFC), respectively. Antigen recognition patterns were analysed by immunoblot. Physicochemical conditions for adsorption of antigens to the polystyrene surface (ELISA plates) were optimized. The diagnostic value of both types of BHCF as well as the diagnostic relevance of oxidation of their carbohydrate moieties with periodate were assessed by ELISA using 42 serum samples from hydatid patients, 41 from patients with other disorders, and 15 from healthy donors. Reactivity of all sera against native antigen were tested with and without free phosphorylcholine. The best diagnostic efficiency was observed using BHCF from periodate-treated PFC using glycine buffer with strong ionic strength to coat ELISA plates.

Evaluation of excretory/secretory products of larval Taenia solium as diagnostic antigens for porcine and human cysticercosis

Excretory/secretory antigens (ES) of larval Taenia solium were obtained by maintaining the bladder worms in Medium 199 for 3 days. Analysis by SDS-PAGE showed that ES antigens consisted of at least 19 polypeptides, with M(r) ranging from 14-116 kDa. Analytical isoelectric focusing revealed eight bands with acidic pI. An immunocytolocalization study using the peroxidase method demonstrated the presence of ES epitopes on the tegument of the wall of the spiral canals of bladder worms. The specificity of ES antigens was evaluated by EITB, ELISA and FAST-ELISA using antisera against the common parasites of Chinese pigs and man. ES antigens cross-reacted with the antiserum against larval T. hydatigena of pigs. However, these antigens were generally more specific in diagnosing human cysticercosis. Three host-like molecules with molecular masses 43, 58 and 66 kDa were present in the ES products.

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.

Partial purification and comparison of the kinetic properties of ovine liver Echinococcus granulosus hydatid cyst fluid malate dehydrogenase and the cytoplasmic enzyme from the host liver

Ovine liver Echinococcus granulosus hydatid cyst fluid and cytoplasmic healthy ovine liver malate dehydrogenases were purified 24- and 30-fold by Sephadex G-200 and DEAE-Sephadex chromatography. Both enzymes were eluted with the same elution volume and the same salt concentration from the respective columns. The pH optimum of the enzymes from both sources was 8.4 in either Tris-HCl or barbital buffer. The Km values for oxaloacetate were 0.211 and 0.200 mM for hydatid cyst fluid and healthy ovine liver enzymes, respectively. The Km values for NADH were 0.220 and 0.213 mM for hydatid cyst fluid and healthy ovine liver enzymes, respectively. Enzyme from both sources demonstrated similar heat denaturation patterns. Both enzyme preparations were inhibited at high concentrations of either substrate. Neither enzyme was inhibited by para-hydroxymercuribenzoate or fumarate, and both enzyme preparations were specific for NADH as a cofactor. The results are discussed in terms of the possible infiltration of the host enzyme into the cyst fluid.

Preliminary characterization of anticomplementary components of hydatid cyst fluid

Sheep hydatid cyst fluid (SHCF) was fractionated on Sephacryl HR S-200 and the anticomplementary activity (alpha-C activity) determined in the fractions obtained; 67% of total alpha-C activity of SHCF was recovered in the void volume fraction (SHCF-I) which contained 61% of SHCF carbohydrates. The bulk of the activity of SHCF-I was eluted by FPLC chromatofocusing on Mono P HR at pH 5.9. After heating at 100 degrees C for 15 min, SHCF and SHCF-I conserved 74 and 54%, respectively of their alpha-C activity. In addition, 37 and 11% of SHCF and SHCF-I alpha-C activity, respectively bound to Protein A. Components not bound to Protein A (SHCFPA and SHCF-IPA) were fractionated on Con A-Sepharose; 71 and 65%, respectively of their total alpha-C activity was retained by this lectin indicating the presence of alpha-D mannoside and alpha-D glucoside residues in the active molecules. Our results suggest that SHCF could contain two classes of alpha-C components: immune complexes and thermoresistant molecules with high carbohydrate content.

Echinococcal disease and mycobacterial infection

The clinical and radiological features of five patients with echinococcal disease in whom mycobacterial infection was also present are described. Three had clinically significant disease due to Mycobacterium tuberculosis (two patients) and M. fortuitum-chelonae (one patient), whilst in two others secondary infection with M. gordonae had occurred. In all cases the mycobacterium infection was found within or close to the anatomical confines of the echinococcal disease, as determined clinically, radiologically or histologically, which suggested a saprophytic-supportive role of the hydatid cyst for the mycobacterium to survive. Mycobacterial disease should be borne in mind in patients with echinococcal disease who remain unwell despite apparently effective treatment for the hydatid cyst.

Protein antigens in the cyst fluid of Taenia saginata cysticerci

Taenia saginata cyst fluid proteins from 4, 8, 12 and 16-week-old cysticerci were analysed by a combination of direct 125I radio-isotope labelling, immunoprecipitation using a panel of sera from infected cattle infected with T. saginata and SDS-PAGE. Protein antigens of 12, 14, 16, 20 and 26 kDa were identified in all of the cyst fluids examined. These were immunogenic and were precipitated by serum taken from cattle from 8 weeks after infection onwards and were therefore considered to be of diagnostic potential. A 185 kDa protein antigen found only in the cyst fluid of 4-week-old cysticerci and a 43 kDa protein antigen first detected in cyst fluid from 8-week-old cysticerci were also identified but were considered to be of more limited diagnostic potential due to their restricted presence. An apparently non-immunogenic 67 kDa protein, found in all the cyst fluids examined, may have been host serum albumin.