Does the expression of granzyme B participate in inflammation, fibrosis, and fertility of hydatid cysts?

Echinococcus granulosus (sensu lato), a cestode that is endemic in Egypt, causes cystic echinococcosis (CE), a significant but neglected zoonotic disease that is prevalent throughout the world. Infected hydatid cysts are classified as fertile or non-fertile based on the presence of protoscoleces; nevertheless, the mechanism of non-fertile CE cysts remains unknown. The study aimed to assess whether granzyme B (GrB) expression and CD4 + /CD8 + could be related to the induction of non-fertile CE cysts. A total of fifty-eight individuals diagnosed with visceral hydatid cysts were selected, and they were further divided according to cyst fertility into fertile and non-fertile. Immunohistochemistry for CD4, CD8, and GrB was done. According to the results, hydatid cysts are common in adults and have no gender preference. The same clinical and laboratory data were shared by patients with fertile and non-fertile cysts (p = 0.186). GrB expression was not impacted by the fibrous deposition inside the hydatid cyst wall (p = 0.85); however, GrB was significantly correlated with the inflammatory density (p = 0.005). GrB expression was also found to be significantly higher in non-fertile cysts (p = 0.04). GrB expression is positively correlated with CD4 and CD8 expression. In conclusion, the expression of GrB in hydatid cysts may exacerbate the inflammatory response and impede cyst fertility while not affecting the fibrous deposition in the cyst wall.

Development of an oral nanovaccine for dogs against Echinococcus granulosus

Dogs are the main source of animal and human cystic echinococcosis caused by the Cestode parasite Echinococcus granulosus. Dog vaccination seems to be a good strategy to control this parasitic disease. Here we present the development of a polymeric nanoparticle-based oral vaccine for dogs against Echinococcus granulosus delivered in enteric-coated capsules. To achieve our target, we encapsulated two recombinant antigens into biodegradable polymeric nanoparticles in the presence of Monophosphoryl lipid A as an adjuvant to ensure efficient delivery and activation of a protective mucosal immune response. The formulated delivery system showed a nanoparticle size less than 200 nm with more than 80 % antigen encapsulation efficiency and conserved integrity and immunogenicity. The nanoparticle surface was coated with chitosan to enhance adhesion to the gut mucosa and a subsequent antigen delivery. Chitosan-coated nanoparticles showed a higher cell internalization in murine macrophages and dendritic cells as well as a higher penetration into Caco-2 cells in vitro. Antigen-loaded nanoparticles were freeze-dried and enteric-coated capsules were filled with the obtained powder. The obtained results show a promising nanoparticles delivery system for oral vaccination.

Genetic diversity and transmission patterns of Echinococcus granulosus sensu stricto among domestic ungulates of Sardinia, Italy

Cystic echinococcosis (CE), a parasitic zoonosis of public health and economic concern, is highly endemic in Sardinia, Italy. The study involved examining the intraspecific variability and demographic structure of Echinococcus granulosussensu stricto (s.s.) in common hosts of this parasite. Molecular surveillance included the fragment amplification of a partial mitochondrial gene, cox1 (750 bp), for a total of 69 isolates derived from sheep (n = 52), cattle (n = 11), pigs (n = 4), and goats (n = 2). It was ascertained that E. granulosus s.s. was the primary agent of infection among these ungulates and G1 genotype was highly prevalent (79.71%). Considerable intraspecific variation was found, revealing the existence of 22 haplotypes with relatively high haplotype (0.8555 ± 0.033) and low nucleotide diversities (0.00281 ± 0.00030). Population demographics indicated an expanding parasitic population signifying negative deviation from neutrality indices. Little genetic differentiation was found between the subpopulations of E. granulosus s.s. in the island. Moreover, the geographic dispersal of genotypes G1 and G3 also indicated similarity between Sardinian and mainland Echinococcus granulosus s.s. populations reaffirming the sympatric occurrence and efficient transmission of G1 and G3 genotypes. Molecular survey of CE has the potential to yield baseline information on the infective genotypes among the intermediate hosts and helps in devising suitable control strategies for curtailing the disease.

Echinococcus granulosus cyst fluid suppresses inflammatory responses by inhibiting TRAF6 signalling in macrophages

Echinococcus granulosus sensu lato has complex defence mechanisms that protect it from the anti-parasitic immune response for long periods. Echinococcus granulosus cyst fluid (EgCF) is involved in the immune escape. Nevertheless, whether and how EgCF modulates the inflammatory response in macrophages remains poorly understood. Here, real-time polymerase chain reaction and enzyme-linked immunosorbent assay revealed that EgCF could markedly attenuate the lipopolysaccharide (LPS)-induced production of pro-inflammatory factors including tumour necrosis factor-α, interleukin (IL)-12 and IL-6 but increase the expression of IL-10 at mRNA and protein levels in mouse peritoneal macrophages and RAW 264.7 cells. Mechanically, western blotting and immunofluorescence assay showed that EgCF abolished the activation of nuclear factor (NF)-κB p65, p38 mitogen-activated protein kinase (MAPK) and ERK1/2 signalling pathways by LPS stimulation in mouse macrophages. EgCF's anti-inflammatory role was at least partly contributed by promoting proteasomal degradation of the critical adaptor TRAF6. Moreover, the EgCF-promoted anti-inflammatory response and TRAF6 proteasomal degradation were conserved in human THP-1 macrophages. These findings collectively reveal a novel mechanism by which EgCF suppresses inflammatory responses by inhibiting TRAF6 and the downstream activation of NF-κB and MAPK signalling in both human and mouse macrophages, providing new insights into the molecular mechanisms underlying the E. granulosus-induced immune evasion.

Human and animal cystic echinococcosis in Konya, Turkey: molecular identification and the first report of E. equinus from human host in Turkey

Cystic echinococcosis is a neglected, zoonotic disease in Turkey. The disease is commonly seen in rural areas where the local population is in close contact with livestock and dogs. This research aimed to molecularly identify of hydatid cysts in cattle and human isolates from Konya, Turkey. Following sample collection, direct microscopy was performed. After direct examination, total DNA was extracted, and positive PCR products of cox 1 mitochondrial gene (~ 875 bp) were sequenced. A total of 83 hydatid cysts (cattle n = 57 and human n = 26), 82 were identified as Echinococcus granulosus sensu stricto (G1–G3 genotypes), and one human isolate was characterized as Echinococcus equinus (G4 genotype). Fertility rates of cysts belonging to cattle for liver and lung cysts were 93.3% and 80%, respectively. Out of 26 human originated isolates, 18 (69.2%) of cysts were found to be fertile. To the best of our knowledge, this is the first report of E. equinus from human host in Turkey.

Transcriptomic Features of Echinococcus granulosus Protoscolex during the Encystation Process

Cystic echinococcosis (CE) is a zoonotic infection caused by Echinococcus granulosus larvae. It seriously affects the development of animal husbandry and endangers human health. Due to a poor understanding of the cystic fluid formation pathway, there is currently a lack of innovative methods for the prevention and treatment of CE. In this study, the protoscoleces (PSCs) in the encystation process were analyzed by high-throughput RNA sequencing. A total of 32,401 transcripts and 14,903 cDNAs revealed numbers of new genes and transcripts, stage-specific genes, and differently expressed genes. Genes encoding proteins involved in signaling pathways, such as putative G-protein coupled receptor, tyrosine kinases, and serine/threonine protein kinase, were predominantly up-regulated during the encystation process. Antioxidant enzymes included cytochrome c oxidase, thioredoxin glutathione, and glutathione peroxidase were a high expression level. Intriguingly, KEGG enrichment suggested that differentially up-regulated genes involved in the vasopressin-regulated water reabsorption metabolic pathway may play important roles in the transport of proteins, carbohydrates, and other substances. These results provide valuable information on the mechanism of cystic fluid production during the encystation process, and provide a basis for further studies on the molecular mechanisms of growth and development of PSCs.

Frozen hydatid cysts can replace incineration and sterilize cysts

In many countries of Mediterranean area, abattoirs are not equipped with incinerators. This led us to find an alternative that may be the freezing of organs before they are thrown into landfills. In this sense, the aim of this study was to evaluate the scolicidal effect of refrigeration at 4°C and freezing at -18°C. Different refrigeration times (24 and 48 h) and freezing times (3, 6, and 9 h) have been used in triplicate. Refrigeration at 4°C was not sufficient to completely kill protoscolex. For 24 h, the mortality rate did not exceed 44.44%. After 48 h, mortality rates varied from 20.13% to 65.49%. The freezing at -18 °C for 3 h remained insufficient to kill all protoscoleces although the mortality rate increased to 87.28%. However, freezing at -18 °C for 6 and 9 h has been found to be very effective in killing all protoscoleces present in the hydatid liquids. The present study demonstrates that freezing organs seized for hydatidosis at -18°C for at least 6 h may be an alternative to incineration and will sterilize hydatid cysts before they are dumped.

Pro-Angiogenic Activity of Monocytic-Type Myeloid-Derived Suppressor Cells from Balb/C Mice Infected with Echinococcus Granulosus and the Regulatory Role of miRNAs

BACKGROUND/AIMS

This study aims to predict the pro-angiogenic functions of monocytic-type myeloid-derived suppressor cells (M-MDSCs) derived from mice infected with Echinococcus granulosus.

METHODS

M-MDSCs were collected from Balb/c mice infected with E. granulosus and normal mice (control) and cultured in vitro. Human umbilical vein endothelial cells (HUVECs) were stimulated with the cell supernatant, and angiogenesis was investigated and analysed by the Angiogenesis module of the software NIH Image J. RNA was extracted from fresh isolated M-MDSCs and analysed with miRNA microarray; differentially expressed miRNAs and their potential functions were analysed through several bioinformatics tools. Finally, quantitative PCR was used to confirm the results of microarray analysis.

RESULTS

M-MDSCs from mice infected with E. granulosus could promote the formation of tubes from HUVECs in vitro. Moreover, vascular endothelial growth factor (VEGF) showed significantly high expression, whereas soluble fms-like tyrosine kinase-1 (sFlt-1) showed low expression at the transcriptional level in M-MDSCs from mice infected with E. granulosus. Microarray analysis of miRNAs showed that 28 miRNAs were differentially expressed in M-MDSCs from the two experimental mice groups, and 272 target genes were predicted using the microRNA databases TargetScan, PITA and microRNAorg. These target genes were mainly involved in the biological processes of intracellular protein transport, protein targeting to the lysosome and protein transport, and mainly located in the cytoplasm, neuronal cell body and membrane. Moreover, they were mainly involved in the molecular functions of protein binding, metal ion binding and SH3 domain binding. Further, the differentially expressed miRNAs were mainly enriched in the endocytosis, Wnt and axon guidance pathways, as well as the MAPK, focal adhesion, PI3K-Akt, cAMP, mTOR and TGF-β signalling pathways, which are linked to immunoregulation and angiogenesis based on the results of bioinformatics analysis with DIANA-miRPath 3.0. In addition, the expression of eight miRNAs was randomly verified by quantitative PCR independently in three mice infected with E. granulosus and three normal mice.

CONCLUSION

M-MDSCs have a potential angiogenic role during E. granulosus infection, and miRNAs may play a role in the immune response and angiogenesis functions of M-MDSCs through regulation of the identified signalling pathways.

Echinococcus granulosus hydatid cyst location is modified by Fasciola hepatica infection in cattle

BACKGROUND

Natural parasite infection occurs in wild and domestics animals with more than one parasite species at the same time, generating an infection called polyparasitism. Cystic echinococcosis reports are usually based only on infection with Echinoccocus granulosus leaving aside other internal parasitoses that could modulate both the immune response and pathogenesis of the natural infection. Fasciola hepatica is another cosmopolitan parasite in ruminants with a similar distribution to E. granulosus in different parts of the world, but no information of the effect of co-infection with E. granulosus has been described. The aims of this report were to establish E. granulosus prevalence and explore the association of F. hepatica co-infection and natural E. granulosus infections in cattle.

RESULTS

From 1725 animals, the prevalence of E. granulosus and F. hepatica was 21.16 and 51.3%, respectively. Considering both infections, older cattle (> 4 years) presented higher prevalence compared to younger animals. In E. granulosus-infected cattle, 5.21% had fertile cysts, 71.78% infertile cysts, and in 23.01% cysts were smaller than 1 cm in diameter. Considering cyst location, 39.72% had lungs cysts, 24.72% had liver cysts and 36.94% had cysts in both organs. Cyst location significantly differed between age groups: 44.68% of younger animals had cysts only in the lungs, while older animals presented hydatid cyst in the lungs and liver simultaneously (44.15%). With E. granulosus infection alone, 30.26% of cysts were found in the lungs, 31.79% in the liver and 37.95% in both organs. Regarding the co-infection of E. granulosus with F. hepatica, the proportion was significantly different (P < 0.05) with most animals having cysts only in the lungs (49.41%) and a lower level of liver infection (15.88%). Analyzing organ cyst distribution and F. hepatica absence/presence ratio within each cyst type, small cysts showed the highest difference in ratio.

CONCLUSIONS

To the best of our knowledge, this is the first report indicating that F. hepatica co-infection in cattle could be affecting the instate of hydatid cysts in the liver, displacing toward lung localization, suggesting an antagonistic relationship.

Estimating the prevalence of Echinococcus in domestic dogs in highly endemic for echinococcosis

BACKGROUND

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly endemic in Xiji County of Ningxia Hui Autonomous Region (NHAR) in China where the control campaign based on dog de-worming with praziquantel has been undertaken over preceding decades. This study is to determine the current prevalence of Echinococcus granulosus and E. multilocularis in domestic dogs and monitor the echinococcosis transmission dynamics.

METHODS

Study villages were selected using landscape patterns (Geographic Information System, GIS) for Echinococcus transmission "hot spots", combined with hospital records identifying risk areas for AE and CE. A survey of 750 domestic dogs, including copro-sampling and owner questionnaires, from 25 selected villages, was undertaken in 2012. A copro-multiplex PCR assay was used for the specific diagnosis of E. granulosus and E. multilocularis in the dogs. Data analysis, using IBM SPSS Statistics, was undertaken, to compare the prevalence of the two Echinococcus spp. in dogs between four geographical areas of Xiji by the χ2 test. Univariate analysis of the combinations of outcomes from the questionnaire and copro-PCR assay data was carried out to determine the significant risk factors for dog infection.

RESULTS

The highest de-worming rate of 84.0% was found in the northwest area of Xiji County, and significant differences (P <  0.05) in the de-worming rates among dogs from the four geographical areas of Xiji were detected. The highest prevalence (19.7%, 59/300) of E. multilocularis occurred in northwest Xiji, though the highest prevalence (18.1%, 38/210) of E. granulosus occurred in southwest Xiji. There was no significant difference (P >  0.05) in the prevalence of E. granulosus in dogs from the northwest, southwest, northeast, and southeast of Xiji, but there were significant differences (P <  0.05) between dogs infected with E. multilocularis from the four areas. None of the other independent variables was statistically significant.

CONCLUSIONS

The results from this study indicate a high prevalence of both E. granulosus and E. muiltilocularis in dogs in Xiji County, NHAR. Transmission of E. multilocularis was more impacted by geographical risk-factors in Xiji County than that of E. granulosus. Dogs have the potential to maintain the transmission of both species of Echinococcus within local Xiji communities, and the current praziquantel dosing of dogs appears to be ineffective or poorly implemented in this area.

Toxic effects of arsenic trioxide on Echinococcus granulosus protoscoleces through ROS production, and Ca2+-ER stress-dependent apoptosis

Cystic echinococcosis is a severe parasitic disease that commonly affects the liver and causes abscesses or rupture into the surrounding tissues, leading to multiple complications, such as shock, severe abdominal pain, and post-treatment abscess recurrence. Currently, there are no efficient measures to prevent these complications. We previously confirmed that arsenic trioxide (As2O3) exhibited in vitro cytotoxicity against Echinococcus granulosus protoscoleces. In the present study, we aimed to explore the mechanism of As2O3-induced E. granulosus protoscoleces apoptosis. After exposing E. granulosus protoscoleces to 0, 4, 6, and 8 μM As2O3, reactive oxygen species (ROS) level was detected by fluorescence microscopy; superoxide dismutase (SOD), and caspase-3 activities were measured; intracellular Ca2+ was detected by flow cytometry; GRP-78 and caspase-12 protein levels were measured by western blot analysis. Our results showed that the expression of caspase-3 was gradually increased and the expression of SOD was gradually decreased in As2O3-treated groups of protoscoleces. Simultaneously, fluorescence microscopy and flow cytometry showed that the ROS level and the intracellular Ca2+ level were increased in a time- and dose-dependent manner. Western blot analysis showed that the expressions of GRP-78 and caspase-12 were higher in As2O3-treated groups than in the control group. These results suggest that As2O3-induced apoptosis in E. granulosus protoscoleces is related to elevation of ROS level, disruption of intracellular Ca2+ homeostasis, and endoplasmic reticulum stress. These mechanisms can be targeted in the future by safer and more effective drugs to prevent recurrence of cystic echinococcosis.

Unique pharmacological properties of serotoninergic G-protein coupled receptors from cestodes

Background

Cestodes are a diverse group of parasites, some of them being agents of neglected diseases. In cestodes, little is known about the functional properties of G protein coupled receptors (GPCRs) which have proved to be highly druggable targets in other organisms. Notably, serotoninergic G-protein coupled receptors (5-HT GPCRs) play major roles in key functions like movement, development and reproduction in parasites.

Methodology/Principal findings

Three 5-HT GPCRs from Echinococcus granulosus and Mesocestoides corti were cloned, sequenced, bioinformatically analyzed and functionally characterized. Multiple sequence alignment with other GPCRs showed the presence of seven transmembrane segments and conserved motifs but interesting differences were also observed. Phylogenetic analysis grouped these new sequences within the 5-HT7 clade of GPCRs. Molecular modeling showed a striking resemblance in the spatial localization of key residues with their mammalian counterparts. Expression analysis using available RNAseq data showed that both E. granulosus sequences are expressed in larval and adult stages. Localization studies performed in E. granulosus larvae with a fluorescent probe produced a punctiform pattern concentrated in suckers. E. granulosus and M. corti larvae showed an increase in motility in response to serotonin. Heterologous expression revealed elevated levels of cAMP production in response to 5-HT and two of the GPCRs showed extremely high sensitivity to 5-HT (picomolar range). While each of these GPCRs was activated by 5-HT, they exhibit distinct pharmacological properties (5-HT sensitivity, differential responsiveness to ligands).

Conclusions/Significance

These data provide the first functional report of GPCRs in parasitic cestodes. The serotoninergic GPCRs characterized here may represent novel druggable targets for antiparasitic intervention.

Cestode parasites are flatworms with the ability to parasitize almost every vertebrate species. Several of these parasites are etiological agents of neglected diseases prioritized by WHO, such as hydatid disease, or hydatidosis, a zoonosis caused by species of the genus Echinococcus that affects millions of people worldwide. Due to the scarcity of anthelmintic drugs available and the emergence of resistant parasites, the discovery of new anthelmintic drugs is mandatory. Neuromuscular function has been the target of commonly used drugs against parasitic diseases to impact movement, parasite development and reproduction. Here we describe three new proteins, some of them highly expressed in cestodes which could be relevant for motility. Using different approaches, the three proteins were identified as G protein coupled receptors for serotonin, an important neurotransmitter and a known modulator of cestode motility. These new receptors exhibit unique characteristics including a particular sensitivity to serotonin as well as a distinctive pharmacology, which will assist their targeting for chemotherapeutic intervention.

Human cystic and alveolar echinococcosis in the Tibet Autonomous Region (TAR), China

Human cystic echinococcosis (CE) is known to be endemic in the Tibet Autonomous Region (TAR), China; however, there is relatively little data from hospital records or community prevalence studies, and the situation regarding occurrence of human alveolar echinococcosis (AE) is unclear. Here we review the available reports about human echinococcosis in the seven prefectures of TAR. In addition, two pilot studies by mass screening using ultrasound (with serology) were undertaken (2006/7) in Dangxiong County of Lhasa Prefecture (north central TAR) and Dingqing County of Changdu Prefecture (eastern TAR). In Dangxiong County a prevalence of 9.9% (55/557) for human CE was obtained but no human AE cases were detected. By contrast, in Dingqing County (N= 232 persons screened), 11 CE cases (4.7%) and 12 AE cases (5.2%) (including one mixed CE and AE case) were diagnosed by ultrasound. Hospital records and published reports indicated that CE cases were recorded in all of seven prefectures in Tibet Autonomous Region, and AE cases in four prefectures. Incidence rates of human CE were estimated to range from 1.9 to 155 per 100,000 across the seven prefectures of TAR, with a regional incidence of 45.1 per 100,000. Incidence of AE was estimated to be between 0.6 and 2.8 cases per 100,000. Overall for TAR, human AE prevalence appeared relatively low; however, the pilot mass screening in Dingqing in eastern TAR indicated that human AE disease is a potential public health problem, possibly similar to that already well described in Tibetan communities bordering TAR in north-west Sichuan and south-west Qinghai provinces.

Identification of Newly Synthesized Proteins by Echinococcus granulosus Protoscoleces upon Induction of Strobilation

Background

The proteins responsible for the key molecular events leading to the structural changes between the developmental stages of Echinococcus granulosus remain unknown. In this work, azidohomoalanine (AHA)-specific labeling was used to identify proteins expressed by E. granulosus protoscoleces (PSCs) upon the induction of strobilar development.

Methodology/Principal Findings

The in vitro incorporation of AHA with different tags into newly synthesized proteins (NSPs) by PSCs was analyzed using SDS-PAGE and confocal microscopy. The LC-MS/MS analysis of AHA-labeled NSPs by PSCs undergoing strobilation allowed for the identification of 365 proteins, of which 75 were differentially expressed in comparison between the presence or absence of strobilation stimuli and 51 were expressed exclusively in either condition. These proteins were mainly involved in metabolic, regulatory and signaling processes.

Conclusions/Significance

After the controlled-labeling of proteins during the induction of strobilar development, we identified modifications in protein expression. The changes in the metabolism and the activation of control and signaling pathways may be important for the correct parasite development and be target for further studies.

In the life cycle of the parasite Echinococcus granulosus, hydatid cysts produce the pre-adult form, which has the ability to either differentiate into an adult worm (strobilation) or dedifferentiate into a secondary hydatid cyst. We used different protein tags that allowed for the visualization and purification of proteins produced specifically after the induction of strobilar development to identify proteins that might be involved in this process (temporally controlled and context-dependent). As a result, we found proteins that are involved in important processes during development, such as energy metabolism, control pathways and cellular communication. We believe that these results will be useful for the development of scientific approaches to controlling and preventing cystic hydatid 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.

In Vitro Anti-Echinococcal and Metabolic Effects of Metformin Involve Activation of AMP-Activated Protein Kinase in Larval Stages of Echinococcus granulosus

Metformin (Met) is a biguanide anti-hyperglycemic agent, which also exerts antiproliferative effects on cancer cells. This drug inhibits the complex I of the mitochondrial electron transport chain inducing a fall in the cell energy charge and leading 5'-AMP-activated protein kinase (AMPK) activation. AMPK is a highly conserved heterotrimeric complex that coordinates metabolic and growth pathways in order to maintain energy homeostasis and cell survival, mainly under nutritional stress conditions, in a Liver Kinase B1 (LKB1)-dependent manner. This work describes for the first time, the in vitro anti-echinococcal effect of Met on Echinococcus granulosus larval stages, as well as the molecular characterization of AMPK (Eg-AMPK) in this parasite of clinical importance. The drug exerted a dose-dependent effect on the viability of both larval stages. Based on this, we proceeded with the identification of the genes encoding for the different subunits of Eg-AMPK. We cloned one gene coding for the catalytic subunit (Eg-ampkɑ) and two genes coding for the regulatory subunits (Eg-ampkβ and Eg-ampkγ), all of them constitutively transcribed in E. granulosus protoscoleces and metacestodes. Their deduced amino acid sequences show all the conserved functional domains, including key amino acids involved in catalytic activity and protein-protein interactions. In protoscoleces, the drug induced the activation of AMPK (Eg-AMPKɑ-P¹⁷⁶), possibly as a consequence of cellular energy charge depletion evidenced by assays with the fluorescent indicator JC-1. Met also led to carbohydrate starvation, it increased glucogenolysis and homolactic fermentation, and decreased transcription of intermediary metabolism genes. By in toto immunolocalization assays, we detected Eg-AMPKɑ-P¹⁷⁶ expression, both in the nucleus and the cytoplasm of cells as in the larval tegument, the posterior bladder and the calcareous corpuscles of control and Met-treated protoscoleces. Interestingly, expression of Eg-AMPKɑ was observed in the developmental structures during the de-differentiation process from protoscoleces to microcysts. Therefore, the Eg-AMPK expression during the asexual development of E. granulosus, as well as the in vitro synergic therapeutic effects observed in presence of Met plus albendazole sulfoxide (ABZSO), suggest the importance of carrying out chemoprophylactic and clinical efficacy studies combining Met with conventional anti-echinococcal agents to test the potential use of this drug in hydatidosis therapy.

Echinococcus granulosus antigen B: a Hydrophobic Ligand Binding Protein at the host-parasite interface

Lipids are mainly solubilized by various families of lipid binding proteins which participate in their transport between tissues as well as cell compartments. Among these families, Hydrophobic Ligand Binding Proteins (HLBPs) deserve special consideration since they comprise intracellular and extracellular members, are able to bind a variety of fatty acids, retinoids and some sterols, and are present exclusively in cestodes. Since these parasites have lost catabolic and biosynthetic pathways for fatty acids and cholesterol, HLBPs are likely relevant for lipid uptake and transportation between parasite and host cells. Echinococcus granulosus antigen B (EgAgB) is a lipoprotein belonging to the HLBP family, which is very abundant in the larval stage of this parasite. Herein, we review the literature on EgAgB composition, structural organization and biological properties, and propose an integrated scenario in which this parasite HLBP contributes to adaptation to mammalian hosts by meeting both metabolic and immunomodulatory parasite demands.

Synthesising 30 years of mathematical modelling of Echinococcus transmission

BACKGROUND

Echinococcosis is a complex zoonosis that has domestic and sylvatic lifecycles, and a range of different intermediate and definitive host species. The complexities of its transmission and the sparse evidence on the effectiveness of control strategies in diverse settings provide significant challenges for the design of effective public health policy against this disease. Mathematical modelling is a useful tool for simulating control packages under locally specific transmission conditions to inform optimal timing and frequency of phased interventions for cost-effective control of echinococcosis. The aims of this review of 30 years of Echinococcus modelling were to discern the epidemiological mechanisms underpinning models of Echinococcus granulosus and E. multilocularis transmission and to establish the need to include a human transmission component in such models.

METHODOLOGY/PRINCIPAL FINDINGS

A search was conducted of all relevant articles published up until July 2012, identified from the PubMED, Web of Knowledge and Medline databases and review of bibliographies of selected papers. Papers eligible for inclusion were those describing the design of a new model, or modification of an existing mathematical model of E. granulosus or E. multilocularis transmission. A total of 13 eligible papers were identified, five of which described mathematical models of E. granulosus and eight that described E. multilocularis transmission. These models varied primarily on the basis of six key mechanisms that all have the capacity to modulate model dynamics, qualitatively affecting projections. These are: 1) the inclusion of a 'latent' class and/or time delay from host exposure to infectiousness; 2) an age structure for animal hosts; 3) the presence of density-dependent constraints; 4) accounting for seasonality; 5) stochastic parameters; and 6) inclusion of spatial and risk structures.

CONCLUSIONS/SIGNIFICANCE

This review discusses the conditions under which these mechanisms may be important for inclusion in models of Echinococcus transmission and proposes recommendations for the design of dynamic human models of transmission. Accounting for the dynamic behaviour of the Echinococcus parasites in humans will be key to predicting changes in the disease burden over time and to simulate control strategies that optimise public health impact.

Direct interaction between EgFABP1, a fatty acid binding protein from Echinococcus granulosus, and phospholipid membranes

Background

Growth and maintenance of hydatid cysts produced by Echinococcus granulosus have a high requirement for host lipids for biosynthetic processes, membrane building and possibly cellular and developmental signalling. This requires a high degree of lipid trafficking facilitated by lipid transporter proteins. Members of the fatty acid binding protein (FABP) family have been identified in Echinococcus granulosus, one of which, EgFABP1 is expressed at the tegumental level in the protoscoleces, but it has also been described in both hydatid cyst fluid and secretions of protoscoleces. In spite of a considerable amount of structural and biophysical information on the FABPs in general, their specific functions remain mysterious.

Methodology/Principal Findings

We have investigated the way in which EgFABP1 may interact with membranes using a variety of fluorescence-based techniques and artificial small unilamellar vesicles. We first found that bacterial recombinant EgFABP1 is loaded with fatty acids from the synthesising bacteria, and that fatty acid binding increases its resistance to proteinases, possibly due to subtle conformational changes induced on EgFABP1. By manipulating the composition of lipid vesicles and the ionic environment, we found that EgFABP1 interacts with membranes in a direct contact, collisional, manner to exchange ligand, involving both ionic and hydrophobic interactions. Moreover, we observed that the protein can compete with cytochrome c for association with the surface of small unilamellar vesicles (SUVs).

Conclusions/Significance

This work constitutes a first approach to the understanding of protein-membrane interactions of EgFABP1. The results suggest that this protein may be actively involved in the exchange and transport of fatty acids between different membranes and cellular compartments within the parasite.

Echinococcus granulosus is the causative agent of hydatidosis, a zoonotic infection that affects humans and livestock, representing a public health and economic burden in many countries. Since the parasites are unable to synthesise most of their lipids de novo, they must acquire them from the host and then deliver them by carrier proteins to specific destinations. E. granulosus produces in abundance proteins of the fatty acid binding protein (FABP) family, one of which, EgFABP1 has been characterised at the structural and ligand binding levels, but it has not been studied in terms of the mechanism of its interaction with membranes. We have investigated the lipid transport properties and protein-membrane interaction characteristics of EgFABP1 by applying biophysical techniques. We found that EgFABP1 interacts with membranes by a mechanism which involves direct contact with them to exchange their cargo. Given that the protein has been found in the secretions of the parasite, the implications of its direct interactions with host membranes should be considered.

Cystic echinococcosis in Sudan and South Sudan: research history of a neglected zoonosis

Cystic echinococcosis is a zoonotic disease affecting mainly various species of livestock and humans. This study aims at highlighting the course of research on cystic echinococcosis in different animals and humans in Sudan (including the recently independent state of South Sudan) since the disease was first reported in 1908. Recent data about the genetic identification of the parasite in the countries in both humans and animals and its importance for future control programs is discussed.

Host-parasite relationship in cystic echinococcosis: an evolving story

The larval stage of Echinococcus granulosus causes cystic echinococcosis, a neglected infectious disease that constitutes a major public health problem in developing countries. Despite being under constant barrage by the immune system, E. granulosus modulates antiparasite immune responses and persists in the human hosts with detectable humoral and cellular responses against the parasite. In vitro and in vivo immunological approaches, together with molecular biology and immunoproteomic technologies, provided us exciting insights into the mechanisms involved in the initiation of E. granulosus infection and the consequent induction and regulation of the immune response. Although the last decade has clarified many aspects of host-parasite relationship in human cystic echinococcosis, establishing the full mechanisms that cause the disease requires more studies. Here, we review some of the recent developments and discuss new avenues in this evolving story of E. granulosus infection in man.

[Primary hydatid cyst of the parotid gland]

INTRODUCTION

The hydatid cyst is an anthropozoonosis due to the development of the Echinococcus granulosus tapeworm larva in humans. Its intraparotid localization is extremely rare.

CLINICAL CASE

A 10-year-old-male patient was admitted for an isolated renitent swelling of the left parotid region having grown for several months. Cervical ultrasonography revealed a left parotid cystic mass, characterized by a double wall, and a small daughter cyst. The CT-scan typically showed the absence of enhancement after iodine contrast medium injection. The imaging-based diagnosis of a hydatid cyst was supported by positive hydatid serology, and confirmed by histological analysis of the cyst. No other hydatid location was found (chest and abdominal).

DISCUSSION

In spite of its rarity, hydatid cyst can be a diagnosis in case of parotid cystic masses. Ultrasonography is the first examination to be performed; it must be completed by CT-scan or even better by MRI. Once the diagnosis of hydatid cyst is confirmed, a chest radiograph and an abdominal ultrasonography should be performed, to screen for other localizations. Surgical resection is the gold standard treatment.

In vitro antihydatic action of IFN-gamma is dependent on the nitric oxide pathway

Hydatidosis is a widely endemic helminthic disease vectored in human by the larval stage of the metacestode Echinococcus granulosus. It is characterized by the long-term coexistence of chronic infection with detectable humoral and cellular responses against the macroparasite. Previous studies demonstrated interferon-gamma (IFN-gamma) and nitric oxide (NO) production (in vivo and in vitro) during hydatidosis. In this study, we tested the hypothesis that NO production after IFN-gamma induction may constitute a host defense against E. granulosus. We also investigated the IFN-gamma effect on protoscolices (larval form of the parasite) viability in coculture with hydatid patients' peripheral blood mononuclear cells (PBMC). PBMCs from hydatic patients incubated with IFN-gamma (100 U/mL) alone are effective in the killing of protoscolices. This scolicidal activity is concomitant with elevation of nitrite levels. NO release and cytotoxic activity are inhibited by N-monomethyl-L-arginine (L-NMMA), a specific inhibitor of the NO pathway and increased by L-arginine, an NO precursor, and tetrahydrobiopterin (BH4), a nitric oxide synthase (NOS) cofactor. Our results indicate that IFN-gamma mediated iNOS induction as one of host defense mechanism against human E. granulosus infection.

The prevalence, organ distribution and fertility of cystic echinoccosis in feral pigs in tropical North Queensland, Australia

An investigation was carried out to study the prevalence of Echinococcus granulosus hydatidosis in feral pigs (Sus domesticus) in the Charters Towers region of tropical North Queensland. Data were collected from a total of 238 carcasses, which were hunted and shot in the Burdekin River catchment area. Organs of the abdominal, thoracic, and pelvic cavities were examined for the presence of hydatid cysts. In the laboratory, cysts and hydatid cyst fluids were examined under a stereoscopic binocular microscope and a compound microscope. An overall prevalence of E. granulosus hydatid cysts in feral pigs was found to be 31.1%. There was no significant difference in either sex or age between infected and non-infected feral pigs. The predilection sites of cysts were livers (23%) and lungs (62%), with more cysts in lungs (252) than livers (48). The ratio of livers to lungs infected with fertile cysts was 1:4 compared to 1:8 sterile cysts. The overall fertility of cysts was 70.1%. The percentage of fertile cysts in liver and lung was 79.2% and 68.7%, respectively. The diameter of fertile cysts ranged from 15 to over 60 mm. There was no significant difference in size between fertile and non-fertile cysts in lungs. The high prevalence rate and fertility of cysts in feral pigs confirm that feral pigs can take part in the sylvatic cycle of the parasite in the region. The public health significance of this observation is potentially very important.

Innovative chemotherapeutical treatment options for alveolar and cystic echinococcosis

Echinococcus granulosus and Echinococcus multilocularis are cestode parasites, of which the metacestode (larval) stages cause the diseases cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. Albendazole and mebendazole are presently used for chemotherapeutical treatment. However, these benzimidazoles do not appear to be parasiticidal in vivo against AE. In addition, failures in drug treatments as well as the occurrence of side-effects have been reported. New drugs are needed to cure AE and CE, which are considered to be neglected diseases. Strategies currently being implemented to identify novel chemotherapeutical treatment options include (i) conventional primary in vitro testing of broad-spectrum anti-infective drugs, either in parallel with, or followed by, animal experimentation; (ii) studies of drugs which interfere with the proliferation of cancer cells and of Echinococcus metacestodes; (iii) exploitation of the similarities between the parasite and mammalian signalling machineries, with a special focus on targeting specific signalling receptors; (iv) in silico approaches, employing the current Echinococcus genomic database information to search for suitable targets for compounds with known modes of action. In the present article, we review the efforts toward obtaining better anti-parasitic compounds which have been undertaken to improve chemotherapeutical treatment of echinococcosis, and summarize the achievements in the field of host-parasite interactions which may also lead to new immuno-therapeutical options.

[Study on the variation of lymphocytes and cytokines in patients with echinococcosis granulosus]

OBJECTIVE

To investigate the variation of lymphocytes and cytokines in patients with cystic echinococcosis (CE).

METHODS

80 CE patients who were diagnosed for the first time (60 of Han and 20 of Uygur nationality), and 37 patients who were to accept the second surgical operation(24 Han and 13 Uygur nationality) were included in the study. The peripheral lymphocytes of patients before operation were analyzed by flow cytometry (FCM) to detect T and B lymphocytes, NK cells bearing surface markers, as well as Thl cytokine IFN-gamma and Th2 cytokine IL-4 in the cytoplasm of lymphocytes. 179 healthy persons served as control.

RESULTS

In the group of Han patients who were diagnosed for the first time, the percentage of total T cells(CD3+) was lower than the control (P<0.05), while among patients accepting the second operation, the ratio of total T cells showed no difference to the control. For the helper T cells (CD3+/CD4+), NK cells (CD3+/CD16,56+) and B cells (CD3+/CD19+), their ratio were significantly lower in both groups than the control (P<0.01), but their cytotoxic T cells (CD3+/CD8+) were higher than the control. In Uygur patients diagnosed for the first time, B cell ratio was lower than that in control (P<0.05). The NK cell level in both groups of patients was lower than control (P<0.01 and P<0.05 respectively). The level of ThO and Th1 showed no statistical difference among the three groups (P>0.05). The Th2 level was significantly higher in the first diagnosed patients than control (P<0.01), but no statistical difference between the group with the second operation and the other two groups.

CONCLUSION

The immune status of echinococcosis patients is inhibited and the level of Th1 and Th2 shows difference in the first and second operation groups.

[Research progress in immunopathogenesis of cystic echinococcosis]

This article reviews the immunopathogenesis of cystic echinococcosis in the following seven aspects: innate immunity, establishment phase immunity, cystic phase immunity, influencing factor of CD4+ T cell polarization, cytokine function in infected host, Echinococcus granulosus infection and allergy, and immune evasion mechanism.

Clustering of hydatid infection in macropodids

The introduced parasite, Echinococcus granulosus, has been reported in numerous macropodid species in various areas of Australia, but no extensive studies investigating the prevalence and risk factors for infection in wild macropodids have been reported. In this study, 2998 macropodid carcasses were examined following commercial culling on 21 properties in southern Queensland. Of the 71 infected animals, all had cysts in the lung tissue, while two also had cysts in the pleural cavity and one animal had a liver cyst. The number of cysts in infected animals ranged from 1 to 17, with the majority of animals (n=64) having one to three cysts. Estimated total cyst volume varied from 0.2 to 1075 cm3. Some animals had a total lung cyst volume likely to have impacted significantly upon respiratory function and cyst degeneration was only seen in approximately one-third of infected animals. Multilevel models were used to investigate putative risk factors at both kangaroo and property levels. At the kangaroo level, females were twice as likely to be infected as males. After adjusting for sex, no property-level risk factors were significantly associated with the presence of hydatid infection. Prevalence varied substantially between properties (range 0-12%) and this high degree of clustering of infection was reflected in a high intra-class correlation co-efficient in the final model (0.333). These results have important implications for both public health and conservation strategies, and suggest that there are important unidentified risk factors for hydatid infection associated with properties. They also demonstrate that spatial clustering should be considered when analysing hydatid infection data in macropodids, particularly when assessing area-level risk factors.

[Cystic echinococcosis in children in Tunisia: fertility and case distribution of hydatid cysts]

Cystic echinococcosis, which commonly starts during childhood or adolescence, is a serious problem of public health in Tunisia. For 121 children (161 cysts), the localization and fertility of cysts as well as viability of their protoscoleces were determined. Results indicated that the lung was the primary localization of cyst (59%) followed by the liver (35%). Children's infection is more frequent in male than in female (sex ratio 1.96) and the greatest number of cases is observed in the 4-9 year age groups (94 cases). The fertility of the cyst was independent of its site or its size and no incidence of age of children was detected. Nevertheless, the fertility rate is higher in females than in males for the liver localization.

Apoptosis as a possible mechanism of infertility inEchinococcus granulosus hydatid cysts

Echinococcus granulosus is a parasitic cestode causing hydatidosis in intermediate hosts (human and herbivorous). Most symptoms of the disease occur by the pressure exerted on viscera by cysts that are formed upon ingestion of the parasite eggs excreted by definitive hosts (canines). Protoscoleces, the developmental form of the parasite infective to definitive hosts, are formed in the germinal nucleated layer of fertile hydatid cysts. For unknown reasons, some cysts are unable to produce protoscoleces (infertile hydatid cysts). In this study, analysis of DNA fragmentation using TUNEL and agarose gel electrophoresis showed higher levels of apoptosis in infertile cysts as compared to fertile cysts. Additionally, caspase 3 was detected both in fertile and infertile cysts; the activity of this enzyme was found to be higher in infertile cysts. We conclude that apoptosis may be involved in hydatid cyst infertility. This is the first report on the presence of programmed cell death in E. granulosus.

Control of cystic echinococcosis/hydatidosis: 1863-2002

Echinococcosis/hydatidosis, caused by Echinococcus granulosus, is a chronic and debilitating zoonotic larval cestode infection in humans, which is principally transmitted between dogs and domestic livestock, particularly sheep. Human hydatid disease occurs in almost all pastoral communities and rangeland areas of the underdeveloped and developed world. Control programmes against hydatidosis have been implemented in several endemic countries, states, provinces, districts or regions to reduce or eliminate cystic echinococcosis (CE) as a public health problem. This review assesses the impact of 13 of the hydatid control programmes implemented, since the first was introduced in Iceland in 1863. Five island-based control programmes (Iceland, New Zealand, Tasmania, Falklands and Cyprus) resulted, over various intervention periods (from <15 to >50 years), in successful control of transmission as evidenced by major reduction in incidence rates of human CE, and prevalence levels in sheep and dogs. By 2002, two countries, Iceland and New Zealand, and one island-state, Tasmania, had already declared that hydatid disease had been eliminated from their territories. Other hydatid programmes implemented in South America (Argentina, Chile, Uruguay), in Europe (mid-Wales, Sardinia) and in East Africa (northwest Kenya), showed varying degrees of success, but some were considered as having failed. Reasons for the eventual success of certain hydatid control programmes and the problems encountered in others are analysed and discussed, and recommendations for likely optimal approaches considered. The application of new control tools, including use of a hydatid vaccine, are also considered.

Development and sexual maturation of Echinococcus granulosus adult worms in the alternative definitive host, Mongolian gerbil (Meriones unguiculatus)

In the present study for the first time an alternative definitive host model has been established for the complete development of Echinococcus granulosus in Meriones unguiculatus (Mongolian gerbils) up to shelled eggs production, as happened in the natural host. Animals treated with methylprednisolone acetate were orally inoculated with approximately 3000 protoscoleces and the development of parasites in the small intestine observed up to 46 days post-infection (p.i.). The cestodes survive, strobilate, mature sexually and complete their development in the intestine up to production of shelled embryonated eggs containing fully formed six-hooked oncospheres, similarly to the natural canid host (stage 7 by Smyth). Shelled eggs are first observed in the rodent/E. granulosus model at 44 days p.i. Somatic growth in gerbils appears to follow a similar trend to dogs, length increasing to over 3mm at 44 days p.i., while, compared to the natural host, organogenesis is observed only to progress at a slower rate in the early developmental stages. Parasite burden was found to vary among non-inbred animals and developmental stages of worms recovered from the same animal differed widely. Worm localisation follows the pattern observed in the natural host, the parasites appearing for the most part distributed in the proximal third of the small intestine. The development of alternative definitive hosts may facilitate research in this field, overcoming legislative impediments that restrict the use of dogs for experimental purposes.

Infection with Echinococcus granulosus (Batsch, 1786) and expression of superoxide dismutase gene at mRNA level in hepatocytes

Superoxide dismutase (SOD) plays an important role in detoxication of the organism. Its function is to protect the organism against the cytotoxic action of free radicals. The highest expression of superoxide dismutase was observed in the hepatocytes adjacent to the hydatid cyst. The expression of this gene in the hepatocytes of infected livers 5 cm apart from the infection site was slightly lower.

Mathematical models for the control of cystic echinococcosis

Cystic echinococcosis (CE) caused by Echinococcus granulosus is a global public health problem. In many areas the disease is being diagnosed in increasing numbers, whilst in other areas it is re-emerging due to the collapse of public health programmes associated with socio-economic changes. Mathematical models of the transmission dynamics between animals can have an important role to play in developing control options. In particular the parasite is highly endemic in many lower income countries where resources to undertake an intensive control programme that has been successful in wealthy countries, such as New Zealand, are not available. Data from dogs and livestock have been collected and modelled from a number of different countries and regions. In Australia and New Zealand transmission modelling was first developed and these models have been refined using data from the Middle East and central Asia. The model indicates that relatively intense anthelmintic treatment of the dog population will result in a substantial decrease in the parasite population over time and has been supported by the results of control programmes. However, if the newly developed sheep vaccine is included in the control programme, then it should be possible to treat dogs less frequently to achieve the same result. This is due to the potentiating effects of attacking the parasite at two places in its life cycle. This should result in considerable cost savings over the use intensive anthelmintic treatment as the sole method of control.

In vitro effects of flubendazole on Echinococcus granulosus protoscoleces

The aim of the present work was to determine the in vitro protoscolicidal effect of flubendazole (FLBZ) against Echinococcus granulosus. Protoscoleces of E. granulosus were incubated with FLBZ at concentrations of 10, 5 and 1 microg/ml. The first signs of FLBZ-induced damage were observed 3 days post-incubation. A clear protoscolicidal effect, reducing the vitality of protoscoleces to 35.6+/-0.7%, was observed after 18 days of incubation. After 25 days of FLBZ incubation (5 microg/ml), the percentage of vital protoscoleces was 13.9+/-5.9%. Protoscolex mortality was 100% (10 and 1 microg/ml) and 0.7+/-0.7% (5 microg/ml) after FLBZ incubation for 30 days. Results of vitality tests were consistent with the tissue damage observed at the ultrastructural level. The primary site of damage was the tegument of the parasite. The morphological changes included contraction of the soma region, formation of blebs on the tegument, rostellar disorganization, loss of hooks and destruction of microtriches. The data reported in this article demonstrate a clear in vitro effect of FLBZ against E. granulosus protoscoleces.

Strain characterization of Echinococcus granulosus protoscoleces of cattle origin using the in vitro vesicular development

The aim of this work was to characterize the strain of protoscoleces of E. granulosus of cattle origin using the in vitro vesicular development. The in vitro development of these samples was compared to samples of sheep origin determined previously by genetic analyses as common sheep strain (G1). There were similarities between sheep and cattle samples not only in the time of microcysts formation, but also in the development process. Vesiculated protoscoleces and protoscoleces with posterior bladders appeared during the first week of incubation. After 14 days of culture, a laminated layer appeared like a fine membrane in one of the extremes of the protoscoleces. In the sheep samples, microcysts were observed between 19 and 20 days. In the cattle samples, microcysts appeared between 20 and 23 days. The coincidence between the development times and physiological characteristics found in the present study may indicate that the parasites from cattle and sheep were of the same strain.

[The specific features of development of Echinococcus granulosus metacestode (exogenous blastogenesis) in man]

The paper describes a case of abnormal development of a parasitic cyst by the type characteristic of alveolar echinococcosis (exogenous blastogenesis) detected in a female patient operated on for echinococcus. The fact that the exogenous blastogenesis has been found allows the mechanism of a postoperative recurrence of human echinococcosis to be explained from basically new standpoints. A parasitological analysis of the punctates of cystic masses and cysts themselves, taken from patients operated on for cystic echinococcosis has revealed one of the signs of malignant exogenous proliferation of elements of a parasytic metacestode, namely, the development of acephalocysts from the germinative cells of the pedicle of protoscoleces. The capacity of cystic echinococcosis metacestodes for exogenous blastogenesis by the type of human alveolar echinococcosis is an early unknown species-specific feature of E. granulosus.

Echinococcus granulosus: Lethal effect of low voltage direct electric current on hydatid cyst protoscoleces

We have studied a small scale method for killing hydatid cyst protoscoleces using low voltage direct electric current. After collecting hydatid cysts from infected organs of slaughtered animals, protoscoleces were cultured in four different media: hydatid cyst fluid, RPMI, normal saline, and Tris buffer, respectively. Protoscoleces from each of the above media were then transferred to an electrolysis device through which different electric current densities were applied. For measuring the survival rate of protoscoleces, flame cell movement and eosin staining was used. The results show that the survival rate of protoscoleces in hydatid fluid was dependent on the electric current density and the time of the applied current. Current densities of 62.5 mA/cm2 (11 V), 53.71 mA/cm2 (10 V), and 18.18 mA/cm2 (5 V) after 1, 2, and 3 min, respectively, killed all the parasites in the hydatid fluid. However, a current density of 7 mA/cm2 (9 V) in RPMI medium after 3 min was most effective.

Echinococcus granulosus: first report of microcysts formation from protoscoleces of cattle origin using the in vitro vesicular culture technique

The aim of this work was the achievement of microcysts formation from protoscoleces of E. granulosus of cattle origin using the in vitro vesicular culture technique. Vesiculated protoscoleces and protoscoleces with posterior bladders appeared during the first week of incubation. After 14 days of culture, a laminated layer appeared like a fine membrane in one of the extremes of the protoscoleces. On day 20, some microcysts with a complete laminated layer were observed. By day 48, microcysts completely developed could be observed. This is the first study where microcysts formation was obtained using protoscoleces of E. granulosus of cattle origin.

Echinococcus multilocularis laminated-layer components and the E14t 14-3-3 recombinant protein decrease NO production by activated rat macrophages in vitro

Echinococcus multilocularis and Echinococcus granulosus cause alveolar and cystic (unilocular) echinococcosis, respectively, in humans and animals. It is known that these parasites can affect, among other molecules, nitric oxide (NO) production by periparasitic host cells. Nevertheless, detailed dissection of parasite components specifically affecting cell NO production has not been done to date. We compare the effect of E. granulosus and E. multilocularis defined metacestode structural (laminated-layer associated) and metabolic (14-3-3 protein, potentially related with E. multilocularis metacestode tumor-like growth) components on the NO production by rat alveolar macrophages in vitro. Our results showed that none of these antigens could stimulate macrophage NO production in vitro. However, a reversed effect of some Echinococcus antigens on NO in vitro production was found when cells were previously exposed to LPS stimulation. This inhibitory effect was found when E. multilocularis laminated-layer (LL) or cyst wall (CW) soluble components from both species were used. Pre-stimulation of cells with LPS also resulted in a strong, dose-dependent reduction of NO and iNOS mRNA production after incubation of cells with the E14t protein. Thus, the E. multilocularis 14-3-3 protein appears to be one of the components accounting for the suppressive effect of the CW and LL metacestode extracts.

Natural history of cystic echinococcosis in humans

This study provides a contribution to understanding of the natural history of the hydatid cyst during its evolution in the human liver examining the high morphostructural variability of larval forms of Echinococcus granulosus. A detailed study of a large sample of intact cysts removed from patients surgically treated by means of total pericystectomy, has enabled to outline the different developmental stages of the parasite over time, up to its death and complete degeneration.

[Up-dated progress in diagnosis and treatment of echinococcosis]

Diagnostic proces and choice of optimal management of cystic echinococcosis have to be related to the natural history of the parasite. The early and the late stages of invasion require a careful differential diagnosis with non-parasitic diseases. These are also the stages that many not require surgery. Chemotherapy, PAIR and "wait and observe approach" are alternative ways of cystic echinococcosis management. Em-18 WB test has a good diagnostic value in alveolar echinococcosis. Management of alveolar echinococcosis is based on radical surgery, prolonged chemotherapy and long-term observation.