[A study of chromosomes of Alveococcus multilocularis (Echinococcus multilocularis). Leuckart, 1863. Preliminary report].
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Chromosomes↗
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Results for “Echinococcus multilocularis”
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In vitro metacestodicidal activities of genistein and other isoflavones against Echinococcus multilocularis and Echinococcus granulosus.
Echinococcus multilocularis and Echinococcus granulosus metacestode infections in humans cause alveolar echinococcosis and cystic echinococcosis, respectively, in which metacestode development in visceral organs often results in particular organ failure. Further, cystic hydatidosis in farm animals causes severe economic losses. Although benzimidazole derivatives such as mebendazole and albendazole are being used as therapeutic agents, there is often no complete recovery after treatment. Hence, in searching for novel treatment options, we examined the in vitro efficacies of a number of isoflavones against Echinococcus metacestodes and protoscoleces. The most prominent isoflavone, genistein, exhibits significant metacestodicidal activity in vitro. However, genistein binds to the estrogen receptor and can thus induce estrogenic effects, which is a major concern during long-term chemotherapy. We have therefore investigated the activities of a number of synthetic genistein derivatives carrying a modified estrogen receptor binding site. One of these, Rm6423, induced dramatic breakdown of the structural integrity of the metacestode germinal layer of both species within 5 to 7 days of in vitro treatment. Further, examination of the culture medium revealed increased leakage of parasite proteins into the medium during treatment, but zymography demonstrated a decrease in the activity of metalloproteases. Moreover, two of the genistein derivatives, Rm6423 and Rm6426, induced considerable damage in E. granulosus protoscoleces, rendering them nonviable. These findings demonstrate that synthetic isoflavones exhibit distinct in vitro effects on Echinococcus metacestodes and protoscoleces, which could potentially be exploited further for the development of novel chemotherapeutical tools against larval-stage Echinococcus infection.
Animals↗
Morphological and molecular characteristics of Echinococcus multilocularis and Echinococcus granulosus mixed infection in a dog from Xinjiang, China.
The Xinjiang plateau of western China has been shown to have a high prevalence for human cystic echinococcosis (CE) caused by Echinococcus granulosus, and human alveolar echinococcosis (AE) caused by Echinococcus multilocularis. The domestic dog is suspected to be the primary definitive host for the transmission of both E. granulosus and E. multilocularis to humans in this locality. Seventeen of 30 stray dogs from Hejing County of Xinjiang were found positive for E. granulosus post mortem, and one double infection was suspected. Worm samples were collected, dyed by carmine, and observed microscopically. Carmine staining examination clearly revealed the differences in number of proglottids and appearance of uterine branches and lateral genital pore for those two species of Echinococcus. Furthermore, gene target DNA fragments were amplified for formal identification of the two parasite species, based on 12s rRNA mitochondrial gene. The PCR products were purified and sequenced. Compared with NCBI GenBank, the DNA sequences demonstrated 100% identity with E. granulosus (sheep strain, G1 genotype) and E. multilocularis.
Animals↗
In vitro culture of Echinococcus multilocularis and Echinococcus vogeli metacestodes: studies on the host-parasite interface.
The larval stage of Echinococcus multilocularis causes alveolar echinococcosis (AE) in various mammalians including humans, while Echinococcus vogeli larvae cause a related disease which is also occasionally found in man. Traditionally, Echinococcus metacestodes have been maintained in the laboratory by serial transplantation passages into susceptible animals such as mice or gerbils, enabling the parasite to proliferate asexually. These experimental animal models have been used extensively to investigate host-parasite interactions and to study immunological events occurring at the host-parasite interface. However, with the use of laboratory animals it has always been difficult to investigate in more detail those factors modulating metacestode differentiation, and investigations on gene expression and respective regulation have been hampered by the complexity of the host-parasite interplay. There has been a need for an in vitro culture model which would enable researchers to dissect specific parasite compartments involved in the host-parasite relationship in more detail. This review summarises the studies leading to the development and application of a suitable in vitro culture model for the maintenance and proliferation of E. multilocularis and E. vogeli metacestodes, including the formation of protoscoleces, in a chemically defined medium devoid of host influence. These culture models have been used to study the basic parameters of metacestode in vitro proliferation and differentiation, and for the dissection of the ultrastructure and composition of the acellular laminated layer, the structure of which is predominantly involved in the physical interaction between the parasite and host immune and non-immune cells and tissues. For E. multilocularis, in vitro cultured parasites have been more extensively employed to study the localisation of several antigens, and to generate defined antigens for immunological studies. Although in vitro culture will not completely eliminate the need of animal experimentation, a wider application of this technique could significantly reduce the use of animals, and thus the costs and time required for respective experimental investigations.
Animals↗
Molecular cloning and characterization of an Echinococcus multilocularis and Echinococcus granulosus stress protein homologous to the mammalian 78 kDa glucose regulated protein.
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Amino Acid Sequence↗
Reduced genetic variability within coding and non-coding regions of the Echinococcus multilocularis genome.
Echinococcus multilocularis, a vulpine intestinal tapeworm, is the causative agent of alveolar echinococosis in humans, one of the most severe and lethal parasitic infections in man. To date, there is very little knowledge about the genetical polymorphism of this parasite. To assess sequence polymorphism, we analysed a sample of 33 E. multilocularis isolates from Europe, North America and Asia by PCR-SSCP followed by nucleotide sequencing. This assessment was performed comparatively to sheep, cattle and pig E. granulosus strains. Coding (nuclear antigen B and mitochondrial NADH dehydrogenase genes) and non-coding (introns of actin and homeobox-containing genes) regions of the parasite genome were chosen as targets. Since the estimated nucleotide diversity among genotypes of E. multilocularis were, in general, 10 times lower than among the recognized different strains of E. granulosus, we suggest that the conventional classification of the former species in 2 separated strains (European and North American) should be reviewed.
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Identification of a laminated layer-associated protein in Echinococcus multilocularis metacestodes.
Echinococcus multilocularis is a cestode parasite that predominantly infects red and arctic foxes as definitive hosts. Ingestion of E. multilocularis eggs and subsequent post-oncospheral infection with the larval stage (metacestode) of the parasite results in alveolar echinococcosis (AE), a life-threatening hepatic disease concerning humans and other intermediate hosts such as small rodents. The primary fluid-filled vesicles of the asexually proliferating metacestode are comprised of an inner germinal layer, a syncytial tegument, and an outer, acellular, so-called laminated layer. This laminated layer may play an important role in protecting the developing E. multilocularis metacestode from host immune reactions, and laminated layer-associated components represent potential targets for intervention during the course of AE. We have used an in vitro cultivation technique for the long-term maintenance and proliferation of E. multilocularis metacestodes in order to generate premature (protoscolex-free) parasite vesicles. A polyclonal antiserum was raised against this host-free parasite tissue. Subsequent immunoblot analysis of parasite fractions obtained by Triton X-114 extraction lead to the identification of a 116 kDa protein (named EmP2) within the Triton-insoluble fraction. The characterization of EmP2 by SDS-PAGE, Western blotting, and by immunofluorescence revealed that EmP2 is a laminated layer-associated protein.
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An intact laminated layer is important for the establishment of secondary Echinococcus multilocularis infection.
Echinococcus multilocularis causes alveolar echinococcosis primarily in rodents, but also in humans where it represents one of the most lethal helmintic infections. We used a susceptible mouse (C57BL/6) model to demonstrate failure in controlling secondary infection with the E. multilocularis metacestode, even when performed at the lowest possible infection dose. This was achieved by intraperitoneal or intrahepatic inoculation of a single parasite vesicle. In secondary infections, the primary physical barrier between the parasite and the host is constituted by the acellular laminated layer (LL), which is predominantly composed of high-molecular-weight glycans and surrounds the entire metacestode. Only those metacestode structures which exhibited an intact LL were successful in establishing infection, whereas metacestodes which were punctured - thus exhibiting an opened LL and thereby an accessible germinal layer - were no longer infective. Conversely, both types of vesicle survived in vivo maintenance, as assessed by RT-PCR based upon II/3 gene expression. In consequence, the encapsulating LL appears to be one of the key factors that mediates survival and successful proliferation of the parasite metacestode in vivo.
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Possible formation of new brood capsule by the previously formed brood capsule in Echinococcus multilocularis metacestodes.
In Echinococcus multilocularis metacestodes obtained from the peritoneal cavity of an experimentally infected jird, cellular accumulations were found not only on the inner surfaces of germinal layers but also on the outer surfaces of brood capsules. These cellular accumulations are believed to represent at incipient form of the brood capsule. It has been thought that brood capsules are produced by the germinal layer, but we speculate that the brood capsule itself, as well as the germinal layer, may have the potential to produce new brood capsules.
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[Comparison observation on the mature alveolar of Echinococcus sibiricensis and Echinococcus multilocularis in the experimentally infected white mice].
The alveolar echinococcus is one of the most dangerous worm parasites in man. Rausch and Schiller reported a new species, Echinococcus sibiricensis n. sp. from arctic fox, Alpex logopus, on St. Lawrence Island of Alaska, USA. According to the view of Vogel, the sibiricensis form is only a geographical race or subspecies of Europe Echinococcus multilocularis. So far, the two names, Echinococcus multiocularis multilocularis and Echinococcus multilocularis sibiricensis, existed in many references and text books. We have found the adults of Echinococcus sibiricensis and Echinococcus multilocularis from sand foxes, Vulpes corsac and their larval stages (alveolar echinococcus) from field voles, Microtus brandti in the Hulunbeier Pasture of Inner Mongolia, northeastern China in 1985 and 1998-1999. Two types of metacestodes with quite different styles of early development of E. sibiricensis and E. multilocularis were found from field voles and laboratory experimental white mice. As one characteristic of alveolar E. multilocularis, the capsules are produced by the exogenous budding of germinal cell layer together with cyst wall. The protoscoleces grow from germinal cells on germinal cell layer. The peduncles of early protoscoleces attached to the germinal cell layer on the inner surface of capsule wall(Plate I, Figs. 1-2). Some protoscoleces in reticular structure were linked with the inner surface of capsule wall (Plate I, Fig. 3) in livers of mice in 9.5th month postinfection. In 14th month old alveolar multilocularis, large number of mature protoscoleces in reticular structure were still linked to the inner surface of capsule wall (Plate I, Figs. 4-8). The cavities of some capsules were filled with protoscoleces in meshes of reticular structure which were also linked around with the inner surface of capsule wall (Plate I, Fig. 9). The superficial surface of livers of positive field voles and experimental mice never showed any hyperemic phenomenon. The superficial surfaces of livers and lungs of positive field voles and experimental mice infected with alveolar E. sibiricensis were highly hyperemic. The metacestodes of E. sibiricensis composed of mother cyst, undifferentiated embryonic cysts and small brood capsules. Cavities of all cysts were fully filled with germinal cell masses. Host reaction appeared to be very strong, all cysts were surrounded by thick connective tissue and dense leukocytes (Plate II, Fig. 10). All alveolar vesicles were found located in lungs tissue of experimental mice. Large germinal cell masses metastasized out from undifferentiated embryonic cysts into host lung tissue, where germinal cell masses developed into accumulation of early protoscoleces (Plate II, Figs. 11-12). Early protoscoleces of alveolar E. sibiricensis were seen earliest in mice lung tissues on 101-104th days after infection. Many small capsules in different sizes and different shapes containing mature protoscoleces and reticular structure (Plate II, Figs. 13-15) were found in lungs of mice in 9th month after infection. Only in one experimental mouse infected with alveolar E. sibiricensis in 8.5th month postinfection, both its lung and liver existed alveolar cysts; the capsules in liver were surrounded by very thick connective tissue of the host, and there were some protoscoleces in their cavities (Plate II, Figs. 16-18).
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Evaluation of fox-chasing enclosures as sites of potential introduction and establishment of Echinococcus multilocularis.
Following detection of Echinococcus multilocularis in red foxes (Vulpes vulpes) illegally imported into South Carolina (USA) for release in fox-chasing enclosures, a survey for E. multilocularis was conducted in four enclosures in Georgia (USA) and six enclosures in South Carolina. Survey methods included examination of potential small mammal intermediate hosts (n = 390) for E. multilocularis larvae, examination of fox and coyote (Canis latrans) scats (n = 59) for taeniid eggs, and examination of one possible canine definitive hosts for adult E. multilocularis. All intermediate and definitive hosts examined were negative for E. multilocularis and taeniid eggs were not recovered from fox and coyote fecal samples. Thus, E. multilocularis may not yet be established in fox-chasing enclosures in Georgia and South Carolina. Despite the failure to demonstrate E. multilocularis in the fox-chasing enclosures surveyed, translocation of wild canids from known enzootic regions should be discouraged because E. multilocularis is known to be ecologically adaptable and because contact with potentially infected definitive hosts during translocation is a public health risk.
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Spatial and temporal aspects of urban transmission of Echinococcus multilocularis.
High prevalences of Echinococcus multilocularis have been reported from foxes of the city of Zurich, Switzerland. In order to characterize transmission in urban areas, a coproantigen ELISA was evaluated for diagnosing the infection in fox faecal samples collected in the environment. In addition, trapped rodents were investigated for the presence of metacestodes. Faecal samples could reliably be classified as being of fox origin by assessing physical properties as shown by the different parasite spectra of putative fox and dog faecal specimens. From the total of 604 tested putative fox faecal samples 156 (25.8%) were positive in the ELISA with a distinct increase in the proportion of positive samples from the urban to the periurban zone. Furthermore, samples collected in the border zone had significantly more coproantigen-positive results during winter. Prevalence of E. multilocularis in rodents was 9.1% (81/889) for Arvicola terrestris (with 3.5% of the animals harbouring between 14 and 244400 protoscoleces) and 2.4% (2/83) for Clethrionomys glareolus. E. multilocularis-infected A. terrestris were found in 9 of 10 trapping sites in the border zone. The high infection pressure in the periphery of urban areas might pose a risk for infection with E. multilocularis for both domestic carnivores as well as for urban inhabitants. Interventions into the cycle aiming at reducing the infection pressure should therefore focus on these areas.
Age Factors↗
Failure to identify alveolar echinococcosis in trappers from South Dakota in spite of high prevalence of Echinococcus multilocularis in wild canids.
Echinococcus multilocularis causes a rare but potentially lethal zoonotic disease in humans. This tapeworm has been known to be endemic in foxes (Vulpes vulpes) and coyotes (Canis latrans) within the northern United States since the 1960s. One purpose of this study was to provide recent data on the prevalence of E. multilocularis in foxes and coyotes from eastern South Dakota. In a survey conducted from 1987 to 1991 and involving 137 foxes and 9 coyotes from this area, 74.5% of the foxes and 4 of the coyotes were infected. To assess the possible prevalence of alveolar echinococcosis in a group at presumptive high risk, we also conducted a serological survey of members of the South Dakota Trappers Association in 1990 and 1991. Serum samples from 115 trappers were evaluated for the presence of E. multilocularis antibodies using enzyme-linked immunosorbent assay tests involving a purified antigen called Em2, a crude E. multilocularis antigen, and a recombinant E. multilocularis antigen called II/3-10. None of the trappers showed antibody evidence for the presence of E. multilocularis. Roughly half of the surveyed individuals had trapped more than 50 foxes during their life, and almost one-fourth had trapped more than 1,000 foxes.
Adolescent↗
Analysis of the monohexosylceramide fraction of Echinococcus multilocularis metacestodes.
Monohexosylceramides of Echinococcus multilocularis metacestodes have been isolated and analyzed by thin-layer chromatography, gas-liquid chromatography and mass spectrometry. 90.9% of the parasite fraction was galactosylceramide; glucosylceramide was present at only 9.1%. The most important fatty acids were normal C16:0 and C26:0 fatty acids. The hydroxylated fatty acids of the ceramide part constituted 20.1% of the total, their major constituents were C18:0 and C26:0. The sphinganine accounted for 70.4% of long-chain bases, phytosphingosine and sphingosine were also detected. The importance of the long chain fatty acids and the presence of sphinganine in the monohexosylceramide fraction were discussed.
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Echinococcus multilocularis.
PURPOSE OF REVIEW: Echinococcus multilocularis is a tapeworm of foxes that may cause a zoonotic infection resulting in a highly pathogenic and potentially fatal chronic liver infestation called human alveolar echinococcosis. Radical liver resection currently offers the only potential cure. Although alveolar echinococcosis is a rare parasitic disease that is restricted to transmission in the northern hemisphere, the parasite is geographically widespread being distributed from Alaska, across Canada and north central USA, through northern Europe and Eurasia to Japan. The present review summarizes the background to this helminthic infection and recent contributions in areas of pathology, diagnosis, treatment and transmission. RECENT FINDINGS: Concern is growing in Europe that the prevalence and distribution of E. multilocularis in red foxes has increased significantly in the last 10-15 years. A retrospective analysis revealed >550 cases of human alveolar echinococcosis diagnosed between 1982-2000, with the majority in France, Germany and Switzerland. Human prevalence rates >3% occur in central northwest China and the disease is of public health concern in northern Japan. Improvements in immunodiagnosis with native and recombinant antigens have enabled more accurate confirmation of hepatic image findings, while development of in-vitro culture of metacestode tissues provides a useful model for screening new anti-alveolar echinococcosis drugs as alternatives to albendazole and surgery. Recombinant molecules from the oncosphere and metacestode stages have shown potential as vaccine candidates. New tools of coproantigen and copro-DNA detection for vulpine infections have proved highly beneficial in epidemiological and transmission ecology studies, as has a landscape ecology approach to develop risk models for communities in endemic areas. SUMMARY: It is possible that human AE will become an emergent zoonosis in some regions of Europe and Eurasia. Improvements in diagnostic and treatment approaches are being investigated. Further understanding of host immune responses will aid in characterization of disease pathology. Control of E. multilocularis in its natural cycles will be difficult due to the involvement of wild animal hosts, however use of anthelminthic baits and dosing of domestic dogs may reduce transmission at local scales.
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Field evaluation of an intravital diagnostic test of Echinococcus multilocularis infection in red foxes.
Echinococcus multilocularis parasitizes the small intestine of red foxes (Vulpes vulpes) and other carnivores, and has a wide distribution throughout the northern hemisphere. This cestode is the causative agent of human alveolar echinococcosis, a life-threatening helminth zoonosis. In 2000-2002, 2130 red foxes were examined for its presence in Slovakia, with a total prevalence of 30.7%. The data on occurrence were obtained by the combination of necropsy of small intestines from red foxes and coproantigen detection in faecal samples. The correlation between the number of detected specimens and the value of optical density of copro-ELISA test was found. When worm burdens were low (1-25 specimens) the sensitivity of the method was 31.3+/-8.64%, when worm burdens were >50 specimens, 81.8+/-0.66%, and with high worm burdens (>1000 specimens) the sensitivity reached 100+/-0.34%. E. multilocularis presence was detected using the nested PCR method from the eggs in the faecal samples with a 100% specificity. In epidemiological surveys of this zoonosis, it is of crucial importance to detect animals with a high level of infection, which are responsible for the bulk of environmental contamination. The advantage of copro-ELISA test lies in allowing the intravital diagnostics to be employed within the epidemiological survey of E. multilocularis occurrence in the protected and urban areas.
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EmsB, a tandem repeated multi-loci microsatellite, new tool to investigate the genetic diversity of Echinococcus multilocularis.
In order to explore the genetic diversity within Echinococcus multilocularis (E. multilocularis), the cestode responsible for the alveolar echinococcosis (AE) in humans, a microsatellite, composed of (CA) and (GA) repeats and designated EmsB, was isolated and characterized in view of its nature and potential field application. PCR-amplification with specific primers exhibited a high degree of size polymorphism between E. multilocularis and Echinococcus granulosus sheep (G1) and camel (G6) strains. Fluorescent-PCR was subsequently performed on a panel of E. multilocularis isolates to assess intra-species polymorphism level. EmsB provided a multi-peak profile, characterized by tandemly repeated microsatellite sequences in the E. multilocularis genome. This "repetition of repeats" feature provided to EmsB a high discriminatory power in that eight clusters, supported by bootstrap p-values larger than 95%, could be defined among the tested E. multilocularis samples. We were able to differentiate not only the Alaskan from the European samples, but also to detect different European isolate clusters. In total, 25 genotypes were defined within 37 E. multilocularis samples. Despite its complexity, this tandem repeated multi-loci microsatellite possesses the three important features for a molecular marker, i.e. sensitivity, repetitiveness and discriminatory power. It will permit assessing the genetic polymorphism of E. multilocularis and to investigate its spatial distribution in detail.
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Limited range of genetic variation in Echinococcus multilocularis.
DNA sequencing of 1.3 kb of rDNA containing both internal transcribed spacers (ITS1, ITS2) and adjoining rRNA coding regions in each of 11 Echinococcus multilocularis isolates from Germany, Japan, and Alaska resulted in identical nucleotide sequences except for a single polymorphic locus 54 bp upstream of the 3' end of the 18S coding region, separating Eurasian isolates from an Alaskan isolate. The same base substitution was found in each of 2 additional isolates from Alaska. The distribution of the resulting genotypes with regard to their origin is highly significant (>99.9%) and corresponds to the traditional subspecies Echinococcus multilocularis multilocularis and Echinococcus multilocularis sibiricensis.
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