首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A morphological study of adult liver flukes and eggs from sheep in a human fascioliasis endemic zone in the Northern Bolivian Altiplano showed that they belong to the species Fasciola hepatica. An exhaustive morphometric comparison with a F. hepatica population from Spanish sheep was made using image analysis and an allometric model: (y2m-y2)/y2 = c(y1m-y1)/y1[b, where y1 = body surface or body length, y2 = one of the measurements analyzed, y1m, y2m = maximum values towards which y1 and y2 respectively tend, and c, b = constants. Only slight allometric differences in worms were observed despite the geographic distance between both Spanish and Bolivian sheep populations and the very high altitude of the Bolivian Altiplano.  相似文献   

2.
Complete sequences of ribosomal and mitochondrial genes of the giant liver fluke Fascioloides magna are presented. In particular, small subunit (18S) and internal transcribed spacers (ITS1 and ITS2) of the ribosomal gene (rDNA), as well as cytochrome c oxidase subunit I (cox1) and nicotinamide dehydrogenase subunit I (nad1) of the mitochondrial DNA (mtDNA), were analyzed. The 18S and ITS sequences were compared with previously published sequences of the liver fluke Fasciola hepatica. Fixed interspecific genetic differences were determined that allow molecular differentiation of F. magna and F. hepatica using either the PCR-RFLP method or PCR amplification of species-specific DNA regions. Additionally, intraspecific sequence polymorphism of the complete cox1 and nad1 mitochondrial genes in geographically distinct F. magna populations was determined. Based on the sequence divergences, short (< 500 bp) variable regions suitable for broader biogeographical studies of giant liver fluke were designed.  相似文献   

3.
The potential of GST as a vaccine candidate against liver fluke infection in ruminants was studied by vaccinating sheep (n = 9) with GST purified from adult worms of Fasciola hepatica and challenging with 500 F. hepatica metacercariae. The immunization induced a high antibody response to GST in contrast to the poor or undetectable response to this Ag observed in naturally infected sheep. Throughout the trial, the progress of the fluke infection was monitored by measuring RBC hemoglobin levels, the extent of liver damage and the fecal egg output in the sheep. This analysis indicated that a subpopulation (n = 4) of the GST vaccinated animals exhibited no anemia, reduced liver damage and a lower mean fecal egg count relative to the infected control group suggesting a lower fluke burden in these animals. Worm burdens in the livers of the GST vaccine group (107 +/- 22) were 57% lower than in the infected control group (250 +/- 25). The subpopulation of the GST vaccine group demonstrated a 78% reduction in mean worm burdens relative to the control group. These results show that GST of adult F. hepatica is a novel Ag that can significantly protect sheep against liver fluke infection. The results suggest that the immune response to GST is directed to the juvenile worm reducing the number of worms that can establish in the liver of the vaccinated animals.  相似文献   

4.
The parasite Fasciola hepatica causes major global disease of livestock, with increasing reports of human infection. Vaccine candidates with varying protection rates have been identified by pre-genomic approaches. As many candidates are part of protein superfamilies, sub-proteomics offers new possibilities to systematically reveal the relative importance of individual family proteins to vaccine formulations within populations. The superfamily glutathione transferase (GST) from liver fluke has phase II detoxification and housekeeping roles, and has been shown to contain protective vaccine candidates. GST were purified from cytosolic fractions of adult flukes using glutathione- and S-hexylglutathione-agarose, separated by 2-DE, and identified by MS/MS, with the support of a liver fluke EST database. All previously described F. hepatica GST isoforms were identified in 2-DE. Amongst the isoforms mapped by 2-DE, a new GST, closely related to the Sigma class enzymes is described for the first time in the liver fluke. We also describe cDNA encoding putative Omega class GST in F. hepatica.  相似文献   

5.
Livestock infection by the parasitic fluke Fasciola hepatica causes major economic losses worldwide. The excretory-secretory (ES) products produced by F. hepatica are key players in understanding the host-parasite interaction and offer targets for chemo- and immunotherapy. For the first time, subproteomics has been used to compare ES products produced by adult F. hepatica in vivo, within ovine host bile, with classical ex host in vitro ES methods. Only cathepsin L proteases from F. hepatica were identified in our ovine host bile preparations. Several host proteins were also identified including albumin and enolase with host trypsin inhibitor complex identified as a potential biomarker for F. hepatica infection. Time course in vitro analysis confirmed cathepsin L proteases as the major constituents of the in vitro ES proteome. In addition, detoxification proteins (glutathione transferase and fatty acid-binding protein), actin, and the glycolytic enzymes enolase and glyceraldehyde-3-phosphate dehydrogenase were all identified in vitro. Western blotting of in vitro and in vivo ES proteins showed only cathepsin L proteases were recognized by serum pooled from F. hepatica-infected animals. Other liver fluke proteins released during in vitro culture may be released into the host bile environment via natural shedding of the adult fluke tegument. These proteins may not have been detected during our in vivo analysis because of an increased bile turnover rate and may not be recognized by pooled liver fluke infection sera as they are only produced in adults. This study highlights the difficulties identifying authentic ES proteins ex host, and further confirms the potential of the cathepsin L proteases as therapy candidates.  相似文献   

6.
Glycosphingolipids from the parasitic liver flukes Fasciola gigantica and Fasciola hepatica were isolated and their carbohydrate moieties were structurally analysed by methylation analysis, exoglycosidase treatment, on-target exoglycosidase cleavage and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. For both liver fluke species, the ceramide monohexosides Gal1-ceramide and Glc1-ceramide were found in relative amounts of 1.0 to 0.1, respectively. From F. gigantica, the ceramide dihexoside was isolated in sufficient amounts to be structurally determined as lactosylceramide, Gal beta4-Glc1-ceramide, while for both liver fluke species the ceramide trihexoside was shown to be Gal alpha4Gal beta4-Glc1-ceramide, which is designated as either globotriaosylceramide, Pk-blood group antigen or CD77 leucocyte cluster of differentiation antigen. To our knowledge, this is the first report on the expression of globo-series glycosphingolipids in non-mammalian species. Ceramide analysis of ceramide monohexosides yielded as major components octadecanoic and 2-hydroxyoctadecanoic fatty acids together with C18- and C20-phytosphingosines. By the use of an anti-CD77 monoclonal antibody and the Escherichia coli Shiga toxin B1 subunit, globotriaosylceramide could be immunolocalised to the tegument of F. hepatica cryosections. The sharing of CD77 between liver flukes and their mammalian hosts fits in with the concept of molecular mimicry, which is closely parallel to the established imitation of host CD15 (Lewis X) displayed by the blood fluke Schistosoma mansoni.  相似文献   

7.
The in vivo efficacy of monensin against Fasciola hepatica was determined in the albino rat. The results were variable, with monensin generally showing greater activity against juvenile (two-week-old) than adult (12-week-old) flukes. Significant (p less than 0.005) reductions in worm burdens were obtained only following treatment of adult flukes with 2 X 10 mg/kg monensin (52.9% efficacy), and of juvenile flukes with 1 X 10 mg/kg (42.4% efficacy) and 2 X 10 mg/kg (56.23% efficacy). Monensin administered in the diet (200 ppm) had a negligible effect on juvenile and adult fluke burdens. Prophylactic treatment of rats with monensin (100 ppm) produced a 45.5% efficacy, but this was not statistically significant. At doses of 1 X 5 mg/kg and 2 X 2.5 mg/kg, monensin had little effect on egg output by F. hepatica. No clear relationship was established between egg output and worm burden, and so faecal egg counting was not a reliable indicator of fluke burdens in the rat.  相似文献   

8.
Thioredoxin reductase (TrxR), an enzyme belonging to the flavoprotein family of pyridine nucleotide-disulfide oxidoreductases, was isolated from the deoxycholate-soluble extract of the common liver fluke, Fasciola hepatica. Purification to homogeneity of the 60-kDa enzyme from the adult worm was achieved by a combination of ammonium sulfate fractionation, anion exchange, and affinity chromatography on 2',5'-adenosine diphosphate-Sepharose. Using the 5,5'-dithiobis(2-nitrobenzoic acid) assay, the purified TrxR showed a specific activity of 7,117 U min(-1) mg(-1). The enzyme activity was completely inhibited by the presence of the gold compound aurothioglucose (IC50 = 120 nm), indicating that F. hepatica TrxR is a selenoenzyme. Also, the enzyme was capable of reducing disulfide bonds in insulin and was activated by the presence of the reduced form of flavin adenine dinucleotide, properties shared with mammalian TrxRs. Furthermore, the isolated enzyme showed very low glutaredoxin (Grx) activity (0.47 U mg(-1)), but no glutathione reductase activity was detected. Affinity-purified IgGs (20 microg ml(-1)) from the antisera produced against the purified TrxR inhibited its activity about 80% with respect to the control. The enzyme was immunolocalized in cells located within the parenchyma and in the testes, but it was not found in the tegument of the adult fluke.  相似文献   

9.
1. The phospholipid composition of Fasciola hepatica, the common liver fluke, was compared to that of the liver of the host animals (rats and cattle). Considerable differences were found:monoacyl-sn-glycero-3-phosphorylcholine, hardly detectable in the liver, was found in significant amounts in the parasite. On the other hand, sphingomyelin, a normal constituent in the liver, appears to be absent in the liver fluke. Fasciola hepatica isolated from rat and cow liver had a strikingly similar phospholipid composition. 2. Qualitative and quantitative differences were also found between the fatty acyl constituents of the phospholipids of the parasite and the liver. The major difference was the presence of eicosaenoic and eicosadienoic acids in the parasite, whereas these acids were not detected in the liver. 3. In vitro incubations of Fasciola hepatica in the presence of (32P)phosphate and (2-3H)glycerol resulted in the labelling of all phospholipids of the parasite, except that the 3H label did not incorporate into ethanolamine plasmalogen. This is in agreement with the concept that in animals, glycerol is introduced into plasmalogens via dihydroxyacetonephosphate. 4. Homogenates of liver flukes were found to catalyze the synthesis of phosphatidylcholine from 1,2-diacyl-sn-glycerols and CDPcholine. 5. These results strongly suggest that Fasciola hepatica is capable of synthesizing at least part of its fatty acids and phospholipids.  相似文献   

10.
Because the synthetic trioxolane OZ78 is active against the liver fluke Fasciola hepatica, we were motivated to investigate the in vivo and in vitro activity against another liver fluke, namely Clonorchis sinensis. Rats infected with C. sinensis for 2 and 5 wk were treated orally with single doses of OZ78 (75, 150, or 300 mg/kg). Worm burden reductions were assessed against untreated control rats. Scanning electron microscopy (SEM) was used to observe adult C. sinensis after recovery from rats 1-3 days posttreatment with a single 300 mg/kg oral dose of OZ78 and after in vitro exposure to concentrations of 1, 10, and 100 microg/ml of OZ78. A single 300 mg/kg oral dose of OZ78 resulted in worm burden reductions of 78.5% and 98.5% against juvenile and adult C. sinensis, respectively. SEM observations revealed tegumental surface alterations, including blebbing and sloughing. OZ78 emerges as a new compound with a broad spectrum of activity against major foodborne trematode infections.  相似文献   

11.
Glutathione S-transferases in Fasciola hepatica   总被引:3,自引:0,他引:3  
Glutathione S-transferases (GST's) are widespread in the tissues of the liver fluke, Fasciola hepatica, and consist of multiple isozymes. Following purification to apparent homogeneity by affinity chromatography on glutathione agarose, fluke GST's were shown to comprise 2 components with molecular weights of about 25,000. Fluke GST's were immunogenic to rats, but when used as a vaccine conferred no protection on the animals against a challenge infection with F. hepatica metacercariae.  相似文献   

12.
Fasciola hepatica has recently emerged as a major pathogen of humans from reports on areas of endemicity and hyper-endemicity for fascioliasis. This situation is aggravated by the lack of standard assays for the screen diagnosis of F. hepatica infection in humans living in endemic areas. Our laboratory has developed an enzyme-linked immunosorbent assay (Fas2-ELISA) based on the capture of IgG antibody by a purified protein Fas2, which is an adult fluke cysteine proteinase. Fas2-ELISA exhibited 95% sensitivity and 100% specificity in 38 individuals infected with F. hepatica diagnosed by finding eggs in stools and 46 serum samples from healthy volunteers. No cross-reaction was observed with 54 serum samples from patients with ten different parasitic infections including the trematodes Paragonimus westermani and Schistosoma mansoni. The high antigenicity of Fas2 is suggested by the fact that antibodies to Fas2 rise rapidly by 1-2 weeks of infection and rise until patency at 8 weeks of infection in experimentally infected alpacas. Field screening for human fascioliasis using Fas2-ELISA and coprology in three endemic locations of the Peruvian Andes resulted in 95.5% sensitivity, 86.6% specificity in a population of 664 children in an age range of 1 to 16 years old. These results provide evidence of the clinical potential of Fas2-ELISA to diagnose fascioliasis in humans exposed to liver fluke infection in endemic areas for this parasite. Fas2-ELISA is currently developed as a standard assay for both field screening for fascioliasis in people living in endemic areas and detecting occasionally F. hepatica infected patients in clinical laboratories.  相似文献   

13.
The acidic (glyco)lipids of the parasitic liver fluke Fasciola hepatica exhibited two different phosphate-containing species, designated AL-I and AL-II, which were analyzed by MALDI-TOF MS, ESI MS, NMR, methylation analysis, and combined GC-MS in conjunction with HF treatment. AL-I was structurally determined as 1-O-hexadecyl-sn-glycerol-3-phosphoinositol, an ether bond variant of lysophosphatidylinositol. The structure of AL-II was shown to be GlcNAcalpha1-HPO3-6Gal(1-1)ceramide. Ceramide analysis revealed as major components 2-hydroxyoctadecanoic acid [18:0(2-OH)] together with C18- and C20-phytosphingosines. AL-II was apparently highly antigenic and strongly recognized by both animal- and human-F. hepatica infection sera. Furthermore, inhibition ELISAs revealed that the unusual antigenic determinant GlcNAcalpha1-HPO3- phosphate might have a potential in the serodiagnosis of F. hepatica infections.  相似文献   

14.
Fasciola hepatica, the liver fluke, secretes a cathepsin L cysteine proteinase. The enzyme is active over the pH range 5-9 and is remarkably stable at 37 degrees C, pH 7.0, in contrast to mammalian cathepsin Ls that are active in the acidic pH range and are inactivated within 15 min at neutral pH. The liver fluke proteinase is also very tolerant of organic solvents, particularly dimethylformamide. However, it is completely inactivated by 1 mM Hg(2+) and adversely affected by other heavy metals and divalent cations. Addition of glycerol and EDTA enhanced the liver fluke enzyme's stability at 50 degrees C, while glucose and glycerol protected the enzyme from inactivation by repeated freeze-thawing. The high stability of liver fluke cathepsin L suggests that it may have potential for use in bioindustrial applications.  相似文献   

15.
This study represents the first beta-tubulin sequence from a trematode parasite, namely, the liver fluke, Fasciola hepatica. PCR of genomic DNA showed that at least one beta-tubulin gene from F. hepatica contains no introns. A number of amino acids in the primary sequence of fluke tubulin are different from those described previously in various nematode species and the cestode, Echinococcus multilocularis. beta-Tubulin is an important target for benzimidazole anthelmintics, although (with the exception of triclabendazole) they show limited activity against F. hepatica. The amino acid differences in fluke beta-tubulin are discussed in relation to the selective toxicity of benzimidazoles against helminths and the mechanism of drug resistance.  相似文献   

16.
A capture enzyme-linked immunosorbent assay (ELISA) using a new monoclonal antibody (mAb MM3) is reported for the detection of Fasciola hepatica excretory-secretory antigens (ESAs) in feces of infected hosts. The mAb MM3 was produced by immunization of mice with a 7- to 40-kDa purified and O-deglycosylated fraction of F. hepatica ESAs, which has previously been shown to be specific for the parasite. The specificity and sensitivity of the MM3 capture ELISA were assessed using feces from sheep and cattle. Sheep feces were obtained from a fluke-free herd (with most animals harboring other nematodes and cestodes), from lambs experimentally infected with 5-40 F. hepatica metacercariae and in some cases treated with triclabendazole at 14 wk postinfection (PI), and from uninfected control lambs. Cattle feces were collected at the slaughterhouse from adult cows naturally infected with known numbers of flukes (from 1 to 154) or free of F. hepatica infection (though in most cases harboring other helminths). The MM3 capture ELISA assay had detection limits of 0.3 (sheep) and 0.6 (cattle) ng of F. hepatica ESA per milliliter of fecal supernatant. The assay detected 100% of sheep with 1 fluke, 100% of cattle with 2 flukes, and 2 of 7 cattle with 1 fluke. The false-negative animals (5/7) were probably not detected because the F. hepatica individuals in these animals were immature (5-11 mm in length). As expected, coproantigen concentration correlated positively (r = 0.889; P < 0.001) with parasite burden and negatively (r = 0.712; P < 0.01) with the time after infection at which coproantigen was first detected. Nevertheless, even in animals with low fluke burdens (1-36 parasites), the first detection of F. hepatica-specific coproantigens by the MM3 capture ELISA preceded the first detection in egg count by 1-5 wk. In all sheep that were experimentally infected and then untreated, coproantigen remained detectable until at least 18 wk PI, whereas in sheep that were experimentally infected and then flukicide treated, coproantigen became undetectable from 1 to 3 wk after treatment. None of the fecal samples from sheep or cattle negative for fascioliasis but naturally infected with other parasites including Dicroelium dendriticum showed reactivity in the MM3 capture ELISA. These results indicate that this assay is a reliable and ultrasensitive method for detecting subnanogram amounts of F. hepatica antigens in feces from sheep and cattle, facilitating early diagnosis.  相似文献   

17.
18.
Economical breeding is important to obtain maximum gain from the breeding in the animal sector. The economic loss has to be eliminated or should be minimized. The liver fluke, Fasciola hepatica, present mostly in sheep and dairy cattle affect the yield of animals and even cause their death. To eliminate or minimize the impact of these parasites on the animals, it is important to understand the genetic diversity of the liver fluke populations and the relationship between parasite and host at regional bases. This research was carried out to determine diversity by sequence analysis of the mitochondrial ND1 gene and ribosomal ITS1 region.  相似文献   

19.
The susceptibility of black-tailed deer (Odocoileus hemionus columbianus) to the common liver fluke (F. hepatica) was studied. Two deer and one sheep comprised each of three experimental groups. Animals in each group were inoculated individually with 250, 500, or 1000 F. hepatica metacercariae. One deer and one sheep given 1000 metacercariae died with lesions consistent with black disease 7 weeks after inoculation. At necropsy 6 or 15 weeks postinoculation, the mean percentage recovery of the inoculum was 38.9% from the deer and 51.9% from the sheep. Fluke eggs recovered from the deer were viable and metacercariae cultured from the eggs were fully infective for sheep. Pathologic changes associated with F. hepatica infection were more severe in the infected deer; consequently, the deer were less resistant to the lethal effects of the parasite than sheep. Considering the experimental results and the fact that naturally acquired common liver fluke infection has been reported infrequently from black-tailed deer, it was concluded that black-tailed deer do not constitute a significant reservoir for F. hepatica in domestic livestock.  相似文献   

20.
1. Extracts of the liver fluke, Fasciola hepatica from three different hosts (cow, sheep, rat) have been subjected to radioimmunoassay using antisera to 6 mammalian regulatory peptides. 2. Immunoreactivity was measured to pancreatic polypeptide, substance P, peptide histidine isoleucine and gastrin-releasing peptide. Levels of each peptide varied considerably in flukes from different hosts. 3. Reverse-phase HPLC of rat and sheep fluke extracts revealed three molecular forms of tachykinin immunoreactivity and single peaks of pancreatic polypeptide and peptide histidine isoleucine immunoreactivity. No GRP-immunoreactivity was detected by RIA of HPLC fractions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号