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PubMed1992

Light and scanning electron microscopic studies of the extrahepatic bile duct of sheep with experimentally induced Fasciola hepatica infection.

Changes in the common bile duct that contained adult Fasciola hepatica of sheep were evaluated by light (LM) and scanning electron microscopy (SEM). Nine ewes were inoculated with F hepatica metacercariae and necropsied 18 weeks after inoculation. The proximal portion of the common bile duct (CBD) that contained adult flukes was recovered and examined by LM and SEM. The CBD from 2 noninoculated ewes were used for control. On gross examination, CBD were markedly large because of the adult flukes, which were free in the lumen of the ducts. Extensive hemorrhage was not found either in intrahepatic or in extrahepatic bile ducts of any sheep. Histologic examination revealed changes, such as villous hyperplasia and hypertrophy of the epithelium; cell infiltration, predominantly with eosinophils or macrophages; and arterial intimal proliferation. By SEM, the epithelial surface of the CBD appeared intact. Villous hyperplasia and hypertrophy of the epithelium observed by LM was clearly seen by SEM. Epithelial damage, seen as small areas of denuded surface by LM and SEM, was confined to a few areas of the mucosa. Lack of extensive hemorrhage and confined epithelial damage were evaluated relative to the mode of feeding of adult flukes.

Animals↗
PubMed1994

Rapid growth of Lymnaea viridis, the intermediate host of Fasciola hepatica, under laboratory conditions.

Reported in this communication is a unusually rapid growth of Lymnaea viridis, the intermediate host of Fasciola hepatica, maintained in the laboratory for experimental purposes. When the snails were fed on blue-green algae at about 20 degrees C, they attained a shell length of 12 mm in 37 days from the date of hatching. The snails began laying eggs from 18 to 24 days following hatching.

Animals↗
PubMed1988

Immunoprecipitation of Fasciola hepatica mRNA in vitro translation products using infection and hyperimmune sera.

Total RNA containing messenger RNA has been isolated from adult Fasciola hepatica and translated in vitro using the rabbit reticulocyte lysate system. L-[35S]-methionine labeled translation products have been immunoprecipitated with sera collected from rabbits infected with F. hepatica, rabbits immunized with adult worm homogenate, and a rabbit and 5 calves immunized with a Fasciola/Schistosoma cross-reactive, cross-protective antigen, denoted FhSmIII(M). Precipitated antigens were analyzed by SDS-polyacrylamide gel electrophoresis. The major antigens recognized by hyperimmune sera had apparent molecular weights of 12,500, 13,500, 14,000, 26,500, and 27,000. The rabbit anti-FhSmIII(M) serum precipitated a 13,500 Mr antigen. Sera collected from calves immunized with FhSmIII(M) also precipitated a 13,500 Mr antigen together with a 26,500 Mr molecule. Antibody with specificity for F. hepatica mRNA translation products could be detected in rabbit serum 2 weeks after infection.

Animals↗
PubMed1997

Cloning of peroxiredoxin, a novel antioxidant enzyme, from the helminth parasite Fasciola hepatica.

A cDNA was isolated from a cDNA expression library using serum prepared against a high molecular mass fraction of Fasciola hepatica excretory-secretory products. The full-length cDNA encodes a member of the recently described peroxiredoxin antioxidant family. Peroxiredoxin could be the major hydrogen peroxide removing antioxidant in F. hepatica since this parasite does not express a catalase and expresses little glutathione peroxidase activity. This novel antioxidant may be involved in functions such as protection against reactive oxygen species (ROS) generated by metabolic processes and/or protection of the parasite against ROS released by immune effector cells.

Amino Acid Sequence↗
PubMed2005

Characterization of the humoral immune response in alpacas (Lama pacos) experimentally infected with Fasciola hepatica against cysteine proteinases Fas1 and Fas2 and histopathological findings.

A characterization of the humoral immune response of alpacas to Fasciola hepatica Fas1 and Fas2 antigens, two abundant cysteine proteinases in the excretory/secretory (E/S) products, was performed over the course of 6 months of experimental infection. Six adult alpacas aged 1-2 years old received a single dose of 200 F. hepatica metacercariae; two non-infected alpacas were kept as control group. All infected animals shed eggs 8 weeks post-infection (PI) and the number of flukes recovered at necropsy averaged 41+/-4. The livers of infected animals showed regions with chronic inflammation, granuloma containing parasite eggs, necrosis and cirrhosis. Peripheral eosinophilia in infected animals was greatly enhanced 6 weeks post-infection and later. A single peak of serum glutamic piruvic transaminase (SGPT) was observed 4 weeks PI and serum glutamic oxalacetic transaminase (SGOT) elevated 3 weeks PI and later. Circulating IgG Abs against Fas1 and Fas2 were measured by enzyme-linked immunosorbent assay (ELISA). Fas2-ELISA detected the infection 10 days PI reaching to highest titer on 7-8 weeks PI and kept elevated, until the end of infection. Fas1-ELISA detected the infection 2 weeks PI and followed the same pattern as Fas2-ELISA. Anti Fas2 IgG Abs were in higher titers and showed stronger avidity than anti Fas1 IgG Abs. In addition, rabbit IgG antibodies raised against cysteine proteinase Fas2 showed infiltration of this parasite antigen associated to the degradation of bile ducts and liver parenchyma of infected alpacas. In the present study we have established a F. hepatica experimental infection of alpacas, Fas2 appears to have a role in the pathogenesis of the liver damage in alpacas caused by the liver fluke. Infected alpacas elicited a strong humoral immune response against fluke cysteine proteinases Fas1 and Fas2, which might be considered as candidates for immunodiagnosis and vaccine development against fasciolosis in alpacas.

Animals↗
PubMed1991

Efficacy of clorsulon for the treatment of experimentally induced infections of Fasciola hepatica in goats.

A dose titration study was undertaken to determine the efficacy of clorsulon against the adult stage of Fasciola hepatica in goats. Thirty-nine goats were experimentally infected with metacercariae of F hepatica. At 14 weeks after infection, each goat was assigned randomly to 1 of 5 groups. Goats in groups 1 to 4 received a single oral administration of clorsulon at dosages of 3.5, 7, 11, and 15 mg/kg of body weight, respectively. The fifth group of goats (control group) was infected with F hepatica, but were not treated with clorsulon. Postmortem examination of goats at 3 weeks after treatment revealed mean reductions in numbers of flukes of 83, 98, 99, and 100% for groups 1 to 4, respectively. Mean percentage of reduction in eggs following treatment of groups was 82, 98, 100, and 100%, respectively. The clinical effects of clorsulon in 24 goats that were not infected with F hepatica were studied. Goats in groups 1 to 3 received a single oral administration of clorsulon at dosages of 7, 21, and 35 mg/kg, respectively, every other day for a total of 3 doses/goat. Group-4 goats (control group) received a vehicle placebo. Goats in group 3 were subject to postmortem examination at 14 days after dosing. Abnormal signs or lesions that could be attributed to clorsulon were not found in any goat.

Animals↗
PubMed2003

Usefulness of 8 kDa protein of Fasciola hepatica in diagnosis of fascioliasis.

This study was designed to detect and evaluate an antigenicity of low molecular weight proteins of Fasciola hepatica in fascioliasis. Low molecular weight protein of F. hepatica was purified by ammonium sulfate precipitation and Sephacryl S-100 HR gel filtration. The protein obtained was estimated to be 8 kDa on 7.5-15% gradient sodium dodecyl sulfate gel electrophoresis. Immunoblotting studies showed that the 8 kDa protein reacted with human fascioliasis sera, but not other trematodiasis sera. This result suggests that the 8 kDa protein of F. hepatica is one of diagnostic antigens in human fascioliasis without cross-reaction with other human trematodiasis.

Animals↗
PubMed1982

EFficacy of albendazole for treatment of naturally acquired fasciola hepatica in calves.

In calves given various doses of albendazole as a 4.55% (w/v) drench suspension, removal efficacies against mature Fasciola hepatica were 77.5% with the dose of 7.5 mg/kg; 92.3%, with 10 mg/kg; and 85.9%, with 15 mg/kg. Against immature F hepatica, drug efficacies with these doses were 32.7%, 20.0%, and 36.7%, respectively. Reductions in length and width measurements of mature and immature flukes recovered from the bile ducts correlated with the larger doses reflected a greater efficacy against mature flukes or a possible inhibiting effect of the drug on fluke size or growth. Numbers of eggs recovered in bile at necropsy were reduced by 87.8% with the dose of 7.5 mg/kg; 91.8%, with 10 mg/kg; and 95.6%, with 15 mg/kg.

Albendazole↗
PubMed1990

[Fasciola hepatica: coprological diagnosis in comparison to the worm burden in sheep and cattle].

Bulls artificially infected with a varying number of metacercariae of Fasciola hepatica were kept under uniform, standardized laboratory conditions. 6 months after the infection the daily range of variation and the distribution of the Fasciola eggs in the faeces were determined 3 times a day (morning, noon and afternoon) over two test periods, each of 5 days. This test, carried out in over 800 individual faeces samples, showed that the excretion of Fasciola eggs over a period of several days fluctuates considerably within one animal and within one infection group; the excretion of Fasciola eggs over one day varies widely at different times in each animal and also in each infection group; the distribution of Fasciola eggs in the faeces is always irregular within one day and also over several days in all animals. The variations demonstrated here must be taken into consideration when assessing the results of coproscopical diagnosis because studies of the faeces carried out on a single occasion can lead to completely incorrect conclusions being drawn.

Animals↗
PubMed2006

Adult triclabendazole-resistant Fasciola hepatica: surface and subsurface tegumental responses to in vitro treatment with the sulphoxide metabolite of the experimental fasciolicide compound alpha.

Mature Fasciola hepatica of the triclabendazole-resistant Sligo isolate were incubated in vitro with 10 microg/ml of the sulphoxide metabolite of compound alpha [5-chloro-2-methylthio-6-(1-naphthyloxy)-H-benzimidazole]; the metabolite will be referred to as alpha.SO. Changes resulting from drug treatment were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tubulin immunocytochemistry (ICC). SEM revealed that disruption to the tegumental surface mainly took the form of swelling and blebbing. Extensive spine loss occurred on the ventral surface of the oral cone, and sloughing of the tegument was observed along the lateral margins of the fluke. Examination of sections from the anterior mid-body region at the TEM level revealed that treatment with alpha.SO led to swelling of the basal infolds and mitochondria within the tegumental syncytium; also, accumulations of secretory bodies beneath the apical plasma membrane. The tegumental cell bodies contained swollen mitochondria and cisternae of granular endoplasmic reticulum, but few Golgi complexes were observed. An increase in T2 secretory bodies was observed, whilst in the T1 tegumental cells, the T1 secretory bodies had decreased in number. Immunocytochemical (ICC) studies showed that incubation with alpha.SO, ABZ.SO and TCBZ.SO did not cause significant changes to the distribution of tubulin within the tegumental syncytium of the Sligo isolate. In contrast, alpha.SO, ABZ.SO and TCBZ.SO caused severe disruption to tubulin organization within the syncytial layer of the TCBZ-susceptible Cullompton isolate. The EM results confirm that compound alpha is a fasciolicide capable of disrupting the tegument of mature TCBZ-resistant F. hepatica; however, this was not accompanied by any change in tubulin immunoreactivity.

Animals↗
PubMed1983

Fasciola hepatica: migration of newly excysted juveniles in resistant rats.

Using transmission and scanning electron microscopy, the early migration of juvenile Fasciola hepatica was examined in naive and resistant rats. In naive rats, the migration of flukes to the peritoneal cavity was uneventful. In resistant rats, flukes were rapidly coated with antibody whilst still in the gut lumen and a proportion of the flukes were unable to penetrate the intestinal wall. Those that did penetrate were unharmed as they crossed the gut wall, but on entering the peritoneal cavity they were coated with antibody and host cells including eosinophils, neutrophils, macrophages, and mast cells. Eosinophils were seen degranulating onto the fluke surface, and this appeared to result in the erosion of the tegumental syncytium.

Animals↗
PubMed1993

Periodicity and sequence degeneration in eggcase precursors (vitelline proteins) from Fasciola hepatica.

Studies of two 3,4-dihydroxyphenylalanine (dopa) containing eggcase precursor proteins (vitelline proteins vpB1 and 2) from the trematode Fasciola hepatica recently concluded that although oligopeptide motifs occurred in the amino acid sequence, the overall structure (in contrast to dopa proteins from other phyla) was highly degenerate and irregular. An analysis of the distribution of individual amino acids and of oligopeptide motifs by two independent probabilistic pattern analysis methods, however, has now shown that despite superficial amino acid variability, an overall periodic structure exists. Moderately conserved hexadic domains account for almost 70% of the secreted protein, and characteristically contain glycine in position 5 of the hexad (76% of all glycine residues), and tyrosine, dopa or phenylalanine in positions 1 and 4 (88% of all aromatic residues).

Amino Acid Sequence↗
PubMed1980

[Description and characteristics of an amebocytic reaction in Lymnaea truncatula Müller infested by Fasciola hepatica L. (author's transl)].

The development of an amebocytic reaction is described in tissues of Lymnaea truncatula infested by Fasciola hepatica. When the snails are bred at 20 degrees C (uniform temperature), this reaction is maximum after five to seven weeks of infestation; afterwards the intensity of the reaction decreases until 10 weeks of infestation. This reaction also develops in snails bred at different temperatures (uniform temperatures of 25 degrees C or 16 degrees C, daily fluctuations from 4 degrees C to 18 degrees C). The maximum intensity of this reaction is chronologically delayed as the temperature goes down. The young snails infested after hatching do not show amebocytic reaction. When the infested snails fast for seven days the number of amebocytes rapidly decreases; these cells disappear from tissues from a snail fasting 14-35 days (depending on the snail organ). The significance of this amebocytic reaction is discussed.

Animals↗
PubMed1983

Fasciola hepatica: development of monoclonal antibodies and their use to characterize a glycocalyx antigen in migrating flukes.

Using mice harbouring early Fasciola hepatica infections, six monoclonal antibodies were prepared against a tegumental antigen present in T1 granules and glycocalyx of flukes. Blocking tests indicated that all monoclonals bound the same T1 epitope (or epitopes in close proximity on the antigen molecule), but this was not the determinant recognized by sheep and cattle. Localization of antibody binding at light and electron microscope levels showed that T1-type antigen also occurred in metacercarial tegument and in glycocalyx of gut cells and excretory ducts in juvenile and adult flukes. This indicates that the natural host-antibody response to F. hepatica may be to one antigen early in the infection. Protein A-gold labelling of monoclonal treated fluke sections revealed that the epitope was probably a polypeptide, unmodified by glycosylation in Golgi bodies. When isolated by immunoadsorption and separated electrophoretically under reducing conditions T1-type antigen was found to consist of a polypeptide mol. wt. 50 000, possibly linked to smaller entities mol. wt. 25-40 000. Tissue-specific variations in the antigen molecule might be conferred by linkage of different polypeptides or carbohydrate side-chains to an antigenic core polypeptide. A component of T1-type antigen was found to have mol. wt. of 25 000, possibly resembling a polypeptide of mol. wt. 24 000 from Schistosoma mansoni tegument.

Animals↗
PubMed2002

Highland populations of Lymnaea truncatula infected with Fasciola hepatica survive longer under experimental conditions than lowland ones.

A retrospective study was carried out on the experimental infections of Lymnaea truncatula with Fasciola hepatica performed over the last 20 years to determine if the populations of snails living in highland or lowland countries had the same ability to sustain trematode larval development. The six highland populations originated from the Peruvian Altiplano (altitude 2,800 m), the French Alps (2,300 m), and the Massif Central (900-1,400 m), whereas the 13 lowland populations came from different sites located in central France (90-250 m). Bimiracidial infections of 4-mm-high snails were performed to study cercarial shedding and to quantify their redial burden. Compared to lowland populations, snail survival at day 30 post-exposure was significantly higher in the highland L. truncatula (57-75% compared to 31-45%) and their lifespan was greater (a mean of 87-96 days for cercaria-shedding snails compared to 64-77 days). The prevalences of F. hepatica infections, the numbers of free rediae within snail bodies, and the numbers of cercariae did not show any significant differences between highland and lowland snails although the numbers of cercariae were clearly higher in the Peruvian and three French highland populations of L. truncatula. The long survival times of highland snails under laboratory conditions might be an adaptation of these L. truncatula to the more extreme highland climate. The better ability of highland snails to sustain parasite larval development suggests that they would be better intermediate hosts in the life cycle of F. hepatica than lowland populations.

Animals↗
PubMed2001

Cercarial productivity of Fasciola hepatica in Lymnaea truncatula during usual and unusual development of redial generations.

Single-miracidium infections of Lymnaea truncatula by Fasciola hepatica were carried out to determine the cercarial productivity of each redial generation when the first-appearing mother redia (R1a redia) normally developed (usual development of redial generations) or quickly died (unusual development). In both developmental patterns of infection, the number of morulae was significantly higher in the second-appearing mother rediae (R1b group) than in either the daughter rediae from R1a rediae (R2a group) or the rediae from subsequent groups (R2b/R3a). The live R1a group did not produce cercariae. The percentages of cercariae produced by the R1b, R2a, and R2b/R3a groups were 28.2%, 62.8%, and 8.9% when the development of redial generations was usual. In contrast, in an unusual development, they were 69.3%, 20.3%, and 10.2%, respectively. Cercarial production until day 63 post-exposure was essentially provided by the R2a rediae, when the development of redial generations was usual, and by the R1b rediae when it was unusual.

Animals↗
PubMed1981

Further studies on resistance to Fasciola hepatica and Echinostoma revolutum in mice infected with Schistosoma sp.

Schistosoma sp. induced cross-resistance to a challenge with Fasciola hepatica and Echinostoma revolutum was studied in mice. Primary patent 56-days-old S. intercalatum and S. bovis infections stimulated a statistically significant level of resistance to a challenge with F. hepatica, and primary patent 100-day-old S. bovis infections induced an almost complete resistance to a challenge with E. revolutum. Primary single-sex S. mansoni infections, either male or female, aged 90 days did not stimulate any resistance to a challenge with E. revolutum. A primary infection with S. mansoni aged 70 days induced a marked reduction (94.1--100%) in the E. revolutum worm recovery already 2 h post-challenge as compared with that of the E. revolutum challenge control group and complete elimination of the echinostome worm population in S. mansoni infected mice had taken place 24 h after challenge. E. revolutum worm populations established in mice harbouring newly patent 36-day-old S. mansoni infections persisted unchanged for a period of at least 33 days into the patent period of the schistosome infection in spite of development of a complete resistance to a challenge with E. revolutum metacercariae during this period.

Animals↗