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[Micromorphology of the nervous system in the trematodes Fasciola hepatica and Dicrocoelium lanceatum].

The nervous system of Dicrocoelium lanceatum and Fasciola hepatica is formed as orthogon including endon and a system of paired longitudinally oriented nerve trunks which are united by transverse commissures. The specific characters of the nervous system of D. lanceatum and F. hepatica are as follows: the location of the peripharyngeal ganglion, topographical anatomy of paired pharyngeal nerve, the character of structure and ways of direction of the paired cephalic nerve, localization and function of additional ganglia.

Animals↗

PubMed1979

[Lewis blood group activity in Fasciola hepatica].

Lewis blood group specificities are detected in the liver Fluke: Fasciola hepatica. Such specificities had never been reported in nature, other than in the human body. The investigation of this phenomenon might contribute to a better understanding of the mechanisms involved in parasite-host relationship.

Animals↗

PubMed2003

The effect of the microtubule inhibitor tubulozole-C on the tegument of triclabendazole-susceptible and triclabendazole-resistant Fasciola hepatica.

The benzimidazole derivative, triclabendazole is the main drug used against Fasciola hepatica, although its precise mode of action remains to be fully determined. Previous studies have suggested that triclabendazole acts as a microtubule inhibitor in the same manner as tubulozole-C. Consequently, flukes from triclabendazole-susceptible and triclabendazole-resistant isolates were treated with tubulozole-C (1x10(-6 )M) in vitro and changes in tegumental morphology and tubulin distribution within the tegument were monitored by scanning and transmission electron microscopy, together with tubulin immunocytochemistry. Tubulozole-C caused severe disruption within the tegument of triclabendazole-susceptible flukes. Tubulin immunoreactivity diminished within the tegumental syncytium of the triclabendazole-susceptible flukes following treatment with tubulozole-C. In contrast, tubulozole-C caused only minor disruption of the tegument in triclabendazole-resistant F. hepatica and did not significantly alter the pattern of tubulin immunostaining within the tegumental syncytium. The results of the present study indicate that tubulozole-C and triclabendazole share the same target molecule and that triclabendazole-resistant flukes are also cross-resistant to tubulozole-C.

Animals↗

PubMed1975

Immune response of sheep to Fasciola hepatica infection.

The IgG immunoglobulin levels and the immune response to Fasciola hepatica digestive tract antigens were studied in experimentally infected lambs. A synchronic increase and decrease of IgG-1 serum levels and indirect fluorescent antibody titres were observed during the course of the infection. Antibody activities were demonstrated in IgG-1, but not in IgG-2 isolates. The antibody activity was partly sensitive to reduction with mercaptoethanol.

Animals↗

PubMed1984

The energy metabolism of Fasciola hepatica during its development in the final host.

Mature liver flukes, Fasciola hepatica, of different ages were isolated from the bile ducts of experimentally infected rats. Their energy metabolism was studied during aerobic incubation with [6-14C]glucose. The results showed that the aerobic potentials of the parenchymal liver flukes are not lost immediately after arrival in the bile ducts, but in a later phase. During the development of the newly excysted juvenile into the mature adult the major part of ATP production in aerobic incubations is successively contributed by three different pathways of glucose breakdown. The Krebs cycle, which is by far the main energy-yielding pathway of the juvenile fluke, is gradually replaced by aerobic acetate formation and, finally, by the anaerobic dismutation reactions of the adult liver fluke. This observed decrease in Krebs-cycle activity per mg protein is not the result of a decrease in activity per individual fluke. The Krebs-cycle activity per fluke actually increases enormously during its whole development. This indicates that the aerobic potential of adult F. hepatica is not just a remnant of earlier aerobic stages but that classical, mammalian type mitochondria are produced during the entire development of the fluke. Calculations are presented which demonstrate that the Krebs-cycle activity of the developing F. hepatica is directly proportional to the surface area of the fluke. This supports our view that Krebs-cycle activity is limited by the diffusion of oxygen and can only occur in the outer layer of the liver fluke during its entire development in the final host.

Adenosine Triphosphate↗

PubMed1995

Streptavidin-reactive protein in Fasciola hepatica.

Streptavidin-binding protein was found in an extract of Fasciola hepatica, and the protein was analyzed by the inhibition assay using avidin or D-biotin, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting using peroxidase-conjugated streptavidin. Inhibition assays revealed that the protein could bind to streptavidin by a mechanism similar to the avidin-biotin reaction, and the molecular size of the protein was estimated by SDS-PAGE to be 71.7 kDa.

Animals↗

PubMed1990

Seasonal transmission of Fasciola hepatica in north central Florida (U.S.A.).

To assess seasonal transmission of Fasciola hepatica 37 groups of fluke-free tracer sheep, one group of four sheep each month in succession, grazed an infected pasture in north central Florida (U.S.A.) from June 1984 to June 1987. At the end of each month, tracers were moved to a fluke-free barn for 2 months, then necropsied and flukes counted. Fluke transmission mostly occurred during the first half of the year, with peak transmission from February to April. No transmission occurred during the warm summer months, having ceased in either May or June of each year to begin again in late autumn or early winter (November-January).

Animals↗

PubMed1991

Quantification and partial characterisation of regulatory peptides in the liver fluke, Fasciola hepatica, from different mammalian hosts.

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.

Animals↗

PubMed1980

A difference in surface proteins of Fasciola hepatica larvae from intact and nude mice.

Larvae of the trematode, Fasciola hepatica, dissected from the livers of intact mice at 12 to 14 days of infection, bind anti-immunoglobulins in vitro. This is not so for larvae harvested from the livers of infected hypothymic nude (nu/nu) mice. When attempts were made to confirm the presence of surface Ig using lactoperoxidase-catalysed radioiodination and analysis by SDS-polyacrylamide gel electrophoresis, proteolysis at the time of solubilization markedly affected the profiles obtained. Provided protease inhibitors were present during processing, a mu-like Ig heavy chain and a gamma-like Ig heavy chain could be demonstrated on larvae from nu/+ mice but not on larvae from nu/nu mice.

Animals↗

PubMed1981

[Unusual forms of Fasciola hepatica infestation. Report of two cases (author's transl)].

Infestation by Fasciola hepatica is being reported with increasing frequency. During a five year period the authors have studied 25 cases of disease caused by F. hepatica, all of them diagnosed by finding eggs of the parasite in the feces or the duodenal fluid. In two cases the ectopic location of th parasite gave rise to unusual clinical manifestations. The first case presented during the course of hepatic fascioliasis both subcutaneous and epididymis locations, with an histologic picture similar to that of the hepatic lesions. The involvement of the epididymis, not previously cited in the literature, gave rise to a hydrocele. The second case presented with signs of central nervous system involvement and a high eosinophil count in the cerebrospinal fluid. Dehydroemetine was effective in all patients, including the unusual cases.

Adult↗

PubMed2001

Development of the vitellaria of the liver fluke, Fasciola hepatica in the rat host.

The development of the vitellaria of Fasciola hepatica within the liver of its rat host was studied by means of whole-mount stained preparations and transmission electron microscopy, together with light and electron immunocytochemistry using an antibody to vitelline protein B, an eggshell precursor protein synthesized by F. hepatica. No vitelline cells could be identified in flukes recovered from the liver parenchyma, by any of the methods used. In contrast, follicles were present in flukes at the earliest time of recovery from the bile duct, namely, 5 weeks 3 days post-infection. The vitellaria in these flukes formed a row of small follicles on either side of the body. Development of the follicles was rapid: by 6 weeks 3 days, the vitellaria resembled those in the adult fluke and eggs were present in the uterus. Immunolabelling was confined to the shell protein globules in the vitelline cells, confirming the packaging of the eggshell protein within the shell globule clusters.

Animals↗

PubMed1987

The interaction between the deacetylated (amine) metabolite of diamphenethide (DAMD) and cytochemically demonstrable Na+/K+-ATPase activity in the tegument of Fasciola hepatica.

The relative effects on tegumental Na+/K+-ATPase activity in Fasciola hepatica of the deacetylated (amine) metabolite of diamphenethide (DAMD) (10 micrograms/ml, 18 h) and the Na+/K+-ATPase inhibitor ouabain (0.1 mM, 0.5 h) have been assessed cytochemically. In the normal tegument, Na+/K+-ATPase activity is particularly concentrated along the invaginations of the apical plasma membrane and the infoldings of the basal plasma membrane. Ouabain pretreatment significantly reduces the overall level of Na+/K+-ATPase activity, but does not induce swelling of the basal infolds. In contrast, DAMD does not significantly reduce either the level or distribution of Na+/K+-ATPase activity, but does cause a pronounced swelling of the basal infolds. The results are discussed in relation to the postulated action of diamphenethide as an inhibitor of Na+/K+-ATPase activity.

Acetanilides↗

PubMed1992

Fasciola hepatica: host responders and nonresponders to parasite glutathione S-transferase.

Fasciola hepatica glutathione S-transferase (FhGST) was isolated from adult worms by glutathione agarose affinity chromatography. SDS-PAGE shows three proteins of M(r) ranging from 29-27.8 kDa. Western immunoblot analyses using SDS-PAGE separated adult worm extracts and probed with a rabbit anti-FhGST antiserum reveal two bands in the same M(r) range. Mice and rabbits immunized with purified FhGST develop copious amounts of anti-FhGST antibodies. Moreover, antisera to F. hepatica adult worms and excretion-secretion products also react with FhGST. Cross-reactivity with schistosomes is evidenced in the reactivity with FhGST of anti-Schistosoma mansoni adult worm antisera and, to a lesser extent, antisera to S. mansoni-soluble egg antigens. The time of appearance of anti-FhGST antibodies in different species of animals infected with F. hepatica was determined. Sheep and a New Zealand white rabbit developed anti-FhGST antibodies detectable by ELISA as early as 2 weeks postexposure with F. hepatica. However, neither mice nor calves infected with F. hepatica developed antibodies to FhGST through the 5-10 weeks of infection tested. But mice infected with S. mansoni developed anti-FhGST cross-reacting antibodies by 6 weeks of infection. Calves immunized with a Fasciola/Schistosoma cross-reactive, cross-protective antigen complex in which a 12,000-kDa protein (Fh12) has been shown to contain immunoprophylactic activity, also developed antibodies to FhGST. Since FhGST is a novel potential vaccine, its protection-inducing capability in a multivalent vaccine combined with Fh12 clearly warrants study. In summary, it appears that hosts with fascioliasis are either responders to FhGST (rabbits, sheep) or nonresponders (mice, cattle), offering interesting models for studying the immune response.

Animals↗

PubMed1984

Fasciola hepatica: tegumental alterations as a consequence of lectin binding.

Adult flukes, Fasciola hepatica, incubated in Hedon - Fleig saline containing concanavalin A (Con A) for 10 and 45 min, respectively, exhibited severe alterations to tegumental morphology involving increased secretory activity, blebbing of the apical plasma membrane, increased total surface area, and swelling of the basal infolds . The effects of Con A were prevented by the addition of alpha-methyl-D-mannoside to the incubating medium. Similar, but less pronounced, effects were caused by wheat germ agglutinin (WGA) binding. Con A and WGA binding indicate the presence of mannose, glucosamine, or glucose moieties and of N-acetylglucosamine. The effects of lectin binding were similar to the early effects of antibody attachment, and it was considered that accelerated membrane turnover was occurring in both cases. Swelling of the basal infolds was thought to be a result of increased apical surface membrane and/or increased permeability due to lectin binding.

Concanavalin A↗

PubMed1982

Demonstration of juvenile-specific antigens of Fasciola hepatica.

A hyperimmune serum was raised in rabbits against soluble antigens of Fasciola hepatica metacercariae. This was subsequently absorbed with antigens from adult flukes and examined by immunoelectrophoresis (IEP) and by an indirect fluorescent antibody test (IFAT). When the absorbed antiserum was tested with F. hepatica metacercarial homogenate and adult homogenates by IEP, three distinct arcs appeared against the metacercarial homogenate and none against the adult homogenate. When tested by IFAT against a developmental series of flukes obtained from mice, the absorbed antiserum was positive on surfaces of whole flukes up to 4 days postinfection (PI) and on the tegument of sectioned flukes up to 7 days PI. Thus juvenile-specific antigens were demonstrated in the tegument of young (up to 7 days in mice) F. hepatica.

Animals↗

PubMed1988

Immunohistochemical and electrochemical detection of serotonin in the nervous system of Fasciola hepatica, a parasitic flatworm.

The head region of the trematode parasite Fasciola hepatica contains 3.47 +/- 0.42 pmol/mg wet wt. of serotonin as measured by high-performance liquid chromatography coupled to electrochemical detection. The head region includes the cerebral ganglia, the transverse commissure and associated nervous tissue that innervates the musculature of the oral sucker, pharynx and body wall. Tissue from the tail, which contains little nervous innervation, has approximately 20 times less serotonin (0.18 +/- 0.01 pmol/mg wet wt.). Immunohistochemistry was used to identify serotonin-like immunoreactive cells. Bipolar and multipolar cell bodies in the cerebral ganglia show serotonin-like immunoreactivity. Also evident are serotonin-like immunoreactive processes in the neuropile and in the transverse commissure that connects the ganglia, and immunoreactive peripheral bipolar cell bodies innervating the musculature of the pharynx and body wall. The cell bodies containing serotonin are organized in bilateral symmetry with homologous cell bodies and processes represented in each ganglion and on both sides of the pharynx.

Animals↗

PubMed1978

The efficiency of diamphenethide in controlling natural infestations of Fasciola hepatica in lambs.

The activity of diamphenethide against natural infestations of Fasciola hepatica in fattening lambs was assessed on a farm with a noted history of fascioliasis. The main experimental groups, two treated and one control, grazed known contaminated pastures for a twelve week period after which they were removed to fluke-free areas to await slaughter. Three groups of four tracer lambs were each grazed for three successive four week periods with the main flock to determine continuity of infection. A single treatment with diamphenethide at 110 mg/kg bodyweight given when the sheep were removed from the trial area was 96.7% effective against the sub-chronic disease which had developed by this time. Three treatments at 110 mg diamphenethide/kg bodeweight given at intervals of four weeks during the grazing period proved to be 100% effective in preventing the establishment of the disease. Significant benefits in terms of weight gain were exhibited by the treated lambs.

Acetanilides↗

PubMed2000

Fasciola hepatica: heterologous expression and functional characterization of a thioredoxin peroxidase.

A Fasciola hepatica cDNA clone of 779 bp was isolated from an adult worm cDNA expression library by immunological screening using a rabbit serum against the excretory-secretory antigens. The nucleotide sequence of the cDNA revealed the presence of an open reading frame of 582 bp which encoded a 194-amino-acid-residue polypeptide (M(r) 21,723 Da) showing a high degree of homology to thioredoxin peroxidases. This putative antioxidant protein gene was expressed in Escherichia coli as a GST fusion protein. The recombinant fusion protein showed in vitro antioxidant properties and protected rabbit muscle enolase and E. coli glutamine synthetase from inactivation by nonenzymatic Fe(3+)/O(2)/DTT or Fe(3+)/O(2)/ascorbate metal-catalyzed oxidation systems.

Amino Acid Sequence↗