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PubMed1994

Neutralization of the activity of a Fasciola hepatica cathepsin L proteinase by anti-cathepsin L antibodies.

Fasciola hepatica secretes a cathepsin L proteinase that is suggested to play an in vivo role in immunoprotection since the enzyme can cleave host immunoglobulin. In the present report, rabbit anti-cathepsin L IgG was shown to bind to the cathepsin L enzyme and inhibit its ability to cleave IgG molecules. Cathepsin L can prevent the antibody-mediated attachment of eosinophils to newly excysted juveniles in in vitro assays; however, if anti-cathepsin L IgG are mixed with the cathepsin L prior to the addition of the enzyme to the assay, eosinophils attach to the newly excysted juveniles. Thus it is possible to prepare antibodies that can bind and disrupt the biological activity of the F. hepatica cathepsin L.

Animals↗
PubMed1994

IgE responses to Fasciola hepatica extract in several inbred mouse strains.

IgE responses to Fasciola hepatica extract in 6 strains of mice (C3H/HeN, CBA/JN, DBA/2N, BALB/cAnN, C57BL/6N and NZBWF1) were investigated. Serum anti-F. hepatica IgE antibodies were determined by passive cutaneous anaphylaxis (PCA). DBA/2N and BALB/cAnN mice showed higher IgE responses than other strains.

Animals↗
PubMed1979

Solubilization of antigens of Fasciola hepatica which react with antibodies to Schistosoma mansoni.

Extracts of Fasciola hepatica adult worms contain antigens reactive with antisera prepared against Schistosoma mansoni adult worms. These antigens are poorly solubilized when homogenized in a phosphate buffered saline (PBS) solution and pellet readily when subjected to high speed centrifugation. Solubilization is improved greatly by the addition of sodium dodecyl sulfate (0.03%) to the PBS. When this is done, one obtains approximately the same total amount of crude Lowry reactive material as with PBS extraction followed by high speed centrifugation but antigenic reactivity to an anti-S. mansoni antiserum increases enormously. The antigens liberated from F. hepatica SDS extraction are largely materials under 200,000 MW and over 60,000 MW.

Animals↗
PubMed1980

[The rabbit as a reservoir host of Fasciola hepatica? (author's transl)].

Following field observations, the ability of Fasciola hepatica to develop in domestic rabbits as compared with sheep was investigated under experimental conditions. The results indicate the development of F. hepatica is impaired in various phases after rabbit passage. Only 4.2 percent of the metacercariae gained after one rabbit passage developed to adult F. hepatica in sheep, whereas the respective percentage after sheep passage was 51.2 percent. It can be calculated that after rabbit passage 4.5 liver flukes develop from 100 F. hepatica eggs as compared with 2,141.3 parasites after sheep passage. The result justify the assumption that rabbits may play only a minor role in the epidemiology of fascioliasis.

Animals↗
PubMed2002

A novel GlcNAcalpha1-HPO3-6Gal(1-1)ceramide antigen and alkylated inositol-phosphoglycerolipids expressed by the liver fluke Fasciola hepatica.

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.

Animals↗
PubMed1989

Identification of GTP-binding proteins in Fasciola hepatica and Schistosoma mansoni by immunoblotting.

Both the liver fluke Fasciola hepatica and the blood fluke Schistosoma mansoni have GTP-binding proteins which are part of the trans-membrane signalling system. These proteins require GTP in order to interact with the catalytic subunit of adenylate cyclase. The technique of immunoblotting was used in order to distinguish the GTP-binding proteins Gs, Gi, and Go. Immunoblotting was carried out using antisera prepared against peptides deduced from bovine cDNA clones specific for alpha or beta subunits of known G proteins. A 41-kDa Gs alpha has been identified in S. mansoni and a 42.5-kDa Gs alpha in F. hepatica. A 41-kDa Go alpha was found in both parasites. A 36-kDa G beta was identified in both parasites using antiserum made against bovine transducin.

Amino Acid Sequence↗
PubMedDate not supplied

Responses of Fasciola hepatica infected sheep to various infection levels.

The response to Fasciola hepatica was studied in sheep infected with 5, 30, 150 metacercariae. The animals were necropsied 12 weeks post-infection (p-i) for counting and measuring flukes. Cellular and humoral responses were detected by peripheral eosinophil count, peripheral blood lymphocyte proliferation with excretory-secretory products (FhESP) and ELISA. All sheep were infected at necropsy except one sheep which was infected with 5 metacercariae. Mean parasitic intensities were 40%, 44% and 27% of the infection dose in sheep infected with 5, 30, 150 metacercariae respectively. FhESP-specific lymphocyte responses of the 3 infected groups were significantly enhanced in weeks 3 and 4 p-i (p < 0.05). The kinetics of the specific humoral response were similar for the 3 infected groups but the antibody level was significantly lower in animals infected with 5 metacercariae than in the 2 other infected groups from week 5 p-i to week 12 p-i (p < 0.05). Peripheral eosinophil count was significantly enhanced (p < 0.05) in infected groups. The numbers of peripheral eosinophils were significantly different between the 3 infected groups in week 3, 4 and 6 p-i and were related to infection level. These results confirm that sheep are highly susceptible to F. hepatica infection, even when infection pressure is very low. Peripheral eosinophilia was dependent of the infection level. The immune response was similar in sheep infected with various numbers of flukes.

Animals↗
PubMed1982

Experimentally induced Fasciola hepatica infection in young calves.

Twenty-four calves between 1 and 66 days of age (allotted to 3 age groups) were each inoculated with 100 Fasciola hepatica metacercariae to determine their susceptibility to fluke infection. Studies included measuring the immune response, as determined by enzyme-linked immunosorbent assay, fecal egg counts (to evaluate the length of the life cycle between times of metacercariae ingestion and fluke maturation), and the numbers of flukes in the liver of the calves at slaughter. Fasciola hepatica ova started appearing in the feces of calves, all ages, at 60 days after inoculations were done and reached average maximal number by 80 to 90 days. The enzyme-linked immunosorbent assay results indicated that the oldest group of calves had significantly (P less than 0.01) greater antibody concentration from 6 weeks until the 18th to 20th week after inoculation than did the 2 younger groups. At slaughter, calves in the 52- to 66-day age group had mean fluke numbers significantly (P less than 0.01) greater than did calves in the 1- to 27-day and 35- to 44-day age groups.

Animals↗
PubMed2005

Fasciola hepatica proteolytic activity in liver revealed by in situ zymography.

Fasciola hepatica secretes cysteine proteases that play a role in facilitating parasite migration. The aim of this study was to detect the inhibition of the proteolytic activity of F. hepatica cysteine proteases in the liver of C57BL/6 cathepsin B knockout mice (cat B-/-) and wild-type controls (cat B+/+) by intraperitoneal administration of N-[N-(L-3-trans-carboxyoxirane-2-carbonyl)-L-leucyl]-agmatine, (E-64) using the film in situ zymography (FIZ) technique and image analysis. The FIZ technique revealed that intraperitoneal administration of E-64 dramatically reduced (85%) F. hepatica proteolytic activity in the liver of experimentally infected mice with no discernable side effects. These results suggest the usefulness of the FIZ for determining in vivo activity of F. hepatica proteases, as well as their inhibition by intraperitoneal administration of E-64 in hepatic tissue of infected mice.

Animals↗
PubMed1995

[Efficacy and tolerance of praziquantel (Biltricide) in the treatment of distomatosis caused by Fasciola hepatica].

OBJECTIVES: Due to the side-effects of dehydroemetine, we have chosen praziquantel, a broad-spectrum antihelmintic, as a treatment for distomatosis secondary to Fasciola hepatica in humans. The aim of this retrospective study was to evaluate the efficacy and tolerance to praziquantel in patients with this disease. METHODS: Twenty-five patients (12 men) with a definite diagnosis of distomatosis and no previous treatment were followed-up between 8 months and 3 years (> 18 months in 76% of cases). The follow-up was based on clinical, biochemical and serological criteria. All patients received praziquantel (75 mg/kg/day orally) for 5 days. Treatment was started after endoscopic or surgical removal of parasites locolized in the biliary tract, in two patients. A similar therapeutic course was administered twice in four patients with persistent clinical symptoms, hypereosinophilia or arch 2 on immunoelectrophoresis. RESULTS: Cumulative rates of patients with normalized eosinophilia and seronegativation at 6, 9 and 12 months were 55, 65, 75% and 55, 70, 100%, respectively. Complete recovery occurred in 18 patients (72%) whereas hypereosinophilia persisted for more than one year in 5 patients. No side-effects, except transient nausea in a few cases, were observed. CONCLUSION: Since praziquantel seems to be both effective and well tolerated in a large proportion of patients, this drug can be recommended as a first choice for distomatosis due to Fasciola hepatica in human.

Adult↗
PubMed1997

Humoral and cellular immune responses to experimental Fasciola hepatica infections in goats.

Humoral and cellular immune responses to Fasciola hepatica excretory-secretory products (ESPs) in primary and secondary experimental infections in goats were studied. Primary infection induced the development of chronic subclinical fascioliasis that did not affect the establishment of flukes coming from the secondary infection, as the same percentages of recovered flukes were found in both groups. The specific IgG response to F. hepatica ESPs was similar in primary and secondary infections; challenge flukes did not induce any modification in the IgG response. The specific lymphocyte response to F. hepatica ESPs was absent in most of the infected goats, both primarily and secondarily infected. A modulation of the nonspecific cellular responses to mitogens was also observed. All infected goats showed a reduced proliferative response to concanavalin A and phytohemagglutinin. According to our results, humoral and cellular responses to F. hepatica ESPs in goats have no protective effect on the establishment of flukes and the development of disease in either primary or secondary infections.

Animals↗
PubMed1988

The effects of bile on the locomotory cycle of Fasciola hepatica.

The rate of production of locomotory cycles in juvenile Fasciola hepatica was significantly decreased following treatment with conjugated chenodeoxycholic acids and significantly increased following treatment with dehydrocholic acid or whole bovine bile. Deoxycholic acid caused death and lysis of the parasites in less than 30 min. These results suggest that bile components act as a specific stimulus for a fixed action pattern (the locomotory cycle) in this parasite.

Animals↗
PubMed1976

The effects of nitroxynil on the survival, growth and morphology of Fasciola hepatica in sheep.

Groups of sheep were experimentally infected with Fasciola hepatica and treated with nitroxynil at 10 mg/kg given subcutaneously at intervals of up to 70 days later. Effects on fluke burden, weight, morphology, egg production and hatchability were recorded. The results showed that the efficacy of nitroxynil and the occurrence of structurally abnormal flukes were directly proportional to the age of infection at treatment. Treatment also deleteriously affected fluke growth and egg hatchability and reduced faecal egg counts.

Animals↗
PubMed1986

Peripheral androgen levels in peripuberal rams infected with Fasciola hepatica.

Three-month-old, Polled Dorset rams infected with Fasciola hepatica and uninfected control rams were monitored throughout the peripuberal phase for peripheral concentrations of testosterone and for body weight. No differences between groups occurred in these measurements from early spring to mid-autumn. However, the infected postpuberal rams demonstrated a reduced ability to remove exogenous testosterone from the circulation. Liver damage induced by moderate infections of flukes apparently impairs hepatic catabolism of this steroid but compensatory mechanisms appear to maintain circulating levels comparable to those of uninfected rams.

Animals↗
PubMed1977

[Studies on the modification of performance and metabolic processes in sheep through experimental Fasciola hepatica infections considering low infestation intensity].

Low experimental infections with Fasciola hepatica (8...17 flukes per animal) in sheep, 6...12 months old, caused less gain weight over a period of 22 weeks. Changes in the number of erythrocytes and in the Hb-concentration were not found. In contrast to the controls the infected sheep showed strong fluctuations in the number of lymphocytes. 3 weeks post infect. a significant eosinophilia was observed, which continued until the end of the investigation. With the beginning of the fourth week post infect. the values of serum albumin were lower, the values of gamma-globulin higher than those of the controls, but there was no statistical significance. The bromosulphalein-test for liver function was negative.

Animals↗
PubMed1993

Sequence analysis of a Fasciola hepatica glutathione S-transferase cDNA clone.

A lambda gt11 Fasciola hepatica cDNA library was previously constructed from poly(A)+ RNA extracted from adult worms. A cDNA encoding F. hepatica glutathione S-transferase (FhGST) (GenBank Accession Number M93434) was cloned by screening the library with a rabbit anti-FhGST antiserum. The FhGSTs are suspected to be early developmentally expressed-proteins that act as potent immunogens and may be useful as candidate vaccines against the parasite. The cDNA was sequenced and contains 627 translated bases encoding a 24,211-Dalton polypeptide with 209 amino acids and an isoelectric point (pI) of 5.324. This polypeptide has significant homology with 26-kD GSTs from Schistosoma mansoni (57.42%) and S. japonicum (57.14%). In addition, we have identified the predicted T cell epitopes in the FhGST protein molecule.

Amino Acid Sequence↗
PubMed1985

Induction of drug metabolizing enzymes in the liver of rats infested with Fasciola hepatica.

Adult, male rats were infected with 20 metacercariae of Fasciola hepatica given orally, other rats were left untreated. Five weeks after infestation, some animals received phenobarbitone, 3-methylcholanthrene, beta-naphthoflavone or Arochlor 1254, to induce liver drug metabolizing enzymes. Fascioliasis provoked decreases in aminopyrine N-demethylase, aniline hydroxylase, the mutagenic activity of cyclophosphamide and cytochrome P-450 concentration in untreated or phenobarbitone or Arochlor pretreated rats. In contrast, cytochrome b5, NADPH cytochrome c reductase, ethyoxycoumarin O-deethylase and the enzymatic activation of ethidium bromide were not affected by fascioliasis whatever pretreatment was given. Fascioliasis decreased liver drug metabolizing enzymes which were specifically induced by both phenobarbitone and Arochlor, this could be due to either the specific action of toxic excretions of flukes or to the particular localization of tissue damage within the liver lobule.

Animals↗