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PubMed2004

Detection and genetic distance of resistant populations of Pseudosuccinea columella (Mollusca: Lymnaeidae) to Fasciola hepatica (Trematoda: Digenea) using RAPD markers.

Twelve natural populations of Pseudosuccinea columella snails, sampled in the western and central regions of Cuba, were analyzed using the RAPD-PCR technique to screen for resistance to Fasciola hepatica. Ten OPA primers previously shown to produce marker bands for resistance and susceptibility were tested. A new population of P. columella (El Azufre, Pinar del Río) exhibited the amplification patterns of resistant snails, and its resistant status was confirmed after experimental exposure to miracidia. No genetic variability was detected across or within the susceptible isolates. Similarly, the novel resistant isolate displayed an RAPD profile identical to the profile of two other isolates previously identified as resistant to F. hepatica. However, clear differences in RAPD banding patterns and genetic distance were observed between resistant and susceptible isolates.

Animals↗
PubMed1997

Fasciola hepatica: vaccination of rabbits with native and recombinant antigens related to fatty acid binding proteins.

The current study was designed to compare the immunogenic and immunoprophylactic properties of native (nFh12) and recombinant (rFh15) antigens from Fasciola hepatica in rabbits infected with the fluke. Levels of specific anti-nFh12 and anti-rFh15 antibodies were significantly higher in the rabbits vaccinated twice compared with non-vaccinated infection controls. A reduction of 40% in worm burdens was found in rabbits immunized with nFh12 and infected 4 weeks after the second immunization. The recombinant vaccine induced lesser levels of protection than the native one, suggesting that both molecules may have slight differences either in immunogenicity or in their configuration. Further biochemical studies are required to define these differences. The mean length of flukes recovered was always smaller in all vaccinated rabbits. In addition, infected control rabbits had higher gamma glutamil transferase (GGT) levels than immunized rabbits. Lastly, gross anatomic observation always showed fewer liver lesions in all vaccinated rabbits than in controls. This finding clearly supports the possibility of vaccination regimes in fasciolosis.

Animals↗
PubMed1976

The establishment and duration of Fasciola hepatica infections in two strains of rats and the development of acquired resistance.

Male and female rats of the inbred Piebald Virol Glaxo ( PVG) and Sprague Dawley (SD) strains were infected with 20 metacercariae of Fasciola hepatica. Three months after infection there was a highly significant difference (P LESS THAN 0-001) in the fluke burden of the two strains. The PVG rats (average 9-4 flukes) were more susceptible than the SD strain (average 2-8 flukes). The PVG males (11-6 flukes) were also found to be significantly more susceptible than the PVG females (average 7-2 flukes) whereas the sex of the SD rats did not affect the fluke burdens significantly. Seven to eight months after infection the PVG rats had eliminated their flukes. These 'self cured' PVG rats were significantly resistant to oral challenge with 20 metacercariae. In marked contrast the SD rats had not eliminated their flukes at the termination of the experiment 12 months after infection.

Animals↗
PubMed2006

The proportion of liver excised in Algerian abattoirs is not a good indicator of Fasciola hepatica infections in local cattle breeds.

Clinical and serological investigations on 175 cattle were carried out in 1999 at the slaughterhouse of Jijel, northeastern Algeria, to verify if partial ablation of a liver infected with Fasciola hepatica represents a good epidemiological indicator in the case of fasciolosis, as partial excision of the liver is widespread throughout North African countries. This study was also performed to determine if there is a direct relationship between the quantity of liver confiscated for fasciolosis and the serological response of slaughtered animals. A significant relationship between highly infected livers and positive serological titres was noted. However, two groups of results were conflicting: the presence of macroscopically healthy, undamaged livers with a positive serology (8.3% of 120 cattle), or the existence of highly damaged livers with a negative serology (13.0% of 31 cattle). These results indicate that partial removal of the liver in the case of fasciolosis is unreliable, so this method does not represent a good tool to establish epidemiological data on this disease.

Abattoirs↗
PubMed1995

Aberrant mitochondrial respiration in the livers of rats infected with Fasciola hepatica: the role of elevated non-esterified fatty acids and altered phospholipid composition.

The non-esterified fatty acid (NEFA) content and phospholipid composition of mitochondria isolated from the livers of Wistar rats infected with Fasciola hepatica were examined in relation to the aberrant mitochondrial respiration previously reported [Rule, Behm, and Bygrave (1989) Biochem. J. 260, 517-523]. At 2 weeks post-infection, elevated NEFA levels were associated with uncoupling of mitochondrial respiration that was reversible in vitro by the addition of BSA. State IV respiration rates showed a strong correlation with NEFA content. At 3 weeks post-infection, NEFA content had increased further and uncoupled mitochondria no longer showed any response to BSA. 31P-NMR analyses of cholate extracts of mitochondria from infected livers at 3 weeks post-infection revealed a marked loss of several major phospholipid species with a concomitant increase in catabolic products, particularly glycerophosphocholine and glycerophosphoethanolamine. Similar changes were observed in microsomal extracts. The NEFA content and phospholipid composition of mitochondria isolated from infected, athymic nude rats were not significantly different from uninfected, athymic rats. These findings suggest that uncoupling of liver mitochondria during infection with F. hepatica is the result of phospholipase activation mediated by the immune system of the host.

Animals↗
PubMed1979

Fasciola hepatica in rats: transfer of immunity by serum and cells from infected to F. hepatica naive animals.

Immune, hyperimmune, and nonimmune serum samples were collected from inbred rats following 10 to 15 weeks of one [5 metacercariae (mc)/rat], two (5 mc followed by 30 mc/rat) or no (uninfected) exposure to Fasciola hepatica. Lymphoid cells also were collected from these donors. Inbred, naive rats in groups receiving immune serum, hyperimmune serum, nonimmune serum (serum control), immune cells, hyperimmune cells, and nonimmune cells (cell control) received intraperitoneally either a total of 20 ml of serum or a total of 3 x 10(8) viable lymphoid cells. A challenge infection of 30 mc/rat was administered orally at about the time of serum or cell transfer. The transfer of immunity was evaluated by examining recipient rats for parasites 4 and 8 weeks after challenge. Some hematological parameters and the precipitating antibody response of the recipients were monitored also. Hyperimmune serum, unlike immune serum, consistently provided a significant degree of protection in recipient rats. The precipitating antibody titre of this serum was higher than that obtained from the immune donor group. The importance of a second sensitization to obtain sufficiently potent serum was demonstrated. Lymphoid cells from infected donors did not consistently confer protection on recipients. Thus, the expression of protective immunity against F. hepatica seemed to be more dependent on the presence of antibodies than on cells. The hematological parameters of the recipients, in general, supported this observation. The precipitating-antibody response of protected rats was lower than that of unprotected animals following challenge, presumably because the development of fewer worms in the former provided less antigenic stimulation.

Animals↗
PubMed1983

Bile flow, bile salt secretion and the excretion of iron, copper, zinc and manganese in the bile of calves infected with Fasciola hepatica.

The rate of flow of bile and the concentrations of iron, copper, zinc and manganese in bile were measured in four bull calves, before and for at least 23 weeks after infection with 1000 metacercariae of Fasciola hepatica. Bile flow rate began to increase about 10 weeks after infection and had increased nearly three-fold by 23 weeks but bile salt (total-cholate) secretion rate remained similar to that of two control calves. The excretion of iron in bile increased rapidly eight weeks after infection from a mean of 21.5 nmol per minute to reach 469 nmol per minute at 14 weeks and this increase was accompanied by an increase in gamma-glutamyl transpeptidase activity in plasma. 59Fe studies showed that most of the iron in the bile of infected calves was derived from red blood cells. There were no changes in the excretion of zinc, copper or manganese in bile which could be associated with the infection.

Animals↗
PubMed1994

Consequences of challenge infections with Fasciola hepatica on rat liver P450-dependent metabolism of sex hormones.

The effect of single or repetitive fluke-infections on rat liver steroid hormone metabolism was studied. Fascioliasis was induced by oral administration of 20 metacercariae of Fasciola hepatica to rats, by week-6 (mono-infected) or 12 and 6 (bi-infected), or 12, 9 and 6 (tri-infected) before killing. Total microsomal cytochrome P450 and P450 isoenzymes were measured spectrophotometrically and by Western-blot analysis, respectively. Progesterone and testosterone metabolism were quantified by normal phase high performance liquid chromatography. In control rats, progesterone and testosterone were mainly converted to 2 alpha- and 16 alpha-hydroxymetabolites. In the liver of mono-infected rats, hepatic cytochrome P450 was significantly decreased by 36-64% whereas the expression of all investigated isoenzymes was decreased by 36-82% with the exception of the unchanged P4502E1. 16 alpha- and 2 alpha-hydroxylations of progesterone and testosterone were significantly decreased by 50-90%, these decreases were correlated with those of P4502B1/2 and P4502C11 isoenzymes, respectively. In bi- and tri-infected rats, steroid hormones were metabolized similarly to control rats. The return of steroid drug metabolizing enzyme activities to control level could be related to the immune response associated to the development of the animal resistance to the parasitic infection.

Animals↗
PubMed1993

5-Hydroxytryptamine and motility in Fasciola hepatica.

The study motility in Fasciola has been practically very difficult. 5-Hydroxytryptamine (5-HT) has a strong stimulatory action on Fasciola movement, increasing both the amplitude and frequency of contractions, but most of the evidence for a transmitter role of 5-HT at the neuromuscular junction comes from fairly elementary pharmacological and neurochemical studies. As discussed here by Lindy Holden-Dye and Robert Walker, it still remains to be established that the effect of 5-HT on motility is mediated by 5-HT receptors actually present on the muscle cells. Analysis of the transmitter role of 5-HT and the delineation of the receptor type(s) involved in its stimulatory action will require the application of molecular techniques such as patch clamping of muscle cells, and cloning, sequencing and expression of 5-HT receptor complementary DNAs.

Journal Article↗
PubMed1980

Killing of juvenile Fasciola hepatica by purified bovine eosinophil proteins.

Eosinophils were isolated from the mammary gland of Fasciola hepatica-infected cattle by intramammary infusion with a crude extract from adult F. hepatica. Up to 5 x 10(9) eosinophils with a purity of over 90% could be obtained from a single quarter of the gland. The major contaminating cells were monocytes which reached their peak several days following the eosinophil peak. Two major proteins were isolated from bovine eosinophil granules, a high molecular weight peroxidase-active protein and a smaller molecular weight predominantly basic protein. This smaller protein was thought to be the bovine equivalent of guinea-pig and human major basic protein (MBP), although it possessed an unusually high concentration of cysteine. The bovine MBP had a profound effect on juvenile F. hepatica in vitro causing damage and death at concentrations down to 1 x 10(-6) M. The damage was detected by a 51Cr release assay and/or a viability assay involving microscopical examination of the flukes. Other cations, especially protamine sulphate, were also shown to kill flukes, although both lysozyme, found in neutrophils, and the peroxidase-positive peak from bovine eosinophils were unable to mediate any detectable damage.

Amino Acids↗
PubMed1994

Fasciola hepatica: mebendazole and thiabendazole pharmacokinetics in sheep.

Pharmacokinetics of the two anthelmintic drugs mebendazole and thiabendazole were determined in sheep before and 4, 8, 13, 19, and 25 weeks after an infestation of animals by an oral administration of 150 metacercariae of Fasciola hepatica. The parasitic pathology was ascertained by the increase in plasma enzyme activities of glutamate dehydrogenase and gamma-glutamyltransferase. After oral administration of mebendazole (25 mg.kg-1), the parent drug and especially its reduced metabolite were present in plasma of animals. A significant 1.5- to 2.7-fold increase in the mean residence time occurred by Weeks 13 to 25 postinfection. This change was related to decreases in both the elimination from the pharmacokinetic compartment representing the reduced metabolite and the area under the curve of plasma metabolite concentration versus time. A 59% decrease in MBZ reduction was demonstrated in liver microsomes prepared from 12-week-infected sheep. This reductase activity was characterized by NADPH dependency and a pH peak activity of 6.0 and was competitively inhibited by daunomycin. In sheep receiving a 50 mg.kg-1 oral dose of thiabendazole, fascioliasis provoked only decreased plasma concentrations of the metabolite 5-hydroxythiabendazole by Weeks 4 to 25 postinfection. This change parallels an increase in urinary excretion of free metabolite but this is of minor significance in the general fate of the drug because of the prevalence of excretion as conjugates. In summary, fascioliasis appears to have more of an effect on the pharmacokinetics of mebendazole, a drug intensively metabolized by the liver into a metabolite present at high concentrations in the plasma of animals and humans.

Administration, Oral↗