Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| stage-specific expression of surface molecules by the larval stages of haemonchus contortus. | three monoclonal antibodies, hc2, hc22 and hc6, were produced against a surface extract of l3 haemonchus contortus and screened against both free living and parasitic stages of the parasite. hc2 and hc22 were of igg2c isotype and their target epitopes were insensitive to periodate treatment. hc6 was of igm isotype and its reactivity was sensitive to periodate treatment of the antigen, suggesting that hc6 is specific for a carbohydrate epitope. western blotting of larval extracts and staining of ... | 1996 | 9223166 |
| the effect of infection with the abomasal nematode, haemonchus contortus, on the avoidance behaviour of sheep in a motivational-choice test. | the behaviour of immune and non-immune sheep infected with h. contortus and undergoing a variety of experimental treatments was investigated in a motivational-choice test, the arena test. this test evaluates motivational state in sheep by pitting the motivation of test animals to approach a small flock of sheep against the motivation to avoid a human decoy located directly in front of the small flock. approach distance is decreased by infection in immune ewes but was unaffected by infection in n ... | 1997 | 9229250 |
| haemonchosis in spanish ibex. | two cases of haemonchosis occurred in the spanish ibex (capra pyrenaica) population of the national hunting reserve of tortosa and beseit, northeastern spain, in july 1992 and may 1993. the animals were cachectic and recumbent and had an acute hemorrhagic, macrocytic and hypochromic anemia; which was related to a high infection of 2,016 and 1,863 haemonchus contortus, respectively, in the abomasum of the animals. | 1997 | 9249719 |
| comparison of the post-parturient rise in faecal egg counts of indigenous and cross-bred ewes. | the breed differences in post-parturient rise (ppr) in faecal egg counts in lambing ewes of different breeds naturally infected with haemonchus contortus were compared. the ewes of nali, 50% nali x 50% russian merino/corriedale and 37.5% nali x 62.5% russian merino/corriedale were treated with fenbendazole while ewes of the above three breeds as well as 25% nali x 75% russian merino/corriedale, were kept untreated. observations from 3 weeks before lambing to 12 weeks post-lambing at weekly inter ... | 1997 | 9271473 |
| reduced egg counts in mixed infections with oestrus ovis and haemonchus contortus: influence of eosinophils? | in all, 2 groups of lambs were infected either with oestrus ovis first-instar larvae or with 10,000 third-stage larvae (l3) of haemonchus contortus. another group of lambs was infected with both parasites. fecal nematode egg counts, plasma pepsinogen concentrations, specific o. ovis enzyme-linked immunosorbent assay (elisa) antibodies, and blood eosinophil counts were monitored and compared to with the values recorded for a control group of uninfected lambs. there was no significant difference b ... | 1997 | 9272567 |
| molecular cloning and characterisation of a putative aspartate proteinase associated with a gut membrane protein complex from adult haemonchus contortus. | a cdna was isolated from an adult haemonchus contortus cdna expression library the deduced amino acid sequence of which showed significant homology to mammalian pepsinogen sequences. the library was screened with antisera raised against haemonchus galactose-containing glycoprotein complex, a gut membrane protein complex with aspartyl proteinase activity which has shown considerable potential as a protective antigen. the amino acid sequence obtained corresponded very closely in part to the n-term ... | 1997 | 9274868 |
| molecular characterization and expression of two putative protective excretory secretory proteins of haemonchus contortus. | it has been shown that vaccination with two low molecular mass excretory secretory (es) antigens of 15 and 24 kda, respectively, afforded a substantial degree of protection against haemonchus contortus to sheep. in vitro cultivation of the parasite usually yields a limited amount of these proteins and therefore, recombinant dna technology was employed to clone the cdnas encoding the es proteins of interest and to express them in a convenient vector system. the n-terminal amino acid sequences of ... | 1997 | 9274880 |
| effects of adult and larval haemonchus contortus on abomasal secretion. | abomasal ph and serum pepsinogen and gastrin were increased in parasite-naive sheep by infection with either larval or adult h. contortus. four sheep received 10000 larvae intraruminally and 9000 adult worms were given directly via an abomasal cannula to another 4 sheep. the latter animals were dosed orally with 0.4 mg kg-1 ivermectin 4 days after worm transfer and their recovery was monitored for a further 8 days. whereas the presence of adult worms rapidly induced changes in the secretory acti ... | 1997 | 9279586 |
| microsatellites of the parasitic nematode haemonchus contortus: polymorphism and linkage with a direct repeat. | to develop tools to analyse parasitic nematode population structures and the effects of selection pressure on the nematode population, we isolated and characterised 13 microsatellite markers of the nematode haemonchus contortus. the density of ca/gt microsatellites, once in 575 kb, is lower than in mammals. although the isolated ca/gt repeats were imperfect, the majority of the microsatellites were polymorphic in one or more populations. an extensive genetic diversity both within and between pop ... | 1997 | 9297704 |
| duration of protective immunity against ovine haemonchosis following vaccination with the nematode gut membrane antigen h11. | to establish for how long protective antibody levels may be maintained, lambs were vaccinated with the gut membrane antigen h11 and challenged with haemonchus contortus 14, 84, 126 or 168 days later. compared to controls, mean faecal egg counts of vaccinated lambs were reduced by 97 per cent, 99 per cent, 92 per cent and 86 per cent respectively. total worm burdens at postmortem five weeks after infection were reduced by 87 per cent, 94 per cent, 92 per cent and 62 per cent respectively. in vacc ... | 1997 | 9300538 |
| epidemiology of gastro-intestinal nematodes of sheep in wet tropical conditions in malaysia. | a study on the seasonal variations in the population structure of haemonchus contortus and trichostronglyus colubriformis was conducted for a period of 12 months in a typical large scale sheep farm on improved pasture in peninsular malaysia which has a wet tropical climate. successive groups of helminth-free tracer lambs were grazed for 4 weeks together with naturally infected sheep and were necropised for worm counts 2 weeks after their removal from the pasture. the monthly populations of h. co ... | 1997 | 9316233 |
| multiple anthelmintic resistance in haemonchus contortus on a sheep farm in kenya. | multiple resistance to albendazole, thiophanate, levamisole and orally administered invermectin was detected in an isolate of haemonchus contortus in sheep on a farm where benzimidazole resistance had already been identified. following a faecal egg count reduction test, this was confirmed by both critical and controlled anthelmintic tests. different groups of sheep infected naturally or given an experimental infection with the benzimidazole-resistant isolate were treated with the recommended dos ... | 1997 | 9345715 |
| the efficacy of closantel and rafoxanide against fenbendazole- and levamisole-resistant haemonchus contortus in small ruminants. | 1997 | 9345716 | |
| characterization of haemolytic activity from adult haemonchus contortus. | adult haemonchus contortus contain a detergent-soluble factor that haemolyses sheep red blood cells in a time- and concentration-dependent manner. this factor had comparable haemolytic activity at ph 5.0 and 8.0; activity was lower at ph 6.0 and 7.0. the activity was heat-stable, unaffected by proteolytic inhibitors, and inhibited by 20 mm polyethyleneglycol. haemolytic activity was associated with the particulate fraction of the isolated intestine, suggesting an essential role for this activity ... | 1997 | 9363486 |
| the effect of feed intake level on the pharmacokinetic disposition of closantel in sheep. | closantel (cls), containing a trace of [14c]cls, was administered intraruminally to sheep whose feed intake was maintained at either 800 or 400 g day-1. the kinetic disposition of [14c]metabolites was determined in rumen and abomasal fluid and particulate digesta and of cls per se in plasma. the slower digesta flow rate in the sheep on low, compared with high, feed intake resulted in the proportion of the dose passing through the abomasum being reduced from 60 to 45%. increased absorption of cls ... | 1997 | 9363491 |
| vaccination against haemonchus contortus with denatured forms of the protective antigen h11. | as part of a systematic examination of the protective epitopes on h11, groups of sheep were vaccinated with preparations of purified h11 used untreated (group a), or progressively denatured (linearized) by incubation with sodium dodecyl sulphate (sds) (group b) or by boiling with sds in the presence of dithiothreitol (group c). all the sheep developed antibodies which bound to the untreated h11. when challenged with 10,000 infective larvae of haemonchus contortus the mean levels of protection re ... | 1997 | 9364553 |
| haemonchus contortus: cloning and functional expression of a cdna encoding ornithine decarboxylase and development of a screen for inhibitors. | polyamines (pa) are essential for viability and replication of all cells; organisms either synthesize pa or acquire them from the environment. how nematodes that parasitize the gut satisfy their pa requirement has not been resolved. the primary regulatory enzyme in pa biosynthesis in most animals is ornithine decarboxylase (odc). this enzyme has recently been characterized in free-living nematodes and in the parasitic species. haemonchus contortus. nematode and mammalian odc are reported to diff ... | 1997 | 9371082 |
| cd4+ t lymphocytes contribute to protective immunity induced in sheep and goats by haemonchus contortus gut antigens. | immunization with parasite antigens derived from the gut of adult haemonchus contortus induces significant levels of protection against the parasite in sheep and goats. however, the mechanisms of immunity involved in this protection are not clear. here, we investigate the requirement for cd4+ t lymphocytes in gut antigen-induced immunity against h. contortus. gut antigen immunized animals were depleted (> 98%) of their cd4+ t lymphocytes in peripheral blood by intravenous injection of an anti-cd ... | 1997 | 9372511 |
| protective immunity induced by vaccination with two haemonchus contortus excretory secretory proteins in sheep. | two excretory secretory (es) antigens of adult haemonchus contortus with molecular weights of 15 and 24 kda, respectively, were evaluated as protective immunogen against haemonchosis. sheep were vaccinated three times and subsequently challenged with 20,000 infective larvae. vaccination induced significant reduction (> 70%) in mean faecal egg counts and abomasal worm burden compared to the non-vaccinated control group or adjuvant control group. vaccination induced es-specific antibodies and stim ... | 1997 | 9372512 |
| role of lipids in the transmission of the infective stage (l3) of strongylus vulgaris (nematoda: strongylida). | infective larvae (l3) of strongylus vulgaris have limited energy stores for host finding and for infection. for transmission to occur, the larvae must have sufficient energy to (a) migrate onto grass, where they are ingested by their equine host (host finding), and (b) penetrate into the host gut. this study is designed to test the hypothesis that l3 larvae of s. vulgaris partition their energy stores between locomotory activity (used in host finding) and infection activity (penetration). chroni ... | 1997 | 9379277 |
| enhanced ability of third-stage larvae of haemonchus contortus to withstand drug exposure following chemically induced exsheathment. | normal (ensheathed) and exsheathed third-stage larvae of haemonchus contortus were exposed in vitro to various concentrations of levamisole or ivermectin. exsheathment was induced by brief exposure to sodium hypochlorite. when observed approximately 2 min after immersion in levamisole at 0, 5, 10, and 100 micrograms/ml (3 trials), the mean percentage motility (to nearest whole number) of normal larvae was 84, 43, 37, and 15, respectively. however, the mean percent motility of exsheathed larvae w ... | 1997 | 9379314 |
| availability of haemonchus contortus l3 larvae on pasture at kiboko: a semi-arid warm agro-climatic zone in kenya. | a study was carried out to determine the availability of haemonchus contortus l3 larvae on pasture in a semi-arid warm agro-climatic zone of kenya. by means of tracer sheep, it was shown that no h. contortus l3 larvae were available on pasture during the dry periods of the year (july-october and february). they were only available on pasture during the rainy season (november-january and march-june). sheep permanently grazed on the same pasture however, harboured adult h. contortus in their aboma ... | 1997 | 9386793 |
| quality control in generic anthelmintics: is it adequate? | we became increasingly concerned about indications of possible substandard efficacy of some generic anthelmintics, particularly after p.c. van schalkwyk (personal communication, 1990) had found some batches of imported generic products obtained from international brokers to be poorly active, despite apparently normal physical characteristics. therefore, considering the serious consequences this would have for sheep farming, it was decided to test the efficacy of some of the generic rafoxanide pr ... | 1997 | 9404842 |
| a survey of anthelmintic resistance in nematodes of sheep in the netherlands. | the prevalence of anthelmintic resistance in nematodes of sheep was surveyed in 1994 on 70 farms in the netherlands. an in vitro egg hatch assay, faecal egg count reduction (fecr) 14 days after treatment, and larval cultures were used as methods of investigation. oxfendazole was tested on 69, ivermectin on 51, and levamisole on 36 farms. the median effective dose (ed50) of thiabendazole could be determined on 64 farms. on 60 farms (94%) the ed50 value was > or = 0.12 microgram ml-1, which is ind ... | 1997 | 9413114 |
| haemonchus placei and haemonchus contortus are distinct species based on mtdna evidence. | debates continue over the extent to which the parasitic trichostrongylids haemonchus placei and haemonchus contortus hybridise in nature, and whether they deserve species status. mitochondrial nd4 gene sequences from individuals of each putative species collected from populations around the united states indicate that the two species are highly differentiated at the mtdna level. furthermore, there was no evidence of introgressive hybridisation occurring in wild populations. | 1997 | 9421728 |
| selection for high levamisole resistance in haemonchus contortus monitored with an egg-hatch assay. | to investigate the characteristics of selection for levamisole resistance in haemonchus contortus, the consecutive nematode generations of an in vivo selection were monitored with a newly developed egg-hatch assay. the in vivo selection was started with a population not previously exposed to any anthelmintics (shs). at first, the levamisole resistance progressed gradually in successive nematode generations by treating sheep with increasing doses of levamisole, the initial dose being 1 mg kg-1. t ... | 1997 | 9421730 |
| partial in vitro reversal of benzimidazole resistance by the free-living stages of haemonchus contortus with verapamil. | 1997 | 9423241 | |
| effects of the excretory/secretory products of six nematode species, parasites of the digestive tract, on the proliferation of ht29-d4 and hgt-1 cell lines. | the excretory/secretory (es) products of the nematode parasite trichostrongylus colubriformis have been found to increase the in vitro proliferation of the epithelial cell line ht29-d4. to assess the specificity of this effect, es products from other trichostrongyle species were tested on colonic (ht29-d4) and gastric (hgt-1) tumour cell lines. adult worms of six different nematode species, parasites of the stomach or the small intestine of ruminants, were incubated in vitro in dulbecco's modifi ... | 1995 | 9439903 |
| the interaction of trypanosoma congolense and haemonchus contortus in djallonké sheep. | the interaction between trypanosoma congolense and haemonchus contortus was studied in 5 groups of 8 djallonké sheep. two groups received a single infection with either h. contortus or t. congolense, and 2 groups were infected with t. congolense followed by h. contortus (th) or vice versa (ht). one group was kept as uninfected controls. mortality due to infection was observed only in the dual infection groups. in the th group, the effects were more acute whereas in the ht group they were more ch ... | 1997 | 9467745 |
| efficacy of closantel, albendazole and levamisole on an ivermectin resistant strain of haemonchus contortus in sheep. | following evidence of reduced efficacy of oral ivermectin in a field population of haemonchus contortus on a sheep farm in kenya, this strain of the parasite was submitted to a controlled anthelmintic test. one hundred and twenty worm-free lambs were randomly split into two groups of 60. each lamb in the first group was infected with 5000 third stage larvae (l3) of the suspected resistant strain the remaining 60 lambs were each infected with 5000 (l3) of a h. contortus strain of known susceptibi ... | 1997 | 9477493 |
| the efficacy of eprinomectin against induced infections of immature (fourth larval stage) and adult nematode parasites in cattle. | eprinomectin is a new endectocide of the avermectin chemical group developed for use in cattle. to establish its effectiveness against cooperia spp., dictyocaulus viviparus, haemonchus contortus, nematodirus helvetianus, oesophagostomum radiatum, ostertagia ostertagi, trichostrongylus axei and trichostrongylus colubriformis (immature infections only), six trials were conducted in europe at two trial sites. in each trial, animals were artificially infected with a number of nematode species and tr ... | 1997 | 9477498 |
| the in vitro uptake of albumin by adult haemonchus contortus is altered by extracorporeal digestion. | fitc (fluorescein isothiocyanate)-labeled albumin was used as a substrate to further characterize the digestion of host blood proteins by adult haemonchus contortus. isolated h. contortus intestine degraded fitc-albumin; degradation was completely inhibited by e-64, a specific inhibitor of cysteine proteases. the in vitro uptake and degradation of fitc-albumin by parasites was also evaluated. uptake of fluorescence was demonstrated; greater than 50% of the fluorescence was associated with degrad ... | 1997 | 9477511 |
| response to challenge infection with haemonchus contortus and trichostrongylus colubriformis in dairy goats. differences between high and low-producers. | the objective of the study was to analyse the influence of the level of milk production in dairy goats on the ability to develop resistance to gastrointestinal nematode infection. two groups of 50 goats were initially exposed (group 'previously infected' pi) or not exposed (group 'not previously infected' npi) to repeated infections with a mixture of haemonchus contortus and trichostrongylus colubriformis. after anthelmintic treatment, goats from both groups remained free of parasites for 2 mont ... | 1997 | 9477513 |
| the influence of dietary supplementation with urea on resilience and resistance to infection with haemonchus contortus. | previous research has indicated that supplementing an apparently adequate diet with additional protein improves both host resistance and resilience in lambs infected with haemonchus contortus. the present study tested the influence of supplementation with non-protein nitrogen (urea). helminth-naive hampshire down lambs were given an apparently adequate basal diet or a diet supplemented with urea. the lambs were then infected with haemonchus contortus for 10 weeks. supplementation with urea had n ... | 1998 | 9481776 |
| inhibitory effect of chlorpromazine on nematode eggs and larvae. | chlorpromazine inhibited the hatching of eggs of the parasitic nematode haemonchus contortus and the free-living nematode caenorhabditis elegans. in both species, hatching occurred at a concentration of 100 microg/ml but was almost totally blocked at 400 microg/ml. in the case of c. elegans, the effect was shown to be reversible by removal of chlorpromazine after exposure of the eggs to the drug for 1 hr. caenorhabditis elegans larvae that hatched in a chlorpromazine concentration of 100 microg/ ... | 1998 | 9488367 |
| response to challenge infection with haemonchus contortus and trichostrongylus colubriformis in dairy goats. consequences on milk production. | the objective of the study was to examine the ability of dairy goats to develop a response to nematode parasites of the digestive tract after a previous contact with the worms. one hundred dairy goats were initially divided into 2 groups. one remained free of parasites (not previously infected: npi). the second group was infected thrice at 50 days interval with a mixture of haemonchus contortus and trichostrongylus colubriformis (previously infected: pi). after this initial exposure to nematodes ... | 1998 | 9493309 |
| epidemiology of gastrointestinal nematode parasitism in suffolk and gulf coast native sheep with special emphasis on relative susceptibility to haemonchus contortus infection. | an eight-year study was conducted to define the epidemiology of gastrointestinal nematode infection in suffolk and gulf coast native (native) breeds of sheep, and to determine if the native sheep is more resistant to infection. for the initial three years, each breed grazed separate pastures where anthelmintic treatments were administered to individual animals on a salvage basis. for the last five years, both breeds grazed concurrently; anthelmintic treatments were administered to individual ani ... | 1998 | 9493310 |
| host range and the maintenance of haemonchus spp. in an adverse arid climate. | three haemonchus species (haemonchus contortus, haemonchus placei and haemonchus longistipes) live in sympatry in sahelian areas such as mauritania (west africa). four host species (dromedary, zebu cattle, sheep and goats) share the same pastures for several months per year. experimental infection by h. contortus or h. placei was achieved only poorly in dromedaries, and h. contortus or h. longistipes infection failed to establish in zebu cattle. conversely, h. placei and h. longistipes successfu ... | 1998 | 9512988 |
| repeated infections with haemonchus contortus and trichostrongylus colubriformis in dairy goats: comparison of resistant and susceptible animals. | a total of 70 strongyle-free french alpine dairy goats were exposed to a combination of sequential and challenge infections with haemonchus contortus and trichostrongylus colubriformis third-stage larvae. the sequential infection consisted of three inoculations at 50-day intervals, each infection being abbreviated by anthelmintic treatment at 40 days postinoculation. the challenge infection, composed of the same nematode strains, was undertaken 2 months later, when goats were at their 1st month ... | 1998 | 9521016 |
| synthesis and endectocidal activity of novel 1-(arylsulfonyl)-1-[(trifluoromethyl)sulfonyl]methane derivatives. | we have recently synthesized a series of novel disulfonylmethane compounds that have shown anthelmintic and insecticidal (endectocidal) activity. several analogues have shown activity against the internal nematode haemonchus contortus. in sheep studies, these analogues have shown 100% control of this internal parasite at a 10 mg/kg rate. in vitro activity against the biting flies, stomoxys calcitrans and haematobia irritans, has been observed at rates as low as 25 and 2.3 ppm, respectively. only ... | 1998 | 9544209 |
| levamisole binding sites in haemonchus contortus. | larval and adult extracts from isolates of haemonchus contortus were assayed for specific [3h]levamisole binding activity. all of the tissue preparations displayed [3h]levamisole binding sites. the sensitive isolate se and resistant isolate rj showed no differences in larval and adult binding data. larval se extracts had higher receptor density (bmax = 648 fmol mg-1) and dissociation constant (kd = 1.28 microm) for [3h]levamisole than larval extracts of the american isolate rusa (bmax = 87 fmol ... | 1998 | 9559359 |
| inheritance of levamisole and benzimidazole resistance in an isolate of haemonchus contortus. | reciprocal crosses between an isolate of haemonchus contortus resistant to both benzimidazole and levamisole anthelmintics and a susceptible isolate were performed in order to determine the mode of inheritance of these resistances. f1 and f2 generations and parent isolates were assayed for susceptibility to thiabendazole and levamisole in vitro. for each drug all of the filial generations were intermediate in susceptibility between the parent isolates, and analysis indicated that resistance was ... | 1998 | 9559368 |
| a survey of anthelmintic resistance on ten sheep farms in mashonaland east province, zimbabwe. | a survey to detect anthelmintic resistance in nematode parasites of sheep was conducted on 10 randomly-distributed farms in the chivhu district, mashonaland east province, zimbabwe. before the survey, a questionnaire was circulated to the farmers concerning nematode parasite control. results showed that parasite control using anthelmintic treatment was the only method practised and that the benzimidazoles were the most frequently used anthelmintic drugs. the faecal egg count reduction test was u ... | 1997 | 9561499 |
| ivermectin resistance in nematodes may be caused by alteration of p-glycoprotein homolog. | resistance to ivermectin and related drugs is an increasing problem for parasite control. the mechanism of ivermectin resistance in nematode parasites is currently unknown. some p-glycoproteins and multidrug resistance proteins have been found to act as membrane transporters which pump drugs from the cell. a disruption of the mdrla gene, which encodes a p-glycoprotein in mice, results in hypersensitivity to ivermectin. genes encoding members of the p-glycoprotein family are known to exist in nem ... | 1998 | 9566525 |
| efficacy of an ivermectin controlled-release capsule against nematode and arthropod endoparasites in sheep. | five controlled trials were conducted in germany or in the united kingdom, using 74 female sheep of merino or dorset horn breeds, to evaluate the efficacy of an ivermectin controlled-release capsule against naturally acquired or induced infections of gastrointestinal nematodes, lungworms and nasal bot larvae and against incoming infections with gastrointestinal and pulmonary nematodes. half of the animals were treated with one ivermectin controlled-release capsule that delivered ivermectin at th ... | 1998 | 9571756 |
| eosinophil-mediated killing of haemonchus contortus larvae: effect of eosinophil activation and role of antibody, complement and interleukin-5. | eosinophils have previously been shown to accumulate around the tissue invasive (l3) stage of sheep gastrointestinal parasites in vivo. in this study, eosinophils obtained from mammary washes of sheep, were shown to immobilize and kill h. contortus larvae in vitro in the presence of antibody specific against a defined l3 surface antigen. eosinophils obtained from sheep primed by repeated infusion of h. contortus larvae were more effective than eosinophils obtained after a single infusion of para ... | 1998 | 9572052 |
| extracellular and cytoplasmic cu/zn superoxide dismutases from haemonchus contortus. | full-length cdnas encoding cytosolic (sodc) and putative extracellular (sode) cu/zn superoxide dismutases (sods) from the ovine gastrointestinal parasitic nematode haemonchus contortus have been isolated and characterized. the predicted sequences of the h. contortus sods showed strong homology to other helminth sods, the highest level of sequence similarity was with those of the free-living nematode caenorhabditis elegans++. the predicted amino acid sequence of the putative extracellular form co ... | 1998 | 9585940 |
| resistance to benzimidazoles and levamisole in nematode parasites of sheep in nyandarua district of kenya. | the occurrence of anthelmintic resistance on 25 sheep farms in the nyandarua district of kenya was investigated, using the faecal egg count reduction test (fecrt), the egg hatch assay (eha) and a larval development assay (lda). in the fecrt, resistance to both benzimidazoles (bzs) and levamisole (lev) was detected on four farms, resistance to lev only on three farms and to bzs, only on two farms. haemonchus contortus was the predominant nematode species in both pre-treatment and post-treatment f ... | 1998 | 9588239 |
| expression of lex antigen in schistosoma japonicum and s.haematobium and immune responses to lex in infected animals: lack of lex expression in other trematodes and nematodes. | adults of the human parasitic trematode schistosoma mansoni, which causes hepatosplenic/intestinal complications in humans, synthesize glycoconjugates containing the lewis x (lex) galbeta1-->4(fucalpha1-->3)glcnacbeta1-->r, but not sialyl lewis x (slex), antigen. we now report on our analyses of lexand slexexpression in s.haematobium and s.japonicum, which are two other major species of human schistosomes that cause disease, and the possible autoimmunity to these antigens in infected individuals ... | 1998 | 9592128 |
| the eosinophil leucocyte, a phenotypic marker of resistance to nematode parasites, is associated with calm behaviour in sheep. | the hypothesis that behaviour in sheep is influenced by resistance to infections with trichostrongylus colubriformis and haemonchus contortus was explored. sheep were assessed phenotypically as resistant and susceptible in four ways and thereafter, the effect of resistance on several behavioural traits was measured in an arena test. the behavioural parameters recorded for each sheep were: approach/avoidance distance; travel; number of moves; and spread. four phenotypic groups of sheep were set u ... | 1998 | 9619485 |
| multiple anthelmintic resistance on a goat farm in kenya. | the anthelmintic efficacy of benzimidazoles, levamisole, rafoxanide and ivermectin was evaluated on an institutional farm in kenya using faecal egg count reduction test, larval cultures and a controlled slaughter trial. the results of this study indicated simultaneous resistance of haemonchus contortus against benzimidazoles, levamisole and rafoxanide and trichostrongylus columbriformis and oesophagostomum sp. against levamisole on the same farm. injectable and orally administered ivermectin was ... | 1998 | 9637220 |
| demonstration of shared carbohydrate epitopes in intestinal proteins of some bovine gastrointestinal nematodes. | the presence of shared carbohydrate intestinal epitopes in bovine gastrointestinal nematodes was demonstrated. proteins were extracted from the intestinal tissue of a laboratory strain of adult haemonchus placei and used to produce monoclonal antibodies (mab). analysis of this detergent extract by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed 7-9 bands ranging from approximately 39 to 298 kda. the mabs reacted with periodate-sensitive epitopes and, in western blots, recogniz ... | 1998 | 9645850 |
| effects of macrocyclic lactones on ingestion in susceptible and resistant haemonchus contortus larvae. | the effects of ivermectin and ivermectin aglycone on pharyngeal uptake of a carbohydrate substrate (3h-inulin) were measured in larvae of a macrocyclic lactone (ml)-susceptible isolate and 2 ml-resistant isolates of haemonchus contortus. the resistant isolates showed a tolerance (in terms of the concentration of compound required to reduce feeding to 50%) toward ivermectin of approximately 4.5- and 9-fold and toward ivermectin aglycone of approximately 14-fold, compared to the susceptible isolat ... | 1998 | 9645874 |
| binding of [3h]m-aminolevamisole to receptors in levamisole-susceptible and -resistant haemonchus contortus. | m-aminolevamisole, a potent analogue of the commercial anthelmintic levamisole, was used to investigate ligand-binding properties of homogenates of larval and parasitic stages of the nematode parasite of sheep, haemonchus contortus. kinetics of the binding of [3h]m-aminolevamisole to homogenates was measured in a drug-susceptible isolate and compared with a levamisole-resistant isolate. equilibrium binding studies and kinetic studies revealed a high affinity binding component with a kd of 3 nm. ... | 1998 | 9650050 |
| attempts to generate immunity against trichostrongylus colubriformis and haemonchus contortus in young lambs by vaccination with viable parasites. | the ability of young merino lambs to achieve protective immunity following vaccination via viable nematode infections was assessed. lambs were infected from 1 month of age by repeated continuous low dose (trickle) administration of trichostrongylus colubriformis or haemonchus contortus infective larvae (l3), or by truncated infections with high doses of viable t. colubriformis l3. after 7 weeks all groups were drenched with anthelmintic and at 3 months of age they were re-infected with the homol ... | 1998 | 9650053 |
| evidence of multiple mechanisms of avermectin resistance in haemonchus contortus--comparison of selection protocols. | three isolates of haemonchus contortus selected for avermectin resistance in sheep were compared in three in vitro pharmacological tests previously shown to discriminate between field isolates of h. contortus resistant and susceptible to the avermectins. two isolates, f7-a and ivc, were selected for avermectin resistance in the laboratory from a reference susceptible isolate using suboptimal doses of ivermectin (ld95) for 7 and 16 generations, respectively. in these isolates avermectin resistanc ... | 1998 | 9650059 |
| changes in the zymogenic cell populations of the abomasa of sheep infected with haemonchus contortus. | the effects of dietary urea supplementation and of a 10-week trickle infection regime, simulating chronic exposure to haemonchus contortus, on the zymogenic population of the abomasa of hampshire down lambs was examined. at necropsy a variety of parameters including plasma pepsinogen concentration, the wet weights of abomasal fundic mucosal pieces and the amounts of pepsinogen contained in them, were assessed. tissue pepsinogen concentration was measured as the total, acid-stable proteolytic act ... | 1998 | 9651940 |
| hypobiosis of haemonchus contortus in natural infections of sheep and goats in a semi-arid area of kenya. | a total of 42 lambs, 42 kids, 21 ewes and 21 does were necropsied during an investigation of the epidemiology of haemonchus contortus infection of sheep (red maasai) and goats (small east african goat) in a semi-arid area of kenya. availability and establishment of the infective stages were monitored by the necropsy of 21 tracer lambs and 21 tracer kids. prevalence of h. contortus was over 90% in both sheep and goats and this species contributed to about 80% of the total worm burden. only about ... | 1998 | 9652383 |
| the novel core fucosylation of haemonchus contortus n-glycans is stage specific. | 1998 | 9662037 | |
| etiology and prophylaxis of helminthiasis in sheep in burkina faso. | helminths of "mossi" sheep from traditional livestock were investigated at three different seasons (humid, cold dry, and hot dry seasons) in the village of donsin from the central land of burkina faso. three prophylaxis plans using fenbendazole were tested. primary parasites identified were: oesophagostomum sp., trichostrongylus sp., and haemonchus contortus. these parasites were noticed mainly during the rainy season with mean egg per gram (epg) numbers of 500 +/- 141.42 in august-september, at ... | 1998 | 9668516 |
| avermectin/milbemycin resistance in trichostrongyloid nematodes. | resistance to levamisole and the benzimidazoles appears to be achieved by one or, at most, two mechanisms in the common trichostrongyloid parasites of sheep. for the avermectin/milbemycin anthelmintic class the picture is more complex. in-vitro assays employing the free-living stages of trichostrongyloid nematodes were used to investigate structure-activity relationships for the avermectins/milbemycins. while avermectin/milbemycin-susceptible isolates of haemonchus contortus, trichostrongylus co ... | 1998 | 9673866 |
| comparative in vitro effects of closantel and selected beta-ketoamide anthelmintics on a gastrointestinal nematode and vertebrate liver cells. | pnu-87407 and pnu-88509, beta-ketoamide anthelmintics that are structurally related to each other and to the salicylanilide anthelmintic closantel, exhibit different anthelmintic spectra and apparent toxicity in mammals. the basis for this differential pharmacology was examined in experiments that measured motility and adenosine triphosphate (atp) levels in larval and adult stages of the gastrointestinal nematode, haemonchus contortus, and in a vertebrate liver cell line and mitochondria. pnu-87 ... | 1998 | 9673959 |
| sustained-release delivery systems and their application for endoparasite control in animals. | a solid formulation of a potent anthelmintic macrocyclic lactone, moxidectin, was administered using a non-degradable delivery device to discharge the agent into the subcutaneous tissues of sheep. in vivo release was monitored in sheep indirectly using faecal egg counts. using a dose of 0.2 mg moxidectin/kg body weight when applied in the form of a solid pellet, protection of sheep against haemonchus contortus challenge was conferred to a level greater than that of sheep which received cydectin, ... | 1998 | 9685905 |
| dietary protein influences on regulation of haemonchus contortus populations in dorsimal lambs. | the influence of dietary protein supplementation upon resistance to haemonchosis was examined in dorsimal (polled dorset x malin) lambs offered two levels of protein. lambs were offered either a complete basal ruminant diet (15% crude protein (cp)) or the same diet supplemented with fish meal as a source of rumen bypass protein (19% cp). lambs from each dietary treatment group were given either a 7-week trickle infection with haemonchus contortus infective larvae (l3) or remained uninfected. all ... | 1998 | 9687595 |
| immunocytochemical localization of a putative inhibitory amino acid receptor subunit in the parasitic nematodes haemonchus contortus and ascaris suum. | a rabbit antiserum was raised against a synthetic peptide corresponding to a region near the n-terminus of the haemonchus contortus inhibitory amino acid receptor subunit, hg1. the antiserum recognized a recombinant form of the n-terminal domain of the subunit on western blots and reacted with the ventral nerve cord of h. contortus in immunofluorescence experiments. immunofluorescence was also detected in specific head neurons of h. contortus: these were tentatively identified as ring motor- and ... | 1998 | 9695104 |
| haemonchus contortus: selection at a glutamate-gated chloride channel gene in ivermectin- and moxidectin-selected strains. | anthelmintic resistance in nematode parasites of livestock is a serious problem worldwide. ivermectin, an avermectin, and moxidectin, a milbemycin, are potent endectocides commonly used to control these parasites. the proposed mode of action of avermectins and possibly the milbemycins involves the binding of the drug to the alpha-subunit of a glutamate-gated chloride channel, which opens or potentiates gating of the channel and leads to the hyperpolarization of the target neuromuscular cell. glu ... | 1998 | 9709029 |
| comparisons of two polymorphic species of ostertagia and phylogenetic relationships within the ostertagiinae (nematoda: trichostrongyloidea) inferred from ribosomal dna repeat and mitochondrial dna sequences. | the first internal transcribed spacer dna (its-1) (rdna) and the mitochondrial (mt) dna-derived cytochrome oxidase i gene (cox-1) were enzymatically amplified, cloned and sequenced from 6 nominal species of ostertagiinae as well as haemonchus contortus and haemonchus placei. the portion of the cox-1 gene analyzed was 393 base pairs (bp) in length and contained 33 within species polymorphic base changes at 28 synonymous sites. the its-1 rdna consensus sequences ranged from 392 bp (ostertagia oste ... | 1998 | 9714215 |
| multiple and multigeneric anthelmintic resistance on a sheep farm in kenya. | the anthelmintic efficacy of benzimidazoles (albendazole, fenbendazole and oxfendazole), levamisole, oral ivermectin and closantel was evaluated on a farm in kenya using faecal egg count reduction test, larval cultures and a controlled slaughter trial. the results of this study indicated simultaneous resistance of haemonchus contortus against benzimidazoles, levamisole and ivermectin, and of trichostrongylus colubriformis and oesophagostomum spp. against levamisole on the same farm. ivermectin r ... | 1998 | 9719844 |
| breed and season effects on the peri-parturient rise in nematode egg output in indigenous ewes in a cool tropical environment. | a study was carried out at the international livestock research institute (ilri) debre berhan research station in ethiopia from 1992 to 1995 to compare the peri-parturient rise (ppr) in faecal nematode egg counts (fec) in ewes of two indigenous sheep breeds. a total of 1439 menz and 1347 horro ewes were single sire mated following oestrus synchronization to lamb in the wet and dry season. three ewe treatment groups were constituted as mated/lactating/undrenched; mated/lactating/drenched; unmated ... | 1998 | 9746282 |
| superoxide dismutase and total antioxidant status of larvae and adults of trichostrongylus colubriformis, haemonchus contortus and ostertagia circumcincta. | superoxide dismutase (sod), a cytosolic enzyme that is specific for scavenging superoxide radicals, is involved in protective mechanism(s) in tissue injury following oxidative processes and phagocytosis. the presence of sod activity in larval and adult trichostrongylus colubriformis, haemonchus contortus and ostertagia circumcincta was examined using a xanthine-xanthine oxidase assay and by polyacrylamide gel electrophoresis (page) and non-denaturing sodium dodecyl sulfate (sds)-page followed by ... | 1998 | 9747937 |
| faecal egg counts are representative of digestive-tract strongyle worm burdens in sheep and goats. | the relationship between faecal egg counts and worm burdens in sheep and goats was studied in a large array of environments, from temperate (ewes, lambs or dairy-goats in france) or steppic (ewes in middle-atlas of morocco) to sahelian (young sheep and goats of mauritania in west africa) climates. the studied temperate worm communities were dominated by teladorsagia and trichostrongylus sp., and those from steppic areas by teladorsagia, marshallagia and trichostrongylus sp.; haemonchus contortus ... | 1998 | 9754309 |
| use of p-glycoprotein gene probes to investigate anthelmintic resistance in haemonchus contortus and comparison with onchocerca volvulus. | a p-glycoprotein gene probe from the sheep parasitic nematode haemonchus contortus was developed and used to analyse restriction fragment length polymorphisms between susceptible isolates and isolates resistant to either benzimidazole; levamisole and benzimidazole; or benzimidazole, ivermectin and closantel. no polymorphism could be correlated with any of the different resistances. a p-glycoprotein gene probe was also isolated from the human nematode parasite onchocerca volvulus and an onchocerc ... | 1998 | 9762570 |
| protein supplementation improves the performance of parasitised sheep fed a straw-based diet. | a study was made of the benefits of protein supplementation for parasitised and non-parasitised lambs. sixty, 5-month-old crossbred wether lambs were placed in individual pens indoors for 9 weeks. half of the animals were experimentally dosed with 1500 haemonchus contortus larvae per head per week and were fed ad libitum and the other half were worm-free, pair-fed controls. diets were formulated to be iso-energetic (9.0 mj of calculated metabolisable energy per kg dry matter) with five levels of ... | 1998 | 9762574 |
| identification and semi-quantitation of ostertagia ostertagi eggs by enzymatic amplification of its-1 sequences. | a region within the first internal transcribed spacer (its-1) of the ribosomal dna repeat of ostertagia ostertagi has been identified that is 408 base pairs (bp) in length and is comprised of a 2 x 204 bp repeat. universal polymerase chain reaction (pcr) primers which span this region, as well as a portion of the 5.8s rdna, generate a 1011 bp fragment using genomic dna from o. ostertagi. however, these same primers generate only a 600 bp (approximate) fragment using dna from haemonchus contortus ... | 1998 | 9763315 |
| resistance of galla and small east african goats in the sub-humid tropics to gastrointestinal nematode infections and the peri-parturient rise in faecal egg counts. | a study was carried out from 1994 to 1996 to compare the resistance to naturally acquired gastrointestinal (gi) nematode infections (predominantly haemonchus contortus) of 88 galla and 114 small east african (sea) goats (does) in the sub-humid coastal region of kenya. live weights (lwt), blood packed cell volume (pcv) and faecal egg counts (fec) were recorded each year at mating, 3-4 months after mating, 1-2 weeks before kidding and 1-4 months after kidding. there was a significant increase in f ... | 1998 | 9777725 |
| development and survival of infective larvae of nematode parasites of sheep on pasture in a cool tropical environment. | the development and survival of nematode parasites of sheep were studied in a cool tropical environment of the highlands of ethiopia on 24 plots serially contaminated with haemonchus contortus, longistrongylus elongata and trichostrongylus colubriformis eggs over a period of 2 consecutive years from june 1993 to may 1995. the availability of infective larvae was monitored by monthly pasture sampling and larvae recovery. infective larvae were recovered from the herbage collected from the plots co ... | 1998 | 9777727 |
| selection at a p-glycoprotein gene in ivermectin- and moxidectin-selected strains of haemonchus contortus. | resistance to anthelmintics that are used to control parasite populations in domestic animals has become a serious problem worldwide. the development of resistance is an evolutionary process that leads to genetic changes in parasite populations in response to drug exposure. the anthelmintic ivermectin is known to bind to the human membrane transport protein, p-glycoprotein, and p-glycoprotein-deficient mice treated with ivermectin have shown signs of neurotoxicity. p-glycoprotein is believed to ... | 1998 | 9803412 |
| infection-induced protection against haemonchus contortus in merino and manchego sheep. relationship to serum antibody response. | resistance to primary and secondary infections with haemonchus contortus was studied in 10-month-old manchego and merino sheep. no notable interbreed differences were observed after primary infections in the parameters determined (prepatency period, faecal egg output, abomasal worm burden). previously infected sheep (200 l-3/kg live weight (lw)) from both breeds showed notable protection after challenge (400 l-3/kg lw), evidenced by lower eggs/g faeces (epg) values and worm burdens. a protective ... | 1998 | 9820113 |
| analysis of sequence homogenisation in rdna arrays of haemonchus contortus by denaturing gradient gel electrophoresis. | testing different theories of concerted evolution experimentally has been hampered mainly due to the lack of appropriate model systems and technical limitations. in this study, we employed a denaturing gradient gel electrophoresis (dgge) approach for the display and definition of nucleotide variations in the second internal transcribed spacer (its-2) of ribosomal dna (rdna) of the parasitic nematode, haemonchus contortus. the its-2 was amplified from individual adult nematodes by pcr and subject ... | 1998 | 9820955 |
| genetic resistance to gastrointestinal nematode parasites in polish long-wool sheep. | a study was undertaken from 1991 to 1994 on a farm in southern poland to evaluate the genetic parameters of resistance to gastrointestinal nematodes. the predominant species were teladorsagia circumcincta and haemonchus contortus. a total of 32 sires were evaluated, around 15 per year. faecal egg counts were measured twice during the 4-month grazing season for lambs (total 659 lambs) and three times for their mothers (total 327 ewes). infection levels were high during the first 2 years and low d ... | 1998 | 9846618 |
| haemonchus contortus: characterization and purification of excretory/secretory protease(s). | the activity of protease(s) has been examined separately in excretory/secretory (e/s) products from male and female haemonchus contortus (nematoda: trichostrongylidae). the e/s proteolytic activity indicated the presence of preabsorptive digestion of host blood and/or tissues. protease activity was optimum at 37 degrees c, ph 8.5 and 8.0 mg casein. these protease(s) were purified to 32.16- and 88.80-folds from male and female e/s products, respectively, by sequential purification with saturated ... | 1998 | 9852772 |
| biological control of haemonchus contortus infective larvae in ovine faeces by administering an oral suspension of duddingtonia flagrans chlamydospores to sheep. | a single oral dose of an aqueous suspension containing 11,350,000 chlamydospores of a mexican isolate of duddingtonia flagrans (ftho-8) given to sheep, resulted in a maximum reduction of 88% (range 86.7-90.4%) of the population of haemonchus contortus infective larvae in the faeces. the effect of this treatment continued for 4-5 days after administration of the suspension. the possible use of this treatment as a method of control of ovine haemonchosis is discussed. | 1998 | 9858632 |
| the ruminant parasite haemonchus contortus expresses an alpha1,3-fucosyltransferase capable of synthesizing the lewis x and sialyl lewis x antigens. | glycoproteins from the ruminant helminthic parasite haemonchus contortus react with lotus tetragonolobus agglutinin and wisteria floribunda agglutinin, which are plant lectins that recognize alpha1,3-fucosylated glcnac and terminal beta-galnac residues, respectively. however, parasite glycoconjugates are not reactive with ricinus communis agglutinin, which binds to terminal beta-gal, and the glycoconjugates lack the lewis x (le(x)) antigen or other related fucose-containing antigens, such as sia ... | 1998 | 9870355 |
| a hemolytic factor from haemonchus contortus alters erythrocyte morphology. | a hemolytic factor from adult haemonchus contortus caused distinct morphological changes in the surface of sheep red blood cells (rbcs). after a 15 min exposure to the hemolytic factor, hemolysis was not detected in incubation media, but rbcs were spherical in shape with numerous surface projections compared to control cells that were smooth-surfaced biconcave disks. after 30 min, a time at which significant hemolysis occurred, echinocytes were formed, and after 90 min, cells were severely disru ... | 1998 | 9877069 |
| natural evolution of gastrointestinal nematodes in goats (capra hircus) in the semi-arid ecosystem of the paraíba backwoods, northeastern brazil. | this study was conducted in patos county, a semi-arid area with caatinga vegetation in paraiba state, northeastern brazil. twenty-four male goats of mixed breeds were used. the animals were separated in age groups from 1-12 months, i. e., 1-2, 3-4, 5-6, 7-8, 9-10, 11-12 months, with four animals in each group. the animals were slaughtered and necropsied to recover and identify adult worms. the goats were exposed to nematode infection from the first month of life. the most prevalent nematodes in ... | 1998 | 9877070 |
| a tissue specific approach for analysis of membrane and secreted protein antigens from haemonchus contortus gut and its application to diverse nematode species. | general methods to conduct tissue specific analysis are largely lacking for nematodes. an approach is described that focused on isolation of membrane and secreted protein genes from the gut of the parasitic nematode haemonchus contortus. the approach capitalized on a monoclonal antibody that recognizes multiple membrane and secreted worm proteins. polyclonal antisera made against these proteins were used to screen expression cdna libraries made either from adult worm gut or whole worm. the genes ... | 1998 | 9879887 |
| cloning and localisation of an avermectin receptor-related subunit from haemonchus contortus. | ivermectin is believed to exert its anthelminthic effects by binding to glutamate-gated chloride channels (glu-cl) and several cdnas encoding subunits of glu-cl have been cloned from caenorhabditis elegans. we report the cloning of cdnas encoding a putative glu-cl subunit (hg4) from the parasite haemonchus contortus. the hg4 cdnas were isolated using rt-pcr and the sequence of the predicted polypeptide has 82% amino-acid identity with the c. elegans glu-cl beta subunit. individual hg4 cdnas show ... | 1998 | 9879896 |
| cloning, sequencing, and developmental expression levels of a novel glutamate-gated chloride channel homologue in the parasitic nematode haemonchus contortus. | glutamate-gated chloride channels (glucls) are the proposed site of action for macrocyclic lactone anthelminthics such as ivermectin (ivm) and the milbemycins such as moxidectin (mox). the importance of this interaction between macrocyclic lactones and glucls is strengthened by the recent genetic evidence that glucls are involved in ivm and mox resistance in the parasitic nematode haemonchus contortus (1). we have cloned two full length glucl putative alpha-subunit cdnas from h. contortus (hcglu ... | 1999 | 9920773 |
| synthesis of gem-difluoro-avermectin derivatives: potent anthelmintic and anticonvulsant agents. | a series of gem-difluoro-avermectin derivatives was synthesized from the corresponding ketones at positions 4", 4', 13, and 23 using diethylaminosulfur trifluoride (dast). these fluorinated avermectins exhibit potent antiparasitic activity in a new haemonchus contortus larval assay and are equipotent to ivermectin. in addition, 23-gem-difluoro-ivermectin displays useful anticonvulsant activity in mouse models. | 1998 | 9934486 |
| flow cytometry analysis of drug transport mechanisms in haemonchus contortus susceptible or resistant to anthelmintics. | the role of membrane drug-transport mechanisms in resistance to anthelmintics was examined using a flow cytometry method. this method was adapted from assays developed for the study of similar mechanisms in tumor cells. rhodamine 123, a p-glycoprotein transport probe, associated with the reversal agent verapamil gave a significantly higher level of green fluorescence in haemonchus contortus-resistant eggs as compared with that of susceptible eggs. in the same way, verapamilbodipy, a new fluoresc ... | 1999 | 9934960 |
| nematode burdens and cellular responses in the abomasal mucosa and blood of florida native, rambouillet and crossbreed lambs. | this experiment was carried out to compare the worm burden and cellular responses in the abomasal mucosa and blood of florida native and rambouillet lambs and also in animals produced by crosses of these two breeds (generations f1 and f2). animals were exposed to infection by gastrointestinal nematodes on three different occasions. the first infection was natural, occurring while they were suckling lambs. after weaning, they were kept indoors for 53 days and then were allowed to graze a contamin ... | 1999 | 9950337 |
| comparison of six in vitro tests in determining benzimidazole and levamisole resistance in haemonchus contortus and ostertagia circumcincta of sheep. | six in vitro methods for the detection of anthelmintic resistance were compared using benzimidazole/levamisole-resistant haemonchus contortus and benzimidazole/levamisole/ivermectin-resistant ostertagia circumcincta as well as susceptible strains of both parasite species. the degree of resistance to thiabendazole and levamisole was compared by (1) an egg hatch assay, (2) an egg hatch paralysis assay, (3) a larval development assay, (4) a larval paralysis assay (5) a larval paralysis assay with p ... | 1999 | 9950347 |
| vaccination against the gastrointestinal nematode, haemonchus contortus, using a purified larval surface antigen. | sheep were immunized with a purified antigen (hc-sl3) expressed on the surface of l3 larvae of the gastro-intestinal parasite, haemonchus contortus, using different adjuvant and immunization routes. in the first experiment, intradermal immunization of sheep with hc-sl3 and quila did not result in reductions in faecal egg counts after subsequent challenge infection while significant reductions were obtained when aluminium hydroxide (ah) was used as the adjuvant. significant protection with hc-sl3 ... | 1999 | 9987175 |
| haemonchus contortus: sequence heterogeneity of internucleotide binding domains from p-glycoproteins. | p-glycoproteins are transmembrane proteins associated with acquired multidrug resistance in mammalian cells and some protozoan parasites by a process of active drug export. p-glycoproteins contain two nucleotide binding domains which couple atp to the drug transport process. the region between the nucleotide binding domains of p-glycoproteins, termed the internucleotide binding domain (ibd), was pcr-amplified from adult and larval cdna libraries using degenerate primers. the 11 clones isolated b ... | 1999 | 10072327 |
| characterization of a hexokinase encoding cdna of the parasitic nematode hhaemonchus contortus. | the nematode haemonchus contortus is an important parasite of cattle and sheep. we describe here the cloning of a cdna encoding a 53 kda hexokinase (ec 2.7.1.1). the deduced protein shows 73% identity to a 50 kda hexokinase deduced from a caenorhabditis elegans cosmid. alignment with mammalian hexokinases reveals two short amino acid insertions in the h. contortus hexokinase. software tools for structural protein analysis (expasy server, geneva) localize these insertions on the surface of the mo ... | 1999 | 10095069 |
| activity of eprinomectin in goats against experimental infections with haemonchus contortus, teladorsagia circumcincta and trichostrongylus colubriformis. | 1999 | 10097316 | |
| features of dna fragments obtained by random amplified polymorphic dna (rapd) assays | random amplified polymorphic dna (rapd) fragments were prepared from samples of calonectris diomedea (cory's shearwater, aves) and haemonchus contortus (nematoda) dna by polymerase chain reaction (pcr) using decamers containing two restriction enzyme sites as primers. six of 19 studied rapd fragments probably originated from traces of commensal microorganisms. many rearranged fragments, absent in the original genomic dna, were synthesized and amplified during the processing of all the dna sample ... | 1999 | 10199010 |
| cloning and characterization of glutamate dehydrogenase (gdh) from the gut of haemonchus contortus. | vaccination of lambs with the membrane-bound (s3) thiol-sepharose binding protein (tsbp) fraction derived from the gut of haemonchus contortus confers significant protection against homologous challenge. the s3 tsbp peptide profile is dominated by a major protein of ca. 60 kda which is strongly recognized by antisera from sheep demonstrably protected following immunization with s3 tsbp. in an attempt to identify this protein, sera from protected lambs were employed to screen a lambda gt11 cdna l ... | 1999 | 10205806 |
| serum antibody response of castellana sheep to haemonchus contortus infection and challenge: relationship to abomasal worm burdens. | primary and secondary serum antibody responses to haemonchus contortus were studied in castellana sheep. ten-month-old sheep were infected (200 l3/kg live weight (lw)) and challenged (400 l3/kg lw) or uninfected and equally challenged with h. contortus. primary infections induced a partially protective response upon challenge, characterized by higher serum protein levels, longer prepatent periods, lower fecal egg counts, and significant reduction in the establishment rate of the parasite and abo ... | 1999 | 10206102 |
| the response of nigerian west african dwarf goats to experimental infections with haemonchus contortus. | one option for controlling haemonchosis in warm pastoral regions is improvement of resistance by selective breeding. variation in acquired immunity to h. contortus and immunological correlates of infection were studied in west african dwarf (wad) goats. following exposure to 5000 l3, 63 per cent of the inoculum established but 77 per cent of established worms were expelled by week 5. all infected animals were anaemic (day 14). when exposed to 2000l3, 36 per cent of the inoculum was still present ... | 1999 | 10208893 |