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role of carbohydrates within variant surface glycoprotein of trypanosoma congolense. protection against proteolytic attack.the effects of tunicamycin on different aspects of structure and biosynthesis of variant surface glycoprotein from trypanosoma congolense have been studied. deglycosylated variant antigen becomes synthesized in vitro, is transported through the cell, and is deposited on the cell surface in equivalent amounts compared to the glycosylated species. in contrast to the glycosylated molecule only marginal amounts of high-molecular-mass fragments can be removed from the parasitic cell by externally add ...19853896788
sulphydryl-dependent enzymes from african trypanosomes. 19853898094
adenosine cycle in african trypanosomes.african trypanosomes can convert adenosine to adenosine monophosphate. however, in trypanosoma brucei, as in t. vivax and t. congolense, most of the adenosine is broken down to adenine before conversion to the nucleotide by adenine phosphoribosyltransferase. trypanosoma brucei and t. vivax use the purine nucleoside hydrolase for adenosine cleavage while t. congolense uses purine nucleoside phosphorylase for the nucleoside cleavage. trypanosoma vivax also deaminates adenine to hypoxanthine before ...19853920982
antibody responses in resistant and susceptible inbred mice infected with trypanosoma congolense.antibody responses were evaluated in inbred mice previously shown to be susceptible (a/j) or resistant (c57bl/6j and b6af1 hybrid) to infections with relatively avirulent trypanosoma congolense. titres and the isotype distribution antibodies specific for the trypanosome variant surface glycoprotein (vsg) were determined by indirect immunofluorescence in sera of mice after primary infections with trypanosoma congolense and after challenge infections with the same variant following drug cure. the ...19863949371
size-fractionation of the small chromosomes of trypanozoon and nannomonas trypanosomes by pulsed field gradient gel electrophoresis.we have compared the molecular karyotypes of trypanosomes from different subgroups within subgenus trypanozoon by pulsed field gradient (pfg) gel electrophoresis. although the overall karyotype was similar, there was much variation in the size of chromosomes between different stocks. two of three stocks of trypanosoma (trypanozoon) brucei gambiense had remarkably small mini-chromosomes: 25-50 kilobase pairs compared to 50-150 kilobase pairs for the mini-chromosomes of other trypanozoon stocks. t ...19863960051
parasite kinetics and immune responses in efferent prefemoral lymph draining skin reactions induced by tsetse-transmitted trypanosoma congolense.localised skin reactions (chancres) occurred on the flanks of cattle at the sites of deposition by tsetse flies of metacyclic forms of trypanosoma congolense. marked enlargement of the draining prefemoral lymph nodes accompanied the development of the skin reactions. lymph from these nodes was collected through polyethylene cannulae inserted into the efferent lymphatics, and examined for trypanosomes, cells and antibody content. within 6-9 days after infected tsetse fly bite, trypanosomes were d ...19863705421
minichromosomal variable surface glycoprotein genes and molecular karyotypes of trypanosoma (nannomonas) congolense.employing orthogonal-field-alternation gel electrophoresis (ofage), we have separated chromosome-sized dna molecules from trypanosoma (nannomonas) congolense clones, the clones being derived from several distinct antigenic repertoires. trypanosome clones that belong to a specific antigenic repertoire appear to have a chromosome pattern characteristic of that particular repertoire. hybridization of the separated chromosomes with cloned dna fragments encoding variable surface glycoproteins reveale ...19863710162
susceptibility and immune responses of zebu and taurine cattle of west africa to infection with trypanosoma congolense transmitted by glossina morsitans centralis.following tsetse-transmitted infection with trypanosoma congolense, major differences in development of localised skin reactions, the ability to control parasitaemia, the degree of anaemia and in antibody response to trypanosomes were found between the reputedly trypanotolerant breeds of cattle (n'dama, n'dama/baoule crosses, baoule) and the trypanosusceptible west african zebu. the local skin reactions that developed in the zebu were large and severe while those that occurred in the other breed ...19863716196
effect of concurrent infections with trypanosoma congolense in rabbits on the development of immunity after trypanocidal drug treatments. 19863729593
extrachromosomal inheritance of susceptibility to trypanosome infection in tsetse flies. ii. susceptibility of selected lines of glossina morsitans morsitans to different stocks and species of trypanosome.two lines of glossina m. morsitans, selected for susceptibility and refractoriness to infection with a single stock of trypanosoma congolense, have now been shown to be susceptible or refractory to different stocks of t. congolense and, also, to different stocks of t. b. brucei and t. b. gambiense. the mean midgut infection rates of the susceptible line obtained in different experiments with t. congolense, t. b. brucei and t. b. gambiense were, respectively, 66%, 56% and 55%; the corresponding m ...19863729601
two enzymically distinct stocks of trypanosoma congolense.two stocks of trypanosoma congolense, isolated from a sheep and a goat on the kenyan coast, were found to be distinctly different from 112 other stocks of the same species after comparing, by isoenzyme electrophoresis, trypanosomes originating from various parts of africa. the results show a marked genetic distinction that may be of epidemiological or taxonomic significance.19863738239
isometamidium chloride prophylaxis against trypanosoma congolense challenge and the development of immune responses in boran cattle.twenty-four boran cattle were injected with isometamidium chloride (1 mg/kg bodyweight) to investigate the duration of drug-induced prophylaxis against infection by metacyclic forms of trypanosoma congolense and to determine if specific antibody responses to the organism were mounted by animals under chemoprophylactic cover. complete protection against either single challenge by five tsetse flies infected with t congolense, or repeated challenge at monthly intervals by five tsetse flies, lasted ...19863739193
interference between different serodemes of trypanosoma congolense in the establishment of superinfections in goats following transmission by tsetse.when domestic ruminants cyclically infected with trypanosoma congolense are superinfected with a different serodeme of the same species, an interference phenomenon occurs which delays the development of the second cyclical infection. experiments were carried out to investigate the influence of the time interval between the two infections on the degree of interference and to follow the course of the superinfection clinically, serologically and histologically. goats infected with tsetse-transmitte ...19863748602
morphological changes in trypanosoma congolense after proteolytic removal of the surface coat.bloodstream forms of trypanosoma congolense were exposed to proteases at various concentrations, and the consequences of this treatment were continuously examined by electron microscopy. unexpectedly, proteolysis did not simply result in the removal of the surface coat, but in dramatic morphological changes characterized by membrane adhesions, subsequently leading to flagella/plasmamembrane and to plasmamembrane/plasmamembrane fusions. the resulting axonemal internalization and rearrangement of ...19863782927
comparison of diagnostic techniques during subclinical single infections of trypanosomiasis in goats.parasitological diagnostic techniques were compared in caprine hosts in which single subclinical infection with trypanosoma vivax, trypanosoma congolense or trypanosoma brucei brucei had been established. the haematocrit centrifuge technique (hct) was the most sensitive for the diagnosis of t. vivax and t. b. brucei while the buffy coat method (bcm) proved superior to all other techniques for t. congolense. except with the miniature anion-exchange/centrifugation technique (maec), each of the con ...19863788024
plasma testosterone in trypanosoma congolense-infected toggernburg goats.trypanosomiasis induces histological testicular degenerative changes leading to suppression of spermatogenesis in goats and laboratory animals. we present evidence associating these changes with trypanosome-induced endocrine dysfunction. toggenburg goats were infected with approximately 100,000 trypanosomes. they were bled every 2 days, and the plasma testosterone was analyzed by radioimmunoassay. testes were perfused with and fixed in bouin's fixative for histological evaluation. the infected p ...19863789879
haematological observations on bovine trypanosomiasis of holstein-friesian breed.haematological investigation was conducted on 20 cases of bovine trypanosomiasis caused by trypanosoma congolense and t. vivax in imported holstein-friesian cattle using standard techniques. comparison of the results with the values obtained for clinically normal animals whose blood samples were consistently negative for trypanosomes indicated that natural bovine trypanosomiasis was associated with a significant (p less than 0.001) fall in haemoglobin concentration, packed cell volume and number ...19863793394
thiol-dependent proteases of african trypanosomes. analysis by electrophoresis in sodium dodecyl sulphate/polyacrylamide gels co-polymerized with fibrinogen.the proteases of several species of african trypanosomes were analysed by electrophoresis in sodium dodecyl sulphate/polyacrylamide gels containing fibrinogen or collagen. after electrophoresis the gels were incubated in the presence of enzyme activators and/or inhibitors and then stained with coomassie brilliant blue. the areas where the proteolytic activity had degraded the fibrinogen did not stain and so formed clear bands against a blue background. the proteases were found to have ph optima ...19863514210
improved method for isolating trypanosoma congolense from mice. 19863523863
analysis of trypanosome variable antigen types in cultures of metacyclic and mammalian forms of trypanosoma congolense.cultured metacyclic forms of trypanosoma congolense display a characteristic repertoire of metacyclic variable antigen types (m-vats) similar to that exhibited in vitro in the tsetse fly. there appeared to be no change in expression of m-vats in cultures of two stocks of t. congolense even after several passages, cryopreservation or long-term cultivation in vitro. metacyclic forms transformed into mammalian forms when transferred to cultures of bovine aorta endothelial cells and whilst one stock ...19863528995
effect of chronic trypanosomiasis on immunization against east coast fever.two experiments were carried out in which uninfected cattle, or cattle chronically infected with trypanosoma congolense, were immunized by the infection and treatment method against east coast fever (ecf; theileria parva infection). chronic trypanosomiasis did not prevent cattle mounting an effective immunological response to ecf immunization and resisting subsequent lethal challenge. there appeared to be no difference in the level or quality of immunity between uninfected cattle and trypanosome ...19863564324
mechanisms of self-cure from trypanosoma congolense infection in mice.the mechanism(s) of resistance to african trypanosomiasis caused by trypanosoma congolense was investigated by using the dinderesso/80/crta/3 isolate to which c57b1/6 are resistant (low parasitemia and self-cure) and balb/c sensitive (high parasitemia and death). the resistance of c57b1/6 is similar to that found in some natural hosts of african trypanosomes such as certain indigenous west african cattle and wild bovidae. the antibody response to epitopes exposed on the variant surface glycoprot ...19863484768
interleukin-1 and interleukin-2 production in resistant and susceptible inbred mice infected with trypanosoma congolense.in vitro production of interleukin-1 (il-1) by lps-stimulated adherent peritoneal exudate and spleen cells and alveolar macrophages, and interleukin-2 (il-2) by concanavalin a-stimulated splenocytes were measured in resistant (c57bl/6j) and susceptible (a/j) inbred mice during the early stages of subacute infections with the african trypanosome, trypanosoma congolense. production of il-1 was severely depressed in both mouse strains as early as 24 hr after intraperitoneal injection of bloodstream ...19863485076
a preliminary comparison of trypanosoma simiae and t. congolense by isoenzyme electrophoresis.trypanosoma simiae, although similar to t. congolense in morphology and mode of development in the tsetse vector, is regarded as a separate species mainly because it is highly pathogenic to the domestic pig and fails to infect rodents. to establish whether the two species are distinct biochemically, we compared by isoenzyme electrophoresis 2 isolates of t. simiae with 7 stocks of t. congolense, together with one of t. brucei. all isoenzyme patterns of the 6 enzymes examined differed in t. simiae ...19862872783
[sensitivity of the card agglutination test (testryp caat) in porcine infection with trypanosoma (nannomonas) congolense in the people' republic of the congo]. 19862872859
infectivity to cattle of metacyclic forms of trypanosoma (nannomonas) congolense propagated in vitro. i. development of localized skin reactions following intradermal inoculation.skin reactions similar to those induced by tsetse infected with trypanosoma congolense were elicited in cattle at sites of intradermal inoculation of in vitro propagated parasites which morphologically resembled metacyclic trypanosomes. the time to detection of the reaction, the time to maximal size and the maximal size attained were dependent on the number of parasites inoculated, although it was possible to induce a skin reaction with as few as 20 trypanosomes. all cattle became infected with ...19862877547
evaluation of sinefungin for the treatment of trypanosoma (nannomonas) congolense infections in goats.caprine trypanosoma (n.) congolense infections were treated with sinefungin, an antifungal antibiotic nucleoside. single doses from 10 to 20 mg/kg bodyweight given intramuscularly were not curative for goats; single doses of 25 and 50 mg/kg were toxic, and caused death. five and 7.5 mg/kg administered twice daily over a three-day period, resulted in a cure in 2 animals, while 2 others relapsed. all animals relapsed when given a single daily dose of 5 or 7.5 mg/kg for 4 consecutive days. when suc ...19862878488
evidence for genetic diversity in trypanosoma (nannomonas) congolense.genetic proximity between two karyotypic groups of trypanosoma congolense was investigated using as hybridization probes: total genomic dna, a 35 nucleotide long synthetic oligonucleotide, and non-variant antigen type (non-vat) specific complementary dnas. the phylogenetic relationship between trypanosoma brucei and t. evansi, both of which are accepted species in the subgenus trypanozoon, was used as a reference to assess the phylogenetic proximity of the two groups of t. congolense. results in ...19863024094
the alternative pathway of complement in sheep during the course of infection with trypanosoma congolense and after berenil treatment.experimental t. congolense infections in sheep resulted in a striking decrease in parameters of the alternative complement pathway (acp), ie. factor b, c3 and haemolytic complement activity (ha) initiated via the acp. the levels of factor b, c3 and ha declined before, during and after the first wave of parasitemia which reached a peak at day 8. levels of 20 to 25% of normal values (factor b) and 20% (c3, ha) persisted throughout the course of the infection. after berenil treatment, when no paras ...19863088536
surface carbohydrates of procyclic forms of african trypanosomes studied using fluorescence activated cell sorter analysis and agglutination with lectins.living culture form procyclics of trypanosoma brucei brucei, t.b. rhodesiense, t.b. gambiense, t. congolense and t. simiae were tested for binding of eight different lectins. the binding of fluorescein isothiocyanate (fitc)-conjugated lectins was measured using a fluorescence activated cell sorter (facs) and by agglutination with unlabelled lectins. five of the lectins failed to bind to any of the procyclic organisms in both tests. all parasites bound concanavalin a (con a) and all t.b. brucei, ...19873106807
chemotherapy of trypanosomiasis: the use of guanylhydrazone compounds in the treatment of experimental murine trypanosomiasis.the efficacy of 1,3,5-triacetylbenzene tris(guanylhydrazone) trihydrochloride i.e. [(tbg)] in the treatment of early and late stage infections of trypanosoma brucei in mice was investigated. successful treatment on day 3 after infection could be achieved by doses of 2 x 2.5 mg kg-1. if treatment was delayed to 21 days after infection then the mice had to be given either suramin (1 x 20 mg kg-1) or difluoromethyl-ornithine (dfmo) 2% solution for 14 days in addition to either 15 mg kg-1 (tbg) dail ...19873124253
sequences of two kinetoplast minicircle dnas of trypanosoma (nannomonas) congolense.random minicircle dna molecules were released from isolated kinetoplast network dna of trypanosoma congolense by bamhi digestion and cloned into plasmid puc19. the sequences of two cloned minicircles (958 bp and 964 bp) were determined. both minicircles contain the 13 bp sequence, 5'-ggggttggtgtaa-3', thought to be the replication origin of minicircles in other trypanosomatids. the two minicircles have extensive homology in the 120 bp preceeding, and the 20 bp following, this 13-mer but only sca ...19873041215
mini-exon gene repeats of trypanosoma (nannomonas) congolense have internal repeats of 190 base pairs.genomic dna hybridizations reveal that the mini-exon gene repeats of trypanosoma (nannomonas) congolense contain from one to greater than 20 internal tandem repeats of 190 base pairs (bp). the sequences of two mini-exon gene repeats were determined, one with three internal 190 bp repeats and one with a single 190 bp sequence. these internal repeats appear just after a very dc/dt-rich region, in the non-transcribed spacer regions between adjacent mini-exon transcription units. they do not occur i ...19872823133
a repetitive deoxyribonucleic acid sequence distinguishes trypanosoma simiae from t. congolense.the dominant repetitive deoxyribonucleic acid (dna) sequence in the genome of a clone of trypanosoma (nannomonas) simiae has been identified and cloned as a recombinant plasmid. the recombinant plasmid was used in hybridization analyses of dna samples obtained from various trypanosome species and subspecies. the results indicated that the t. simiae repetitive dna sequence hybridized with dna derived only from t. simiae; it did not hybridize with dna derived from clones or stocks of t. congolense ...19872827093
identification and selection of cattle naturally resistant to african trypanosomiasis.cattle were exposed to natural trypanosome challenge in an area of high glossina density (samandéni, burkina faso) for various periods of time during 1982, 1983, 1984 and 1985. all of 30 zebu proved to be sensitive to trypanosomiasis i.e. they died or were treated in extremis in 10 +/- 4 weeks. twenty-one (31%) baoulé were as sensitive as the zebu while 47 (69%) were resistant i.e. they survived in good condition. twenty ndama/baoulé crosses, indigenous to samandéni were all resistant. weekly bl ...19872884840
epidemiology of animal trypanosomiasis on a cattle ranch in kilifi, kenya.a study of the epidemiology of animal trypanosomiasis was carried out on a 2500 ha cattle ranch, with a history of trypanosomiasis, in the coast province of kenya in 1982. the tsetse survey on the ranch revealed one breeding focus of glossina austeni in a thicket of approximately 50 ha. trypanosomes were detected in 20% of the 46 dissected tsetse. during the study period of 9 months, 0.8% of the 3315 samples collected from 2300 ayrshire x sahiwal crossbred cattle were found infected with trypano ...19872884841
trypanosoma (nannomonas) congolense: properties of hexokinase and phosphofructokinase from cultured procyclic trypomastigotes and bloodstream forms.the distribution and kinetics of two key glycolytic enzymes hexokinase (hk) and phosphofructokinase (pfk) were studied in animal-infective bloodstream forms (haematozoic trypomastigotes) and uninfective procyclic forms (insect trypomastigotes) of trypanosoma congolense. the results show that in both forms of t. congolense hk and pfk are particulate and are probably localized in a membrane-delimited organelle, the glycosome. hexokinases of bloodstream and procyclic forms of t. congolense are kine ...19872892364
trypanosoma congolense: differentiation to metacyclic trypanosomes in culture depends on the concentration of glutamine or proline.the effect of glutamine on the number of metacyclic trypanosomes produced in insect form cultures of trypanosoma congolense treu 1457 was investigated. when cultured in the absence of glutamine, trypanosomes did not develop to metacyclic forms. while metacyclics were produced in all cultures maintained with glutamine in the concentration range 2-20 mm, optimum numbers were obtained between 4 and 12 mm glutamine. this pattern was constant in flasks cultured for over two months. the substitution o ...19872892365
dose and stage dependency for the development of local skin reactions caused by trypanosoma congolense in goats.intradermal inoculation of metacyclic forms of trypanosoma congolense propagated in vitro caused skin reactions in goats similar to the local skin reaction (chancre) induced by the bite of an infected tsetse fly. the onset, size and duration of these local skin reactions were dose-dependent. whereas one cultured metacyclic t. congolense was sufficient to cause a local skin reaction in a goat, over 10(7) bloodstream forms of t. congolense were necessary to elicit a detectable skin reaction and wh ...19872892366
high density lipoprotein levels in the serum of trypanosensitive and trypanoresistant cattle. changes during trypanosoma congolense infection.nonpermissiveness to trypanosome infection has been correlated in some instances with the presence of toxic serum factors, e.g. high density lipoproteins (hdl) of human serum can lyse t.b. brucei. the present study examines the possibility of a role for such factors in west african cattle that are resistant to trypanosomiasis. cattle used in this study were previously selected as resistant or sensitive to trypanosomiasis under heavy natural glossina challenge. - a comparison of the direct effect ...19872892367
the effect of the trypanocidal drugs berenil and samorin on infections of glossina morsitans centralis by trypanosoma congolense. 19872892374
adaptation of trypanosoma congolense stocks to in vitro culture does not change their sensitivity to isometamidium. 19872892376
variant surface glycoproteins of trypanosoma congolense bloodstream and metacyclic forms are anchored by a glycolipid tail.the variant surface glycoproteins (vsgs) of both metacyclic and bloodstream forms of trypanosoma congolense are shown to be anchored to the plasma membrane through a glycolipid similar to that found in trypanosoma brucei. release of soluble vsg from both metacyclic and bloodstream forms is associated with the exposure of an antigenic determinant homologous to the cross-reacting determinant of t. brucei vsgs. release of soluble vsg of t. congolense can be achieved by lysates of both bloodstream a ...19872437450
characterization of epitopes on a variant surface glycoprotein from trypanosoma congolense by six monoclonal antibodies.monoclonal antibodies were isolated from mice immunized with variant surface glycoprotein of trypanosoma congolense. five out of the six monoclonals were able to detect epitopes at the cell surface in an indirect immunofluorescence analysis. one antibody did not react. using protein-a-containing bacterial adsorbent all monoclonal antibodies precipitate glycosylated as well as non-glycosylated variant surface glycoprotein. carbohydrate chains therefore do not appear to be part of the immunodeterm ...19872443352
peripheral blood leucocytes subpopulation dynamics during trypanosoma congolense infection in boran and n'dama cattle: an analysis using monoclonal antibodies and flow cytometry.a panel of monoclonal antibodies (moab) with specificities for bovine leucocyte subsets were used in conjunction with routine haematological procedures to analyse sequential changes in peripheral blood leucocyte populations during the course of tsetse fly-transmitted trypanosoma congolense infection in trypanotolerant n'dama and trypanosusceptible boran cattle. subsequent to the first parasitaemic wave, the n'dama cattle maintained packed cell volumes (pcv) above 22 and lower levels of parasitae ...19873496577
glycosyl-sn-1,2-dimyristylphosphatidylinositol is the membrane anchor for trypanosoma equiperdum and t. (nannomonas) congolense variant surface glycoproteins.we have analysed the structures of the trypanosoma (nannomonas) congolense and t. equiperdum variant surface glycoprotein (vsg) membrane anchors. myristic acid uptake, phospholipase treatment, and nitrous acid deamination showed that, for each species, the anchor is glycosyl-sn-1,2-dimyristylphosphatidylinositol, as has been previously described for t. brucei. osmotic lysis of these trypanosomes resulted in the release of soluble vsg, lacking fatty acid. in both species and in t. evansi, an endo ...19872957588
suppressive action of samorin on the cyclical development of pathogenic trypanosomes in glossina morsitans centralis.male glossina sexually sterilized by gamma-irradiation are as efficient vectors of trypanosomiasis as fertile males. an attempt was made, using isometamidium chloride (samorin), to interfere with the cyclical development of trypanosomes in sterile males, destined for use in the sterile insect release (sir) method of tsetse eradication. the infection rate with mature trypanosoma congolense broden was effectively reduced in sterile male glossina morsitans centralis machado, when the flies were fed ...19872979543
lectin mediated establishment of midgut infections of trypanosoma congolense and trypanosoma brucei in glossina morsitans.d+glucosamine, which has been shown in vitro to specifically inhibit tsetse midgut lectin activity, when fed to glossina morsitans morsitans with the infective feed significantly increased midgut infection rates of trypanosoma congolense and t. brucei rhodesiense. all flies infected with t.b. rhodesiense and maintained on a diet of blood with d+glucosamine throughout their lives developed midgut infections. midgut extracts from flies bred for refractoriness to infection with trypanosomes showed ...19873432950
trypanocidal activity of a 5-substituted 2-nitroimidazole compound (ro 15-0216) in mice.the trypanocidal activity of a 5-substituted 2-nitroimidazole compound (ro 15-0216, 2-(dimethylamino)-4'-[(1-methyl-2-nitroimidazole-5-yl) methoxy] acetanilid) was tested in stocks of t.b. brucei, t.b. evansi, t. vivax, and t. congolense. the trypanosome stocks showed different sensitivities, the trypanozoon group was most sensitive followed by t. vivax and t. congolense. administration of the compound in the drinking water was superior to single intraperitoneal injections. a t.b. brucei stock w ...19873432951
the role of antibody in natural resistance to african trypanosomiasis.the nature and usefulness of trypanoresistance in west african baoule cattle was studied by exposing animals in areas of high glossina density. under such conditions, zebu and some baoule died soon with high parasitaemia while resistant baoule showed little patent parasitemia, almost no anaemia and thrived. subsequently the role that specific antibody may play in such trypanoresistance was analyzed. in the first instance we examined protective antibody titres during t. congolense infection of in ...19873433662
a simple in vitro method for infecting tsetse with trypanosomes. 19873446032
characterization of trypanosoma congolense serodemes in stocks isolated from cattle introduced onto a ranch in kilifi, kenya.a herd of 20 cattle was introduced on a ranch in kilifi, coast province of kenya, where they were in contact with glossina austeni for 6 months. in total, 65 trypanosome isolates were made from these animals. examination of the isolates revealed that 61 were trypanosoma congolense and 4 were t. theileri. out of the 61 t. congolense isolates, 55 were successfully passaged and cloned in mice to provide trypanosome populations for further analyses. the stocks and their clones were inoculated into g ...19873295687
a new method for fixation and preservation of trypanosomal antigens for use in the indirect immunofluorescence antibody test for diagnosis of bovine trypanosomiasis.a new method for fixation of trypanosomes for use in the indirect immunofluorescent antibody test (ifat) is described. the method involves fixation of live trypanosomes, in suspension, using a mixture of 80% cold acetone and 0.25% formalin in saline. the fixed trypanosomes were stored in suspension at -60 degrees c, 4 degrees c or at room temperature for at least one year without loss of antigenicity. using trypanosomes prepared this way as antigens in ifat, species-specific antibodies were dete ...19873299658
monoclonal antibodies that distinguish trypanosoma congolense, t. vivax and t. brucei.monoclonal antibodies (moabs) were derived against in-vitro-propagated procyclic forms of trypanosoma congolense, t. vivax, t. brucei brucei and t.b. rhodesiense in order to identify antigens for use in immunodiagnosis of african trypanosomiasis. the antibodies have been tested against procyclic and bloodstream form trypanosomes of 13 t. congolense, six t. vivax six t.b. brucei, four t.b. rhodesiense, five t.b. gambiense and three t. simiae isolates from different geographical areas by indirect ...19873306569
enhanced resistance of highly susceptible balb/c mice to infection with trypanosoma congolense after infection and cure.balb/c and c57bl/6 mice were cured with berenil after infection with cloned organisms of trypanosoma congolense and challenged with homologous or heterologous variants. the mice were fully protected against infection with 10(3) but not 10(5) organisms of the homologous variant. normal balb/c mice infected with 10(5) organisms developed uncontrolled parasitemia and had a mean survival time of 8.4 days. challenge of drug-cured balb/c mice with 10(5) organisms of the homologous variant established ...19873309242
purification of african trypanosomes can cause biochemical changes in the parasites.bloodstream forms of african trypanosomes are routinely purified from blood components by a combination of centrifugation and chromatography on deae cellulose at ph 8.0. here we report that the nonphysiological conditions used for deae chromatography of the parasites result in changes in the atp levels of the trypanosomes and an enhanced release from the parasites of proteins such as variable surface glycoprotein, peptidase, and phospholipase. some of these changes can be reduced by the addition ...19873323477
trypanosoma congolense: structure and molecular organization of the surface glycoproteins of two early bloodstream variants.the complete primary structures of two variant specific glycoproteins (vsgs) of the nannomonad trypanosoma (n.) congolense are presented. these coat proteins subserve the function of antigenic variation. the secondary structure potentials of both vsgs have been calculated. the amino acid sequences and secondary structure potentials of these vsgs have been compared with the primary structures and secondary structure potentials of several trypanosoma brucei complex vsgs. in homologous regions, the ...19873567147
trypanosoma congolense: host responses following tsetse transmitted infection of kilifi isolates in goats.east african x galla goats, when infected with trypanosoma congolense isolates from the kilifi area of kenya by glossina morsitans centralis, did not develop the characteristic chancre reaction at the bite sites, whereas bites of tsetse infected with the cloned t. congolense il.1180 from serengeti, tanzania, resulted in chancres in the same goats. histological changes could not be observed in skin biopsies collected 8 or 9 days after infection with kilifi isolates. however, all goats became para ...19873582569
potential value of localized skin reactions (chancres) induced by trypanosoma congolense transmitted by glossina morsitans centralis for the analysis of metacyclic trypanosome populations.goats infected with trypanosoma congolense transmitted by glossina morsitans centralis and then treated with the trypanocidal drug diminazene aceturate are immune to tsetse-transmitted infection with a homologous, but not heterologous trypanosome clone. immune animals fail to develop localized skin reactions (chancres) and do not become infected, whereas on heterologous challenge chancres appear followed by parasitaemia. in this study, the feasibility of using chancre reactions to characterize s ...19873601446
the virulence of trypanosoma congolense can be determined by the antibody response of inbred strains of mice.three inbred strains of mice, balb/c, c57bl/6 and cba/j were infected with three clones of trypanosoma congolense, dind/3.1, sam/28.1 and kar/57.1, which were obtained from three different stocks. dind/3.1 was of high virulence for balb/c and cba/j but of negligible virulence for c57bl/6. sam/28.1 was of high virulence and kar/57.1 of negligible virulence for the three strains of mice. in each case, high virulence was correlated with a late, transient and low titre protective antibody response m ...19873601447
cibarial infections of trypanosoma vivax and t. congolense in glossina.in a percentage of laboratory bred glossina infected with trypanosoma congolense or t. vivax, trypanosomes colonized the cibarium as well as the midgut and/or the proboscis. field-caught tsetse flies also had t. congolense and t. vivax cibarial infections. t. congolense cibarial infections occurred in all species of glossina examined: g. tachinoides, g. palpalis palpalis, g. morsitans morsitans and g. m. submorsitans. t. vivax was only found in the cibarium of g. tachinoides. trypanosomes were f ...19873615393
subcellular localization of a variable surface glycoprotein phosphatidylinositol-specific phospholipase-c in african trypanosomes.african trypanosomes contain a membrane-bound enzyme capable of removing dimyristylglycerol from the membrane-attached form of the variable surface glycoprotein (mfvsg; ferguson, m. a. j., k. halder, and g. a. m. cross, 1985, j. biol chem., 260:4963-4968). although mfvsg phospholipase-c has been implicated in the removal of the vsg from the trypanosome surface (cardoso de almeida, m. l., and m. j. turner, 1983, nature (lond.)., 302:349-352; ferguson, m. a. j., k. halder, and g. a. m. cross, 1985 ...19873624307
bovine trypanosomiasis in southern tanzania: parasitological and serological survey of prevalence.in a survey for bovine trypanosomiasis blood smears from 1,617 cattle at 72 sites were examined. trypanosomes were found in 93 cattle, representing 16% of the cattle in herds in which trypanosomiasis was confirmed. of the positive cattle 56% had infections with t. congolense, 17% t. vivax and 2.2% t. brucei. five cattle had mixed infections and in 18 cattle the species was not identified. sera from 1,352 cattle were tested using microelisa. ten out of 16 sites, at which no trypanosomes were foun ...19873660451
stable introduction of exogenous dna into trypanosoma brucei.the lack of a homologous transformation system for trypanosomes is a serious handicap to the study of gene expression in these protozoans. attempts to develop such a system have been complicated by the lack of suitable homologous vectors and ignorance of the requirements for mrna synthesis which is discontinuous in trypanosomes. we have found that trypanosoma congolense, a close relative of t. brucei, contains exceptionally small chromosomes, which can be isolated whole and distinguished from th ...19873665883
use of species-specific dna probes for detection and identification of trypanosome infection in tsetse flies.species- and subspecies-specific trypanosome dna hybridization probes have been employed in the detection and identification of trypanosome infections in glossina morsitans centralis. several ways of sample preparation including the use of tsetse organ suspensions, proboscides and dissected midguts, as well as tsetse abdominal content touch-blots were explored. the results of hybridization of radio-isotope-labelled species-specific dna probes to tsetse samples indicated that it was possible to d ...19873670893
the effect of trypanosoma congolense infection on the oestrous cycle of the goat. 19873676690
trypanosoma congolense: lack of correlation between the resistance of cattle subjected to experimental cyclic infection or to field challenge.twelve male cattle of the baoulé breed were exposed to natural trypanosome challenge in an area of high glossina density, to characterize them as trypanoresistant or trypanosensitive. weekly blood samples were taken for the determination of parasitemia and packed cell volume, as a measure of anemia. seven zebu cattle were also exposed to challenge at the same time. the zebu proved to be trypanosensitive with high parasitemia, pronounced anemia and died or were drug treated in extremis. five baou ...19873678447
pathobiochemical alterations in experimental chronic and acute trypanosomal infection in mice.during an experimental chronic infection of inbred mice with trypanosoma congolense several physiological parameters become altered. splenomegaly followed later by hepatomegaly are predominant. lactate dehydrogenase and aminotransferase activities of the plasma are elevated, the number of erythrocytes and thrombocytes decreases, whereas monocytic cells are detected in higher concentrations. gamma-globulins and transferrin become elevated. some of the pathobiochemical alterations depend directly ...19873694125
sheep trypanosomiasis in somalia. 19883354058
a model of tsetse-transmitted animal trypanosomiasis.the data needed to develop analytical models of trypanosomiasis transmission have become available only recently. by making some simplifying assumptions, models of the dynamics of the disease in vector, cattle and wild mammal populations can be constructed in order to determine criteria for successful disease control by mass and targetted chemotherapy, and by vector control. the heterogeneity in transmission due to tsetse fly feeding preferences and the variability of immunological characteristi ...19883362578
structure and transcription of the actin gene of trypanosoma brucei.in trypanosoma brucei, the actin gene is present in a cluster of two, three, or four tandemly linked copies, depending on the strain. each cluster seems to exist in two allelic versions, as suggested by the polymorphism of both gene number and restriction fragment length in the dna from cloned trypanosomes. the amplification of the gene copy number probably occurs through unequal sister chromatid exchange. the chromosomes harboring the actin genes belong to the large size class. the coding seque ...19883386635
effect of chronic experimental trypanosoma congolense infection on the ovaries, pituitary, thyroid and adrenal glands in female goats.changes in the ovaries, pituitary, thyroid and adrenal glands in small east african normally cycling female goats chronically infected with trypanosoma congolense are described. marked fibrosis of the ovaries, a decrease in the number of primordial and primary follicles and atresia of growing follicles at the tertiary stage resulting in lack of corpora lutea were observed. the pituitary glands revealed reduced degranulation of the basophils and slight hypertrophy of the acidophils. the thyroids ...19883387663
development of trypanosoma congolense, t vivax and t brucei in the skin reaction induced in goats by infected glossina morsitans centralis: a light and electron microscopical study.the development and distribution of trypanosoma congolense, t vivax and t brucei in the skin of goats was examined after the animals were bitten by infected glossina morsitans centralis. following the tsetse bite, the trypanosomes in the skin multiplied, reaching maximum numbers when the skin reaction (chancre) of the host attained its maximum size. in goats infected with t vivax and t brucei, trypanosomes were observed circulating in the blood before the peak of the chancre, while in t congolen ...19883387665
the role of lectins and trypanosome genotype in the maturation of midgut infections in glossina morsitans.feeding d + glucosamine to glossina morsitans throughout their life significantly reduced the proportions of midgut infections which developed into mature infections with three different stocks of trypanosoma congolense. in one stock of t. congolense, maturation was completely blocked by this carbohydrate, which is known to specifically inhibit tsetse midgut lectin activity. similar experiments with t. brucei showed that d + glucosamine also inhibited maturation and, when combined with results f ...19883387828
factors influencing the duration of isometamidium chloride (samorin) prophylaxis against experimental challenge with metacyclic forms of trypanosoma congolense.the duration of a single isometamidium chloride (samorin) prophylactic treatment against trypanosoma congolense ilnat. 3.1 and t. congolense il 285 was examined in 24 boran steers with regard to (1) the dose of drug, (2) the level of metacyclic challenge and (3) the influence of infection with an unrelated serodeme at the time of treatment. the cattle were repeatedly challenged at monthly intervals between 2 and 7 months following treatment, either by five infected glossina morsitans centralis o ...19883388736
depression of ovarian function and plasma progesterone and estradiol-17 beta in female goats chronically infected with trypanosoma congolense.adult normocyclic female goats experimentally infected with trypanosoma congolense developed irregular and shorter estrous cycles before complete cessation at the fourth cycle post-infection. this was followed within a month by a decline in the mean plasma progesterone and estradiol-17 beta levels. the peak luteal progesterone as well as pre-ovulatory estradiol-17 beta level declined progressively from the second to the fourth cycle post-infection. the ovaries became atretic with reduced numbers ...19883389040
immune responses of trypanoresistant and trypanosusceptible cattle after cyclic infection with trypanosoma congolense.to study the mechanisms by which certain west african taurine cattle are able to resist trypanosomiasis, the disease course and several immune parameters were examined in eleven baoulé and five zebu cattle after infection with tsetse-transmitted t. congolense (clone 1180 of stock serengeti/71/stib/212). all animals showed a similar onset of parasitemia but subsequently a continuum of disease was observed ranging from four baoulé which were mildly susceptible (controlled parasitemia by week 10 po ...19883394256
prevalence of trypanosomiasis in cattle in south-west zambia.a trypanosomiasis survey was conducted in south-west zambia. from a total of 3,346 cattle sampled 342 cattle showed a positive trypanosomiasis parasitaemia. during the survey trypanosome species and pcv values were also recorded. with simple statistical analysis populations with higher and lower prevalence rates were differentiated. the results indicated that the kwando river basin tsetse fly belt and the kafue river basin tsetse fly belt infested a larger area than originally assumed and that a ...19883400114
ro 15-0216: a nitroimidazole compound active in vitro against human and animal pathogenic african trypanosomes.in vitro systems for the continuous cultivation of trypanosoma brucei brucei, t. b. gambiense, t. b. rhodesiense, t. congolense and t. vivax were used to determine the antitrypanosomal activity of the 2-substituted nitroimidazole ro 15-0216. for all trypanosome species, the concentration which inhibited parasite growth by 50% (ic50 value) was established: 0.0957 microgram ml-1 (t. b. brucei tc221), 0.1327 microgram ml-1 (t. b. gambiense stib 754-a), 0.0450 microgram ml-1 (t. b. rhodesiense stib ...19883401068
genetically discrete populations of trypanosoma congolense from livestock on the kenyan coast.twenty-seven stocks of nannomonas trypanosomes isolated from livestock in 1982 on a ranch at kilifi on the kenyan coast were characterized by isoenzyme electrophoresis and by the abilities of the parasite's dna to hybridize to two repetitive sequence dna probes. all the kilifi stocks which were examined had isoenzyme patterns which were markedly different from the 75 patterns previously described from 78 stocks of trypanosoma congolense. on average only 15% of the enzyme bands present in the kil ...19883405633
trypanosoma congolense: the distribution of enzymic variants in east and west africa.a total of 114 stocks of trypanosoma congolense originating from kenya, uganda, tanzania, zambia and sudan, but including, for comparison, stocks from the gambia, liberia, ivory coast, nigeria and cameroun, were compared by isoenzyme electrophoresis for 6 enzymes. the zymodemes were grouped, both from a dendrogram and using a cladistic method, after calculating the dissimilarity, or distance, between profiles. previous observations are broadly confirmed, the zymodemes clustering separately accor ...19883405634
the requirement for epimastigote attachment during division and metacyclogenesis in trypanosoma congolense.in cultures of tsetse proboscis stages during the development of trypanosoma congolense, attached epimastigote forms multiply and give rise to free nondividing metacyclic trypanosomes. prevention of attachment by shaking the cultures or by providing a polypropylene substratum does not inhibit epimastigote division but does prevent the differentiation of metacyclics. we conclude that epimastigote attachment forms a necessary part of the program of metacyclic development.19883413039
trypanosome-induced depression of plasma thyroxine. levels in prepubertal and adult female goats.changes in plasma t4 levels were investigated in prepubertal and adult female goats during the course of an experimental trypanosoma congolense infection. a significant decline in the t4 levels was observed within 1 week of trypanosome challenge. the levels remained low up to the end of the 7th weeks when prepubertal goats received a trypanocidal treatment, whereafter the values started to rise to normal pre-infection values. the post-infection plasma t4 values in the untreated adult goats did n ...19883414317
comparative study on the infection rates of different laboratory strains of glossina species by trypanosoma congolense.teneral glossina morsitans centralis machado, g.austeni newstead, g.palpalis palpalis robineau-desvoidy, g.p.gambiensis vanderplank, g.fuscipes fuscipes newstead, g.tachinoides westwood and g.brevipalpis newstead, from laboratory-bred colonies, were fed at the same time on the flanks of ten goats infected with trypanosoma congolense broden isolated in tanzania or in nigeria. the seven tsetse species were infected over the range 0.3-49.2%. survival of both t.congolense isolates was best in g.m.ce ...19882980181
trypanothione reductase of trypanosoma congolense: gene isolation, primary sequence determination, and comparison to glutathione reductase.the gene encoding trypanothione reductase, the redox disulfide-containing flavoenzyme that is unique to the parasitic trypanosomatids (shames et al., 1986), has been isolated from the cattle pathogen trypanosoma congolense. library screening was carried out with inosine-containing oligonucleotide probes encoding sequences determined from two active site peptides isolated from the purified crithidia fasciculata enzyme. the nucleotide sequence of the gene was determined according to the dideoxy ch ...19883167026
the effects of trypanosoma congolense infection on the oestrous cycle of the boran cow. 19883167553
the effect of trypanosoma vivax and trypanosoma congolense infections on the reaction time and semen characteristics in the zebu bull. 19883167554
formation of filopodia in trypanosoma congolense by crosslinking the variant surface antigen.trypanosoma congolense was exposed to various substances binding to the variant surface antigen (vsg). all methods of crosslinking vsg molecules caused the rapid accumulation of ligands along the line of flagellar attachment and their shedding by formation of coat-covered vesicles and filopodia. this phenomenon was observed after treatment of the parasites with concanavalin a (con a), anti-vsg-igg plus protein a-gold, attachment of the cells to surfaces coated with poly-l-lysine and con a and to ...19883171247
endocytosis and intracellular occurrence of the variant surface glycoprotein in trypanosoma congolense.trypanosoma congolense bloodstream forms were examined for binding sites of polyclonal anti-variant surface glycoprotein (vsg) antibodies using immunoelectron microscopy. besides the surface, the antibodies labeled intracellular vesicles, the tubular membrane system, secondary lysosomes, and the digestive vacuole. protein a gold (pag), peroxidase gold (pog), anti-vsg antibodies preincubated with pag, ferritin, concanavalin a-ferritin, and microperoxidase were examined for their suitability as en ...19883171248
the chromosome profiles of trypanosoma congolense isolates from kilifi, kenya and their relationship to serodeme identity.chromosomal dna from 117 trypanosoma congolense clones from 54 stocks, isolated from cattle introduced onto a ranch in kilifi in the coastal area of kenya, was fractionated by the orthogonal field alternation gel electrophoresis technique. the technique resolved chromosomes in the size range of 100 kb-1 mb. the chromosome profile for cloned trypanosome populations was relatively stable with regard to number and size of the chromosome bands following transmission in mice, cattle, goats or tsetse ...19883173429
species-specific dna probes for the identification of african trypanosomes in tsetse flies.we have obtained 5 specific dna probes for african trypanosomes of the subgenera trypanozoon and nannomonas. each probe consists of one repeat unit of the major repetitive dna (satellite dna) of each species or intra-specific group. one probe hybridized with all members of subgenus trypanozoon (except t. equiperdum which was not tested). in subgenus nannomonas, one probe recognized t. simiae, but 3 probes were needed to identify all stocks of t. congolense available. each of the 3 latter probes ...19883174239
[localization of trypanosoma (nannomonas) congolense broden, 1904 (kinetoplastida, trypanosomatidae) in the proboscis of glossina morsitans morsitans westwood, 1850 (diptera, glossinidae)].transverse sections of the proboscis of g. m. morsitans infected with t. (n.) congolense initiated after a single infective blood meal were studied. trypanosomes were located in the lateral, dorso-ventral and latero-ventral regions of the food canal. parasites were also found around the whole of the circumference of the canal. such localizations influence the transmission of trypanosomes and the epidemiology of trypanosomiasis.19883190120
[trypanosoma (nannomonas) congolese broden, 1904 (kinetoplastida, trypanosomatidae) in epithelial cells of the anterior segment of the midgut of glossina morsitans morsitans westwood, 1850 (diptera, glossinidae)]. 19883217562
pyrethroid impregnated ear tags in trypanosomiasis control. 19883238775
some concepts of the interaction of trypanosoma (nannomonas) congolense and glossina pallidipes.light and electron microscope investigations were carried out on the infection with trypanosoma (nannomonas) congolense of laboratory-reared tsetse flies glossina pallidipes. trypanosomes became entombed in the peritrophic membrane (pm) to form intraperitrophic cavities which were more electron-translucent than the amorphous layer of the pm. a hypothesis is suggested that after migration anteriorly in the ectoperitrophic space, the trypanosomes become enmeshed in the pm during its formation in t ...19883250337
drug resistance in recent isolates of trypanosoma brucei and trypanosoma congolense. 19883253857
quantitative correlation of parasitological and serological techniques for the diagnosis of trypanosoma congolense infection in cattle.a comparison was made between serological and parasitological techniques for the diagnosis of bovine trypanosomiasis in zambia. overall sero-prevalence rates as determined by ifat and elisa were respectively 2.7-fold and 2.9-fold greater then the percentage of samples found positive with the dark ground/phase contrast buffy coat technique (dg). the results obtained by the two serological techniques were found to be closely correlated (94.2%) agreement) and titres obtained by elisa tended to be s ...19883287755
selection for drug resistance in trypanosoma congolense during cyclic transmissions through glossina morsitans morsitans and drug treated rabbits.a drug-sensitive trypanosoma congolense (il 1180 strain), with a known cd50 and cd90 (doses required to cure 50 and 90% of the infected animals) was cyclically passaged through tsetse flies. the infected flies were then fed on rabbits which received weekly prophylactic treatment of samorin. it was observed that the infections arising from flies maintained for over 60 days on drug-treated rabbits required higher curative doses to achieve a 50 and 90% cure. the results of this work suggest that a ...19882896442
nuclear dna content of trypanosoma congolense.we have measured the nuclear dna content of the major life cycle stages of trypanosoma congolense, in two clones of geographically distant origin. we find that nuclear dna content in epimastigote, mammalian blood-stream and metacyclic forms is constant and that the nuclear dna contents of the two clones were 0.1 pg and 0.09 pg, respectively.19882896443
assessment of sensitivity of trypanosoma congolense to isometamidium chloride: a comparison of tests using cattle and mice.the sensitivities of 3 strains of trypanosoma congolense to isometamidium chloride (samorin) were determined in mice and cattle, with the objective of evaluating sensitivity testing in mice as a means of predicting curative doses in cattle. comparison of mouse effective dose 80% (ed80) or curative dose 80% (cd80) values with cattle minimum curative dose (mcd) values demonstrated a wide variation between trypanosome strains. although a mouse test may give a broad indication of the sensitivity of ...19882901202
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