Publications

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in vitro studies on the biosynthesis of the surface glycoprotein of trypanosoma congolense.tritiated leucine, glucosamine, mannose, and galactose were incorporated into the variant specific surface glycoprotein (vsg) of trypanosoma congolense in vitro. the uptake of the precursors is shown by sds-polyacrylamide electrophoresis and fluorography, by assay of the radioactivity in immunoprecipitates obtained with specific antisera, and by the isolation of the labeled antigens by affinity chromatography on concanavalin a-sepharose and isoelectric focusing. the in vitro labeled vsg exhibits ...19846470988
continuous cultivation of animal-infective bloodstream forms of an east african trypanosoma congolense stock. 19846486939
studies on the influence of non-steroidal anti-inflammatory drugs upon trypanosomiasis in goats and sheep.the non-steroidal anti-inflammatory drug (nsaid) flurbiprofen caused a rise in parasitaemia in goats infected with trypanosoma vivax, trypanosoma congolense and trypanosoma brucei. all trypanosome-infected goats treated with flurbiprofen showed many dividing trypanosomes. this also included the short-stumpy forms of t. brucei. in t. vivax-infected goats flurbiprofen treatment resulted in 100% mortality in the acute and chronic stages of the infection. the increase in parasitaemia of t. brucei in ...19846512919
a special case of trypanosoma congolense infection produced in laboratory mice. 19846527201
detection of circulating trypanosomal antigens by enzyme immunoassay.antisera raised against trypanosoma evansi and t. congolense were used in a double antibody sandwich enzyme immunosorbent assay (elisa) to detect trypanosomal antigens in sera from experimentally infected rabbits and goats. assays quantitated using reference antigen preparations and the homologous antisera showed that antigens could be detected at protein concentrations of 1.5 microgram ml-1. the antisera also cross-reacted with soluble antigens prepared from t. brucei and t. vivax at similar pr ...19846532328
sequences homologous to variant antigen mrna spliced leader in trypanosomatidae which do not undergo antigenic variation.trypanosomes which parasitize mammals have evolved mechanisms to evade immune attack, such as the occupation of 'safe' intracellular sites (for example, trypanosoma cruzi), or antigenic variation, exemplified by the salivarian trypanosomes (for example, trypanosoma brucei). antigenic variation is mediated by sequential expression of single variant surface glycoprotein (vsg) genes, and often involves transposition of the active gene. every vsg transcript examined shares the same 5' terminal 35-nu ...19846709074
the role of antibody and complement in the cellular response to trypanosoma congolense.the in vitro cytotoxic response of bovine granulocytes and monocytes and of murine peritoneal macrophages against trypanosoma congolense in the presence of antibody, antibody plus complement or complement alone was assessed using luminol aided chemiluminescence as a second parameter for effector cell activation. neither cell type exhibited any trypanolysis exceeding that of antibodies and complement alone. the kinetics of the chemiluminescence response in the course of these reactions closely co ...19846713731
growth of trypanosoma brucei gambiense, t. b. rhodesiense, and t. congolense in bone marrow cultures of genetically anemic sl/sld mice. 19846737165
glycosyltransferase activities in golgi complex and endoplasmic reticulum fractions isolated from african trypanosomes.highly enriched golgi complex and endoplasmic reticulum fractions were isolated from total microsomes obtained from trypanosoma brucei, trypanosoma congolense, and trypanosoma vivax, and tested for glycosyltransferase activity. purity of the fractions was assessed by electron microscopy as well as by biochemical analysis. the relative distribution of all the glycosyltransferases was remarkably similar for the three species of african trypanosomes studied. the golgi complex fraction contained mos ...19846746739
structural studies on the major oligosaccharides in a variant surface glycoprotein of trypanosoma congolense.the carbohydrate moieties in the four isotypes of a variant surface glycoprotein from trypanosoma congolense were analyzed. all variant surface glycoprotein isotypes were found to contain up to 15% by weight of d-galactose, d-mannose, and n-acetyl-d-glucosamine in molar ratios approaching 1:3.2:3.9 (isotypes i-iii) or 1:2.4:2.4 (isotype iv); in addition, the presence of sialic acid could be demonstrated. after metabolic labelling with d-[6-3h]glucosamine, the four isoglycoproteins were successiv ...19846749184
immune mechanisms in c57b1 mice genetically resistant to trypanosoma congolense infection. ii. aspects of the humoral response.some aspects of the humoral response in trypanotolerant c57b1 mice and susceptible a/j mice were investigated to determine the possible basis of trypanotolerance. when the hepatic uptake of 75se-labelled t. congolense by infected mice was measured as an index of antibody production, it was found that only c57b1 mice could remove circulating labelled parasites, this ability persisting for several weeks after infection. estimation of the immunoglobulin concentrations in both strains of mice showed ...19836657296
enzyme polymorphism and the distribution of trypanosoma congolense isolates.conditions were established for demonstrating, by electrophoresis, polymorphism in 12 soluble enzymes from trypanosoma congolense. three enzymes had identical mobilities in every stock, variation occurring among the remaining nine. enzyme profiles were determined in 78 stocks collected from various hosts in a number of african countries, and were used by the computer to establish relationships within the collection. the major groupings formed solely from the isoenzymes corresponded remarkably cl ...19836660953
specific antibody responses to the variable surface glycoproteins of trypanosoma congolense in infected cattle.sera from cattle infected with three trypanosoma congolense clones (ilnat 2.1, ilnat 3.1 and ilrad 588) derived from different stocks were analysed for the presence of specific antibodies against the surface glycoproteins (vsgs) of the infecting trypanosomes using the solid and liquid-phase radioimmunoassays and the neutralization of infectivity test. high levels of igm, igg1 and igg2 antibodies against the vsgs of the infecting variable antigen types (vats) as well as other vats that arose duri ...19836622055
alternative pathway activation of complement by african trypanosomes lacking a glycoprotein coat.an in vitro culture trypanosoma congolense cell line was established using the mammalian cell feeder layer system. one of the principle characteristics of this parasite was its ability to multiply in culture at 35 degrees c, as an uncoated trypanosome (lacking a glycoprotein surface coat) unlike the original blood stream form from which it was derived. this trypanosome was lysed when incubated in normal human serum in contrast to the parasite which possessed a surface coat. the lytic reaction as ...19836634218
observation on drug resistance of trypanosoma (nannomonas) congolense and trypanosoma (duttonella) vivax in cattle at a feedlot in the northern ivory coast.studies carried out on feedlot cattle show berenil at 7 mg/kg to be the treatment of choice in trypanosomiasis although repeated doses may be necessary. resistant strains of trypanosoma (duttonella) vivax and trypanosomas (nannomonas) congolense survived dosages of between 0.5 mg/kg and 1.0 mg/kg of trypamidium and were cross resistant to homidium bromide.19836636303
studies in rabbits on the disposition and trypanocidal activity of the anti-trypanosomal drug, diminazene aceturate (berenil).after intramuscular injection of 3.5 mg kg-1 to rabbits, diminazene aceturate shows biphasic pharmacokinetics with maximum blood and interstitial fluid concentrations occurring after 15 min and 3 h respectively. seven days after treatment, 40-50% of the dose had been excreted in the urine and 8-20% in faeces. highest diminazene residues were determined in liver: 7 days after dosage, residues of 40.53 +/- 4.00 micrograms g-1 were present, corresponding to 35-50% of the dose. the recommended dose ...19836652366
natural agglutinins to african trypanosomes.agglutinins to uncoated culture forms of the african trypanosomes, t. congolense and t.b. brucei were detected in sera from a variety of mammals not exposed to the parasites. the agglutinins in bovine serum were shown to be specific antibodies with opsonic properties selective for the species of trypanosome. these findings suggest a possible role for the glycoprotein coat in preventing access of cross-reacting antibodies to the plasma membrane of african trypanosomes.19836657292
interference with anti-trypanosome immune responses in rabbits infected with cyclically-transmitted trypanosoma congolense.rabbits were infected with two clones of antigenically distinct stocks of trypanosoma congolense transmitted through glossina morsitans. local skin reaction development and the appearance of neutralizing antibodies were followed in animals infected with one or other of the trypanosome stocks, with both stocks simultaneously or with both stocks consecutively. there was little difference in local skin reaction development on rabbits infected with a single stock or with both stocks simultaneously b ...19836657293
rat liver glucose-6-phosphate dehydrogenase isozymes: influence of infection with trypanosoma.glucose-6-phosphate dehydrogenase (g6pd) changes were studied in livers of rats inoculated with trypanosoma lewisi, trypanosoma rhodesiense, trypanosoma congolense and trypanosoma brucei. marked increases in g6pd were directly related to the degree of parasitemia. no essential differences in g6pd levels were seen in animals inoculated with physiological saline when compared with uninoculated controls. elevation of g6pd was observed only from day 10 to 20 in rats inoculated with t. lewisi. after ...19836349921
antibody levels during bovine hemoparasitic diseases: trypanosomiasis, anaplasmosis, and babesiosis. 19836399967
immune depression in bovine trypanosomiasis: effects of acute and chronic trypanosoma congolense and chronic trypanosoma vivax infections on antibody response to brucella abortus vaccine.cattle were vaccinated with brucella abortus (s19) vaccine during acute (25 days) and chronic (25 weeks) trypanosoma congolense and chronic trypanosoma vivax (25 weeks) infections in order to determine the effect of such infections on the antibody response to the vaccine. it was found that the specific antibody responses of igg1 and igg2 sub-classes were profoundly depressed (80%) in both the acute and chronic infections with t. congolense. whereas igm antibody response was also profoundly depre ...19836408588
a quantification of the risk of trypanosomiasis infection to cattle on the south kenya coast.the number of trypanosome-infected bites received by cattle grazed around an 8 ha area of forest harbouring a semi-isolated population of glossina pallidipes austen was estimated. the absolute size of the tsetse population was determined by mark-release-recapture techniques, the tsetse host range by the identification of blood-meals, and trypanosome infection rates by dissection of samples of tsetse. feeding frequency was estimated and the number of cattle present was known. it was estimated tha ...19836142631
reverse transcription of trypanosome variable antigen mrnas initiated by a specific oligonucleotide primer.african trypanosomes change their antigenicity by successively expressing different members of a group of related but highly diverse proteins, the variant surface glycoproteins (vsgs). we describe a synthetic oligonucleotide that can prime specifically reverse transcription of vsg mrna out of total trypanosome poly(a)+ rna. the specificity of this priming was verified by cdna sequence analysis of the transcription products and by the demonstration of variant-specific hybridization of the individ ...19836188156
all metacyclic variable antigen types of trypanosoma congolense identified using monoclonal antibodies.vaccination against the tsetse-borne trypanosomiases has proved impossible because of the trypanosome's ability to generate a seemingly inexhaustible number of variable antigen types in the blood or tissues of the host. each variable antigen is a glycoprotein which forms a surface coat on the trypanosome and each glycoprotein is the product of a single gene. the full repertoire of such antigens has not been identified for any trypanosome serodeme (genotype) as yet, but the number of genes coding ...19836196642
increase in jugular circulation of trypanosoma congolense in infected calves caused by effective trypanocides. 19836681919
effect of trypanocides on jugular concentration of trypanosoma congolense in the west african dwarf sheep.the effects of various trypanocides on parasitaemia was investigated in sheep experimentally-infected with trypanosoma congolense strain 58/98. intravenous injection of berenil at the height of the first parasitaemic wave increased jugular parasite concentration by 12 and 16 times at the 9th and 20th minute post-treatment, respectively. with pentamidine, maximum counts were 5.0-8.6 times zero-time concentration during the same periods. peak effects of samorin, novidium and ethidium were observed ...19836686383
improved field diagnostic technique for trypanosomiasis by use of a minicentrifuge. 19836356572
comparative aspects of purine metabolism in some african trypanosomes.some enzymes of purine salvage were detected in the cell-free preparations from bloodstream forms of african trypanosomes: trypanosoma vivax; t. brucei and t. congolense. extracts of trypanosomes cleave adenosine and inosine hydrolytically except in t. congolense where adenosine cleavage was mediated by a phosphorylase. all the trypanosomes apparently lacked adenosine deaminase. adenine aminohydrolase was found only in t. vivax while adenosine monophosphate deaminase was detected in t. brucei an ...19836419098
trypanosoma congolense: susceptibility of cattle to cyclical challenge.cattle primed by cyclical infection with glossina morsitans morsitans infected with cloned derivatives of trypanosoma congolense and treated with the trypanocidal drug berenil after 3 or 4 weeks were immune to cyclical challenge with homologous clones 3 to 5 weeks later. in these animals, localized skin reactions (chancres) and parasitemia did not develop. the same results were obtained in cattle given a homologous superinfection without prior treatment. on the other hand, cattle subjected to a ...19836133773
a simple classification of different types of trypanosomiasis occurring in four camel herds in selected areas of kenya.camels from herds in four different areas of kenya were sampled at regular intervals over periods of 9-15 months and examined for the presence of trypanosomiasis. five hundred and eight camels divided into three age categories were studied. trypanosomiasis caused by t. evansi, t. brucei and t. congolense was shown to be present in varying degrees in all the herds. camels were divided into 5 types according to mortality, the presence or absence of circulating trypanosomes and antibody, and the pr ...19836141655
immune mechanisms in c57bl mice genetically resistant to trypanosoma congolense infection. i. effects of immune modulation.the effect of immune modulation on the pattern and course of infection with t. congolense was investigated in a strain of mice (c57bl) which is known to possess a significant degree of trypanotolerance, and a susceptible strain (cflp) which rapidly succumbs to infection. immunosuppression of c57bl mice by splenectomy, cyclophosphamide treatment or gamma irradiation reduced their survival to near that of susceptible strains of mice. in contrast, attempts to enhance the immune response of suscepti ...19836828326
the susceptibility of gamma-irradiated glossina palpalis palpalis at different ages to infection with trypanosoma congolense. 19836859970
the effect of trypanosoma congolense infection on acquired immunity to the tick rhipicephalus appendiculatus. 19836882069
congenital transmission of trypanosoma congolense in mice.pregnant mice were infected with a strain of t. congolense which produces a chronic infection, to determine if congenital infection can occur. some of the mice were killed before delivery and tissues of foetuses injected into clean male mice. other mothers were allowed to deliver and the tissues of some of the 1-day-old young inoculated into male mice while the remaining members of each litter were suckled by the infected mother until weaning. some but not all males infected from foetuses and 1- ...19836886090
infection, immunity and the development of local skin reactions in rabbits infected with cyclically-transmitted stocks of trypanosoma congolense.the development of local skin reactions following bites by tsetse flies (glossina morsitans) infected with trypanosoma congolense was observed in normal rabbits, in rabbits with concurrent infections with t. congolense and in rabbits challenged after immunization by infection and treatment. local reactions developed in normal rabbits within seven days of fly bite and were resolved by approximately 19 days after infection. in rabbits with concurrent infections no typical local reactions developed ...19836660964
trypanosoma congolense: surface glycoproteins of two early bloodstream variants. iii. immunochemical characterization. 19827056338
immune depression in african trypanosomiasis: the role of antigenic competition.the capacity of trypanosome-infected cattle to mount an immune response to a simultaneous or subsequent challenge with other trypanosomes was investigated using various clones of trypanosoma congolense and t. brucei. in animals infected simultaneously with equal numbers of trypanosomes of two different clones, the variant-specific antibody response to one clone was severely depressed while the response to the other was not affected. in cattle infected with one clone and then subsequently challen ...19827075022
inheritance of susceptibility to trypanosoma congolense infection in glossina morsitans. 19827092373
trypanosoma congolense: thrombocyte survival in infected steers. 19827095072
partial protection of rats against trypanosoma congolense by passive transfer of igm. 19826891856
curative effect of alpha-difluoromethylornithine on fatal trypanosoma congolense infection in mice.the curative effect of alpha-difluoromethylornithine (dfmo) on fatal t. congolense infection in mice was investigated using various concentrations administered orally in drinking water. permanent cure was achieved in mice receiving 4% for 3 days or 2% for 5 days. mice receiving less became parasitemic again but then, without any further treatment, resisted death due to trypanosomes for an average of 34.5 days, while untreated controls were dead within 8 days after trypanosomes were first seen in ...19826814025
the susceptibility of glossina palpalis palpalis at different ages to infection with trypanosoma congolense. 19827103580
cultivation of procyclic trypomastigotes of trypanosoma congolense in a semi-defined medium with direct adaptation from bloodstream forms.bloodstream forms of trypanosoma congolense added to the semi-defined medium 109-c (minimum essential medium with earle's salts, 60 mm hepes, haemin, and heat-inactivated fbs) and incubated at 28 degrees c transformed into procyclic trypomastigotes. established cultures of the procyclic forms yielded up to 4.5 x 10(7) parasites/ml. the cultivated populations consisted only of trypomastigotes and were not infective for mice. the amino acids consumed to the greatest extent were glutamine, proline, ...19827113354
ethidium bromide: pharmacokinetics and efficacy against trypanosme infections in rabbits and calves.[14c]ethidium bromide has been used to determine drug levels in tissues and body fluids of rabbits and calves following intramuscular injection. uninfected and trypanosoma brucei- or trypanosoma congolense-infected animals were studied. blood and tissue fluid level reached a maximum with 1 h and then fell rapidly; after 96 h 80-90% of the radioactivity injected had been excreted, approximately one third in urine and two thirds in faeces. by 1 h after injection of 1 mg [14c]ethidium/kg into a t. ...19827122121
in vitro phagocytic activity of neutrophils of various cattle breeds with and without trypanosoma congolense infection.a simple in vitro-technique using latex beads was used for the investigation of the phagocytic activity of neutrophils in bovines of different breeds, infected and non-infected with t. congolense. it was found that the n'dama, assumed to be trypanotolerant, have a significantly higher number of neutrophils and neutrophils with phagocytic activity per mm3 blood, compared to the more susceptible zebu, the baoulé and the crossbreed m75, ranging between these two breeds. the first appearance of t. c ...19827135473
cytotoxic effect of unilamellar detergent dialysis liposomes on trypanosoma brucei and trypanosoma congolense bloodstream forms in vitro. 19827138525
purification of trypanosoma brucei variable surface glycoproteins: analysis of degradation occurring during isolation.trypanosoma brucei variable surface glycoproteins (vsgs), isolated from some antigenic types of trypanosomes, degraded during isolation. we show that this degradation occurred immediately after breakage of the organism, presumably because of liberation of internal enzymes, and resulted in heterogeneity of isolated vsgs with respect to charge and/or molecular weight. degradation and consequent heterogeneity of these vsgs could be abolished by releasing vsg from the trypanosome surface without bre ...19827177702
a comparative evaluation of the parasitological techniques currently available for the diagnosis of african trypanosomiasis in cattle.the parasitological techniques currently in use for the diagnosis of african trypanosomiasis were compared in a series of experiments for their capacity to detect trypanosoma congolense, t. vivax and t. brucei in the blood of cattle. the darkground/phase contrast buffy coat method proved to be more sensitive than the haematocrit centrifugation technique, thick, thin and wet blood films in detecting t. congolense and t. vivax. on the other hand with t. brucei, mouse inoculation was the most sensi ...19826131590
immunosuppression in bovine trypanosomiasis: response of cattle infected with trypanosoma congolense to foot-and-mouth disease vaccination and subsequent live virus challenge.the primary and secondary antibody responses to foot-and-mouth disease virus vaccine were examined in cattle infected with trypanosoma congolense and the response of some of these animals to live foot-and-mouth disease virus challenge was assessed. infected groups of cattle had rather lower antibody responses than uninfected control cattle after primary vaccination but the antibody titres were not significantly depressed until after secondary vaccination. these levels remained depressed for the ...19826285433
study on a proteolytic enzyme from trypanosoma congolense. purification and some biochemical properties.a protease has been purified from trypanosoma congolense bloodstream forms by osmotic disruption, freeze-thawing of the cells, followed by chromatography using thiopropyl-sepharose and gel filtration. the enzyme is a thiolprotease. a combination of sds-polyacrylamide gel electrophoresis and contact print zymograms using casein as substrate showed a single proteolytic band with a molecular weight of 31 000. the isoelectric point of the enzyme as ascertained by isoelectric focusing extended from p ...19826755218
the effect of double infections with trypanosomes and gastrointestinal nematodes on the productivity of sheep and goats in south mozambique.the effect of simultaneous infections with trypanosomes (trypanosoma vivax and trypanosoma congolense) and gastrointestinal nematodes on the productivity of sheep and goats was studied in 20 animals (6 male goats and 14 male sheep) at a farm near maputo. the animals were divided into 4 groups which received either treatment against gastrointestinal nematodes, or against trypanosomes, or treatment against both, or no treatment at all. in two-weekly and later in weekly intervals body weight, packe ...19826892177
interference in the establishment of superinfections with trypanosoma congolense in cattle.to examine the influence of an established infection on subsequent challenge with another unrelated trypanosome serodeme, cattle were subjected to two challenges, 5 to 6 wk apart, with unrelated isolates of trypanosoma congolense. the primary infection inhibited the establishment of the second infection despite the initial absence of detectable antibody to the trypanosomes used for the second challenge. this was true whether the second challenge consisted of bloodstream forms of the parasite or ...19827131183
early events following challenge of cattle with tsetse infected with trypanosoma congolense: development of the local skin reaction.a local skin reaction (chancre) was elicited in susceptible cattle after the successful feeding of glossina morsitans morsitans infected with one of two different cloned isolates of trypanosoma congolense. the chancre first appeared as a small 2 to 3 mm nodule at the site of the challenge as early as day 5 and reached maximum activity by days 10 to 13 when it had developed into a raised, indurated, hot, painful swelling measuring up to 100 mm in diameter. thereafter it declined in size and activ ...19827072104
activation of the alternative pathway of bovine complement by trypanosoma congolense.homogenates of trypanosoma congolense and particulate and supernatant fractions thereof were, by two different techniques, shown to activate bovine complement via the alternative pathway. (1) all three preparations converted complement factor bbov to its split product b gamma 2 as demonstrated (a) qualitatively by immunoelectrophoresis and (b) quantitatively by radial immunodiffusion. (2) lysis of guinea-pig erythrocytes by bovine complement via the alternative pathway was inhibited by whole hom ...19827145463
the response of the murine lymphoid system to a chronic infection with trypanosoma congolense. ii. the lymph nodes, thymus and liver. 19826752363
the susceptibility of young sheep and goats to an experimental trypanosoma congolense infection. 19817296022
development of local skin reactions in rabbits infected with metacyclic forms of trypanosoma congolense cultured in vitro. 19817316583
immunodepression in trypanosome-infected mice. vi. comparison of immune responses of different lymphoid organs.mitogen stimulation of cells from various lymphoid organs of c3h/he mice chronically infected with an isolate of trypanosoma congolense was studied at different time intervals after infection, using concanavalin a (con a) and lipopolysaccharide (lps). at the same time, changes in the percentages of t, b and null lymphocytes in these organs were determined by immunofluorescence staining. the responses of t and b lymphocytes in the spleen were totally depressed, and the cellular composition was dr ...19816452282
antiparasitic structure-activity relationships of congocidine derivatives.several congocidine analogs were synthesized and tested for in vivo activity against trypanosoma congolense and in vitro activity against amastigotes of leishmania tropica. the tripyrrole derivative, beta-([n-methyl-4-[n-methyl-4-(guanidinoacetamido)pyrrole-2-carboxamido]pyrrole -2-carboxamido]pyrrole-2-carboxamido)butyroamidine dihydrochloride, was less toxic and more active than congocidine. the guanidinoacetyl moiety appears to be a structural requirement for antiparasitic activity in the con ...19816267245
antigenic variation and the surface glycoproteins of trypanosoma congolense.two trypanosoma congolense variant-specific glycoproteins, which are expressed sequentially during a relapsing infection, have been purified. the proteins, termed vsg-1 and vsg-2, both have a molecular weight of 53,000 as determined by sds polyacrylamide electrophoresis. when either antigen is electrophoresed through a ph gradient on an isoelectric focusing (ief) gel, it gives a characteristic spectrotype of three bands. the ief components of each vsg are antigenically similar to each other but ...19816163660
trypanosoma congolense: surface glycoproteins of two early bloodstream variants. i. production of a relapsing infection in rodents. 19816168484
cultivation of infective forms of trypanosoma congolense from trypanosomes in the proboscis of glossina morsitans.two stocks of trypanosoma congolense were established in culture at 28 degrees c using trypanosomes from the proboscides of infective glossina morsitans. successful primary cultures were initiated by placing an infected tsetse proboscis beside a bovine dermal collagen explant in eagle's minimum essential medium supplemented with foetal calf serum. the trypanosomes multiplied rapidly in the medium and also gradually formed an adherent layer o the plastic surface of the culture vessel. three prima ...19817208105
purification of the variant antigens of trypanosoma congolense: a new approach to the isolation of glycoproteins.we describe a new and rapid method for the isolation and purification of the variant antigens of trypanosoma congolense. the procedure consists of (a) partial lysis of trypanosomes with dioxane, (b) lectin-affinity-chromatography with con a-sepharose, (c) electrophoretic desorption and concomitant separation of con a-sepharose-bound glycoproteins in a granulated electrofocusing gel, (d) electrophoretic elution of focused proteins from the granulated gel particles. the efficiency of each step was ...19817236702
[effect of bovine sera on infectivity and pathogenicity of trypanosoma congolense in mice]. 19817247921
sialic acids are responsible for charge heterogeneity of the variant surface glycoprotein of trypanosoma congolense.intact living cells of trypanosoma congolense can be labeled by periodate/borotritide. the procedure described introduces a radioactive label nearly exclusively into the variant surface glycoprotein (vsg). the label can be removed from the vsg by either neuraminidase treatment or by mild acid hydrolysis. using thin-layer chromatography the labeled compounds comigrated with 5-acetamido [or 5-glycolamide]3,5-dideoxygalactooctulosonic acid and 5-acetamido [or 5-glycolamide]3,5-dideoxyarabinoheptulo ...19817329438
the interaction of trypanosoma congolense and haemonchus contortus infections in 2 breeds of goat. 1. parasitology. 19817343578
the interaction of trypanosoma congolense and haemonchus contortus infections in 2 breeds of goat. 2. haematology. 19817343579
response of the murine lymphoid system to a chronic infection with trypanosoma congolense. i. the spleen.the response within the different cellular compartments of the spleen in mice infected with trypanosoma congolense was evaluated using histologic and cytologic methods and immunofluorescence to detect intracellular and cell surface immunoglobulin. the isolate of t. congolense used produces a chronic infection in c3h/he mice leading to death 40 to 70 days after inoculation. previous studies had shown that this infection resulted in a marked immunodepression as judged by a range of in vitro assays ...19817033658
experimental bovine trypanosomiasis (trypanosoma congolense). lack of relation of the level of parasitemia to the j blood group.twenty-five holstein-friesian steers were experimentally infected with trypanosoma congolense eatro 1721. they were tested for their j blood group status. twelve steers were found to belong to ja blood group and thirteen steers were either js or jcs. the level of parasitemia did not significantly differ between these two groups of cattle. it was concluded that the level of parasitemia is not influenced by j blood group antigens.19817256834
trypanosoma congolense: natural and acquired resistance in the bovine. 19817274369
the in vitro response to mitogens of leucocytes from cattle infected with trypanosoma congolense.the in vitro proliferative response of bovine leucocytes from peripheral blood to lps, pwm and con a was monitored during the course of infection with t. congolense. the stimulatory effect of lps and pwm on pbl was significantly decreased in infected cattle while the reduction of stimulatory response to con a was less marked. there was a high background proliferation of unstimulated leucocytes from infected cattle. this increase in background counts correlated with the parasitaemia in that both ...19817285394
trypanosoma congolense: surface glycoproteins of two early bloodstream variants. ii. purification and partial chemical characterization. 19817318988
trypanosomiasis in zebu cattle. reappearance of trypanosoma congolense in brain tissue after treatment with berenil. 19817335941
inhibition of leukopoiesis by sera from trypanosoma congolense infected calves: partial characterization of the inhibitory factor.sera collected from calves infected with trypanosoma congolense inhibited bovine granulocyte/macrophage colony formation in vitro, but not erythroid colony formation. the inhibitor was found to be tca precipitable in nature and on sephadex g-200 chromatography, it was found to elute with the second major peak. sonicated t. brucei, t. congolense, and t. theileri added directly into the cultures had no effect on granulocyte/macrophage colony formation, but induced significant enhancement of erythr ...19807414680
the effects of trypanosoma congolense infection on the testis and epididymis of the goat. 19807437534
uptake of purine bases and nucleosides in african trypanosomes.uptake of radioactivity labelled purine bases and nucleosides by suspensions of trypanosoma brucei and trypanosoma congolense in bicine buffer was determined at 37 degrees c. with t. brucei, the rate of uptake of adenosine was much greater than that of the other compounds tested, the uptake of which decreased in the order adenine, inosine, guanosine and hypoxanthine. with t. brucei, adenosine uptake increased with concentration in a manner suggesting two mechanisms, one with high and the other w ...19807443300
trypanosoma congolense: specific transformation in vitro of leukocytes from infected or immunized cattle. 19807428912
the quantitation of trypanosoma congolense in calves. ii. biochemical changes.changes in serum electrolytes, osmolality, total proteins and protein fractions, lipid levels and organ function tests were determined in neonatal and 6-month-old calves infected with t. congolense treu 112 and control calves. there were no consistent changes in electrolytes or osmolality for either age group of calves. there was a decrease in total serum protein in the infected 6-month-old calves, caused by decreases in the albumin and beta 2-globulin fractions. the total serum protein level re ...19807445066
the quantitation of trypanosoma congolense in calves. iii. a quantitative comparison of trypanosomes in jugular vein and microvasculature and tests of dispersing agents.hemocytometer and cytofluorometric methods were used to count trypanosomes in the blood of neonatal and six-month-old calves infected with t. congolense. the correlation between these methods was highest in the six-month-old calves because their parasitemia was greater and the accuracy of cytofluorometric counting is reduced below 1,000 trypanosomes per microliter of blood. fine needle aspiration biopsies showed many trypanosomes marginated in cerebral cortical capillaries, but few in muscle or ...19807445067
studies on trypanosoma (nannomonas) congolense iii. antigenic variation in three cyclically transmitted stocks.cyclical transmission of different variable antigen types of trypanosoma congolense stib 228 resulted in the development of metacyclic trypanosome populations which were similar in their variable antigen composition as judged by immunofluorescence and neutralization assays. the variable antigen types present in the ingested bloodstream populations were not found in the metacyclic populations. the bloodstream populations which were obtained from cyclically infected, irradiated (900 rad.) mice con ...19806992057
injury induced by trypanosoma congolense adhesion to cell membranes.trypanosoma congolense binds to erythrocytes and the walls of the microvasculature. experiments were conducted to determine if the attachment of t. congolense, alone or in combination with antitrypanosome antibody, was damaging to host cells. bovine erythrocytes were labelled with 51cr and incubated with t. congolense to promote adhesion. plasma from the same donor as the red blood cells was added to the erythrocyte-trypanosome aggregates and the release of 51cr measured. there was a two- to thr ...19807365637
immunosuppression in bovine trypanosomiasis. the establishment of "memory" in cattle infected with t. congolense and the effect of post infection serum on in vitro (3h)-thymidine uptake by lymphocytes and on leucocyte migration.cattle infected with trypanosoma congolense were intravenously immunized with leptospira biflexa 15 days after trypanosomal infection. the primary immune response to l. biflexa was considerably reduced as compared to uninfected controls. the infected cattle mounted a secondary response when they were cured of trypanosomes by treatment with berenil 25 days after infection and re-immunized 8 days later. the mean secondary response in these previously infected animals was lower tha, but not signifi ...19807376244
genetic resistance to trypanosoma congolense infections in mice.the mechanisms of genetic resistance or "trypanotolerance" to infection with trypanosoma congolense were investigated in two strains of mice. one strain c57bl, is outstandingly resistant to most stabilates of t. congolense and can survive for over 80 days, whereas cflp, in common with most other strains, generally succumbs in less than 20 days. evaluation of several pathophysiological and immunological parameters showed that after infection both strains initially developed similar levels of para ...19807380550
hemolytic complement and serum c3 levels in zebu cattle infected with trypanosoma congolense and trypanosoma vivax and the effect of trypanocidal treatment.total hemolytic complement and c3 levels were found to drop to 6.25% and 50% of preinfection levels, respectively, during trypanosome infections. chemotherapeutic elimination of the trypanosomes with berenil led to recovery of preinfection levels within 7 days and 11 days when cattle infected with trypanosome congolense and trypanosoma vivax, respectively, were treated 37 days after onset of infection. recovery was slower in t. vivax-infected cattle treated on day 50. berenil treatment had no ef ...19807380555
evidence for concanavalin a binding sites on the surface coat of trypanosoma congolense.glycoproteins of trypanosoma congolense have been detected on sds-polyacrylamide gels using the concanavalin a peroxidase technique. using [35s]diazoniobenzenesulphonate as a marker for cell surface proteins it was possible to distinguish between internal glycoproteins and the surface coat proteins. on sds-polyacrylamide gels con a reacted with the surface coat proteins. results obtained from con a-induced agglutination of living trypanosomes indicated that sugars of the surface coat proteins we ...19807383705
the effect of trypanosoma congolense and t vivax infections on the antibody response of cattle to live rinderpest virus vaccine.infections with trypanosoma congolense or t vivax did not significantly depress the neutralising antibody response of cattle to live rinderpest vaccine when vaccination was carried out eight or 25 days after infection.19807414077
the quantitation of trypanosoma congolense in calves. 1. hematological changes.anemia due to trypanosoma congolense infection in neonatal and 6-month-old calves was hemolytic and moderately responsive. the red cells were macrocytic and normochromic in both groups of calves and the anemia was milder in infected neonatal calves compared to the 6-month-old calves. the neonatal calves maintained normal white blood cell counts and developed a lymphocytosis at two weeks of infection. the six-month-old calves developed mild neutropenic leukopenia at one week post-infection withou ...19807414679
isometamidium-dextran complex: toxicity and activity against trypanosoma vivax and trypanosoma congolense in rats and mice. 19806156522
studies on glycerol kinase and its role in atp synthesis in trypanosoma brucei.glycerol kinase of trypanosoma brucei has been shown to be capable of catalysing sn-glycerol-3-phosphate dependent adp phosphorylation for atp generation. the rate of this reaction (vr) is sufficient to account for the observed rate of glycerol production from anaerobic glucose metabolism by intact cells and to account for net atp synthesis. glycerol kinase has been purified by preparing a post-nuclear, particulate fraction and solubilizing the enzyme with 0.5% (w/v) triton x-100. this treatment ...19806258071
the initial stage of infection with cyclically-transmitted trypanosoma congolense in rabbits, calves and sheep. 19806115869
depressed immunoconglutinin responses in calves experimentally infected with trypanosoma congolense.contrary to expectation, immunoconglutinin levels failed to rise significantly in calves infected with trypanosoma congolense. in addition, it was shown that trypanosome infection appeared to inhibit the immunoconglutinin response to brucella abortus strain 19. the possible reasons for these findings are discussed.19806774392
the quantitation of trypanosoma congolense in calves. iv. in vitro culture of myeloid and erythroid marrow cells.myeloid and erythroid cultures were prepared from bone marrow aspirates taken from control and t. congolense infected neonatal and six-month-old calves. the aspirates obtained from the infected animals were more cellular than the controls and it was found that the removal of adherent cells prior to ficoll separation improved the sensitivity of the cultures to colony stimulating factors and removed the background connective tissue cells and megakaryocytes from the resulting colonies. there was an ...19807233539
distribution and attachment of trypanosoma (nannomonas) congolense in the proximal part of the proboscis of glossina morsitans morsitans.the distribution and attachment of trypanosoma congolense were investigated in the proximal part of the proboscis of glossina m. morsitans. in the food canal, epimastigotes and trypomastigotes formed tufts or compact layers. trypanosomes were attached to the cuticle by their flagella, which formed zonar hemidesmosomes. the flagella were mostly attached parallel to the axis of the labrum and often pointed to its tip. foot-like processes of the flagella came into contact with adjacent flagella lea ...19806106351
studies on trypanosoma (nannomonas) congolense iv. experimental immunization of mice against tsetse fly challenge.groups of mice were exposed to multiple bites by tsetse flies (glossina morsitans morsitans) infected with a clone of trypanosoma congolense spread over a periof of 8 days. the mice were subsequently treated with berenil 10 days after the first fly bite as were uninfected control mice. the group of mice which received 12--15 infectious fly bites on two occasions, 21 days apart, were subsequently resistant to infection when re-challenged by flies infected with the same clone of t. congolense. the ...19806155654
in vitro binding of trypanosoma congolense to erythrocytes.trypanosoma congolense broden, an intravascular parasite, binds to vessel walls and erythrocytes of infected hosts. in an attempt to characterize t. congolense adhesion to host cells, an in vitro assay was devised. it was shown in the in vitro experiments that t. congolense binds to bovine, sheep, and goat erythrocytes, but not always to erythrocytes of rats, mice, rabbits, horses or humans. only the anterior part of live trypanosomes adheres to erythrocytes, and the attachment site on the trypa ...197939167
immunosuppression in experimental african trypanosomiasis. polyclonal b-cell activation and mitogenicity of trypanosome-derived saturated fatty acids.changes in antibody responses in adult mice infected with trypanosoma congolense and subsequently challenged with unrelated antigens (sheep red blood cells and pneumococcal polysaccharide) were studied. immune responses were significantly depressed within 1 week of infection, and complete suppression of both igm and igg responses to both types of antigen was established 15 days after immunization. coincidentally with the development of high parasitaemias, background igm plaque-forming cell respo ...1979312771
conversion of dihydroorotate to orotate in parasitic protozoa.the conversion of dihydroorotate to orotate, one of the key reactions in the de novo pyrimidine biosynthetic pathway, has been studied in a number of parasitic protozoa. enzyme activities capable of carrying out this reaction were detected in six members of the kinetoplastida (trypanosoma brucei, trypanosoma congolense, trypanosoma vivax, trypanosoma lewisi, trypanosoma cruzi, leishmania enriettii) and three members of the genus plasmodium (p. knowlesi, p. berghei, p. gallinaceum). the mechanism ...1979217438
suppression of antibody response to leptospira biflexa and brucella abortus and recovery from immunosuppression after berenil treatment.zebu cattle infected with either trypanosoma congolense eatro 1800 or trypanosoma vivax eatro 1721 had suppressed humoral immune responses to leptospira biflexa injected intravenously and to attenuated brucella abortus injected subcutaneously. t. congolense infections were more suppressive than t. vivax infections. in cattle infected with t. vivax, the suppression of immune responses to both bacterial immunogens was abrogated when the animals were treated with berenil at the time of antigen admi ...1979118933
cyclical transmission of trypanosoma brucei rhodesiense and trypanosoma congolense by tsetse flies infected with culture-form procyclic trypanosomes.culture procyclic forms of trypanosoma brucei rhodesiense and trypanosoma congolense were fed to glossina morsitans morsitans through artificial membranes. a very high percentage of the flies so fed produced established midgut infections, a proportion of which went on to develop into mature metacyclic trypanosomes capable of infecting mammalian hosts. the method offers a safe, clean way of infecting tsetse flies with african trypanosomes which reduces the need for trypanosome-infected animals in ...1979536930
bovine trypanosomiasis: the red cell kinetics of ndama and zebu cattle infected with trypanosoma congolense.the responses of susceptible ndama and zebu cattle to needle challenge with trypanosoma congolense were followed using parasitological, haematological and radio-isotopic methods and compared with those of corresponding uninfected animals. in both breeds, infection became patent at the same time but peak parasitaemias were significantly lower, were attained later and were of short duration in the ndama. all infected animals became anaemic, the severity of which correlated with the level and durat ...1979481905
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