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antibody-dependent cell-mediated cytotoxicity in cattle: activity against 51cr-labeled chicken erythrocytes coated with protozoal antigens.bovine mononuclear cells in the presence of bovine anti-chicken erythrocyte sera at high dilutions induce release of chromium-51 from labeled chicken erythrocytes. bovine effector cells are capable of recognizing both bovine immunoglobulin g(1) and bovine immunoglobulin g(2); in contrast, human effector cells only recognize immunoglobulin g(1). effector cell activity of bovine mononuclear cells is equally distributed between peripheral blood and spleen. as in other species, thymus and lymph node ...1978103832
induction of infective stages of theileria parva by exposure of host ticks to high temperature.it was demonstrated that theileria parva parasites infective to cattle could be induced by exposure of infected adult rhipicephalus appendiculatus ticks to 37 degrees c. the production of the sporozoites of t parva was not as efficient as by feeding ticks on rabbits.1979119344
experimental therapy of theileriosis.a tissue culture method was used to screen compounds for activity against theileria parva, and demonstrated that the hydroxy-alkylated naphthoquinones, 'menoctone' and 993c were highly active, with ed50 values around 0,005 mg/l. when injected into cattle artificially infected the t. parva, menoctone cured all of 7 cattle at a total dosage of 10 mg/kg injected intravenously (i.v.). a further trial showed that injection of menoctone, 10 mg/kg, as a single dose gby the intramuscular (i.m.) route wa ...1979553970
the effect of leucocytes from cattle immunized against east coast fever on the migration of bovine lymphoblasts infected with theileria parva. 1975812298
[electron microscope studies on developmental stages of theileria parva (theiler, 1904) in the intestine of the tick hyalomma anatolicum excavatum (koch, 1844) (author's transl)].the developmental stages of theileria parva within the intestine of ticks were studied by electron microscopy. on the 2nd-4th day post repletionem (p.r.) the intestine of the ticks contained numerous stages, which were very similar to microgamonts and microgametes of haemosporidia. from these results it seemed likely that gamogony of theileria parva takes place in the intestine of ticks, too. the microgamont-like stages were spear-head-like; they measured about 10.5 mum in length with a maximum ...1976821188
immunization against east coast fever (theileria parva infection of cattle) by infection and treatment: chemoprophylaxis with n-pyrrolidinomethyl tetracycline.cattle were immunized against east coast fever by the inoculation of a tick-derived stabilate of theileria parva infective particles and the intramuscular injection, at daily intervals, of n-pyrrolidinomethyl tetracycline at a dose level of 5 mg/kg. four doses of the tetracycline, starting on the day of inoculation of the infective stabilate, minimised the ecf reactions in the cattle during immunization. immunity to homologous t. parva stabilate challenge was demonstrated in 27 out of 27 cattle ...1977910283
the effect of calf lymph and bovine red blood cells on in vitro cultivation of theileria parva-infected lymphoid cells.calf lymph introduced to cultures of theileria parva-infected lymphoid cells caused a stimulation of both cells and parasites resulting in the formation of rapidly dividing cells and the developmental stages of the parasite. the presence of piroplasms was confirmed when washed bovine red blood corpuscles were added to the culture1976968954
an ultrastructural study of heterokaryons derived from theileria parva-infected bovine lymphoblasts and ehrlich ascites tumour cells.an ultrastructural study was made of sendai virus induced heterokaryons derived from theileria parva-infected lymphoblasts and ehrlich ascites tumour cells. when fusion occurred, parasites were successfully integrated into the cytoplasm of the resulting heterokaryons where they appeared as morphologically normal macroschizonts. homokaryon formation was also noted. this occurred frequently between ehrlich ascites tumour cells and rarely with lymphoblasts. a small proportion of heterokaryons conta ...1976987607
interactions between chemotherapy and immunity in bovine theileriosis.in bovine theileriosis the use of chemotherapy to control an infection sufficiently long to permit the establishment of a solid protective immune response has been developed as a routine vaccination procedure. infections with theileria parva and t. annulata can be prevented by the administration of carefully controlled numbers of sporozoites simultaneously with a long acting tetracycline and this form of immunization has been widely used for the control of east coast fever in africa with conside ...19921308933
detection of a carrier state in theileria parva-infected cattle by the polymerase chain reaction.two sets of oligonucleotide primers, one derived from a repetitive sequence and the other from the gene encoding a 67 kda sporozoite antigen of theileria parva, were used to amplify parasite dna from the blood of t. parva-infected carrier cattle using the polymerase chain reaction (pcr). pcr amplification products were obtained from 15 carrier cattle infected with one of 4 different t. parva stocks. successful amplifications were performed using dna from 2 cattle infected with t. p. parva pemba ...19921350672
theileria parva: cd4+ helper and cytotoxic t-cell clones react with a schizont-derived antigen associated with the surface of theileria parva-infected lymphocytes.theileria parva is a protozoan parasite which infects and transforms bovine lymphocytes, resulting in a fatal lymphoproliferative disease. there is evidence that immunity to the intralymphocytic schizont stage is mediated by t cells. we have previously reported derivation of cd4+ t-cell clones which recognize parasite-derived antigens presented on the surface of infected cells in conjunction with mhc molecules and partial characterization of the antigens. the present study further evaluated one ...19921353459
immune cd4+ t cells specific for theileria parva-infected lymphocytes recognize a 24-kilodalton protein.theileria parva is a protozoan parasite that infects and transforms bovine lymphocytes. here we report the partial purification of a t. parva-specific protein from infected lymphocytes that is recognized by cd4+ parasite-specific t-cell clones derived from immune cattle. t. parva-infected lymphocytes were homogenized in dulbecco's phosphate-buffered saline in the presence of protease inhibitors. the antigen was purified from a postmicrosomal supernatant by using a combination of deae-cellulose c ...19921354201
cloning and characterization of the casein kinase ii alpha subunit gene from the lymphocyte-transforming intracellular protozoan parasite theileria parva.theileria parva is an obligate intracellular protozoan parasite which is the causative agent of east coast fever, an acute, leukemia-like disease of cattle. the intralymphocytic stage of the parasite induces blastogenesis and clonal expansion of quiescent bovid lymphocytes. experiments in our laboratory have shown a marked increase of casein kinase ii- (ck ii-) like activity in t. parva-transformed lymphocytes. we have also detected ck ii activity in purified t. parva schizonts. to explore the s ...19921378299
improved isolation of rinderpest virus in transformed bovine t lymphoblast cell lines.bovine t lymphoblast cell lines transformed by the protozoan theileria parva were compared with bovine kidney (bk) and vero cells for their ability to isolate various strains of rinderpest virus from tissues and infected secretions. all of the strains of rinderpest virus that were tested, including attenuated cell-culture, caprinised and lapinised vaccines, and both mild and virulent pathogenic strains, readily induced syncytial cytopathic effect (cpe) in t lymphoblasts. the cpe could often be d ...19921410806
a clinical trial of buparvaquone in the treatment of east coast fever.a clinical trial was conducted to test buparvaquone (butalex; coopers pitman-moore) in the treatment of east coast fever under field conditions in kenya. data from 229 cases were analysed following treatment with one (69), two (142) or three (18) doses at 2.5 mg/kg. the majority of cattle (95.2 per cent) were exotic (bos taurus) or improved (bos taurus cross bos indicus) and 39.3 per cent were infected with anaplasma marginale. there was an overall recovery rate of 85.6 per cent, with 90.1 per c ...19921441098
development and persistence of cowdria ruminantium specific antibodies following experimental infection of cattle, as detected by the indirect fluorescent antibody test.different breeds of cattle were experimentally infected with palm river, a zimbabwean isolate, or ball-3, a south african isolate of cowdria ruminantium, derived from tissue culture or tick or blood stabilates. c. ruminantium specific antibody responses were detected by an indirect fluorescent antibody test (ifat) using c. ruminantium-infected bovine aortic endothelial (bae) cell cultures as antigen. the first detection of antibodies to c. ruminantium generally coincided with the peak of the feb ...19921441219
immunisation of cattle against theileriosis in nakuru district of kenya by infection and treatment and the introduction of unconventional tick control.one hundred and one cross european-boran cattle (50 cows and 51 calves), on a farm in nakuru district, kenya, were immunised against theileriosis using theileria parva lawrencei and theileria parva parva stocks from another district of kenya. the stabilates used were t.p.lawrencei (mara iii) used at 10(-1.7) dilution and t.p.parva (kilae) used at 10(-1.0) dilution. the stabilates were combined and inoculated simultaneously with a short-acting formulation of oxytetracycline hydrochloride given in ...19921496782
transformation of theileria parva derived from african buffalo (syncerus caffer) by tick passage in cattle and its use in infection and treatment immunization.a sporozoite stabilate (st. 199) of theileria parva was obtained by feeding nymphal rhipicephalus appendiculatus on an african buffalo (syncerus caffer) and was used to immunize cattle by the infection and treatment method. nymphal ticks were applied to one of the steers 90 days later and it was shown that the resultant adult tick had become infected. using tick/cattle passage, two passage lines of t. parva were established. by the fifth tick/cattle passage, the parasite stocks had changed their ...19921496792
further evaluation of the use of buparvaquone in the infection and treatment method of immunizing cattle against theileria parva derived from african buffalo (syncerus caffer).three experiments were undertaken to determine the efficacy of different doses of buparvaquone in the infection and treatment immunization of cattle against theileria parva derived from african buffalo (syncerus caffer). two of these experiments also compared buparvaquone with standard doses of long- and short-acting formulations of oxytetracycline. in addition, different dilutions of stabilates were used in the experiments. in the first experiment, a 10(-1.0) dilution of stabilate was used to i ...19921496799
characterisation of the gene encoding a candidate vaccine antigen of theileria parva sporozoites.we have cloned and characterised the gene encoding the 67-kilodalton stage-specific surface antigen, p67, of theileria parva (muguga) sporozoites. the gene which is present in a single copy, is divided into 2 exons by an intron 29 bp long and is transcribed into mrna of about 2500 nucleotides. the gene is present in all stocks of t. parva and there is a related gene in theileria annulata. the deduced amino acid sequence of 709 residues predicts that p67 is a membrane protein and that it lacks ta ...19921565135
how individual cells develop from a syncytium: merogony in theileria parva (apicomplexa).the central problem for theileria parva during merogony is how to form numerous individual, uninucleate merozoites from a syncytial schizont so that each merozoite contains a single nucleus and a prescribed assortment of organelles. the way t. parva packages all the requisite organelles into free merozoites is by binding these organelles to the nuclear envelope, which in turn becomes associated, both directly and through the rhoptry complex, with the schizont plasma membrane. formation of the me ...19921569119
cytokines inhibit the development of trophozoite-infected cells of theileria annulata and theileria parva but enhance the proliferation of macroschizont-infected cell lines.the following bovine (bo) and human (hu) cytokines--bo rtnf-a, bo rifn-g, hu ifn-a, hu ril-1, hu ril-2--significantly inhibited the in vitro development of trophozoite-infected cells of three stocks of theileria annulata and of theileria parva (muguga). however, none of these cytokines inhibited the proliferation of established t. annulata or t. parva macroschizont-infected cell lines. indeed, bo rtnf-a and hu ril-2 consistently enhanced the proliferation of macroschizont-infected cell lines of ...19921570169
standardization of a technique for analysing the frequency of parasite-specific cytotoxic t lymphocyte precursors in cattle immunized with theileria parva.a limiting dilution microculture system was optimized to quantify the frequency of theileria parva-specific cytotoxic t lymphocyte precursors (ctlp) in peripheral blood mononuclear cells (pbmc) from immune cattle. optimal results were obtained with responder cell input levels ranging from 2 x 10(4)/well to 6.25 x 10(2)/well, along with 1-5 x 10(3)/well stimulator cells in standard supplemented rpmi 1640 medium containing 2.5-5% t cell growth factors. thirty-six microtitre wells were established ...19921570170
growth of theileria annulata and theileria parva macroschizont-infected bovine cells in immunodeficient mice: effect of irradiation and tumour load on lymphocyte subsets.bovine cells infected with macroschizonts of the protozoan parasites theileria annulata and theileria parva formed solid tumours when injected into irradiated balb/c and irradiated balb/c nude mice. t. annulata tumours grew more vigorously than t. parva tumours, when initiated with similar doses of infected cells in mice exposed to the same doses of gamma-irradiation. in irradiated balb/c mice, tumours of both species of parasites began to regress 2-3 weeks after injection of cells but grew with ...19921644524
characterisation of the gene encoding a 104-kilodalton microneme-rhoptry protein of theileria parva.a neutralizing antiserum, c16, raised against sporozoites of theileria parva parva was used to screen a lambda gt11 expression library of t. parva parva (muguga) genomic dna fragments. proteins encoded by one phage clone, lambda tps-17, were reactive with the c16 antiserum. detailed characterisation of the dna insert showed it to encode determinants found on four theilerial antigens of approximately 104, 90, 85 and 35 kda. the sequence encoded by the clone is expressed during sporogony as a sing ...19901689460
identification of lambda gt11 clones encoding the major antigenic determinants expressed by theileria parva sporozoites.an antiserum, c16, was raised in cattle against freeze-thawed extracts of sporozoites of theileria parva (muguga). this antiserum, which neutralizes sporozoite infectivity in vitro, identified theileria-specific antigens having approximate molecular masses of 105, 90, 85, 69, 67, 52, 47, and 43 kilodaltons (kda) on western blots (immunoblots) of infected tick salivary gland extracts. the antiserum was used to screen an expression library of t. parva (muguga) genomic dna fragments. three recombin ...19901692810
immunization with theileria parva parasites from buffaloes results in generation of cytotoxic t cells which recognize antigens common among cells infected with stocks of t. parva parva, t. parva bovis, and t. parva lawrencei.immunity to infection by the protozoan parasite theileria parva in cattle is partially attributable to cytotoxic t cells, which kill lymphocytes infected with the schizont stage of the parasite. here we evaluated five stocks of buffalo-derived t. parva lawrencei parasites and two stocks of cattle-derived t. parva parva parasites for their ability to induce in vivo cytotoxic t cells which can kill lymphocytes infected with a wide variety of strains of t. parva parasites. a group of seven full-sib ...19901699896
production of interferons by bovine and ovine cell lines infected with theileria annulata or theileria parva.three bovine cell lines and four ovine cell lines infected with theileria parva or theileria annulata were examined for the production of interferon (ifn). biologically active ifn was detected in the tissue culture supernatants of four of the cell lines. only one, a bovine cell line infected with t. parva, produced ifn-gamma as measured by specific neutralization with a monoclonal antibody to bovine ifn-gamma. this observation was confirmed by analysing rna from the cell lines on northern blots ...19911712932
distinction of naive and memory bocd4 lymphocytes in calves with a monoclonal antibody, cc76, to a restricted determinant of the bovine leukocyte-common antigen, cd45.a murine igg1 monoclonal antibody (mab), cc76, has been produced that, based on findings of the relative molecular mass of polypeptides that it recognized, staining of leukocytes in blood and tissues, and the biological properties of the t lymphocyte subpopulations with which it reacts, is considered to identify an isoform of the leukocyte common antigen (lca) family of molecules in cattle. the mab is more similar to human cd45r which detect products requiring the presence of the b exon within t ...19911716214
a recombinant sporozoite surface antigen of theileria parva induces protection in cattle.at present immunization against theileria parva is by infection with live sporozoites and simultaneous treatment with a long-acting oxytetracycline. this method has major limitations in that live organisms are used and the immunity engendered is parasite stock specific. in an attempt to develop an alternative immunization procedure, the gene encoding p67, a major surface antigen of sporozoites, has been expressed by using the plasmid expression vector pmg1. the gene, which has been characterized ...19921731322
re-assessment of tick control after immunization against east coast fever in the eastern province of zambia.east coast fever, caused by the protozoon theileria parva and transmitted by the ixodid tick rhipicephalus appendiculatus is one of the most important cattle diseases in east and central africa, responsible for considerable direct losses and necessitating expensive control measures. traditionally, the disease was controlled by means of intensive tick control. the belgian animal disease control project was requested to study the disease epizootiology and vector ecology in order to formulate and i ...19911793284
exposure of ankole and crossbred cattle to theileriosis in rwanda.susceptible ankole (sanga: bos indicus/bos taurus) and crossbred ankole x jersey (b. taurus) and ankole x sahiwal (b. indicus) cattle derived from a farm in rwanda with no recent history of theileriosis, were infected with theileria parva stocks from rwanda either by feeding infected rhipicephalus appendiculatus ticks on the ears, inoculation of tick derived stabilate or natural exposure to tick challenge. the ankole cattle originated from local stock born and bred in east coast fever (ecf) ende ...19911796523
cell surface phenotype of two cloned populations of bovine lymphocytes displaying non-specific cytotoxic activity.monoclonal antibodies specific for t cell differentiation antigens were tested on four cloned populations of lymphocytes derived from the peripheral blood mononuclear cells of an animal immunised with theileria parva. the clones were defined functionally in terms of cytotoxic activity, mhc restriction and expression of messenger rna for cd3 and t cell receptor (tcr). two clones contained rna transcripts for cd3, tcr-alpha and beta and were positive for cd2, cd5 and cd6; one of these was a typica ...19911826981
[activation of trans-acting transcription factors in t-lymphocytes infected by the intracellular parasitic protozoan theileria parva].the intracellular protozoan parasite, theileria parva, causes a lymphoproliferative disease of t-cells in cattle and uncontrolled lymphocyte proliferation in culture. we have identified and characterized in infected cells the trans-acting transcription factors nf-kappa b, ap1 and nf1 controlling lymphocyte-specific expression of several genes. theileria infected lymphocytes contain constitutively high levels of active nf-kappa b in nuclear fraction. factor ap1 had high levels of binding activity ...19911874431
lymphocytes infected with theileria parva require both cell-cell contact and growth factor to proliferate.lymphocytes infected with the intracellular parasite theileria parva proliferate continuously as lymphoblastoid cell lines. we have previously shown that the continuous proliferation of the t. parva-infected (tpi) cell line tpm(803) is mediated in part by an autocrine mechanism (dobbelaere, d. a. e. et al., proc. natl. acad. sci. usa 1988. 85:4730). we now report that continuous proliferation also requires surface stimulation through cell-cell contact. under standard culture conditions this surf ...19911899385
the entry of theileria parva sporozoites into bovine lymphocytes: evidence for mhc class i involvement.we have examined the process of theileria parva sporozoite entry into susceptible bovine lymphocytes and have begun to identify one of the possible molecular interactions involved in the process. the entry process involves a defined series of events and we have used a number of experimental procedures in combination with a method of quantitation to examine various aspects of this process. t. parva sporozoites are nonmotile organisms and the initial sporozoite-lymphocyte interaction is a chance e ...19911901066
characterization of a polymorphic immunodominant molecule in sporozoites and schizonts of theileria parva.this study examines several aspects of a polymorphic, immunodominant molecule (pim) found in the protozoan parasite, theileria parva. the antigen is present in all t.p. parva stocks examined, and in the related subspecies, t.p.bovis and t.p.lawrencei. it is the predominant antigen recognized by antisera from immune cattle on western blot analysis of schizont-infected lymphocytes, and is the only antigen which has been shown to react with anti-schizont monoclonal antibodies (moabs) on western blo ...19911901640
analysis of the reactivity of anti-bovine cd8 monoclonal antibodies with cloned t cell lines and mouse l-cells transfected with bovine cd8.mouse l-cells transfected with bovine cd8 and two theileria parva-infected cloned t cell lines expressing bovine cd8 were used to screen the panel of ten monoclonal antibodies (mabs) submitted to the workshop. eight of the ten mabs reacted with the transfectant and both the cloned t cell lines. however, two mabs cc58 and bat82a did not recognise the transfectant and only reacted with one of the t cell lines. further biochemical studies indicated that the eight mabs react with both homo- and hete ...19911902341
activity of buparvaquone against theileria cervi in white-tailed deer.buparvaquone, a naphthoquinone with known efficacy against theileria parva parva in cattle, was tested for activity against theileria cervi piroplasms in both an in vitro culture system and in vivo in experimentally infected white-tailed deer. the in vitro data showed a significant decrease in the incorporation of 3h-hypoxanthine by infected red blood cells treated with buparvaquone when compared to that seen with imidocarb and chloroquine treatment. in both intact and splenectomized deer treate ...19911902608
epidemiological observations on theileriosis following field immunisation using infection and treatment.thirty-seven high grade cattle were immunised against corridor disease (theileria parva lawrencei infection) on a farm with a history of heavy and often lethal theilerial challenge. nineteen cattle were immunised by treating with two doses of long-acting oxytetracyclines given at 20 mg/kg on days 0 and 4 after sporozoite stabilate inoculation, while the other 18 were treated with naphthoquinone buparvaquone, given as a single dose of 2.5 mg/kg simultaneously with stabilate inoculation. all the c ...19911907045
theileria parva: influence of vector, parasite and host relationships on the epidemiology of theileriosis in southern africa.the protozoan parasite theileria parva, transmitted by the ixodid tick rhipicephalus appendiculatus, is the cause of east coast fever (ecf) and the related syndromes of corridor disease and january disease in cattle of eastern, central and southern africa. it is likely that buffalo (syncerus caffer) are the natural host of t. parva. in eastern and southern africa, there exists both buffalo-adapted and cattle-adapted t. parva. disease caused by buffalo-adapted parasites is called corridor disease ...19911907728
a simple and efficient method for purifying and quantifying schizonts from theileria parva-infected cells.an improved method for the purification of theileria parva schizonts from infected bovine cells is described. the technique is simpler and more rapid than previously described methods and gives rise to greater yields of schizonts with negligible contamination by host-cell components. in addition, a fluorescent staining technique was developed whereby live schizonts purified from infected cells can be enumerated and sorted using the flow cytometer. an assessment of the quality of schizonts prepar ...19911924254
effects of gamma interferon, tumor necrosis factor alpha, and interleukin-2 on infection and proliferation of theileria parva-infected bovine lymphoblasts and production of interferon by parasitized cells.theileria parva is a protozoan parasite that infects bovine b cells and alpha beta and gamma delta t cells and transforms them into continually proliferating cells. cd4+ t. parva-antigen-specific immune t cells have been shown to produce cytokines in response to stimulation with parasitized cells, and t. parva-infected lymphocytes produce and consume t-cell growth factors and interleukin-2 (il-2). to ascertain the role of t-cell cytokines on t. parva infections, we evaluated recombinant gamma in ...19911937812
oxytetracycline inhibition of mitochondrial protein synthesis in bovine lymphocytes infected with theileria parva or stimulated by mitogen.oxytetracycline (otc) significantly inhibited cytochrome c oxidase activity in bovine lymphocytes infected with theileria parva and in uninfected mitogen-stimulated lymphocytes. the inhibitory effect was detected in vitro within 24 h of treatment with drug concentrations as low as 1 micrograms/ml. following mitogen stimulation of lymphocytes, concentrations of 3 and 10 micrograms/ml otc completely inhibited an increase in cytochrome c oxidase activity for 48-72 h. this inhibitory activity was co ...19901965455
strain specificity of bovine theileria parva-specific cytotoxic t cells is determined by the phenotype of the restricting class i mhc.to determine whether the major histocompatibility complex (mhc) phenotype of cattle could affect the parasite strain specificity of immunity to theileria parva by influencing the antigenic specificity of theileria-specific cytotoxic t lymphocytes (ctl), we investigated the parasite strain specificity of theileria-specific ctl clones derived from cattle of different class i mhc phenotypes. thirty-one class i-restricted ctl clones were generated from four cattle immunized with the muguga stock of ...19901968884
sfii and noti polymorphisms in theileria stocks detected by pulsed field gel electrophoresis.dnas of theileria parva parva, t. p. lawrencei, t. p. bovis and theileria mutans stocks, from kenya, uganda, zanzibar and zimbabwe were digested with either sfii or noti and analysed using contour-clamped homogeneous electric field (chef) and field-inversion gel electrophoresis (fige). the sfii-digested t. parva genomic dna resolved into approximately 30 fragments while the noti digestion produced between 4-7 bands. the summation of the sizes of sfii fragments gave an estimate of 9-10 x 10(6) ba ...19901972977
expression of tac antigen component of bovine interleukin-2 receptor in different leukocyte populations infected with theileria parva or theileria annulata.the tac antigen component of the bovine interleukin-2 receptor was expressed as a cro-beta-galactosidase fusion protein in escherichia coli and used to raise antibodies in rabbits. these antibodies were used for flow cytofluorimetric analysis to investigate the expression of tac antigen in a variety of theileria parva-infected cell lines and also in three theileria annulata-infected cell lines. cells expressing tac antigen on their surface were found in all t. parva-infected cell lines tested wh ...19901979317
il-2 can enhance the cyclosporin a-mediated inhibition of theileria parva-infected t cell proliferation.the effect of cyclosporin a on the continuous proliferation of theileria parva-infected t cells was tested and compared with its effect on the con a-induced proliferation of bovine lymph node cells. the effect of ril-2 on cyclosporin a-treated cells was also tested. whereas the con a-induced proliferation of bovine lymph node cells was completely inhibited by cyclosporin a, the continuous growth of t. parva-infected cells was only partly inhibited. in both cases the inhibition was accompanied by ...19902104902
the effects of oxytetracycline on theileria parva in vitro.when bovine peripheral blood leucocytes were infected with theileria parva sporozoites, immediate treatment with oxytetracycline (otc) inhibited the development of sporozoites to mature schizonts. the extent of inhibition was dependent on drug concentration and duration of treatment. concentrations of 5 micrograms/ml otc, or higher, for 8 days completely inhibited the establishment of schizonts and their ability to transform host cells. a cytostatic effect on schizont-infected cell lines was fou ...19902107502
a single exon codes for the enzyme domain of a protozoan cysteine protease.theileria parva is an intracellular protozoan parasite of cattle. we have determined the nucleotide sequence of a gene and cdna coding for a cysteine protease of t. parva. the gene is divided into two exons. the first exon codes for a signal sequence and for part of the "pro" region of the zymogen. the second exon codes for the remainder of the pro region, including residues thought to be involved in zymogen processing, and for the entire enzyme domain. part of this exon cross-hybridizes, at hig ...19902120221
low-dose oral administration of human interferon alpha can control the development of theileria parva infection in cattle.two natural human interferon alpha preparations, (nhuifn-alpha [cantell]) and (nhuifn-alpha [isi]), were used for the oral treatment of cattle experimentally infected with theileria parva parva. in the first experiment, 8 friesian bulls were inoculated with a 1 in 10 dilution of a sporozoite stabilate of t.p. parva (marikebuni) stock. four of the cattle were treated daily with 1 international unit/kg body weight (i.u./kg bwt) of nhuifn-alpha (cantell) from day -2 to day 8 p.i. none of the 4 calv ...19902124670
immunization of cattle against theileria parva bovis and their exposure to natural challenge.theileria parva bovis isolates were tested for their immunizing capacity under natural field challenge on willsbridge farm in the highveld of zimbabwe. fifteen susceptible sussex yearlings were immunized with the boleni stock and 15 with a mixture of three isolates from the farm, using tick-derived sporozoite stabilates. no chemoprophylaxis was used. a dose of 0.1 ml of stabilate appeared to be safe in preliminary laboratory experiments, but the reactions were severe in the sussex cattle and one ...19902125158
a bovine class i major histocompatibility complex molecule plus a theileria parva antigen resembles mouse h-2kd.two bot2+, bot8+ cytotoxic t cell clones were generated from peripheral blood of a steer immunized with the intracellular protozoan parasite theileria parva. both cytotoxic t cell clones appeared to be restricted by the same major histocompatibility complex (mhc) molecule and were specific for the immunizing parasite clone. however, one of the two clones also recognized uninfected mouse cell lines carrying the h-2d haplotype. inhibition of cytotoxicity with monoclonal antibodies specific for pol ...19902125183
theileria parva: the nature of the immune response and its significance for immunoprophylaxis.theileria parva is a tick-borne haemoprotozoan parasite of cattle and buffalo which is responsible for considerable economic losses to cattle farming in eastern, central and southern africa. infection with the parasite results in an acute lymphoproliferative disorder with high mortality, but animals which survive infection are solidly immune to homologous challenge. such immunity can be reproduced by infecting cattle with the parasite and treating them with tetracyclines or theilericidal drugs, ...19902132688
recognition of soluble theileria parva antigen by bovine helper t cell clones: characterization and partial purification of the antigen.theileria parva-specific bovine bot4+ th cell clones were used to characterize ag associated with t. parva schizont-infected lymphoblastoid cells. all of the clones tested responded to cells infected with the immunizing (muguga) as well as heterologous stocks of t. parva, indicating that the t cells are specific for an ag shared by several geographically diverse parasites. the response was apparently mhc-restricted, and induced by ag expressed on the infected cell surface. in the presence of aut ...19902136883
cytotoxic t cells in immunity to theileria parva in cattle. 19902137767
development of recombinant antigen vaccines for the control of theileriosis.immunization against theileria parva involves infection with sporozoites and simultaneous treatment with a long-acting tetracycline. for t. annulata, immunization is achieved by inoculation of attenuated schizont-infected lymphocytes. the two methods are inadequate because of the use of live organisms and the methods are also bedevilled by the multiplicity of strains, particularly of t. parva. for these reasons, alternative methods of control are being sought. in this review an attempt is made t ...19902149448
characterization of a bovine leucocyte differentiation antigen of 145,000 mw restricted to b lymphocytes.a new bovine b-cell differentiation antigen is described that is detected by three monoclonal antibodies (mab). the antigen is not an immunoglobulin and is precipitated from peripheral b cells as a molecule with an approximate molecular weight (mw) of 120,000 or 145,000 before and after reduction, respectively. data obtained from two-colour cytofluorimetry and immunohistochemistry confirmed that the antigen was found only on mature b cells and on cells with dendritic morphology in the follicles ...19902185984
age resistance to theileria parva bovis infection in calves.data collected in the zimbabwean province of mashonaland-west, in the period 1980-1988, showed that mortality in calves owing to theileria parva bovis infection (january disease) was significantly lower in animals younger than 7 months than in older cattle. groups of seven holstein-friesian calves from non-immune dams aged approximately 1, 4, 7, 10 and 13 months were infected with a theileria parva bovis tick-derived stabilate. the dose chosen was lethal for 40% of the calves in the trial. morta ...19902267723
geographical information systems for studying the epidemiology of cattle diseases caused by theileria parva.data on selected variables which influence the epidemiology of cattle diseases caused by theileria parva were assembled and entered in a computerised geographical information system. variables studied included the distributions of major hosts (cattle and buffalo), the vector ticks (rhipicephalus appendiculatus and related species) and the reported presence of east coast fever, corridor disease and january disease. in addition, the distribution of climatic suitability for r appendiculatus was ass ...19902327044
evaluation of infection and treatment methods in immunization of improved cattle against theileriosis in an endemic area of kenya.five experiments were carried out to determine the efficacy of immunization against theileriosis in an endemic area of kenya using artificial infection with a mixture of stabilates of theileria parva stock or natural infection and treatment with parvaquone or several formulations of oxytetracyclines. for the first four experiments, introduced, susceptible sahiwal/friesian crosses were used and in the fifth, calves of boran/maasai zebu crosses born on the site. cattle were infected either artific ...19902343540
bovine alloreactive cytotoxic cells generated in vitro: target specificity in relation to bola phenotype.cytotoxic cells of bovine origin were generated in primary mlc using stimulator cells of bola w8/w11 phenotype. bovine lymphoblasts transformed by the protozoan parasite theileria parva parva acted as target cells in studies of the specificity of cytotoxicity. when responder cells in mlc did not share w8 or w11 with stimulator cells, cytotoxicity was evident with all targets bearing w8 or w11, or both, and was almost entirely restricted to these products of the bola-a locus. when responder and s ...19852409001
theileria parva: expression of a sporozoite surface coat antigen.a monoclonal antibody specific for the theileria parva sporozoite, which recognizes a determinant on the surface coat and blocks sporozoite infectivity, was used to investigate the presence of the determinant on other stages of the parasite lifecycle. immunofluorescence techniques did not demonstrate this determinant on the kinete, schizont, merozoite, or piroplasm stages of the parasite. immunoautoradiography, using a tritiated form of the monoclonal antibody, on sections of infected salivary g ...19852410290
alloreactive bovine t lymphocyte clones: an analysis of function, phenotype, and specificity.a bovine alloreactive cell population was subjected to complement-dependent lysis with monoclonal antibody (mab) il-a11. the original population and the population depleted of cells bearing the determinant recognized by mab il-a11 were cloned. parent cultures and 21 clones were examined for cytolytic function and for expression of determinants recognized by mab il-a11 and two additional mab, il-a12 and il-a17. clones could be classified according to maximal achievable levels of cytolysis by usin ...19862423592
bovine helper t-cell clones specific for lymphocytes infected with theileria parva (muguga).t-cell clones specific for lymphocytes infected with theileria parva were derived from animals immunized by infection with t. parva (muguga). these clones were non-cytolytic and had the bot4+ bot8- surface phenotype, bot4 and bot8 being the bovine analogues of human cd4 and cd8 molecules. the clones proliferated in response to irradiated autologous lymphoblasts infected with t. parva (muguga) but not to autologous uninfected lymphoblasts or monocytes. they were parasite strain-specific, in that ...19872442694
isolation and characterization of rna from the intracellular parasite theileria parva.using a rapid procedure to isolate schizonts of the intracellular parasite theileria parva from infected bovine lymphocytes, we have prepared parasite rna that is more than 90% pure. characterization of this schizont rna has revealed the presence of two ribosomal rna species of 3.3 kb and 1.8 kb and a third non-adenylated abundant rna species of 1.9 kb. in vitro translation of the isolated schizont mrna has identified about 200 parasite specific polypeptides, only a few of which could be detecte ...19892469012
biochemical characterization of activation-associated bovine class i major histocompatibility complex antigens.utilizing a 'sandwich' elisa assay we have been able to demonstrate that mab w6/32, b1g6 and il-a19 are reactive with three different monomorphic determinants on bovine class i major histocompatibility complex (mhc) molecules. sequential immunoprecipitations performed with the mab revealed that class i molecules on pbm comprise a single population with respect to reactivity with the mab in that the beta 2m-associated proteins bear all three epitopes. by contrast, tcgf-driven lymphoblasts and cel ...19892481992
theileria parva: the immune status of calves born of dams immunised against east coast fever.eight friesian cross cows three months pregnant to a single friesian bull were immunised against east coast fever by infection with theileria parva (muguga) sporozoite stabilate and treatment with pyrrolidino-methyl tetracycline. they were challenged with the homologous stock four times before calving and a fifth time after calving, and resisted all five challenges which killed all of the five groups of five susceptible controls. calves born to these hyperimmunised dams were fully susceptible on ...19892493670
theileria parva: reappearance of schizonts in infected lymphoblastoid cells treated with parvaquone is dependent on interleukin 2-like growth factors.schizont-infected cell lines derived by in vitro infection of bovine t cell clones with the muguga isolate of theileria parva were treated for 72 hr with the theileriacidal drug, parvaquone, at a concentration of 10 micrograms/ml. this treatment completely eliminated schizonts from the recovered cells, which failed to undergo further proliferation and died. however, treated cells cultured with either bovine t cell growth factor or human recombinant interleukin 2 remained viable, underwent prolif ...19892495228
theileria parva in cattle: characterization of infected lymphocytes and the immune responses they provoke. 19892497579
immunization of cattle with a theileria parva bovis stock from zimbabwe protects against challenge with virulent t.p. parva and t.p. lawrencei stocks from kenya.following inoculation of 34 bos indicus (boran) cattle with a theileria parva bovis (boleni) stock from zimbabwe, 18 animals underwent mild theilerial reactions, 12 underwent moderate reactions, three suffered severe reactions and one died. when these animals were subsequently challenged with different virulent stocks of either t.p. parva (muguga, marikebuni or mariakani) or t.p. lawrencei (ngong 1 or nanyuki) from kenya, all except two animals resisted challenge. the two reactors were part of t ...19892506688
theilerial parasites isolated from carrier cattle after immunization with theileria parva by the infection and treatment method.groups of cattle were immunized with 10(-2) dilutions of sporozoite stabilates of theileria parva lawrencei derived from african buffaloes either alone or in combination with theileria parva parva derived from cattle and concomitant treatment with either long or short-acting formulations of oxytetracyline. at 90 or 120 days after infection, uninfected rhipicephalus appendiculatus nymphal ticks were applied to individual immunized cattle and the resultant adults ticks were applied to individual s ...19892508037
immunisation of cattle against theileriosis in coast province, kenya: laboratory evaluation of a theileria parva parva stabilate for use in 'infection and treatment' immunisation in the field.theileria parva parva marikebuni stock, previously shown to give good protection to immunised cattle in kilifi district, coast province of kenya, was chosen for large scale immunisation in the district. a large sporozoite stabilate was prepared and evaluated for efficacy and safety in the 'infection and treatment' method, using a long or short acting formulation of oxytetracycline. susceptible cattle were infected with selected doses of stabilate (10(0), 10(-1), 10(-1.7) and left either as untre ...19892508204
comparative infection rates of theileria parva lawrencei in salivary glands of rhipicephalus appendiculatus and rhipicephalus zambeziensis.three cattle, which had been experimentally infected with theileria parva lawrencei and maintained as carriers of the infection, were each infested simultaneously with clean nymphal rhipicephalus appendiculatus and rhipicephalus zambeziensis in ear bags on separate ears. after moulting, the ensuing adult ticks were fed on rabbits for 4 days and their salivary glands were examined for infective stages of the parasite. microscopic examination revealed significantly higher infection rates in the sa ...19892510107
infection with the intracellular protozoan parasite theileria parva induces constitutively high levels of nf-kappa b in bovine t lymphocytes.the intracellular protozoan parasite theileria parva causes a lymphoproliferative disease of t cells in cattle and uncontrolled lymphocyte proliferation in culture. we have identified and characterized in infected cells the transcriptional activator, nf-kappa b, whose recognition motifs have been identified in several gene enhancers important for lymphocyte-specific gene expression. nf-kappa b is normally constitutively activated in nuclear extracts derived from b cells and can be induced in t c ...19892513476
protein changes in bovine lymphoblastoid cells induced by infection with the intracellular parasite theileria parva.protein and glycoprotein changes induced in bovine lymphoblasts by infection with theileria parva were analyzed by high-resolution two-dimensional gel electrophoresis. uninfected and infected cloned bovine t and b lymphoblasts were biosynthetically labeled with [35s]methionine and their two-dimensional autoradiographic patterns were compared with each other and with the pattern obtained using purified labeled schizonts. ten proteins were found in infected cells which were not present in uninfect ...19892514355
phenotypic characterization of theileria parva schizonts by two-dimensional gel electrophoresis.biosynthetically radiolabelled theileria parva schizonts were purified from bovine lymphoblastoid cells and their proteins were analyzed by two-dimensional gel electrophoresis and autoradiography. the protein spot patterns of schizont proteins from three stocks of t. parva parva indicated that the phenotypic diversity among the stocks was minimal, with the mariakani and uganda stocks being identical and the muguga stock showing only a few differences in minor spots. comparison of the spot patter ...19892516314
infection of bovine monocyte/macrophage populations with theileria annulata and theileria parva.infection and transformation of cells of the bovine immune system by theileria annulata and t. parva were compared. preliminary experiments with mammary gland macrophages indicated that they were permissive to infection by t. annulata but only to a limited extent by t. parva. further experiments involved several purified subpopulations of bovine cells including bovine monocytes, t cells and mhc class ii positive and negative populations. these subpopulations were incubated with t. annulata or t. ...19892516673
theileria parva: bovine helper t cell clones specific for both infected lymphocytes and schizont membrane antigens.two theileria parva-specific bovine helper t cell clones were used to identify t. parva-derived antigens expressed on the surface of schizont infected lymphoblastoid cells. although the clones proliferated in response to both the immunizing (muguga) and heterologous stocks of t. parva, the patterns of the responses differed, showing that the two clones recognized different antigenic epitopes. both clones were stimulated by autologous infected cells, without an additional source of antigen-presen ...19892529135
differential response of bovine t-cell lines to membrane and soluble antigens of theileria parva schizont-infected cells.t-cell lines generated from theileria parva-immune cattle were used to identify antigens associated with schizont-infected lymphoblastoid cells. homogenates prepared from t. parva-infected cells were fractionated by differential centrifugation, and antigenically distinct soluble and membrane-bound antigens were detected by the differential stimulation of cell lines derived from two animals. activity in the soluble fraction was not attributable to either a mitogen or interleukin 2. activity in th ...19892533341
improved characterization of theileria parva isolates using the polymerase chain reaction and oligonucleotide probes.theileria parva dna was purified from piroplasms isolated from cattle infected with 5 different east african isolates of the parasite, including the east coast fever reference stock t. p. parva muguga. total cellular dna was prepared from t. parva schizont-infected bovine lymphoblastoid cell cultures (11 isolates). two probes, previously isolated from t. p. parva muguga repetitive genomic dna, were hybridized to restriction digests; closely similar restriction fragment length polymorphism (rflp) ...19892570351
infection of bovine t cell clones with genotypically distinct theileria parva parasites and analysis of their cell surface phenotype.different stocks and stabilates within a stock of theileria parva were analysed for genotypic differences and for their effect on the expression of host cell surface antigens following infection of bot8+ t lymphocyte clones. the parasites were characterized in vitro by hybridization of t. parva-specific dna probes to southern blots of endonuclease-digested dna from the infected t cell clones. phenotypic changes in the host lymphoblastoid cells before and after infection were examined using linea ...19892574438
pharmacokinetics of halofuginone in cattle.the pharmacokinetics of the antitheilerial drug halofuginone were evaluated in healthy calves following oral administration, at a dose of 1.2 mg/kg body weight, repeated after 48 h. the maximum plasma concentration after the first dose ranged from 3.8 to 7.7 ng/ml (6.5 ng/ml, mean) and occurred at between 12 and 32 h (22 h, mean). after the second dose, the maximum plasma concentration was 4.8-8.6 ng/ml (7.2 ng/ml, mean) occurring between 12 and 32 h (17 h, mean). the apparent terminal eliminati ...19892590824
transmission of theileria parva bovis (boleni strain) to cattle resistant to the brown ear tick rhipicephalus appendiculatus (neumann).four crossbred bos taurus oxen resistant to rhipicephalus appendiculatus and three tick naive oxen of the same breed, which were all infested with adult r. appendiculatus infected with the boleni strain of theileria parva bovis, acquired theileria infection. all four tick resistant oxen recovered after a mild febrile reaction. two of the tick naive oxen died while the third recovered after a protracted period. it is suggested that tick resistance in cattle may be an important factor in establish ...19892665253
expression and characterization of the interleukin 2 receptor in theileria parva-infected bovine lymphocytes.we have previously shown that interleukin 2 receptors (il2r) are constitutively expressed on the surface of bovine lymphocytes infected with the parasite theileria parva (dobbelaere, d.a.e. et al., proc. natl. acad. sci. usa 1988. 85: 4730). in the present work we characterized these further and showed that il2r (tac antigen) gene expression depended on the continuous presence of the parasite in the host cell cytoplasm. by northern blot analysis we showed that elimination of the parasite, using ...19892786471
the role of the mhc in immunity of cattle to the protozoan parasite theileria parva. 19892817738
chemotherapy of east coast fever. treatment of infections induced by isolates of theileria parva with halofuginone.cattle were infected with three isolates of theileria parva and treated with halofuginone lactate during acute clinical disease. the health, weight gain and carrier state of the cattle were monitored for 15 months. limited treatment rapidly reduced fever and parasitosis but parasite recrudescences occurred and 12 out of 21 treated cattle died. persistent carrier states were identified with two t. p. parva isolate infections and a transient carrier state with t. p. lawrencei. three cattle which d ...19862874713
chemotherapy of field cases of east coast fever using halofuginone lactate.the chemotherapeutic effect of halofuginone lactate (terit, hoechst) was tested against natural pathogenic theileria parva infections (east coast fever, ecf) in 24 cattle. halofuginone lactate, administered per os, 1.2 mg per kg b.wt and repeated after 48 h manifested a potent schizonticidal effect, observed between 5 and 11 days post treatment. disappearance of erythrocytic forms (ef) took long, ranging from 6 to 34 days post treatment. differences on efficacy between halofuginone lactate table ...19862882667
dna probes detect genomic diversity in theileria parva stocks.different stocks of theileria parva were analysed for restriction fragment length polymorphisms by agarose gel electrophoresis, orthogonal-field-alternation gel electrophoresis (ofage) and southern hybridization with dna probes. polymorphisms seen with dna from purified piroplasms of different t. parva stocks, after digestion with restriction enzymes, were more clearly apparent with ofage than with standard agarose gel electrophoresis. genomic differences between these theilerial parasites were ...19872892129
theileria parva: genomic dna studies reveal intra-specific sequence diversity.theileria parva parva piroplasm dna was purified from 11 different infections of cattle with 6 different east african isolates of the parasite. total dna was also prepared from bovine lymphoblastoid cells infected with schizonts of one of the isolates. two of the infections were with cloned parasites. the dna was of high molecular weight and free from protein and rna, but some of the samples contained a proportion of bovine dna. the 6 samples least contaminated with bovine dna had a mean 'meltin ...19882897626
isolation of theileria parva schizonts from infected lymphoblastoid cells.this study set out to develop a rapid method for the isolation of schizonts from theileria parva-infected bovine and buffalo lymphoblastoid cells. parasitized lymphoblastoid cells were lysed by treatment with the cytolytic toxins, aerolysin and ah-1 hemolysin, produced by aeromonas hydrophila, and the schizonts were separated by percoll density-gradient centrifugation. light and electron microscopic examination showed that the isolated schizonts from lymphoblastoid cells infected with t. parva ( ...19882903622
the bovine autologous theileria mixed leucocyte reaction: influence of monocytes and phenotype of the parasitized stimulator cell on proliferation and parasite specificity.in the autologous theileria mixed leucocyte reaction (mlr), irradiated theileria parva-infected cells induce proliferative responses in autologous peripheral blood mononuclear leucocytes (pbm), irrespective of the immune status of the donor animal. in this paper we have analysed the cellular basis of this response in naive and immune cattle to determine the theileria specificity of the response. the magnitude of proliferation is dependent on two parameters, namely the presence or absence of mono ...19872950050
a study of bola class ii antigens with bot4+ t lymphocyte clones.it has hitherto proved difficult to phenotype cattle for class ii histocompatibility antigens using standard serological techniques because of problems of reagent specificity and antigen expression on peripheral blood mononuclear cells (pbms). we recently described the production of class ii-specific alloreactive bovine t cell clones characterized by the bot4+ phenotype. in this report we describe studies of the application of four such clones, derived from a single mixed leucocyte culture (mlc) ...19872955723
corridor disease in south africa: a review of the current status.the african buffalo (syncerus caffer) is a reservoir host of theileria parva lawrencei the causative organism of corridor or buffalo disease of cattle. this organism can apparently transform its behaviour when tick-passaged through cattle to resemble that of theileria parva parva, causing classic east coast fever (ecf). these are major considerations for the strict quarantine measures imposed on buffaloes from corridor disease endemic areas in south africa. results of continuing studies on diagn ...19883058976
passive endocytosis of sporozoites of theileria parva in macrophages at 1-2 degrees c.phagocytosis by macrophages is generally considered to involve two steps which can be experimentally dissociated: attachment, which is not energy-dependent, and interiorization, which does not occur below 15 degrees c. we have previously reported entry of the sporozoites of theileria parva into bovine lymphocytes at 2 degrees c by a process of passive endocytosis which appears to depend entirely upon progressive circumferential binding of ligands on the parasite to receptors on the host cell mem ...19863083113
chemotherapy of east coast fever: the long term weight changes, carrier state and disease manifestations of parvaquone treated cattle.the weight changes, carrier state and nature of chronic disease in cattle following infection with five isolates of theileria parva and treatment with parvaquone were studied over an 18 month period while the cattle were maintained on normal management under strict tick control. cattle infected with the t.p. parva pugu ii isolate gained weight similarly to uninfected control cattle and did not develop a detectable carrier state or show chronic disease. the cattle in the 4 other isolate groups re ...19863084600
induction of immunity against infection with theileria parva (east coast fever) in cattle using plasma membranes from parasitized lymphoblasts.protection against challenge with theileria parva was conferred on three of four calves given three or four inocula of plasma membranes prepared from 6 to 12 x 10(8) autologous parasitized lymphoblasts from cultured cell lines. in contrast, calves remained susceptible to infection following immunization with membranes prepared from allogeneic parasitized lymphoblasts. similarly, calves vaccinated with either gamma-irradiated autologous or allogeneic infected cells also died of east coast fever a ...19863085324
comparative analysis of infection and transformation of lymphocytes from african buffalo and boran cattle with theileria parva subsp. parva and t. parva subsp. lawrencei.this study compared infection and transformation of peripheral blood mononuclear cells (pbm) of boran cattle and african buffalo in vitro to determine whether differences occurred which could account for the greater susceptibility of boran cattle to infection with theileria parva subsp. parva and t. parva subsp. lawrencei. pbm from buffalo and cattle had a similar percentage of cells which bound t. parva subsp. parva sporozoites (24 to 34%) and in which schizonts developed during the first week ...19863087880
bovine cytotoxic t-cell clones specific for cells infected with the protozoan parasite theileria parva: parasite strain specificity and class i major histocompatibility complex restriction.we present information on the specificity of three bovine cytotoxic t-cell clones reactive with lymphoblasts infected with the protozoan parasite theileria parva. the clones were derived from peripheral blood mononuclear cells of an animal immunized with t. parva (muguga stock), after five stimulations in vitro with an autologous parasitized cell line. the three clones belonged to the bot8+ subset of t cells, which is similar to the human cd8+ t-cell subset. on the basis of analysis on a panel o ...19863088572
maintenance of theileria parva parva infection in an endemic area of kenya.the maintenance of theileria parva parva infection in an endemic area of kenya on the shore of lake victoria was studied in the field and laboratory. high prevalences of antibodies against t. parva and t. mutans and intra-erythrocytic piroplasms were detected in local zebu (bos indicus) cattle. the mean infection rate of theileria parasites in the tick, rhipicephalus appendiculatus, in field collections was 1.1%. most of the infection was attributed to t. parva parva by application of field tick ...19863092172
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