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the influence of various bovine sera on the maintenance of theileria parva lymphoblastoid cell culture.theileria parva infected lymphoblastoid bovine cells were grown in a medium based on hepes-buffered rpmi 1640 with glutamine and antibiotics, supplemented with bovine serum. there were no significant differences in growth rate, viability, and percentage of infected cells when the substrate contained 10 or 20 per cent of either commercially available newborn calf serum of serum prepared from adult non-infected friesian cattle or of serum prepared from a friesian calf immunised against east coast ...19826815877
titration in cattle of infectivity and immunogenicity of autologous cell lines infected with theileria parva.cell lines infected with theileria parva were derived by infection of bovine peripheral blood lymphocytes with sporozoites in vitro. cattle were inoculated with doses of autologous infected cells ranging from 1 x 10(1) to 1 x 10(8). infection became established in animals which received 1 x 10(2) or more cells. while 1 x 10(2) cells resulted in sub-patent infection with development of immunity to challenge with sporozoites, larger doses of cells gave rise to patent infections of increasing sever ...19846435303
superinfection of established theileria-infected bovid cell lines with theileria parva sporozoites. 19846435553
chemotherapy of theileria parva lawrencei infections in cattle with halofuginone.halofuginone lactate, given once orally at a dosage rate of 1,2 mg/kg body mass on the 1st, 3rd or 5th days of fever, resulted in the recovery of only 1 out of 5 splenectomized cattle. three splenectomized animals, treated on the 1st as well as the 4th day of fever, recovered and were then carriers. six untreated controls all died. the potential value of a chemotherapeutic agent for theileria parva lawrencei infections in south africa is discussed.19836877791
characterization of the effector cell that mediates cytotoxicity against theileria parva (east coast fever) in immune cattle.after fractionation and depletion of peripheral blood leukocytes from cattle that were immune to theileria parva, the effector cells which mediated cytotoxicity against parasitized autologous lymphocytes were considered to be thymusderived lymphocytes.19816972917
the eradication of east coast fever in south africa.an epizootic of east coast fever followed the introduction of a highly fatal strain of theileria parva parva into south africa in 1902. this is a brief historical review of the campaign to control and finally eradicate the disease through tick control, quarantine and the slaughter of exposed cattle. the disease was responsible for an estimated 5.5 million deaths before its final eradication in 1954.19817021829
comparison of long acting oxytetracycline and parvaquone in immunisation against east coast fever by infection and treatment.two groups of five cattle were immunised with a field isolate of theileria parva as stabilate and simultaneously treated with long acting oxytetracycline or parvaquone in early clinical disease. the oxytetracycline group suffered a marked fall in leucocyte count and one animal died during immunisation. the parvaquone group suffered a less severe fall in leucocyte count and all survived. the surviving immunised cattle were immune to homologous challenge but susceptible to subsequent challenge wit ...19846438743
a comparative study of the disease in cattle caused by theileria parva or t. lawrencei: ii. hematology, clinical chemistry, coagulation studies and complement.theileria lawrencei tick-derived stabilate infection of 8 cattle resulted in the development of panleukopenia and hypoproteinemia. in addition to these changes, t. parva infection caused mild normocytic, normochromic, non-responsive anemia at either of two dose rates. disseminated intravascular coagulation, as indicate by positive protamine paracoagulation tests, prolonged prothrombin and partial thromboplastin times, and thrombocytopenia, developed in cattle infected with either of the theileri ...19827201709
sequential study of lymph node and splenic aspirates during theileria parva infection in calves.the development of theileria parva infection in calves with partially exteriorised spleens was studied. macroschizont infected cells were detected in the spleen and prescapular lymph node on the same day following inoculation of stabilate in front of the ear, indicating a haematogenous dissemination of the parasite. macroschizont infection reached a peak on day 14 in the lymph nodes and in the spleen. the time to the appearance of of piroplasms and the development of parasitaemia were similar in ...19817255908
the effect of immunisation with bcg on theileria parva infection in cattle.cattle were immunised with 10(8) bacillus calmette-guerin (bcg) organisms 32 days before challenge with a lethal dose of theileria parva stabilate. the disease reactions of immunised and control cattle were similar and all infected cattle died. it is suggested that the failure of bcg to protect cattle against t parva infection is because the cattle response to this non-specific immunisation is poorly developed.19807375725
survival of rhipicephalus appendiculatus (acarina: ixodidae) and persistence of theileria parva (apicomplexa: theileriidae) in the field. 19846439668
partial inhibition of theileria parva-infected t-cell proliferation by antisense il2r alpha-chain rna expression.antisense rna expression was used to assess the role of the interleukin 2 receptor (il2r) alpha-chain in proliferation of t cells transformed by infection with the intracellular parasite theileria parva. two vectors were constructed, in which part of the bovine il2r alpha-chain cdna was inserted in either a sense or antisense orientation in the plasmid phs1-cat, which is expressed by induction of the human metallothionein iia (hmt-iia) with cadmium (cd2+). a t. parva-infected t-cell line, tpm(80 ...19957481077
a rapid method to select rhipicephalus appendiculatus salivary glands infected with theileria parva. 19846439849
genetically restricted cell-mediated cytotoxicity in cattle immune to theileria parva. 19816451808
a histocompatibility barrier to immunization against east coast fever using theileria parva-infected lymphoblastoid cell lines.histocompatibility may be a barrier to the infection of cattle when theileria parva parva-infected tissues or in vitro cultured macroschizont-infected lymphoblastoid cell lines are used for immunization. by inoculating 10(3) and 10(5) infected cells into autologous recipients infection was achieved and immunity engendered. cell lines inoculated into bola matched recipients did not produce patent infections but some recipients developed antibodies to the parasite and 3/5 were immune to challenge. ...19846739121
theileria parva: isolation of macroschizonts from in vitro propagated lymphoblastoid cells of cattle. 19816797837
theileria? taurotragi: a probable agent of bovine cerebral theileriosis.a case of bovine cerebral theileriosis was confirmed at autopsy on a farm where 4 animals out of 70 died. all were less than 2 years old and all showed nervous signs. serologically, no evidence was found of theileria mutans or the theileria parva group in young animals born on the farm. six out of 13 calves 6-9 months of age were, however, serologically positive for theileria? taurotragi and it was concluded this species was the probable cause of death of the 4 animals.19816801568
theileriosis: cell-mediated and humoral immunity.the protozoan parasite of cattle theileria parva transforms lymphoid cells into permanently proliferating cell lines. antibodies reacting with parasite antigens can be detected by several methods, but there is no evidence that they are protective. two cellular responses to infection have been found. in immune animals powerful cytotoxicity restricted to syngeneic infected cells rapidly appears; this is thought to be mediated by t-lymphocytes and to play a major role in resistance to reinfection. ...19816781356
the entry of sporozoites of theileria parva into bovine lymphocytes in vitro. electron microscopic observations.the entry of sporozoites of theileria parva into bovine lymphoid cells in vitro was studied with the electron microscope. endocytosis is completed in less than 10 min. no local mobilization of actin or other cytoskeletal elements is detected in the cytoplasm of the cell being invaded and no engulfing pseudopods are formed. at the site of initial contact, the membranes of parasite and host cell come into very close apposition. as the zippering up of the membranes spreads laterally, the sporozoite ...19826806100
salivary gland of the tick vector of east coast fever. iii. the ultrastructure of sporogony in theileria parva.sporogony of the sporozoan theileria parva in the salivary gland of the tick vector of east coast fever was studied in electron micrographs. the findings differ in several respects from previous interpretations based upon light microscopy. cytokinesis of the primary sporoblast to form secondary and tertiary sporoblasts is not substantiated. instead it is suggested that the parasite develops as a ramifying, multinucleate syncytium rapidly increasing in size and complexity until it gives rise to m ...19826806940
theileria parva parasites transform a subpopulation of t lymphocytes. 19816787130
evaluation of an enzyme immunoassay for serodiagnosis of infections with theileria parva and t annulata.an enzyme linked immunosorbent assay (elisa) was used to determine antibody levels in cattle infected with theileria parva and t annulata, using antigens prepared from the intra-erythrocytic piroplasm stage of the parasites. antibody levels in calves infected with t parva increased from the 16th day after infection to reach peak values at days 28 to 35 and then declined rapidly, but in calves infected with t annulata antibody levels rose steadily up to day 40. similar patterns of antibody produc ...19806789420
adoptive transfer of immunity to infection with theileria parva (east coast fever) between cattle twins.resistance to a lethal challenge with theileria parva (muguga) was transferred between two pairs of chimeric bovine co-twins with 5 to 9 x 10(10) syngeneic thoracic duct leucocytes from the immunised partner. in one recipient, the infection became established and was eliminated. in the second recipient, the disease did not become patent. both recipients were immune to a second challenge of t parva (muguga). the results confirm both that chimeric twin calves are suitable as a model for the adopti ...19816789424
in vitro activity of 2-alkyl-3-hydroxy-1,4-naphthoquinones against theileria parva.a variety of naphthoquinones have veen prepared and evaluated in vitro against the causative agent of the cattle disease east coast fever-theileria parva infection. it is concluded from structure-activity studies that a 2-hydroxyl moiety es essential for high activity. the most active compounds tested were 2-hydroxy-3-alkyl-1,4-naphthoquinones in which the alkyl moiety was cyclohexyl, cyclohexylcyclohexyl, tridecyl, or tetradecyl.19816790703
treatment of stabilate-induced east coast fever with menoctone.groups of cattle were infected with theileria parva by the injection of stabilate material prepared from infected rhipicephalus appendiculatus ticks. the cattle were treated with the hydroxy alkylated naphthoquinone, menoctone, which was administered intravenously (i/v), intramuscularly (i/m), or orally (p/o) up to 4 days after the disease became apparent. the disease was rapidly controlled and all the treated cattle (15) recovered following (i/v) or i/m injection of a single dose of menoctone a ...19816806956
characterization of the gene encoding the polymorphic immunodominant molecule, a neutralizing antigen of theileria parva.theileria parva, a tick-transmitted protozoan parasite related to plasmodium spp., causes the disease east coast fever, an acute and usually fatal lymphoproliferative disorder of cattle in africa. previous studies using sera from cattle that have survived infection identified a polymorphic immunodominant molecule (pim) that is expressed by both the infective sporozoite stage of the parasite and the intracellular schizont. here we show that mab specific for the pim ag can inhibit sporozoite invas ...19957636202
the initial stages of infection of cattle cells with theileria parva sporozoites in vitro.large numbers of theileria parva sporozoites were separated from rhipicephalus appendiculatus adult ticks by filtration and were then concentrated by centrifugation. the sporozoites were incubated at 37 degrees c with leucocytes from 6 cattle of bos indicus and b. taurus types. giemsa-stained smears and living preparations under interference contrast microscopy were used to follow the course of the infection of the leucocytes with sporozoites. sporozoites were seen to attach rapidly to about 25% ...19816791118
development and evaluation of pcr assay for detection of low levels of cowdria ruminantium infection in amblyomma ticks not detected by dna probe.the sensitivities of a pcr assay and a dna probe assay were compared for the detection of cowdria ruminantium in amblyomma ticks that were fed on c. ruminantium-infected, clinically reacting, and recovered carrier animals. the pcr assay and dna probe detected infection in 86.0 and 37.0%, respectively, of 100 ticks fed on a febrile animal. in 75 ticks fed on carrier animals, pcr and the dna probe detected infection in 28.0 and 1.33% of ticks, respectively. this demonstrates that the dna probe has ...19957699036
isolation of theileria parva (sao hill) and theileria parva (west kilimanjaro) and their cross-immunity with theileria parva (kasoba).two theileria parva stocks were isolated from control cattle during east cost fever (ecf) field immunization trials at sao hill and west kilimanjaro in the southern and northern parts of tanzania respectively. both parasite stocks caused severe clinical ecf which required antitheilerial treatment for 3 of the 5 experimentally infected cattle. cattle recovering from infection with the two t. parva stocks did not develop a fever and only 1 of 4 animals developed scanty schizont parasitosis for one ...19947709032
electron microscopical study on the effect of halofuginone on theileria parva.the effect of halofuginone (stenorol) on schizonts of theileria parva was studied by means of the electron microscope. after administration of 1,2 mg halofuginone per kg, it was observed that infected lymphocytes burst apart, whereas the intracellular parasites were at first little affected, showing some expansion of the perinuclear spaces. once they were released from the cells, the schizonts degenerated completely. apparently they are not capable of surviving outside the host cells. probably t ...19816808727
the response of bos taurus and bos indicus cattle types to inoculation of lymphoblastoid cell lines infected with theileria parva schizonts.in a preliminary experiment eight bos indicus type cattle were inoculated with 10(9) cells of a bos taurus lymphoblastoid cell line infected with theileria parva schizonts. four cattle showed patent infections and one died of theileriosis. on challenge of the surviving cattle with a tick derived stabilate of the same stock of t. parva no animal died of theileriosis. to test the susceptibility of bos taurus and bos indicus cattle to cell lines of both cattle types infected with t. parva of the sa ...19826808728
theileria parva carrier state in naturally infected and artificially immunised cattle.rhipicephalus appendiculatus adult ticks, collected in the field from zebu (bos indicus) and exotic (bos tarus) cattle with high antibody titres to theileria parva schizont antigen, transmitted theileria parva infection typical of east coast fever to susceptible cattle. uninfected r. appendiculatus nymphs applied to naturally recovered zebu and exotic cattle kept under tick-free conditions in the laboratory for 16 and 7 months respectively, transmitted fatal theileriosis to susceptible cattle. c ...19957770947
epidemiology of east coast fever: some effects of temperature on the development of theileria parva in the tick vector, rhipicephalus appendiculatus.the moulting behaviour of nymphal rhipicephalus appendiculatus from the laboratory colony and 3 field strains from kenya was greatly influenced by constant temperatures between 18 and 37 degrees c but was not significantly different for the 4 tick strains. six batches of r. appendiculatus (muguga laboratory) nymphs which had engorged on cattle parasitaemic with 4 stocks of theileria parva (kiambu 4, kiambu 5, muguga and mbita 4) isolated in kenya were incubated at constant temperatures between 1 ...19816791119
production of rhipicephalus appendiculatus with high infections of theileria parva. 19816795330
salivary gland of the tick vector of east coast fever. iv. cell type selectivity and host cell responses to theileria parva.responses of cells in the tick salivary gland to parasitism by theileria parva were studied by electron microscopy. the gland is composed of three distinct types of acini (i, ii, iii) which together include ten or more different cell types. of some 30 infected cells observed in the present study, all were e-cells of acinus iii. the parasite thus exhibits a high degree of selectivity for acinus and cell type. the glandular cell invaded undergoes massive hypertrophy and accumulates glycogen deposi ...19826810500
lack of reactivity of sera from theileria parva-infected and recovered cattle against cell membrane antigens of theileria parva transformed cell lines.sera from theileria parva infected, recovered and rechallenged cattle were tested in complement-dependent cytotoxicity, membrane immunofluorescence and antibody-dependent cellular cytotoxicity assays for the presence of antibodies against cell membrane antigens of t. parva transformed cell lines. in the complement-dependent antibody-mediated cytotoxicity assay, sera from lethally infected animals were negative. some recovered cattle showed a positive reaction, but such reactions were also observ ...19826812275
cycle of bovine lymphoblastoid cells parasitised by theileria parva.the events were studied which occurred during different stages of the cell cycle of bovine lymphoblastoid cells infected with the parasite theileria parva. the mean number of nuclei in macroschizonts was about 16 for cells in interphase and 30 for those in metaphase. pulse labelling with 3h thymidine showed that macroschizonts normally incorporated thymidine when the host cell was in early mitosis. thymidine incorporation by macroschizonts thus occurred at a different stage in the cell cycle to ...19826818647
indirect fluorescent antibody test for experimental and epizootiological studies on east coast fever (theileria parva infection in cattle). evaluation of a cell culture schizont antigen fixed and stored in suspension.a schizont antigen for the indirect fluorescent antibody test against theileria parva was prepared from a t parva-infected bovine lymphoblastoid cell line by fixing the cells in suspension with a mixture of acetone and formaldehyde. the antigen was stored in suspension in phosphate buffered saline for one and a half years at -60 degrees c without loss of activity; the antigen could also be lyophilised. the fluorescence of the intracellular schizonts was bright and specific with t parva positive ...19826818649
salivary gland of the tick vector (r. appendiculatus) of east coast fever. i. ultrastructure of the type iii acinus.the brown ear tick rhipicephalus appendiculatus is the vector for east coast fever, a disease that seriously limits livestock production in east africa. the sporozoites of the infectious agent theileria parva develop in the tick salivary gland. this paper describes the organization of the type iii acinus of the gland and establishes unambiguous ultrastructural criteria for identification of the three secretory cell types: the d-cell, e-cell and f-cell. these observations are basic to exploration ...19817198303
dna measurements and ploidy determination of developmental stages in the life cycles of theileria annulata and t. parva.the relative dna levels of different developmental stages of theileria annulata and t. parva in the cow and the tick were measured by the cytophotometric dna technique using the fluorochrome hoechst 33258 as a staining dye. the results revealed that sporozoites, merozoites, gamonts, and gametes were haploid, whereas multinucleated intralymphocytic schizonts were polyploid. no difference was observed between t. parva and t. annulata in these stages. for both theileria species, the dna measurement ...19957479648
detection of theileria parva in the salivary glands of rhipicephalus appendiculatus: evaluation of staining methods.a comparison of ten methods for staining tick salivary glands for detection of theileria parva infection from ticks fed on rabbits for various periods was undertaken. staining with azure without hydrochloric acid hydrolysis was found to be the most reliable method for detection of the presporozoite stages (sporoblasts) of t. parva in the salivary gland acini of unfed rhipicephalus appendiculatus and could be applied to field ticks. all the stains proved suitable for the detection and quantitatio ...19957536922
parasite strain specificity of bovine cytotoxic t cell responses to theileria parva is determined primarily by immunodominance.the parasite strain specificity of ctl responses to theileria parva varies among cattle immunized with the same parasite stock. we have investigated the influence of class i mhc on the strain specificity of ctl responses to t. parva in 19 cattle of defined class i phenotype immunized with either of two t. parva populations, in which protection to subsequent reciprocal challenge correlated with ctl strain specificity. in the majority of animals the response was restricted by the products of one m ...19957594488
immunity to a parasite that transforms t lymphocytes.the past year has seen the first direct evidence that parasite-specific cd8+ t cells can protect cattle against patent infection with theileria parva. these studies were based on the adoptive transfer between monozygous twins of lymphocytes responding to a challenge with the parasite. immunization trials are also continuing with a candidate neutralizing vaccine based on the dominant antigen of the t. parva sporozoite surface. this progress has considerably enhanced the prospects for an improved ...19947946043
characterisation of the telomeres at opposite ends of a 3 mb theileria parva chromosome.bacteriophage lambda clones containing theileria parva genomic dna derived from two different telomeres were isolated and the nucleotide sequences of the telomeric repeats and adjacent telomere-associated (tas) dna were determined. the t.parva telomeric repeat sequences, a tandem array of ttttaggg or tttaggg interspersed with a few variant copies, showed a high degree of sequence identity to those of the photosynthetic algae chlamydomonas reinhardtii (97% identity) and chlorella vulgaris (87.7% ...19957596822
targeting ticks for control of selected hemoparasitic diseases of cattle.development in and transmission of hemoparasites by tick vectors are phenomena closely synchronized with the tick feeding cycle. in all known life cycles, initial infection of tick tissues occurs in midgut epithelial cells and transmission is effected as ticks feed after parasites have developed and multiplied in salivary glands. many factors reviewed affect development and transmission of hemoparasites by ticks including age of ticks, artificial temperature, climate and/or season, tick stage or ...19957597779
characterization of theileria parva which infects waterbuck (kobus defassa).theileria-free waterbuck (kobus defassa) born in captivity were successfully infected with theileria parva sporozoites derived from ticks infected by feeding on african buffalo (syncerus caffer). all waterbuck underwent mild infections with the development of sporadic schizont and piroplasm parasitosis when inoculated with sporozoite doses lethal to cattle. a carrier state of t. parva was demonstrated by feeding clean r. appendiculatus nymphs on two of these infected waterbuck. tick batches from ...19948052510
theileriosis: progress towards vaccine development through understanding immune responses to the parasite.studies of the immune responses of cattle to theileria parva have provided evidence that immunity to the parasite can operate at two levels, namely the sporozoite and the schizont-infected lymphoblast. antibodies that neutralize the infectivity of sporozoites have been detected in the serum of hyperimmunized cattle, and a recombinant sporozoite surface antigen has been shown to induce neutralizing antibodies and protection against experimental challenge. however, the immunity that develops follo ...19957597782
identification of candidate vaccine antigens of bovine hemoparasites theileria parva and babesia bovis by use of helper t cell clones.current vaccines for bovine hemoparasites utilize live attenuated organisms or virulent organisms administered concurrently with antiparasitic drugs. although such vaccines can be effective, for most hemoparasites the mechanisms of acquired resistance to challenge infection with heterologous parasite isolates have not been clearly defined. selection of potentially protective antigens has traditionally made use of antibodies to identify immunodominant proteins. however, numerous studies have indi ...19957597783
live vaccines against hemoparasitic diseases in livestock.live vaccines against hemoparasitic diseases in livestock are based on parasites derived from culture (theileria annulata), from blood of infected animals (babesia bovis, babesia bigemina, anaplasma centrale, (attenuated) anaplasma marginale and cowdria ruminantium), and from ticks (theileria parva). the t. annulata attenuated cultured schizont vaccine is safe for all varieties of cattle. blood derived vaccines are recommended mainly for young cattle, the age limit varying with the different vac ...19957597786
estimation of heritability of susceptibility to infection with theileria parva in the tick rhipicephalus appendiculatus.heritability of susceptibility to infection with theileria parva was estimated from full sib families of rhipicephalus appendiculatus ticks. male and female ticks of 2 stocks were mated singly. nineteen full sib families of the muguga stock and 17 full sib families of the kiambu stock were obtained. nymphae of these families were fed on cattle infected with t. parva so that the ticks became replete on days 16 and 17 after infection when the blood was parasitaemic with intraerythrocytic piroplasm ...19957609988
the naming game: the changing fortunes of east coast fever and theileria parva.since first being recognised at the turn of the century, east coast fever of cattle and its causal parasite theileria parva have undergone numerous name changes as scientists have observed differences in the distribution, severity, characteristics and host associations of the disease within africa. these changes have caused considerable confusion to scientists and affected the control of infections caused by t parva in the field. the justification for the decisions affecting the nomenclature of ...19938128551
generation and characterization of cloned theileria parva parasites.a 3-step procedure for cloning theileria parva parasites was developed. the first step involved the in vitro infection of a fixed number of bovine lymphocytes with titrated sporozoites. the cell lines obtained from infections initiated using sporozoite/lymphocyte ratios below 1:100 were then selected for cloning as these contained schizont-infected cells, each of which was derived from infection with a single sporozoite. in the second step, these cell lines were cloned by limiting dilution. as s ...19957609989
mhc class i molecules are an essential cell surface component involved in theileria parva sporozoite binding to bovine lymphocytes.the major histocompatibility complex (mhc) class i molecules are ubiquitous cell surface molecules involved in the cell-mediated immune response. we show here, using a number of different, independent approaches, that these proteins are an essential component of the host cell surface receptor involved in theileria parva sporozoite invasion. monoclonal antibodies (mabs) reactive with common determinants on mhc class i molecules and with beta-2 microglobulin inhibited sporozoite entry by specifica ...19957615677
humoral immune responses to theileria parva in cattle as measured by two-dimensional western blotting.humoral immune responses to schizont antigens from six stocks of theileria parva were compared by two-dimensional western blotting using sera from cattle that had been infected with a t. parva stock or a clone. isoelectric points of a polymorphic immunodominant molecule (pim) of schizonts that induces strong antibody responses in cattle ranged from acidic to basic. molecular masses (mr) of the pim of the respective t. parva stocks were as follows: t. parva muguga, 86 kda; mariakani, 83 kda; mari ...19957624293
differential development and emission of theileria parva sporozoites from the salivary gland of rhipicephalus appendiculatus.the initiation of feeding of infected rhipicephalus appendiculatus adults induces the rapid development of theileria parva sporoblasts within the salivary gland acini leading to the production of numerous sporozoites which are inoculated into the mammalian host initiating infection. in this study the pattern of development, host cell specificity and emission of t. parva sporozoites within the salivary glands of heavily infected, 4-day fed adult r. appendiculatus ticks was examined. infected acin ...19957675529
sequence and expression of a 90-kilodalton heat-shock protein family member of theileria parva.a theileria parva specific full-length cdna clone, t7, which encodes a protein with more than 60% homology to heat shock protein 90 (hsp90) of other organisms, has been identified. t7 appears to be a single copy gene. the gene is expressed as a protein of 87 kda in both the sporozoite and schizont stages of t. parva. the protein was not found in the piroplasm stage, although the corresponding transcript was detected, suggesting post-transcriptional regulation of the gene. in the schizont stage t ...19947739669
characteristics of tick, rhipicephalus appendiculatus, glands distinguished by surface lectin binding.incubation of fluorescein-conjugated and biotinylated lectins with rhipicephalus appendiculatus salivary glands revealed differences between the basal laminae of the haemocoelic surfaces of the three acinal types. there were some similarities in the lectin binding characteristics of the surfaces of type ii and type iii acini when con a, pna and tva were applied, indicating the presence of galactose, mannose and glucose moieties on the acinal surfaces. the binding of bpa, hpa and haa lectins, spe ...19938311579
nitric oxide inhibits establishment of macroschizont-infected cell lines and is produced by macrophages of calves undergoing bovine tropical theileriosis or east coast fever.nitric oxide (no) was produced when bovine peripheral blood mononuclear cells (pbmc) or purified, adherent pbmc (macrophages) were incubated in vitro with bovine recombinant interferon gamma (bo rifn-gamma). no was produced by cells from naive, uninfected calves as well as by cells from cattle either infected with or recovered from infection with theileria annulata or theileria parva. pbmc of cattle undergoing tropical theileriosis (t. annulata infection) or east coast fever (t. parva infection) ...19957761113
effects of haemagglutination (lectin) inhibitory sugars on theileria parva infection in rhipicephalus appendiculatus.we have previously described the presence of haemagglutinins in tissues of the tick, rhipicephalus appendiculatus and determined their sugar specificities by inhibition experiments. in this study, haemagglutination inhibitory sugars are shown to have an effect in vivo on the abundance of theileria parva infected salivary gland acini in rhipicephalus appendiculatus. a significant increase (p < 0.05) was observed in t. parva acinar infection rates in the salivary glands of r. appendiculatus fed on ...19957797369
evidence for two single copy units in theileria parva ribosomal rna genes.bacteriophage clones containing ribosomal rna genes of theileria parva were isolated from genomic dna libraries. physical mapping studies revealed 2 ribosomal dna units, which were distinguishable by restriction enzyme site polymorphisms in flanking sequences. the cloned ribosomal dna units were mapped to 2 separate t. parva chromosomes. analysis of sequences contained in lambda embl3 recombinants, together with southern blot analysis of genomic dna and data on the copy number of the rrna genes, ...19947808475
theileria: improved species discrimination using oligonucleotides derived from large subunit ribosomal rna sequences.partial nucleotide sequences of large subunit ribosomal rna (lsu rrna) coding genes of theileria parva and t. taurotragi were determined. alignment of the t. parva and t. taurotragi sequences revealed species-specific regions within the lsu rrna genes. a major species-variable region, located between the first and second conserved secondary structure domains of lsu rrna, was identified. the sequence of the major species-variable region was determined for t. annulata, t. buffeli, and an unclassif ...19957821400
the growth of cell culture-attenuated rinderpest virus in bovine lymphoblasts with b cell, cd4+ and cd8+ alpha/beta t cell and gamma/delta t cell phenotypes.cloned bovine lymphoblastoid cell lines, transformed by the protozoan parasite theileria parva were infected with cell culture-attenuated rinderpest virus vaccine. the virus grew readily in lymphoid b cells, cd4+ and cd8+ alpha/beta t cells and gamma/delta t cells producing new infectivity, viral antigens, c.p.e. and total cell death. there did not appear to be a predilection for any particular phenotype of lymphoblast. the results imply that if the vaccine causes immunosuppression, it could do ...19938429305
characterization of an insect cell-derived theileria parva sporozoite vaccine antigen and immunogenicity in cattle.previous data showed that six out of a group of nine cattle inoculated with ns1-p67, a recombinant form of a 67-kda theileria parva sporozoite surface protein, were immune to east coast fever. this bacterially expressed antigen encoded all 709 amino acid residues of p67 fused to the c-terminal end of 87 residues derived from ns1, a structural protein of influenza virus, and a linker dna sequence. ns1-p67 lacked reactivity with tpm 12, a monoclonal antibody to native p67, and had an estimated mol ...19957822014
molecular characterization of theileria parasites: application to the epidemiology of theileriosis in zimbabwe.forty theileria schizont-infected lymphocyte culture isolates from zimbabwe were characterized using a panel of antischizont monoclonal antibodies (mabs) and 4 theileria parva dna probes containing cloned extrachromosomal element, tpr repetitive, ribosomal and telomeric sequences. the theileria isolates were assigned as t. parva or t. taurotragi on the basis of reactivities with mabs and restriction fragment length polymorphisms (rflps) detected using the extra-chromosomal element probe. cattle- ...19947831093
casein kinase ii in theileriosis. 19957846527
an assay for the identification of antigens recognized by cytotoxic t cells, based on transient transfection of cos cells.the studies reported here describe methodology permitting the direct identification of antigens recognized by cytotoxic t lymphocytes. we demonstrated that bovine alloreactive ctl can detect a bovine mhc molecule transiently expressed in a cos cell population in a standard microcytotoxicity assay. we then showed that alloreactive ctl can detect cells expressing the bovine class i mhc molecule in a population of cells transfected with the plasmid containing the corresponding gene plus 100-fold as ...19957490463
characterization of a late activation antigen defined by monoclonal antibodies of cluster bowc8 (tc23).three monoclonal antibodies (mabs), p13 (#90), il-a78 (#76) and il-a79 (#77), defined a new cluster, called bowc8. the antigen defined by these mabs is a molecule of 160 kda under reducing conditions, and is expressed on lymphocytes late (6 days) after activation. the molecule can be expressed on multiplying t cells, but not on b cells.19937508656
preliminary analysis of the transmission dynamics of theileria parva in eastern africa.two mathematical models are developed that investigate the transmission dynamics of theileria parva by the ixodid tick rhipicephalus appendiculatus to cattle in endemically stable areas. a method of estimating the rate of infection to cattle of t. parva at the endemically stable state is given. empirical estimates of all the parameters in the model are available. the degree to which animals that have recovered from theileriosis (the 'carrier' state) are able to transmit the infection to tick nym ...19938488062
theileriosis in zambia: etiology, epidemiology and control measures.in zambia, theileriosis manifests itself in the form of corridor disease (cd), caused by theileria parva lawrencei, and east coast fever (ecf), caused by t. parva parva. of the approximately 3 million cattle in zambia, 1.4 million are at risk to theileriosis. ecf is found in the northern and eastern provinces of the country, while cd appears in southern, central, lusaka and copperbelt provinces. theileriosis is a major constraint to the development of the livestock industry in zambia, with losse ...19947933764
a rapid, single-step purification method for immunogenic members of the hsp 70 family: validation and application.gelatin affinity chromatography has been developed as a simple one-step procedure for purification of members of the hsp 70 kda family from mdbk cells (a bovine epithelioid cell line), rat liver microsomes and three different protozoan parasites. the ability of the isolated proteins to bind to denatured proteins like gelatin together with their apparent molecular masses, constitutive and inducible expression and their release from gelatin-agarose beads by atp suggested that these proteins are mo ...19947983383
separation of sister chromatids in mitosis requires the drosophila pimples product, a protein degraded after the metaphase/anaphase transition.mutations in the drosophila genes pimples and three rows result in a defect of sister chromatid separation during mitosis. as a consequence, cytokinesis is also defective. however, cell cycle progression including the mitotic degradation of cyclins a and b is not blocked by the failure of sister chromatid separation, and as a result, metaphase chromosomes with twice the normal number of chromosome arms still connected in the centromeric region are observed in the following mitosis, pimples encod ...19968548823
discrimination between theileria parva and t. taurotragi in the salivary glands of rhipicephalus appendiculatus ticks using oligonucleotides homologous to ribosomal rna sequences. 19948036242
severe anaemia due to haematopoietic precursor cell destruction in field cases of east coast fever in tanzania.examinations were made on erythrocytes, thrombocytes, leukocytes, lymph nodes, thymus, haemal nodes and bone marrow in field cases of east coast fever (ecf) in tanzania. seventy-six clinically sick short-horn zebu and taurine-zebu crosses, positive for theileria parva piroplasms and schizonts and 55 apparently healthy cattle were studied. the syndrome observed was characterised by severe pancytopenia, with massive normocytic, normochromic anaemia, panleukopenia and thrombocytopenia, but no retic ...19948073608
detection of polymorphisms among theileria parva stocks using repetitive, telomeric and ribosomal dna probes and anti-schizont monoclonal antibodies.a total of 21 theileria parva stocks from 6 countries were characterized using t. parva repetitive and ribosomal dna probes, a plasmodium berghei telomeric oligonucleotide and a panel of anti-schizont monoclonal antibodies (mabs). hybridization of the repetitive dna probe to southern blots of ecori-digested t. parva dna revealed 20 different restriction fragment patterns among dna samples isolated from infections initiated using 16 parasite stocks. the panel of anti-schizont mabs defined 8 diffe ...19938102796
a 7.1 kb linear dna molecule of theileria parva has scrambled rdna sequences and open reading frames for mitochondrially encoded proteins.theileria parva, an intralymphocytic protozoan parasite of cattle, contains a linear 7.1 kb dna element with terminal inverted repeat sequences. the molecule is transcribed into low molecular weight rna, and both dna strands encode short stretches of unique sequences, usually < 100 nucleotides, which are similar to large (lsu) or small (ssu) ribosomal subunit rna. phylogenetically conserved conformational rrna domains were assembled from the discontinuous rdna sequences using comparative seconda ...19948112303
adoptive transfer of immunity to theileria parva in the cd8+ fraction of responding efferent lymph.evidence that class i major histocompatibility complex-restricted cytotoxic t lymphocytes (ctl) are involved in immunity to malaria has highlighted the potential importance of these cells in protection against intracellular parasites. parasite-specific ctl are a prominent feature of the immune response of cattle to theileria parva, a related apicomplexan parasite. the relationship between the appearance of these cells in the blood of immune cattle under challenge and the clearance of infection s ...19948127915
progress towards a vaccine against theileria parva: relevance for heartwater research.such progress has been made in the last decade in the characterization of bovine immunity to theileria parva. the evidence is overwhelming that cattle that become immune through infection can clear subsequent challenge infections by deploying parasite-specific cytotoxic t lymphocytes (ctl). furthermore, high titres of neutralising antibodies are generated against the sporozoite surface after multiple exposure to the parasite, and these can neutralise infection in vitro. although unlikely to be o ...19938134638
antibody select procedure for characterization of expression clones. 19938220723
transmission of theileria parva to cattle by rhipicephalus appendiculatus adults fed as nymphae in vitro on infected blood through an artificial membrane.a technique is described for the efficient feeding of rhipicephalus appendiculatus nymphae on cattle blood through an artificial membrane bearing tactile and olfactory stimuli. the effect of four anticoagulation methods on the feeding of nymphae was compared and heparinized blood was found to be the most efficacious, followed by defibrinated blood. blood treated with acid citrate dextrose (acd) or ethylenediamine tetraacetate (edta) inhibited nymphal feeding. nymphae fed on heparinized and defib ...19938233588
the molecular basis of transformation of lymphocytes by theileria parva infection.the protozoan intracellular parasites, theileria parva and theileria annulata, infect cattle and cause severe and fatal leukocytic proliferative diseases. the proliferation is dependent on the presence of the parasites in the host cell cytoplasm. t. parva-infected cells proliferate permanently in cell culture and exhibit many features characteristic of tumor cells. the proliferation is reversible by treatment with parasite-specific drugs. constitutive expression of interleukin-2, its receptor an ...19938257788
characterisation of a glutamine- and proline-rich protein (qp protein) from theileria parva.we have isolated a clone from a theileria parva infected lymphocyte cdna library which has the potential to encode a protein of 480 amino acids. this protein is particularly rich in glutamine and proline and has some short repeated amino acid motifs based on the sequences qpxp and qpxq. we have called it the 'qp protein'. southern blotting suggests that the qp protein gene is present as a single copy in the t. parva muguga genome. northern blotting revealed that the gene is transcribed in both s ...19938264721
theileria parva: detection of genomic polymorphisms by polymerase chain reaction amplification of dna using arbitrary primers.genomic dna fingerprints were generated from theileria parva piroplasm dna by polymerase chain reaction amplification using arbitrary decamers as primers. four of 12 primers tested generated amplified fragments which were polymorphic between different t. parva stocks or clones. hybridization of radiolabeled total amplification products to southern blots of t. parva piroplasm and uninfected bovine dna confirmed that none of the amplified fragments were derived from any contaminating bovine dna wh ...19938344406
antibodies against major histocompatibility complex class ii antigens directly inhibit the growth of t cells infected with theileria parva without affecting their state of activation.we have analyzed the effect of antibodies (abs) directed against major histocompatibility complex (mhc) class ii abs on the proliferation of theileria parva-infected (tpi) t cells. anti-mhc class ii abs exert a direct effect on tpi t cells causing an acute block in their proliferation. the inhibition does not involve apoptosis and is also entirely reversible. the rapid arrest of dna synthesis caused by anti-mhc class ii abs is not due to interference with the state of activation of the t cells s ...19938350052
progress in research on tick-borne diseases: theileriosis and heartwater.the rapid population growth in subsaharan africa necessitates a great increase in animal production in the more humid zones. vector-borne diseases occurring in these zones will assume more importance, but are difficult to control. they include theileriosis and heartwater. recent developments in research on these diseases are presented. indigenous animal populations in endemic areas, subjected to natural selection, are far less susceptible than exotic stock. heartwater, caused by the rickettsia c ...19938372422
discrimination between six species of theileria using oligonucleotide probes which detect small subunit ribosomal rna sequences.the complete small subunit ribosomal rna (srrna) gene of theileria parva was cloned and sequenced. two primers were designed which permitted the specific amplification of part of the theileria srrna gene from theileria-infected cell line samples which were predominantly (> 95%) bovine dna. the sequence of the central (variable) region of the srrna genes of t. annulata, t. taurotragi, t. mutants and two unidentified parasites referred to as theileria sp. (buffalo) and theileria sp. (marula) were ...19938414670
characterization of the parasite-host cell interactions involved in theileria parva sporozoite invasion of bovine lymphocytes.sporozoite invasion of bovine lymphocytes by theileria parva is a ph-dependent process that occurs without the need for de novo protein synthesis. the process was inhibited by rgd(s) peptides, fibronectin and, in the presence of serum, by antibodies reactive with fibronectin. invasion was also blocked by a range of sulphated glycoconjugates, but treatment of lymphocytes with heparitinase did not inhibit entry. enzymic modifications of the lymphocyte surface demonstrated that trypsin-insensitive ...19968811851
differential in vitro and in vivo expression of mhc class ii antigens in bovine lymphocytes infected by theileria parva.the expression of major histocompatibility complex class ii (mhc ii) non-polymorphic antigens detected by four monoclonal antibodies was investigated in theileria parva-infected and non-infected cloned lymphoid cell lines, bulk cultures, and in peripheral blood mononuclear cells (pbmc) and lymph node cells (lnc) of experimentally infected calves. compared with non-infected cell lines, both immunofluorescence microscopy and flow cytofluorometry analysis of infected lines of alpha beta t-cell, gam ...19938430496
casein kinase ii alpha transgene-induced murine lymphoma: relation to theileriosis in cattle.infection of cattle with the protozoan parasite theileria parva results in a fatal lymphoproliferative syndrome that is associated with the overexpression of casein kinase ii. the role of this enzyme in the pathogenesis of lymphoproliferative disorders was investigated by expressing the catalytic subunit in lymphocytes of transgenic mice. adult transgenic mice displayed a stochastic propensity to develop lymphoma; co-expression of a c-myc transgene in addition to casein kinase ii resulted in neo ...19957846532
a review on vaccination against protozoa and arthropods of veterinary importance.the recent advances in immunology and biotechnology have stimulated much research on the control of parasitic diseases through vaccination. this is a review of the state of the art regarding important protozoan and arthropod veterinary parasites. a live oocyst vaccine for avian coccidiosis is still in use but much work has been done on the identification, cloning, and assay of protective antigens. the sporozoites of eimeria tenella have been the preferred subject and at least four recombinant an ...19947886919
parasite strain specificity of precursor cytotoxic t cells in individual animals correlates with cross-protection in cattle challenged with theileria parva.class i major histocompatibility complex-restricted parasite-specific cytotoxic t lymphocytes (ctl) are known to be a major component of the bovine immune response to the protozoan parasite theileria parva, but formal proof for their role in protection of cattle against infection with t. parva has been lacking. animals immunized with one stock of t. parva show variations in the degree of protection against heterologous challenge and also in the parasite strain specificity of their ctl responses. ...19957890382
tick salivary gland extract and interleukin-2 stimulation enhance susceptibility of lymphocytes to infection by theileria parva sporozoites.intracellular parasites show host cell specificity, and precise information on the range of host cells is a prerequisite for the identification of host molecules that account for the specificity and are involved in entry processes. the sporozoite stage of the tick-borne protozoan parasite theileria parva binds to and enters bovine lymphocytes, but precise information on the susceptibility of other cell types present at the tick attachment site is unavailable. we quantitatively examined the susce ...19938454354
evidence for the induction of casein kinase ii in bovine lymphocytes transformed by the intracellular protozoan parasite theileria parva.theileria parva is an obligate, intracellular, parasitic protozoan that causes east coast fever, an acute leukemia-like disease of cattle. t. parva and the related parasite, theileria annulata, are unique among protozoa in that their intralymphocytic stages induce transformation of bovid lymphocytes. comparison of in vitro protein kinase activities between uninfected il-2-dependent t lymphoblasts and t. parva-infected lymphocytes revealed a 4.7- to 12-fold increase in total phosphorylation and t ...19938467809
proliferation of theileria annulata and theileria parva macroschizont-infected bovine cells in scid mice.theileria annulata and theileria parva macroschizont-infected bovine cells formed tumours at the inoculation site when injected subcutaneously into c.b.-17 scid mice. t. annulata tumours showed more vigorous growth than t. parva tumours. the tumours did not regress and infected cells spread to other tissues. intraperitoneal injection of high doses of t. annulata-infected cells resulted in the development of ascites: the infected cells colonized abdominal organs, in particular mesenteric tissue. ...19938468139
analysis of dinucleotide frequency and codon usage in the phylum apicomplexa.dinucleotide frequency (dif) and codon usage (cu) were analysed in gene sequences from four parasitic protozoa, babesia bovis, theileria parva, toxoplasma gondii and eimeria tenella, of the phylum apicomplexa. in keeping with the 'genome hypothesis', cu was found to be non-random and species specific in these organisms, although cu among members of the same subclass was found to be very similar. several low-usage (lu) codons were identified, and the usage of lu codons appears to be related to th ...19938482530
production of interferon by theileria annulata- and t. parva-infected bovine lymphoid cell lines.theileria annulata and t. parva-infected lymphoblastoid cells were examined for their capacity to produce interferon (ifn). supernatants of such cells were tested in biological assay for their antiviral activity. only t. parva-infected cells of t-cell origin were capable of producing ifn-gamma. supernatants of some but not all t. annulata-infected cells showed also antiviral activity, which was greatly reduced after exposure to a ph of 2. northern-blot analysis of the cells using an ifn-gamma cd ...19938493239
selection of diversity at putative glycosylation sites in the immunodominant merozoite/piroplasm surface antigen of theileria parasites.the immunodominant merozoite/piroplasm surface antigen of theileria parasites has potential as a diagnostic reagent and as a component of a sub-unit vaccine. this molecule is known to be antigenically diverse, and it is important to determine the nature and extent of this heterogeneity. in the present study nucleotide sequences, representing alleles of the gene (tams1) encoding this molecule in theileria annulata were compared to each other and to sequences of homologous genes in theileria serge ...19958538686
mobilization of intrasporozoite ca2+ is essential for theileria parva sporozoite invasion of bovine lymphocytes.the entry of theileria parva sporozoites into bovine lymphocytes occurs rapidly and involves a defined series of events. in the present study the role of calcium in sporozoite entry was examined. depletion of ca2+ from the external medium had little effect on sporozoite entry suggesting that the initial sporozoite-host cell interaction is a ca(2+)-independent process. sporozoite entry could, however, be inhibited by a range of ca2+ channel blockers (verapamil, nicardipine, diltiazem) and calmodu ...19958549593
pathogenicity of theileria parva is influenced by the host cell type infected by the parasite.theileria parva has been shown to infect and transform b cells and t cells at similar frequencies in vitro. however, the majority of parasitized cells in the tissues of infected cattle are alpha/beta t cells. the aim of this study was to determine whether the cell type infected with t. parva influenced the pathogenicity of the parasite. the initial approach, which involved inoculation of cattle with autologous cloned cell lines of different phenotypes, failed to resolve the issue, because of pro ...19968550207
cd45ro expression on bovine t cells: relation to biological function.the 180,000 mw isoform of cd45 (cd45ro) has been identified in cattle with a novel monoclonal antibody (mab) (il-a116). this has allowed a more precise analysis of t-cell function in relation to cd45 isoform expression. within the cd4+ and cd8+ t-cell populations, cd45ro+ and cd45ro- subsets were evident. most cd4+ and cd8+ t cells that expressed the cd45ro isoform did not express the 220,000 and 205,000 mw isoforms recognized by mab cc76. in contrast, the wc1+, cd2-, cd4-, cd8-, gamma delta t-c ...19958567018
structure and sequence variation of the genes encoding the polymorphic, immunodominant molecule (pim), an antigen of theileria parva recognized by inhibitory monoclonal antibodies.the polymorphic, immunodominant molecule (pim) of theileria parva is the predominant antigen recognized by sera from infected cattle and by monoclonal antibodies (mab) used to differentiate parasite strains. as such, the antigen is under consideration as a diagnostic antigen, and since the mabs can neutralize sporozoite infectivity in vitro, in immunization experiments. initial comparison of two pim cdna sequences suggested that the pim genes consist of conserved 5' and 3' termini flanking a cen ...19958577324
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