| delivery of the p67 sporozoite antigen of theileria parva by using recombinant salmonella dublin: secretion of the product enhances specific antibody responses in cattle. | the p67 sporozoite antigen of theileria parva has been fused to the c-terminal secretion signal of escherichia coli hemolysin and expressed in secreted form by attenuated salmonella dublin aroa strain sl5631. the recombinant p67 antigen was detected in the supernatant of transformed bacterial cultures. immunization trials in cattle revealed that sl5631 secreting the antigen provoked a 10-fold-higher antibody response to p67 than recombinant sl5631 expressing but not secreting p67. immunized calv ... | 1998 | 9573089 |
| organisation and informational content of the theileria parva genome. | when compared with other apicomplexan organisms, theileria parva has an exceptionally small, 10-12 mbp, genome. there are only 4 chromosomes, each in the mbp range, and a complete physical map, based on sfii linking data, is available for each one. a number of genes and cdnas have been mapped to specific sfii fragments. telomeres consist of the simple repeat sequence typical of chromosomal ends but sub-telomeric homologies do not extend beyond 5 kbp. the only dispersed repetitive sequences ident ... | 1998 | 9763284 |
| modulation of enzymatic activity of src-family kinases in bovine t cells transformed by theileria parva. | after infection with sporozoites of the protozoon theileria parva (tp) bovine t cells are readily transformed to permanent growth in vivo and in vitro. their transformed state depends on the constant presence of the parasite but membrane signals remain important. non-receptor tyrosine kinases play a critical role in the transduction of membrane signals in haematopoietic cells. we have investigated src-family kinases in bovine t cells transformed by tp. the t cell receptor-associated tyrosine kin ... | 1998 | 9778632 |
| cloning and characterization of a 150 kda microsphere antigen of theileria parva that is immunologically cross-reactive with the polymorphic immunodominant molecule (pim). | to identify the genes encoding novel immunodominant antigens of theileria parva a lambda gt11 library of piroplasm genomic dna was immunoscreened with bovine recovery serum and a gene encoding a 150 kda antigen (p150) was identified. the predicted polypeptide contains an n-terminal secretory signal sequence and a proline-rich region of repeated amino acid motifs. the repeat region is polymorphic between stocks of t. parva in both copy number and sequence, and analysis of the repeat region from 1 ... | 1998 | 9820853 |
| stage-specific activity in vitro on the theileria infection process of serum from calves treated prophylactically with buparvaquone. | an in vitro method for testing activity of buparvaquone in serum on the infection and development of theileria in its bovine host mononuclear cells is described and results compared with the effect exhibited in vivo. serum samples were collected over a time course from calves in a clinical trial of 5 mg kg(-1) buparvaquone prophylaxis on theileria annulata or t. parva experimental infection. to evaluate drug levels and persistence in each animal for a period of 14 days and its effect on the earl ... | 1998 | 9870365 |
| interference by the intracellular parasite theileria parva with t-cell signal transduction pathways induces transformation and protection against apoptosis. | the intracellular parasite theileria parva transforms bovine t-lymphocytes, inducing uncontrolled proliferation. upon infection, cells cease to require antigenic stimulation and exogenous growth factors to proliferate. earlier studies have shown that pathways triggered via stimulation of the t-cell receptor are silent in transformed cells. this is reflected by a lack of phosphorylation of key signalling molecules and the fact that proliferation is not inhibited by immunosuppressants such as cycl ... | 1999 | 10614498 |
| immunohistochemical detection of parasite antigens in theileria parva-infected bovine lymphocytes. | theileria parva is the causal agent of east coast fever (ecf), a fatal disease of cattle characterized by pyrexia, transient lymphadenopathy and panleukopenia. we have evaluated monoclonal antibodies (mab) against three distinct antigens (p67, pim and p32) of the parasite as immunohistological reagents for monitoring the kinetics of infection in cattle. bovine lymphocytes were stained with the mab at various intervals after infection in vitro and in vivo. the p67 sporozoite surface antigen was d ... | 1998 | 9870366 |
| pathological effects and reduced survival in rhipicephalus appendiculatus ticks infected with theileria parva protozoa. | pathological effects have been demonstrated in a number of arthropod species as a consequence of parasitic infection. this is usually manifest as reduced arthropod survival and/or fecundity. this paper describes the detrimental effects the protozoan parasite, theileria parva has on rhipicephalus appendiculatus ticks. r. appendiculatus ticks were dissected and sectioned at regular intervals during their nymph to adult moult after detaching from a t. parva infected calf, and assessed by light and ... | 2000 | 10726991 |
| linear peptide specificity of bovine antibody responses to p67 of theileria parva and sequence diversity of sporozoite-neutralizing epitopes: implications for a vaccine. | a stage-specific surface antigen of theileria parva, p67, is the basis for the development of an anti-sporozoite vaccine for the control of east coast fever (ecf) in cattle. by pepscan analysis with a series of overlapping synthetic p67 peptides, the antigen was shown to contain five distinct linear peptide sequences recognized by sporozoite-neutralizing murine monoclonal antibodies. three epitopes were located between amino acid positions 105 to 229 and two were located between positions 617 to ... | 1999 | 10024569 |
| the incidence, calf morbidity and mortality due to theileria parva infections in smallholder dairy farms in murang'a district, kenya. | a prospective observational study was conducted among smallholder dairy farmers in murang'a district, kenya, to estimate the incidence of theileria parva infections, as well as calf morbidity and mortality caused by the infection. the study was conducted between march 1995 and august 1996, in five cohorts of female calves from birth to six months of age from different agro-ecological zones (aezs) and grazing-system strata shown previously to have varying prevalences of t. parva infection. a tota ... | 1999 | 10081789 |
| bovine gammadelta t-cell responses to the intracellular protozoan parasite theileria parva. | t cells bearing the gammadelta antigen receptor (gammadelta t cells) can constitute up to 50% of t cells in the peripheral blood and lymphoid organs of young cattle. we present data showing that gammadelta t cells are involved in immune responses against theileria parva. gammadelta t cells isolated from peripheral blood mononuclear cells (pbmc) of t. parva-naive and -immune cattle proliferated in the presence of fixed or unfixed autologous t. parva-infected lymphoblasts (tpl) and heat-stressed c ... | 1999 | 10225880 |
| is interleukin 2 necessary for the autocrine proliferation of theileria-infected bovine cells? | theileria-infected bovine lymphoblastoid cells are induced to proliferate permanently such that the division of the parasites and that of their host cells occur synchronously. the mechanism by which the parasites induce the transformation of their host cells is unknown. we investigated the growth-factor dependency of a number of theileria-infected cell lines. supernatants of the majority of the cell lines tested in our study showed no growth-enhancing activity. however, supernatants of a limited ... | 1999 | 10227059 |
| the intracellular parasite theileria parva protects infected t cells from apoptosis. | parasites have evolved a plethora of strategies to ensure their survival. the intracellular parasite theileria parva secures its propagation and spreads through the infected animal by infecting and transforming t cells, inducing their continuous proliferation and rendering them metastatic. in previous work, we have shown that the parasite induces constitutive activation of the transcription factor nf-kappab, by inducing the constitutive degradation of its cytoplasmic inhibitors. the biological s ... | 1999 | 10377411 |
| review: theileria schizonts induce fundamental alterations in their host cells. | the sporozoites of theileria annulata and t. parva invade bovine leukocytes, where they differentiate into schizonts. the latter can immortalize and induce fundamental changes in their host cells. t. annulata infects mainly major histocompatibility complex class ii cells, whereas t. parva preferentially transforms t-lymphocytes, which proliferate continuously without the need for exogenously added growth factors. most of the cell lines appear to be independent of a growth factor but may express ... | 1999 | 10382602 |
| a 32 kda surface antigen of theileria parva: characterization and immunization studies. | previous studies using monoclonal antibody (mab) 4c9 specific for a 32 kda antigen (p32) of theileria parva demonstrated expression of the antigen on the surface of the sporozoite, making it a potential antigen for sporozoite neutralization. a full-length cdna encoding the major merozoite/piroplasm surface antigen (mmpsa) of t. parva was cloned and expressed in bacteria. the expressed product reacted strongly with mab 4c9, demonstrating identity between the p32 and mmpsa of t. parva. using immun ... | 2000 | 10874718 |
| theileria parva ribosomal internal transcribed spacer sequences exhibit extensive polymorphism and mosaic evolution: application to the characterization of parasites from cattle and buffalo. | we sequenced the rrna genes and internal transcribed spacers (its) of several theileria parva isolates in an attempt to distinguish between the causative agents of east coast fever and corridor disease. the small subunit (ssu) and large subunit (lsu) rrna genes from a cloned t. p. lawrencei parasite were sequenced; the former was identical to that of t. p. parva muguga, and there were minor heterogeneities in the latter. the 5.8s gene sequences of 11 t. parva isolates were identical, but major d ... | 1999 | 10406032 |
| comparison of indirect fluorescent antibody test and enzyme linked immunosorbent assay in the detection of exposure of cattle to theileria parva in kenya. | appraisal of the indirect fluorescent antibody test (ifat) and antigen enzyme linked immunosorbent assay (elisa) serological tests as carried out to detect cattle exposed to theileria parva at the national veterinary research centre, muguga (nvrc), kenya is reported. using sera from t. parva naive cattle and cattle experimentally exposed to t. parva, the two tests were appraised in terms of their sensitivity and specificity. ifat and elisa had the same sensitivity of 90% while elisa had a higher ... | 1999 | 10486828 |
| immunization against diseases caused by theileria parva: a review. | theileria parva is the causative agent of three epidemiologically different diseases, east coast fever (ecf), corridor disease and january disease, caused by 3 types of t. parva, t. p. parva, t. p. lawrencei and t. p. bovis, respectively. the history of immunization against these diseases has been marked by salient discoveries such as the immune status in recovered animals, the activity of tetracyclines during the incubation period, the possibility for cryopreserving supernatant of prefed ticks ... | 1999 | 10540307 |
| molecular epidemiology of theileria parva in the field. | molecular tools based on seminested rflp-pcr techniques to characterize field parasites in bloodspots dried on filter paper permitted investigation of the extent and the dynamics of diversity of theileria parva populations in the field. parallel molecular studies explored the long-term genome stability of various isolates by probing southern blots of ecori digested total genomic dna with four different reference nucleic acid probes. three polymorphic single copy loci encoding for antigen genes w ... | 1999 | 10540308 |
| vector competence of 7 rhipicephalid tick stocks in transmitting 2 theileria parva parasite stocks from kenya and zimbabwe. | the competence of 7 different stocks of rhipicephalus appendiculatus and r. zambeziensis to transmit 2 different stocks of theileria parva was compared by feeding nymphae of each tick stock simultaneously on infected cattle and assessing the infections in the salivary glands of the resultant adult ticks. there were significant differences in the patterns of infection of the 2 stocks (t. parva muguga and t. parva boleni) in the different stocks of ticks, and these differences were shown to be rep ... | 1998 | 9651937 |
| immunization against east coast fever in field cattle with low infectivity theileria parva stabilate--preliminary assessment. | two theileria parva sporozoite stabilates stored at -196 degrees c, then at -70 degrees c for six weeks (stabilate 1) and more than six months (stabilate 2) were inoculated into four eight-month old male calves, 1 and 2 (stabilate 1), and 3 and 4 (stabilate 2). calves 1 and 2 developed pyrexia, enlargement of lymph nodes, and the former died of east coast fever. calves 3 and 4 showed slight enlargement of lymph nodes without fever. lymph node smears from all calves (from day 10 to 20 post-inocul ... | 1998 | 9652382 |
| development of sero-diagnostic and molecular tools for the control of important tick-borne pathogens of cattle in africa. | tick-borne diseases (tbds) are a major economic constraint to livestock production in sub-saharan africa. ilri is focussing on developing a range of products, such as vaccines, diagnostics and decision support services to underpin improved control programmes against these diseases. we have developed three highly sensitive and specific enzyme linked immuno-assays (elisas), which allow precise diagnosis of theileria parva, babesia bigemina and anaplasma marginale. these tests have been standardise ... | 1999 | 11071549 |
| characterization and discrimination of three theileria parva stabilates involved in east coast fever vaccination. | three vaccine stabilates of theileria parva, of which sporozoites are being used against east coast fever, were characterized by immunological and molecular biology techniques before being used for a national vaccination campaign in kenya. t. parva marikebuni stabilates 316 and 3014, and t. parva lanet were used in this study and were discriminated from other kenyan field theileria isolates. ifat results showed that all the animals were producing antibodies regardless of the stock used. primers ... | 1998 | 9668450 |
| a pcr-based field evaluation of theileria infections in cattle and ticks in kenya. | theileria parva is a hemoprotozoan parasite responsible for causing east coast fever in east and central africa. the vaccine currently available is an "infection and treatment" procedure which involves the injection of live sporozoites followed by drug therapy to prevent clinical illness. before introducing potentially new strains of parasite into an area, however, it is crucial to check the disease situation in the field first. we looked at three different areas in kenya: limuru in which many c ... | 1998 | 9668451 |
| detection and differentiation of theileria annulata and theileria parva using macroschizont-derived dna probes. | a lamda gt11 expression library based on t.annulata-infected cells was screened with an antiserum raised in rabbits against partially purified schizonts of t.annulata. two clones were detected, sequenced and designated as sa288 and sb288 (shayan et al., submitted for publication). from the sequences of these two genes oligonucleotide primers were designed for specific amplification of parasite dna by polymerase chain reaction (pcr). we could show that these genes are of parasitic origin and do o ... | 1998 | 9668454 |
| delivery of the theileria parva p67 antigen to cattle using recombinant vaccinia virus: il-2 enhances protection. | to evaluate vaccinia virus as a delivery system for recombinant antigen in cattle, calves were immunized with a recombinant vaccinia virus (rvv) expressing the sporozoite surface antigen (p67) of theileria parva (v-67) combined with those expressing bovine il-4 (v-il4) or il-2 (v-il2). the anti-p67 antibody levels detected in calves inoculated with the combination of v-67 and v-il4 were higher than those produced by animals injected with v-67 alone or v-67 and v-il2. on challenge with cryopreser ... | 1998 | 9682391 |
| proteolytic cleavage of surface proteins enhances susceptibility of lymphocytes to invasion by theileria parva sporozoites. | a flow cytometric method using anti-parasite antibodies was developed to measure binding of theileria parva sporozoites to the target bovine lymphocyte membrane. parasite-host cell interactions could be inhibited by monoclonal antibodies to bovine mhc class i and partially by one of two antibodies to bocd45r. proteolysis of the lymphocyte surface removed cd45r but not mhc class i determinants, and enhanced sporozoite binding. these observations support the hypothesis that cd45r and cd45r antibod ... | 1998 | 9696352 |
| integrated molecular diagnosis of theileria and babesia species of cattle in italy. | a reverse line blot hybridization (rlb) test was developed to specifically identify six theileria spp. (t. annulata, t. parva, t. mutans, t. velifera, t. taurotragi, and t. buffeli/orientalis) and three babesia spp. (b. bovis, b. bigemina, and b. divergens). no cross reaction was observed with other livestock pathogens (such as anaplasma marginale, a. centrale, a. ovis, cowdria ruminantium, trypanosoma brucei, t. congolense, and t. vivax). this method was used to test bovine blood samples collec ... | 2000 | 11193668 |
| chemoprophylaxis of theileria annulata and theileria parva infections of calves with buparvaquone. | a clinical trial testing the prophylactic effect of a 5 mg kg-1 dose of buparvaquone on either theileria annulata or theileria parva experimental infections of calves demonstrated its efficacy for periods of at least seven days. the drug given 1 h or seven days before 50% lethal t. annulata sporozoite infection protected all eight calves, but prophylaxis was insufficient after 14 days to protect two out of four calves from severe reaction. when immunity was challenged by a lethal second parasite ... | 1998 | 9703615 |
| the current epidemiological status of bovine theileriosis in eastern zambia. | results of a longitudinal study conducted in the eastern province of zambia from 1994 to 1997 indicate that it is doubtful whether a state of endemic stability of east coast fever (ecf) can be reached in the near future. even in endemic areas, the mortality of theileria parva infections is still estimated above 50%. the main factors limiting progress towards endemic stability are high innate susceptibility of the zebu cattle, the virulence of the parasite and the climate. the unimodal rainfall p ... | 1999 | 10540309 |
| transformation of leukocytes by theileria parva and t. annulata. | theileria parva and t. annulata provide intriguing models for the study of parasite-host interactions. both parasites possess the unique property of being able to transform the cells they infect; t. parva transforms t and b cells, whereas t. annulata affects b cells and monocytes/macrophages. parasitized cells do not require antigenic stimulation or exogenous growth factors and acquire the ability to proliferate continuously. in vivo, parasitized cells undergo clonal expansion and infiltrate bot ... | 1999 | 10547684 |
| theileria parva (kasoba): isolation and challenge of cattle recovered from infection with other theileria parva stocks. | a pathogenic theileria stock was isolated from control cattle during an east coast fever (ecf) field immunization trial at kasoba near karonga town in northern malawi. a stabilate of this stock caused severe fevers and prolonged parasitosis in theileria parva naive cattle, resulting in the death of 5 out of 12 cattle despite treatment. in contrast, this parasite stock caused mild to moderate reactions in 17 cattle immunized with the trivalent t. parva stabilate except in 3 animals which develope ... | 1996 | 8881419 |
| an epidemic of east coast fever on a dairy farm in eastern tanzania. | during the period august-september 1995, an epidemic of east coast fever occurred at a dairy farm in morogoro region of eastern tanzania. due to an intensive dipping scheme since 1970, a very unstable endemic status had been established in the animals. a breakdown in the dipping scheme caused a major disease outbreak; the dip wash was not changed for 18 months prior to the outbreak and dipping continued in a dip wash of unknown strength. there was also a delay in detecting the disease at an earl ... | 2001 | 11267688 |
| the use of nocodazole in cell cycle analysis and parasite purification from theileria parva-infected b cells. | theileria parasites transform bovine leukocytes and induce uncontrolled lymphoproliferation only in the macroschizont stage of their life cycle. the isolation of highly purified stage-specific parasite rna and proteins is an essential prerequisite when studying the theileria-host relationship. we therefore improved a protocol based on the cytolytic bacterial toxin aerolysin by taking advantage of the microtubule inhibitor nocodazole. in this report we describe that nocodazole-mediated separation ... | 1999 | 10580273 |
| treatment of east coast fever: a comparison of parvaquone and buparvaquone. | two trials were conducted to compare the efficacy of parvaquone and buparvaquone for the treatment of naturally acquired east coast fever (ecf, theileria parva infection) which, if untreated, is almost invariably fatal in european breeds of cattle. in the first trial 28 naive cattle were exposed in a paddock infested with ticks carrying a virulent form of the disease. twelve were treated with each drug when they developed clinical ecf. all 24 cattle were cured. in the second study, 100 cases of ... | 1999 | 10628697 |
| theileria parva genomics reveals an atypical apicomplexan genome. | the discipline of genomics is setting new paradigms in research approaches to resolving problems in human and animal health. we propose to determine the genome sequence of theileria parva, a pathogen of cattle, using the random shotgun approach pioneered at the institute for genomic research (tigr). a number of features of the t. parva genome make it particularly suitable for this approach. the g+c content of genomic dna is about 31%, non-coding repetitive dna constitutes less than 1% of total d ... | 2000 | 10731569 |
| reciprocal cross-protection induced by sporozoite antigens spag-1 from theileria annulata and p67 from theileria parva. | theileria annulata and theileria parva both possess a major surface antigen on the sporozoite stage of the life-cycle, called spag-1 and p67, respectively. in each case, these antigens are vaccine candidates and have been shown to induce a degree of homologous protection in earlier work. these antigens share sequence homology and are serologically cross-reactive. here, we confirm that these antigens confer protection against homologous species challenge. more importantly, they mutually confer a ... | 2000 | 10792761 |
| a statistically derived index for classifying east coast fever reactions in cattle challenged with theileria parva under experimental conditions. | a statistically derived disease reaction index based on parasitological, clinical and haematological measurements observed in 309 5 to 8-month-old boran cattle following laboratory challenge with theileria parva is described. principal component analysis was applied to 13 measures including first appearance of schizonts, first appearance of piroplasms and first occurrence of pyrexia, together with the duration and severity of these symptoms, and white blood cell count. the first principal compon ... | 2000 | 10811278 |
| differences in the epidemiology of theileriosis on smallholder dairy farms in contrasting agro-ecological and grazing strata of highland kenya. | a prospective cohort study was conducted in five purposively-sampled agro-ecological zone (aez)-grazing system strata in murang'a district, kenya, between march 1995 and june 1996. the study strata were selected based on a preliminary characterization study to represent the widest range of risks to east coast fever (ecf) in the district and included zero-grazing and open-grazing farms. in total, 225 calves from 188 smallholder farms were examined from birth to 6 months of age and visited within ... | 2000 | 10813159 |
| a highly sensitive, non-radioactive assay for t cell activation in cattle: applications in screening for antigens recognised by cd4(+) and cd8(+) t cells. | we describe a highly sensitive, non-radioactive assay for t cell activation, based on the rapid induction of class ii mhc expression by constitutively negative bovine endothelial cells, when cultured in the presence of supernatants derived from activated bovine t cells. we demonstrate the effectiveness of this assay in detecting rboifngamma and activation of immune cd4(+) and cd8(+) t cell lines and clones in response to specific antigen and transfected cos-7 cells, respectively. we also demonst ... | 2000 | 10821950 |
| cloning, sequence and mrna expression of bovine interleukin-16. | a lambda gt11 cdna library was constructed using mrna isolated from theileria parva-infected bovine lymphocytes. sequencing of random clones of this library resulted in the identification of a cdna encoding bovine interleukin-16 (il-16). the cdna has an open reading frame of 1134 bp, and a 3' untranslated region of 275 nucleotides with a polyadenylation signal 16 bases upstream from the poly (a) tail. the protein predicted by the cdna sequence contains 378 amino acids and the level of amino acid ... | 2000 | 10826703 |
| the bovine cytotoxic t cell: mhc restriction and antigen-specificity. | the analysis of the immune mechanisms operative against the bovine intracellular protozoan parasite theileria parva resulted in the identification and characterisation of the bovine cytotoxic t lymphocyte (ctl) and its important role in protection against this parasite. by the use of polyclonal and monoclonal antibodies specific for bovine mhc antigens and lymphocyte populations and the use of mhc-haplotyped animals it was possible to demonstrate the mhc restriction and antigen-specificity of th ... | 2000 | 10905120 |
| a theileria parva type 1 protein phosphatase activity. | the protozoan parasite theileria (spp. parva and annulata) infects bovine leukocytes and provokes a leukaemia-like disease in vivo. in this study, we have detected a type 1 serine/threonine phosphatase activity with phosphorylase a as a substrate, in protein extracts of parasites purified from infected b lymphocytes. in contrast to this type 1 activity, dose response experiments with okadaic acid (oa), a well characterised inhibitor of type 1 and 2a protein phosphatases, indicated that type 2a i ... | 2000 | 10989153 |
| the entry of theileria parva merozoites into bovine erythrocytes occurs by a process similar to sporozoite invasion of lymphocytes. | the entry of theileria parva merozoites into bovine erythrocytes in vivo is described and compared to sporozoite invasion of lymphocytes. merozoites make initial contact with erythrocytes with any part of their surface and invasion of the host cell does not require the re-orientation of the apical end of the merozoite towards the surface of the erythrocyte. after the initial attachment the merozoite and host cell membranes form a continual close junction with the two apposed membranes separated ... | 1995 | 11023409 |
| optimization of the in vitro feeding of rhipicephalus appendiculatus nymphae for the transmission of theileria parva. | an apparatus for artificial feeding of rhipicephalus appendiculatus nymphae was modified to improve feeding performance. heparinized blood was supplied above a treated artificial membrane while the ticks attached below on its undersurface. the feeding apparatus was incubated at 37 degrees c in an atmosphere of 3% co2 concentration and a relative humidity of 75-80%. under these conditions, 91% of the engorged nymphae attained a mean weight of 6-11 mg, and an average of 93% of those nymphae moulte ... | 1995 | 11023410 |
| transmission of theileriosis in the traditional farming sector in the southern province of zambia during 1995-1996. | the incidence of first contact with the protozoan theileria parva was determined in three traditional cattle herds in the southern province of zambia in 1995 and 1996. the majority of first contacts occurred during the dry season in june, july and august, at a time of nymphal activity and in the absence of rhipicephalus appendiculatus adults, indicating that larva to nymph transmission plays a more prominent role than nymph to adult transmission under the prevailing conditions. | 2000 | 11059039 |
| polymorphic open reading frames encoding secretory proteins are located less than 3 kilobases from theileria parva telomeres. | polymorphic, multicopy gene families are frequently located in subtelomeric regions of the genomes of parasitic protozoa. theileria parva telomere-associated (ta) dna from two chromosomes contained long open reading frames (orfs) 54% identical at the n-termini, whose 3' ends were 2670 and 2680 bp from the telomeric repeats. probes derived from these orfs revealed related sequences close to additional telomeres. the 3' end of an unrelated orf was approximately 2720 bp from a third telomere. these ... | 2000 | 11071289 |
| microsequence heterogeneity and expression of the lsu rrna genes within the two single copy ribosomal transcription units of theileria parva. | the nucleotide sequences of the large subunit ribosomal rna coding genes within the two single copy ribosomal dna transcription units of a cloned theileria parva isolate from a buffalo were determined. the two lsu rrna coding units differed by 11 nucleotide substitutions and two deletions of 1 and 6 bp, all located in the 5' end of the lsu coding region. we also observed microsequence heterogeneity between the two buffalo parasite lsu sequences and the previously determined lsu rrna gene of a t. ... | 2000 | 11080596 |
| molecular and immunological characterisation of theileria parva stocks which are components of the 'muguga cocktail' used for vaccination against east coast fever in cattle. | the 'muguga cocktail' which is composed of three theileria parva stocks muguga, kiambu 5 and serengeti-transformed has been used extensively for live vaccination against east coast fever in cattle in eastern, central and southern africa. herein we describe the molecular characterisation of the t. parva vaccine stocks using three techniques, an indirect fluorescent antibody test with a panel of anti-schizont monoclonal antibodies (mab), southern blotting with four t. parva repetitive dna probes a ... | 2001 | 11137270 |
| immunisation against theileria parva in eastern zambia: influence of maternal antibodies and demonstration of the carrier status. | immunisation of calves by the infection and treatment method (i & t) has been extensively used in the eastern province of zambia to control east coast fever (ecf), a protozoan tick-borne disease. this paper presents the results of a field longitudinal study, which included a total of 148 angoni calves. after immunisation against ecf, they were monitored for a full rainy season, coinciding with the main peak of activity of the vector of theileria parva, the tick rhipicephalus appendiculatus. dysi ... | 2002 | 12446089 |
| distribution and phenology of ixodid ticks in southern zambia. | distribution data for epidemiologically important ticks (acari: ixodidae) in the southern province of zambia, one of the main cattle areas of the country, are presented. boophilus microplus (canestrini) was not recorded in southern zambia, whereas boophilus decoloratus (koch) is present throughout the area. new distribution patterns for less economically important ixodid ticks are also discussed. southern zambia is a transition zone because it is the most northern area in africa where mixed rhip ... | 2002 | 12510896 |
| cellular immunity against theileria parva and its influence on parasite diversity. | theileria parva, a tick-borne parasite of african cattle, causes a fatal disease known as east coast fever. cattle that recover from the disease develop strong parasite-specific mhc-class i-restricted cytotoxic t-lymphocyte responses. protection can be transferred between immune and naïve calves in the cd8+ t cell fraction emanating from a responding lymph node. in vitro studies suggest that this response requires input from activated cd4+ t cells. the t parva life cycle involves developmental s ... | 2001 | 11170857 |
| the epidemiology of theileria parva infections on smallholder dairy farms in kenya. | the purpose of the study was to characterize the differences in epidemiology (risks of infection, morbidity, mortality) and potential control of east coast fever (ecf) between the selected strata. evidence of theileria parva infection was assessed by increased antibody levels as measured in an indirect elisa test by the percent positivity (pp) of serum samples relative to a strong positive reference serum. a prospective cohort study was conducted in five purposively sampled agroecological zone ( ... | 2000 | 11193631 |
| vaccines against theileria parva. | bovine theileriosis caused by theileria parva continues to be a major economic problem in many parts of eastern, southern, and central africa. due to the unsustainable nature of the present control method--using toxic acaricides to kill ticks--alternative control methods are being sought. live vaccines are being used in many countries in the region. these vaccines are based on the infective sporozoite stage of the parasite. sporozoites are inoculated in cattle with simultaneous administration of ... | 2000 | 11193661 |
| theileria parva: taking control of host cell proliferation and survival mechanisms. | the intracellular parasite theileria parva infects and transforms bovine t-cells, inducing their uncontrolled proliferation and spread in non-lymphoid as well as lymphoid tissues. this parasite-induced transformation is the predominant factor contributing to the pathogenesis of a lymphoproliferative disease, called east coast fever. t. parva-transformed cells become independent of antigenic stimulation or exogenous growth factors. a dissection of the signalling pathways that are activated in t. ... | 2000 | 11207566 |
| economics of theileriosis control in zambia. | for an economic analysis of theileriosis control, we adopted the total economic cost (tec) method, which calculates the sum of output losses from tick damage, theileriosis mortality and morbidity, and expenditures for treatment or prevention of the disease. at farm level, the tec can be minimized by a specific combination of vector control and/or immunization and an acceptable level of losses. expenditures for vector control include acaricides, construction of dipping or spraying facilities and ... | 1999 | 10540312 |
| transmission of theileria parva in the traditional farming sector in the southern province of zambia during 1997-1998. | the incidence of first contact with the protozoan theileria parva was determined in two traditional cattle herds in the southern province of zambia during a period of average rainfall in 1997 and 1998, following a drought in the previous two years. compared to that period, there was a marked increase in the number of rainy season first contacts attributable to transmission by rhipicephalus appendiceulatus adults. however, there were still more dry season contacts that resulted from nymphal trans ... | 2001 | 11254072 |
| tick-theileria interactions in response to immune activation of the vector. | watt, d. m., walker, a. r., lamza, k. a., and ambrose, n. c. 2001. tick-theileria interactions in response to immune activation of the vector. experimental parasitology 97, 89-94. immune mechanisms towards the haemoprotozoan parasite theileria parva were investigated in their tick vector, rhipicephalus appendiculatus. the exoskeletons of adult ticks were initially pierced with bacteria-coated, saline-coated, or sterile dry glass needles. haemolymph was extracted from the ticks at 6, 24, 48, and ... | 2001 | 11281705 |
| the akt/pkb pathway is constitutively activated in theileria-transformed leucocytes, but does not directly control constitutive nf-kappab activation. | the intracellular protozoan parasites theileria parva and theileria annulata transform leucocytes by interfering with host cell signal transduction pathways. they differ from tumour cells, however, in that the transformation process can be entirely reversed by elimination of the parasite from the host cell cytoplasm using a specific parasiticidal drug. we investigated the state of activation of akt/pkb, a downstream target of pi3-k-generated phosphoinositides, in theileria-transformed leucocytes ... | 2001 | 11488815 |
| the immunisation of cattle against east coast fever (theileria parva infection) using tetracyclines: a review of the literature and a reappraisal of the method. | | 1965 | 14344196 |
| the impact of theileria parva infections and other factors on calf mean daily weight gains in smallholder dairy farms in murang'a district, kenya. | the association between mean daily weight gain, theileria parva infections, clinical east coast fever and other possible determinants of weight gain were examined in a longitudinal observational study that was conducted in cohorts of female calves from five agro-ecological zone (aez)-grazing strata. the strata were upper-midlands (um) 1 zero-grazing, um 1 open-grazing, um 2 zero-grazing, um 4 zero-grazing and um 4 open-grazing. in total, 225 calves on 188 smallholder dairy farms were visited wit ... | 2001 | 11535277 |
| seroprevalences of vector-transmitted infections of small-holder dairy cattle in coastal kenya. | a cross-sectional study was carried out from july to september 1989 in kaloleni division, coast province, kenya to estimate the prevalence of vector-transmitted diseases in small-holder dairy cattle and to identify the risk factors associated with different management systems. one hundred and thirty of the 157 herds with dairy cattle in kaloleni division were surveyed. these were from three agro-ecological zones (coconut-cassava, cashew nut-cassava and livestock-millet), comprised two management ... | 2001 | 11566374 |
| identification of a target population for immunisation against east coast fever in coastal kenya. | two experiments were carried out to identify the target population of cattle for immunisation against east coast fever (ecf) using the infection-and-treatment method. firstly, a sentinel-calf study was used to determine the age window for ecf immunisation by determining ages at clinical detection of infection with theileria parva. six groups of five naive cross-bred (bos taurus/bos indicus) male calves, introduced at intervals of 2 months at a mean age of 26 days, were exposed to natural tick ch ... | 2001 | 11566376 |
| a panel of microsatellite and minisatellite markers for the characterisation of field isolates of theileria parva. | mini- and microsatellite sequences show high levels of variation and therefore provide excellent tools for both the genotyping and population genetic analysis of parasites. herein we describe the identification of a panel of 11 polymorphic microsatellites and 49 polymorphic minisatellites of the protozoan haemoparasite theileria parva. the pcr products were run on high resolution spreadex gels on which the alleles were identified and sized. the sequences of the mini- and microsatellites were dis ... | 2003 | 14636680 |
| comparison of the transmission of theileria parva between different instars of rhipicephalus appendiculatus. | the transmission of theileria parva by nymphal and adult rhipicephalus appendiculatus was compared by the assessment of salivary gland infections in tick batches fed on the same group of infected cattle at the same time. when larval and nymphal r. appendiculatus muguga ticks were fed concurrently on cattle undergoing acute infection with t. parva muguga, the resultant nymphae developed a slightly lower prevalence of infection than did the adult ticks. the abundance of infection was 5-20 times hi ... | 1996 | 8811849 |
| immunity and vaccine development in the bovine theilerioses. | there are three economically important bovine theileria species: theileria annulata, which causes tropical theileriosis and occurs across north africa and most of central asia; theileria parva, which causes east coast fever and is found in east and central africa; and theileria sergenti, which is predominantly a problem in japan and korea. theileria annulata preferentially infects macrophages in vivo. it is controlled largely by means of live, attenuated vaccines, which are produced by prolonged ... | 1999 | 10563395 |
| characterization of a secretory type theileria parva glutaredoxin homologue identified by novel screening procedure. | the schizont stage of the protozoan parasite theileria parva induces features characteristic of tumor cells in infected bovine t-cell lines. most strikingly t. parva-infected cell lines acquire unlimited growth potential in vitro. their proliferative state is entirely dependent on the presence of a viable parasite within the host cell cytoplasm. it has been postulated that parasite proteins either secreted into the host cell or expressed on the parasite surface membrane are involved in the paras ... | 1997 | 9006954 |
| epidemiological observations of zimbabwean theileriosis: disease incidence and pathogenicity in susceptible cattle during rhipicephalus appendiculatus nymphal and adult seasonal activity. | fifty-nine hereford cattle susceptible to tick-borne diseases were used as tracer animals to assess the tick challenge and pathogenicity of theileria parva under field conditions in zimbabwe. they were moved periodically in groups of five to three commercial farms (one group consisted of four) during seasons of rhipicephalus appendiculatus nymphal and adult activity. all tracer cattle were herded together with the farm cattle but were not dipped. the nymphal tick counts were high on two of the f ... | 2001 | 11769350 |
| exposure of cattle immunized with different stocks of theileria parva to buffalo-associated theileria challenge on two game parks in zimbabwe. | eight cattle immunized with cattle-derived theileria parva boleni stabilate together with six susceptible controls were released in dombawera game park on the highveld of zimbabwe. this coincided with rhipicephalus appendiculatus nymphal activity. the cattle grazed together with african buffaloes (syncerus caffer) and were not treated against tick infestation. the nymphal tick infestation was high, and seven of the eight immunized cattle and three of the controls had severe and fatal reactions. ... | 2001 | 11769351 |
| application of a reverse line blot assay to the study of haemoparasites in cattle in uganda. | recent advances in genomic technology have focused many veterinary researchers on the possibility of producing one multivalent recombinant vaccine against all the haemoparasites that infect cattle in the tropics. before such a vaccine is developed it is essential to define target cattle populations as well as the range of anti-pathogen vaccines required in order to control disease. to further this objective, we have evaluated a reverse line blot (rlb) assay, which simultaneously detects the prin ... | 2004 | 15064125 |
| laboratory and field investigations into the theileria parva carrier-state in cattle in zimbabwe. | the theileria parva carrier-state in cattle on commercial farms on zimbabwe was investigated using parasitological and serological methods. the proportion of cattle showing theileria piroplasms on two farms, which had recent histories of disease outbreaks, were 64% (n = 106, total of heifers and weaned calves examined) and 71.5% (n = 60) while the proportion of t. parva antibodies for the same animals were 59% and 98.5%, respectively. on four farms where no cases of the disease occurred for over ... | 2001 | 11769352 |
| immunization of cattle against east coast fever using theileria parva (marikebuni) and relaxation of tick control in north rift, kenya. | a total of 90 animals was immunized against east coast fever (ecf) using theileria parva (marikebuni) stock on three large-scale farms in kiminini division, trans-nzoia district, north rift, kenya. another 90 cattle served as non-immunized controls. following immunization the number of cattle with significant indirect fluorescent antibody (ifa) titres increased from 43.9% to 84.4% and 6.7% of the cattle developed clinical ecf reactions. two months after immunization, the immunized and non-immuni ... | 2001 | 11769354 |
| validation of an in vitro method to determine infectivity of cryopreserved sporozoites in stabilates of theileria spp. | the infectivity of 15 cryopreserved theileria spp. sporozoite stabilates was assessed semi-quantitatively by titration using naive peripheral blood mononuclear cells (pbm) in vitro in multi-well plates. using the method described, the effective dilution, which would result in 50% of replicate wells infected (ed50), was calculated. the ed50 for 11 theileria annulata stabilates in bovine pbm ranged from 10(-2.6) to 10(-4.2) dilutions of 1 tick equivalent (t.e.) ml(-1), one stabilate of theileria p ... | 2002 | 11812618 |
| characterization of a polymorphic theileria annulata surface protein (tasp) closely related to pim of theileria parva: implications for use in diagnostic tests and subunit vaccines. | theileria annulata is a tick-transmitted protozoan that causes tropical theileriosis, an often fatal leukoproliferative disorder of cattle. to characterize and identify parasite proteins suitable as diagnostic antigens and/or vaccine candidates, a cdna clone encoding a macroschizont stage protein was isolated and characterized (here designated tasp). the gene, present as a single copy within the parasite genome, is transcribed in the sporozoite and schizont stage and codes for a protein of about ... | 2002 | 11897130 |
| the persistence of theileria parva infection in cattle immunized using two stocks which differ in their ability to induce a carrier state: analysis using a novel blood spot pcr assay. | an improved theileria parva dna detection assay based on the polymerase chain reaction (pcr) using primers derived from the 104 kda antigen (p104) gene was developed to detect parasite dna in blood spots on filter paper. the specificity of the assay was validated using dna from a wide range of cattle-derived and buffalo-derived stocks of t. parva. dna of t. annulata, t. buffeli, t. lestoquardi, t. mutans and t. taurotragi was not amplified using the p104 primers. the detection threshold of the a ... | 2002 | 11922428 |
| theileria parva epidemics: a case study in eastern zambia. | this paper presents the results of the follow-up of three sentinel herds between 1994 and 2000 during an east coast fever (ecf) epidemic in eastern zambia. the animals of the sentinel herds were closely monitored clinically and serologically together with detailed rhipicephalus appendiculatus counts. peaks of disease incidence occurred in the rainy season (december-february) and the dry months of may-july with nymph-to-adult tick transmission dominating the infection dynamics. a second wave of a ... | 2002 | 12072213 |
| comparative studies of the efficacy of parvaquone and parvaquone-plus-frusemide in the treatment of theileria parva infection (east coast fever) in cattle. | comparative studies of the efficacy of parvaquone (parvexon) and parvaquone-plus-frusemide (fruvexon) bimeda chemicals, ireland, were done on 60 naturally infected cases of east coast fever (ecf; theileria parva infection in cattle). small-scale dairy farmers in the peri-urban of dar es salaam city reported ecf-suspected cases from march to mid-october 2001 and were treated with the two drugs alternately, as were diagnosed positive for ecf. four sub-groups of 15 cattle each (early stage, 15; adv ... | 2002 | 12237138 |
| buffalo-associated theileria parva: the risk to cattle of buffalo translocation into the highveld of zimbabwe. | there has been an increase in the introduction of game animals, including african buffaloes, into the highveld of zimbabwe to establish private game reserves on condition that they are confined in separate and secured paddocks. owing to shortages of pastures cattle were grazed in buffalo-grazed paddocks resulting in outbreaks of buffalo-derived theileriosis. this paper reports the results of epidemiological observations carried out on two game reserves to assess the risk of buffalo translocation ... | 2002 | 12381605 |
| constitutive exclusion of csk from hck-positive membrane microdomains permits src kinase-dependent proliferation of theileria-transformed b lymphocytes. | infection of bovine t cells and b cells with the intracellular protozoan parasite theileria parva induces a transformed phenotype with characteristics comparable to leukemic cells. the transformed phenotype reverts on drug-induced parasite death, and the cured lymphocytes acquire a resting phenotype and eventually die by apoptosis if not further stimulated. here, we show that both lymphocyte proliferation and activation of the transcription factor ap-1 are mediated by src-family protein tyrosine ... | 2003 | 12411311 |
| fusion to green fluorescent protein improves expression levels of theileria parva sporozoite surface antigen p67 in insect cells. | east coast fever (ecf) is a fatal disease of cattle caused by the protozoan parasite theileria parva. the development of a subunit vaccine, based on the sporozoite-specific surface antigen p67, has been hampered by difficulties in achieving high-level expression of recombinant p67 in a near-authentic form. therefore two sets of recombinant baculovirus vectors were constructed. the first set, encoding various regions of p67, produced low levels of the corresponding p67 domains in high five cells, ... | 2002 | 12553568 |
| immunity to east coast fever in cattle induced by a polypeptide fragment of the major surface coat protein of theileria parva sporozoites. | full-length recombinant versions of p67, the 709 amino acid major surface protein of theileria parva sporozoites, induce immunity to east coast fever (ecf) in cattle. we show that a soluble escherichia coli recombinant version of p67 (p67(635)), in which a prokaryotic signal peptide replaces the eukaryotic one, confers protection comparable to that induced by the full-length molecule, but is unstable. peptides encoding 80 (p67c) and 205 (p67n) amino acid fragments of p67, containing epitopes rec ... | 2003 | 12559799 |
| evaluation of pcr to detect theileria parva in field-collected tick and bovine samples in tanzania. | the ability of pcr to detect infections of theileria parva, the cause of east coast fever, in field-collected tick and bovine samples from tanzania was evaluated. pcr-detected infection prevalence was high (15/20, 75%) in unfed adult rhipicephalus appendiculatus ticks that fed as nymphs on an acutely-infected calf, but low (22/836, 2.6%) in unfed adult r. appendiculatus collected from field sites in tanzania. tick infection prevalence was comparable to that in previous studies that used salivary ... | 2003 | 12591193 |
| constitutive pi3-k activity is essential for proliferation, but not survival, of theileria parva-transformed b cells. | theileria is an intracellular parasite that causes lymphoproliferative disorders in cattle, and infection of leucocytes induces a transformed phenotype similar to tumour cells, but the mechanisms by which the parasite induces this phenotype are not understood. here, we show that infected b lymphocytes display constitutive phosphoinositide 3-kinase (pi3-k) activity, which appears to be necessary for proliferation, but not survival. importantly, we demonstrate that one mechanism by which pi3-k med ... | 2000 | 11207589 |
| comparison of cryoprotectants in the preservation of theileria parva sporozoites using an in vitro infectivity assay. | an in vitro infectivity assay was used to examine five cryoprotectants for their suitability for preserving theileria parva sporozoites. all five were capable of preserving t. parva sporozoites through freezing, the optimal concentrations being 7.5% for glycerol, 5% for dimethyl sulphoxide (dmso), poly (vinylpyrrolidone) (pvp) and poly(ethylene glycol) (peg), and 2.5% for hydroxyethyl starch (hes). when the five cryoprotectants were compared at their optimal concentrations, using a modification ... | 2001 | 11234190 |
| endemic stability for theileria parva infections in ankole calves of the ankole ranching scheme, uganda. | a population-based study was carried out on the ankole ranching scheme in south-west uganda with the aim of determining the endemic status of theileria parva infections. for this purpose, the age-related sero-prevalence of t. parva and the specific calf mortality associated with the parasite were assessed. blood samples were collected from 931 ankole calves of up to 12 months of age from 81 randomly selected herds. the relationship between rainfall pattern and whole-body rhipicephalus appendicul ... | 2004 | 15580767 |
| variation in body size in the tick complex rhipicephalus appendiculatus/rhipicephalus zambeziensis. | we examined the relationship between body size and the phenology of the tick complex rhipicephalus appendiculatus/rhipicephalus zambeziensis. these ticks transmit theileria parva in cattle. in africa, the body size of r. appendiculatus increases with latitude while the body size of the morphologically similar rhipicephalus zambeziensis is constant at two different latitudes. a larger body size is necessary once survival becomes a constraint. the most plausible explanation for the smaller r. appe ... | 2004 | 15707294 |
| evaluation of the indirect fluorescent antibody test as a diagnostic tool for east coast fever in eastern zambia. | serological surveys using the schizont indirect fluorescence antibody test (ifat) are routinely carried out to monitor the theileria parva infection prevalence. the present study evaluates the diagnostic accuracy of the ifat in eastern zambia, where the transmission of t. parva is highly seasonal. the data set resulted from a sentinel herd (n = 105 animals) study carried out between 1995 and 2000 and was split into an epidemic period, during which the majority of the cattle became infected, and ... | 2004 | 15710519 |
| baculovirus surface display of theileria parva p67 antigen preserves the conformation of sporozoite-neutralizing epitopes. | theileria parva is an intracellular protozoan parasite that causes east coast fever, a severe lymphoproliferative disease in cattle. previous attempts to produce recombinant sporozoite surface antigen (p67) in bacterial or insect cells for vaccine purposes have not resulted in a correctly folded protein. here, we report the expression of n- and c-terminal domains of p67 fused to the baculovirus envelope glycoprotein gp64 by cloning the appropriate p67 cdna segments between the signal sequence an ... | 2003 | 12646695 |
| merogony in in vitro cultures of theileria parva. | in vitro studies were focussed on the duration and cessation of merogony in theileria parva infected blood lymphocyte cell cultures. the cultures were infected using purified tick stabilates as an alternative to in vitro infections, using sporozoites obtained by labour intensive dissections of salivary glands from infected ticks. after establishment of infection in peripheral blood lymphocytes (pbl), merozoites were temporarily produced for about 2 months after which lymphoblasts only contained ... | 2003 | 12788254 |
| survival of theileria parva in its nymphal tick vector, rhipicephalus appendiculatus, under laboratory and quasi natural conditions. | groups of nymphal rhipicephalus appendiculatus muguga, having a mean of 1 or 9 theileria parva muguga-infected salivary gland acini per tick, were kept under quasi-natural conditions at an altitude of 1950 m or 20 degrees c at a relative humidity of 85% in the laboratory and their survival and infection prevalence and abundance determined over time. theileria parva infections for both categories of ticks survived in the nymphal ticks for 50 or 26 weeks post salivary gland infection under quasi-n ... | 2003 | 12866795 |
| theileria parva-transformed t cells show enhanced resistance to fas/fas ligand-induced apoptosis. | lymphocyte homeostasis is regulated by mechanisms that control lymphocyte proliferation and apoptosis. activation-induced cell death is mediated by the expression of death ligands and receptors, which, when triggered, activate an apoptotic cascade. bovine t cells transformed by the intracellular parasite theileria parva proliferate in an uncontrolled manner and undergo clonal expansion. they constitutively express the death receptor fas and its ligand, fasl but do not undergo apoptosis. upon eli ... | 2003 | 12874209 |
| a tumour necrosis factor alpha autocrine loop contributes to proliferation and nuclear factor-kappab activation of theileria parva-transformed b cells. | theileria infection of bovine leucocytes induces uncontrolled proliferation and a transformed phenotype comparable to tumour cells. infected cells have many characteristics of activated leucocytes and use autocrine loops to augment proliferation. we have shown previously that, in infected b cells, pi3-k controls a granulocyte-macrophage colony-stimulating factor (gm-csf) autocrine loop to increase both proliferation and activation of the activator protein 1 (ap-1) transcription factor. we show h ... | 2003 | 12969376 |
| apoptosis of theileria-infected lymphocytes induced upon parasite death involves activation of caspases 9 and 3. | the intracellular parasite theileria parva (t. parva) can infect bovine b and t-lymphocytes. t. parva-infected cells become transformed, and they survive and proliferate independently of exogenous growth factors. in vivo the uncontrolled cellular proliferation associated with lymphocyte transformation underlies the pathogenesis of the disease called east coast fever. the transformed state of parasitised cells can be reversed upon elimination of the parasite by specific theilericide drugs. in thi ... | 2003 | 14585544 |
| lyophilisation and resuscitation of sporozoites of theileria parva: preliminary experiments. | lyophilisation of theileria parva sporozoite stabilates used for immunisation of cattle against east coast fever would greatly improve vaccine storage and delivery. we report three attempts to lyophilise and resuscitate the sporozoites of t. parva. sporozoites survived lyophilisation and were effective for immunisation. lyophilised stabilate survived for 2 weeks at 5 degrees c and for 12 weeks at -20 degrees c. although the viability of the stabilates was severely reduced during lyophilisation, ... | 2003 | 14615148 |
| survival of theileria parva-infected adult rhipicephalus appendiculatus under laboratory and quasi-natural conditions. | adult rhipicephalus appendiculatus muguga, having high or low intensities of theileria parva muguga infection in their salivary glands, were exposed to 20 degrees c and 85% relative humidity in the laboratory or quasi-natural conditions. survival of the ticks and t. parva infections in their salivary glands was then monitored over a two year period. ticks, having an average infection level of 2 infected acini per female, survived for up to 70 or 106 weeks after moulting under the laboratory or q ... | 2003 | 14635820 |
| an unusual mosaic structure of the pim gene of theileria parva and its relationship to allelic diversity. | genetic diversity and structural organisation of the polymorphic immunodominant molecule (pim) gene of the protozoan parasite theileria parva was studied in isolates from sympatric and allopatric areas. the analyses revealed a mosaic structure consisting of highly conserved regions shared among some of the isolates from geographically different areas and homologous sequence runs shared among isolates from one area. the specific pattern of diversity in which large insertions and deletions were ob ... | 2004 | 14698429 |
| in vitro titration of theileria parva tick derived stabilates. | immunization against the protozoan theileria parva by infection and treatment has proved to be very efficient for the control of east coast fever, an acute and often-fatal lymphoproliferative tick-borne disease of cattle in eastern, central and southern africa. the immunizing dose of live t. parva sporozoites used in this method is usually determined by in vivo titration. an alternative in vitro method of quantification of sporozoites in whole tick-derived stabilates is proposed. the method cons ... | 2004 | 15030000 |
| treatment of east coast fever of cattle with a combination of parvaquone and frusemide. | pulmonary oedema is a common sign of east coast fever (ecf, theileria parva infection) of cattle. a trial was conducted on farms in uganda to compare a product containing both the antitheilerial compound parvaquone and the diuretic compound frusemide with one containing only parvaquone, in the treatment of ecf. the trial involved 40 clinical cases of ecf, some of them complicated by other infections, in cattle of all ages and on several farms. confirmed cases were treated with either parvaquone+ ... | 2004 | 15080540 |
| bovine leukocyte antigen major histocompatibility complex class ii drb3*2703 and drb3*1501 alleles are associated with variation in levels of protection against theileria parva challenge following immunization with the sporozoite p67 antigen. | initial laboratory trials of an experimental subunit vaccine against theileria parva based on the 67-kda major sporozoite surface antigen revealed a range of responses to challenge. we have analyzed convergence in seven sets of monozygotic twins which suggests that genetic factors may have an influence in determining the degree of protection provided by p67 immunization. in addition, we have examined whether allelic diversity at major histocompatibility complex class ii loci influences protectio ... | 2004 | 15102783 |
| improved immunogenicity of novel baculovirus-derived theileria parva p67 subunit antigens. | east coast fever (ecf) in cattle is caused by the tick-borne protozoan parasite theileria parva. the major sporozoite surface antigen of t. parva (p67) is an important candidate for inclusion in a subunit vaccine. recently, we reported the expression and production of different parts of p67 as fusions to either gfp or to the baculovirus gp64 envelope glycoprotein in insect cells, which resulted in stable proteins recognized by a monoclonal specific for native p67. the immunogenicity of these fus ... | 2004 | 15110403 |