Publications

lyophilised bovine serum as a substitute for frozen serum in the cultivation of babesia bigemina and b bovis.	lyophilised serum offers significant advantages over frozen serum when it comes to shipping such material over long distances. babesia bigemina and b bovis were cultured in medium supplemented by either frozen-thawed or lyophilised-rehydrated serum. there were no significant differences between the two types of medium in the growth of parasites and percentage of infected cells during subcultivation for 18 days.	1992	1553430
a cloned dna probe for cowdria ruminantium hybridizes with eight heartwater strains and detects infected sheep.	the dna probe pcs20, which was cloned from the dna of the crystal springs heartwater strain from zimbabwe, cross-reacted with dnas of heartwater strains from all endemic areas, including four heartwater strains from zimbabwe, two strains from south africa, one strain from nigeria, and the gardel strain from the caribbean island of guadeloupe. by nucleic acid hybridization, the pcs20 dna probe detected cowdria ruminantium dna in all dna preparations made from plasma samples from infected sheep be ...	1992	1572987
detection of babesia bovis carrier cattle by using polymerase chain reaction amplification of parasite dna.	carrier cattle infected with babesia bovis are difficult to detect because of the low numbers of parasites that occur in peripheral blood. however, diagnosis of low-level infections with the parasite is important for evaluating the efficacies of vaccines and in transmission and epidemiological studies. we used the polymerase chain reaction (pcr) to amplify a portion of the apocytochrome b gene from the parasite and tested the ability of this method to detect carrier cattle. the target sequence i ...	1992	1624551
chromosomes of babesia bovis and babesia bigemina.		1992	1625699
evaluation of a dna-based probe for the detection of cattle experimentally infected with babesia bigemina.	a digoxigenin-labeled probe was used for hybridization to various preparations of babesia bigemina-infected erythrocyte extracts. dot blot hybridization and immunological detection of dna hybrids revealed that the probe was specific for b. bigemina dna because it did not hybridize to the dna of b. bovis, a closely related species. studies of sensitivity showed that the probe would bind to as little as 1 ng of b. bigemina dna, but not to 1 microgram of the b. bovis dna. the probe reacted with equ ...	1992	1626862
biology and transmission of babesia bigemina in boophilus microplus.		1992	1626891
rrna-based method for sensitive detection of babesia bigemina in bovine blood.	three synthetic oligonucleotide probes complementary to unique regions of babesia bigemina small-subunit rrna were developed for detecting the parasite in bovine blood. these probes specifically detected a parasitemia of 2 x 10(-5)% by autoradiography in less than 24 h by using a 200-microliters sample of bovine blood. these probes did not bind to total rna or genomic dna isolated from another closely related species, babesia bovis, or to bovine leukocyte rna. this method detected b. bigemina in ...	1992	1629339
babesia bigemina: quantitation of infection in nymphal and adult boophilus microplus using a dna probe.	candidates for a subunit vaccine against bovine babesiosis include surface proteins of infective forms found in the salivary glands of tick vectors. however, low numbers of infective forms are present within ticks and hinder analysis of this stage. to solve this problem, conditions which yield high numbers of infective forms were investigated with the use of a babesia bigemina-specific dna probe. dna from progeny of female boophilus microplus infected with b. bigemina was hybridized to probe dna ...	1992	1730269
immunogenic b-cell epitopes of babesia bovis rhoptry-associated protein 1 are distinct from sequences conserved between species.	babesia bovis merozoite apical membrane polypeptide bv60 was found to be rhoptry associated by immuno-electron microscopy and was redesignated rhoptry-associated protein 1 (rap-1). the n-terminal 300 amino acids of rap-1 have a high level of sequence similarity to the same n-terminal region of p58, its homolog from babesia bigemina. however, the interspecies conserved sequences did not include rap-1 surface-exposed b-cell epitopes as defined by monoclonal antibodies. furthermore, neither heterol ...	1993	7687587
babesia bigemina: isolation and characterization of merozoite rhoptries.	babesia bigemina apical membrane polypeptide p58, encoded by a multigene family with homologues in other babesia spp. and sequence similarity to rhoptry proteins in other apicomplexan parasites, was identified within merozoite rhoptries using immunoelectron microscopy. to identify additional b. bigemina rhoptry proteins, rhoptries were isolated from french pressure cell-disrupted merozoites fractionated by differential centrifugation and isopycnic sucrose density gradient centrifugation. a fract ...	1993	8224087
multiplex polymerase chain reaction based assay for the detection of babesia bigemina, babesia bovis and anaplasma marginale dna in bovine blood.	a highly sensitive polymerase chain reaction (pcr) based method was developed to detect, in the same blood sample, dna of hemoparasites frequently found together infecting cattle in tropical and subtropical areas. bovine blood containing equal parasitemias of babesia bigemina, b. bovis and anaplasma marginale infected erythrocytes was mixed to standardize the test. twenty microliters of 10-fold dilutions from the pooled blood sample were resuspended in pcr mixture buffer containing each of the s ...	1993	8291198
babesia bovis: characterization of the t helper cell response against the 42-kda merozoite surface antigen (msa-1) in cattle.	the babesia bovis major merozoite surface antigen (msa-1) is a 42-kda integral membrane glycoprotein previously shown to induce immunodominant antibody responses in cattle protectively immune to b. bovis and to induce neutralizing antibody. recent studies have also shown that msa-1 b cell epitopes common to new world strains of b. bovis are not present in either israel or australia strains. to understand the potential role of this protein in protective immunity, t helper cell responses specific ...	1993	8344411
characterisation of a family of multi-copy genes encoding rhoptry protein homologues in babesia bovis, babesia ovis and babesia canis.	a monoclonal antibody that had been raised against a protease-containing fraction of babesia bovis, and shown to bind to a protein located in the rhoptries, was used to screen a b. bovis cdna expression library. the sequence of the protein encoded by a positive clone was almost identical to the equivalent region of a previously described b. bovis 60-kda rhoptry protein (bv60). a tandem repeat of the gene encoding bv60 was identified in all australian isolates of b. bovis examined. genes encoding ...	1993	8433711
a nonsubjective assay for antigenic modifications of the babesia bovis-parasitized erythrocyte surface.	intracellular protozoan parasites induce numerous alterations in the invaded host cell, including antigenic modifications of the host cell plasma membrane. we have developed a quantifiable, non-subjective assay for the detection of novel antigenic reactivities on the host cell surface using as a model system bovine erythrocytes infected with babesia bovis. infected erythrocytes, metabolically labeled with l-[35s]methionine, were sensitized by incubation with bovine immune serum, then were captur ...	1993	8459338
efficacy of an australian babesia bovis vaccine strain in malawi.	three calves vaccinated with the australian ka strain of babesia bovis were fully protected against experimental infection with an isolate from a farm on which four of 210 vaccinated cattle had died from b bovis infection. a degree of cross protection against the isolate was demonstrated in one calf which had been infected previously with babesia bigemina.	1993	8470344
human interferon alpha fails to inhibit the development of babesia bigemina and anaplasma marginale infections in cattle.	studies were undertaken to determine whether human interferon alpha (huifn-alpha) administered orally could inhibit the development of clinical disease caused by the intraerythrocytic protozoan babesia bigemina and the intraerythrocytic rickettsia anaplasma marginale in cattle. huifn-alpha did not inhibit intraerythrocytic multiplication of either of the two parasites, suggesting that there is no role for huifn-alpha administered orally in the control of these pathogens.	1993	8493761
molecular variation and diversity in candidate vaccine antigens from babesia.	recombinant vaccines are being developed against a number of species of protozoan parasites in the genus babesia. protozoan parasites are notorious for their diversity of strains and their ability to express families of equivalent, but antigenically distinct, surface proteins. in order to reduce the likelihood of evasion of the immune response induced by a recombinant vaccine, ideal components should be essential proteins encoded by single copy genes. the proteins should also have a limited abil ...	1993	8100672
live and soluble antigens for cattle protection to babesia bigemina.	attenuated babesia bigemina were multiplied in vivo and in vitro to vaccinate two groups (groups 2 and 3) of holstein friesian heifers. another group (group 1) of heifers was vaccinated twice with purified soluble antigens obtained from the supernatant of in vitro culture combined with saponin. all these heifers plus controls (group 4) were inoculated with heterologous pathogenic b. bigemina 5 months later. heifers vaccinated with live organisms (group 2 and 3) were able to stand the challenge w ...	1993	8128585
use of multiplex polymerase chain reaction-based assay to conduct epidemiological studies on bovine hemoparasites in mexico.	a study was conducted to test the applicability of a polymerase chain reaction (pcr)-based approach for the simultaneous detection of the bovine hemoparasites babesia bigemina, b. bovis and anaplasma marginale. bovine blood samples from cattle ranches of a previously determined enzootic zone in the yucatan peninsula of mexico, were collected from peripheral blood and processed for pcr analysis. blood samples were subjected to dna amplification by placing an aliquot in a reaction tube containing ...	1993	8134659
a study of autoantibodies to phosphatidyl-serine in babesia bovis and babesia bigemina infections in cattle.	sera from cattle infected with babesia bovis were found to contain antibodies to phosphatidyl-serine (ps), a negatively charged phospholipid normally found on the internal membrane of erythrocytes. in contrast, no autoantibodies were detected following babesia bigemina infection indicating that the autoimmunity is not genus specific. during infection with babesia bovis, ps translocates to the external membrane and it is suggested that this may result in ps behaving as an autoantigen owing to a t ...	1994	8160363
fluorescence-activated cell sorting-derived clones of babesia bigemina show karyotype polymorphism.	use of the fluorescence-activated cell sorter proved to be an accurate and highly efficient means for cloning babesia parasites. these qualities were examined by separating a mixed population of babesia-infected bovine erythrocytes composed of two isolates with different karyotypes. direct evidence of polymorphism was detected during comparison of the resultant clones.	1994	8202447
identification of babesia bigemina infected erythrocyte surface antigens containing epitopes conserved among strains.	the presence of previously uncharacterized antigens (new antigens) on the surface of intact erythrocytes infected with three strains of babesia bigemina from kenya and one each from puerto rico, mexico, st. croix, and texcoco-mexico was demonstrated by indirect immunofluorescent antibody (ifa) reactions. these antigens were not strain specific because antibodies in bovine immune serum to either the mexico or kenya isolates reacted with all seven strains tested. homologous and heterologous immune ...	1994	8208585
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 ...	1994	7886919
antigenic profile of a pure isolate of anaplasma marginale of brazilian origin, using a western blot technique.	anaplasma marginale initial bodies of the brazilian isolate aufv1 were purified from infected erythrocytes using a combination of lysis, ultrasonic disruption and differential centrifugation. initial bodies were solubilised with a buffer containing protease inhibitors and non-ionic detergents. immunochemical analysis by the western blot technique revealed at least five proteins with apparent molecular weights (mw) of 105, 100, 97, 87 and 38 kda when homologous sera were used as primary antibodie ...	1994	8030178
isolation of babesia bigemina and babesia bovis merozoites by ammonium chloride lysis of infected erythrocytes.	1. we describe the isolation of viable merozoites from erythrocytes infected with babesia bovis or babesia bigemina organisms by ammonium chloride lysis. 2. parasite morphology was examined by both light and transmission electron microscopy. erythrocyte-free parasites maintain their viability and infectivity, retain their antigenicity and are suitable for use in the indirect fluorescent antibody assay.	1994	7549981
seasonal incidence and hemoparasite infection rates of ixodid ticks (acari: ixodidae) detached from cattle in costa rica.	to determine the tick species hindering the cattle industry in costa rica and to assess infection rates of ticks with three important hemoparasite species, cattle were monitored during a period of six months (october 1992-march 1993). four farms were located in the dry pacific region of the canton of tilarán and a fifth farm on the slopes of the poás volcano in a cool tropical cloud-forest ecosystem. on each farm 3 to 5 animals of 6 to 24 months of age were selected at random. all ticks were rem ...	1994	7501871
interstrain conservation of babesial rap-1 surface-exposed b-cell epitopes despite rap-1 genomic polymorphism.	members of the babesial rhoptry-associated protein 1 (rap-1) family express surface-exposed b-cell epitopes and are candidate antigens for vaccine development. the relationship between rap-1 genomic polymorphism and surface-exposed b-cell epitope expression was analyzed by comparison of biological clones of mexico strain babesia bigemina and babesia bovis with strains isolated in argentina. despite genomic polymorphism between strains, including sequences located within the open reading frame, d ...	1994	7518810
antibody response to a babesia bigemina rhoptry-associated protein 1 surface-exposed and neutralization-sensitive epitope in immune cattle.	protective immunity against babesia bigemina is hypothesized to involve antibodies directed against merozoite surface-exposed epitopes. levels of antibody against a rhoptry-associated protein 1 (rap-1) b-lymphocyte epitope, defined by surface-reactive and inhibitory monoclonal antibodies, in immune cattle sera were determined. all cattle produced antibodies to the epitope; however, there was limited correlation between immune protection induced by infection or rap-1 immunization and the level of ...	1994	7525490
monoclonal antibody to a conserved epitope on proteins encoded by babesia bigemina and present on the surface of intact infected erythrocytes.	to define babesia bigemina-specific antigens on the surface of infected erythrocytes, monoclonal antibodies (mabs) were identified by live-cell immunofluorescence. as determined by live-cell immunofluorescence, two mabs made to the mexico strain reacted with the mexico strain and three kenya strains, while three mabs made to the kenya-ngong strain reacted with the kenya strains but not the mexico strain. binding of mab 44.18 (made to the mexico strain) to a strain-common epitope was confirmed by ...	1995	7543884
effects of tick infestation and tick-borne disease infections (heartwater, anaplasmosis and babesiosis) on the lactation and weight gain of mashona cattle in south-eastern zimbabwe.	the effects of ticks and tick-borne disease infections on the lactation and weight gain of mashona cattle were studied at mbizi quarantine station in the south-eastern lowveld of zimbabwe. twenty-nine mashona cows were allocated to 2 balanced groups and kept in separate paddocks at a stocking rate of one animal per 8 ha. one group received regular acaricide treatment to control bont (amblyomma hebraeum) and other ticks. the other group was left untreated. the cows were artificially inseminated. ...	1995	7502343
dna measurements reveal differences in the life cycles of babesia bigemina and b. canis, two typical members of the genus babesia.	the relative dna levels of different developmental stages of babesia bigemina and b. canis were measured by cytophotometry using the fluorochrome hoechst 33258 as a staining dye. the dna measurements provided direct proof of sexual reproduction, i.e., fusion of gametes resulting in the formation of zygotes followed by a meiotic division. both babesia species are considered to be typical members of the genus babesia; however, the dna measurements revealed important differences in the life cycle o ...	1995	7479652
epidemiology of babesiosis and anaplasmosis in south and central america.	babesiosis (babesia bovis and babesia bigemina) and anaplasmosis (anaplasma marginale) affect native cattle from uruguay and northern argentina to guatemala. the distribution of babesia follows the dissemination of the tick vector. seroepidemiological studies showed that enzootic instability exist in herds in several areas of the region. however, clinical cases occurred less frequently than expected. the babesial tick infection rate is related to the vector abundance which in turn is regulated b ...	1995	7597777
strategies for the control of one-host ticks and relationship with tick-borne diseases in south america.	a variety of hemoparasites occurs in ruminants of south america (12 degrees 00'n-56 degrees 00's), but there is consensus on the significant economic impact of babesiosis (babesia bovis and babesia bigemina) and anaplasmosis (anaplasma marginale). the tick vector for the babesia spp. for the whole region is boophilus microplus which has been the most important target in control/eradication programs. boophilus microplus and many different hematophagous diptera species are considered vectors of a. ...	1995	7597780
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 ...	1995	7597786
molecular basis for vaccine development against anaplasmosis and babesiosis.	immunization of livestock against the erythroparasitic pathogens anaplasma marginale, babesia bigemina, and babesia bovis with safe and effective killed vaccines is not yet feasible on a practical basis. however, the immune protection afforded by recovery from natural infection and premunition indicates that microbial epitopes capable of inducing immunity exist and that the bovine immune system can be primed appropriately. induction of protection by immunization with killed parasite fractions, e ...	1995	7597787
small extrachromosomal nucleic acid segments in protozoan parasites.	viruses have been described in the following protozoa: babesia spp., trichomonas vaginalis, giardia lamblia, leishmania braziliensis and eimeria spp. in order to study the babesia bovis virus, merozoites have been prepared from the blood of infected cattle. agarose gel electrophoresis of nucleic extracts from the bovine protozoa b. bovis and babesia bigemina were separated into genomic dna and at least two additional nucleic acids. one molecule with a relative mobility of 5.5 kilobase pairs (kbp ...	1995	7597793
susceptibility to different tick genera in gambian n'dama and gobra zebu cattle exposed to naturally occurring tick infestations.	tick collection on one side of the body and whole tail was performed weekly over one year on 11 gambian n'dama (bos taurus) and 11 gobra zebu (bos indicus) cattle to assess breed susceptibility to naturally occurring ticks. enzyme-linked immunosorbant assay was also performed to assess the serological prevalence of anaplasma marginale antigen and babesia bigemina antibody. packed red cell volume was measured and liveweight gain was recorded. significantly higher numbers of amblyomma variegatum ( ...	1995	7652946
babesia bigemina: host factors affecting the invasion of erythrocytes.	babesia bigemina merozoites enter their host's erythrocytes by an unknown mechanism that likely involves parasite surface components. identification of the parasite ligands involved in invasion is hampered by a lack of basic information about the invasion characteristics of babesia bigemina. therefore, restrictions on the species of red blood cells (rbc) that are susceptible to invasion were examined as well as the roles of erythrocyte ligands. an invasion assay and a proliferation assay were de ...	1995	7821413
[diagnosis of babesia bigemina with the immunoperoxydase test].	an immunoperoxidase assay for the serological diagnosis of babesia bigemina was developed. the antigen slides were prepared from b. bigemina-infected blood and stored at -20 degrees c. one hundred and sixty five sera were tested, comparing the immunoperoxidase assay to the indirect fluorescent antibody test. a coincidence of 95% was observed between both tests. for the immunoperoxidase assay, a relative sensitivity of 94.8%, a relative specificity of 95.5%, and a positive predictive value of 96. ...	1995	8745747
babesia bigemina: identification of b cell epitopes associated with parasitized erythrocytes.	rhoptries are involved in host cell invasion and rhoptry polypeptides, including the babesia bigemina rhoptry-associated protein-1 (rap-1), are targets for protective immune responses. polyclonal antisera produced against isolated rhoptries is directed predominantly against rap-1 and reacts with both the merozoite and the membrane of parasitized erythrocytes. to determine whether these b cell epitopes associated with the parasitized erythrocyte are derived from rap-1 or, alternatively, from prev ...	1995	8542990
detection of theileria annulata in blood samples of carrier cattle by pcr.	we report the detection of theileria annulata, the causative agent of tropical theileriosis, by pcr in blood samples obtained from carrier cattle. the assay employs primers specific for the gene encoding the 30-kda major merozoite surface antigen of t. annulata. a 721-bp fragment was amplified from blood samples taken monthly from calves experimentally infected with one of four different stocks of t. annulata originating in either mauritania, portugal, spain, or turkey. at the end of the experim ...	1995	8567902
observations on the use of elisa for detection of babesia bigemina specific antibodies.	an indirect enzyme-linked immunosorbent assay (elisa) was evaluated to study the cause of the high level of background reactions which hinders the application of elisa as a field diagnostic test for babesia bigemina. different blockers to improve the specificity of the elisa were compared. the use of soya milk (25%), gelatin (2.5%) and chicken serum (2%) did not significantly improve the specificity of the test. it was noted that the presence of fibrinogen contributed to the positive elisa resul ...	1996	8638393
cd4+ t-helper lymphocyte responses against babesia bigemina rhoptry-associated protein i.	a multigene family of 58- to 60-kda proteins, which are designated rhoptry-associated protein 1 (rap-1) and which come from the parasites babesia bigemina and babesia bovis, is a target for vaccine development. the presence of multiple gene copies and conserved sequences and epitopes of rap-1 implies that these proteins are functionally important for the survival of these parasites. furthermore, it was previously shown that b. bigemina rap-1 induced partial protection against challenge infection ...	1996	8675310
effect of mycobacterium phlei on the development of immunity to babesia bigemina.	the immunomodulatory role of mycobacterium phlei against intracellular blood protozoan babesia bigemina was demonstrated following experimental immunisation and challenge in bovine calves. a lysate of erythrocytes infected (6 x 10(9)) with b. bigemina was used as a source of dead antigen either with freund's complete adjuvant (fca) or with a trypsinised culture of m. phlei as a non-specific immunomodulation (nsi) agent with appropriate controls. following virulent challenge with b. bigemina infe ...	1996	8686168
acquisition of resistance to the tick amblyomma variegatum in boran cattle, bos indicus and the effects of trypanosoma congolense and babesia bigemina on host resistance.	resistance was induced in cattle to the tick amblyomma variegatum by five consecutive infestations with nymphs and adults. using the principal component analysis (pca), it was found that percentage of adults engorged, percentage of adults which died, percentage of nymphs which engorged, percentage of nymphs which moulted and percentage of nymphs which died, were the main indicators of resistance against a. variegatum. the percentages of nymphs which engorged or moulted after the third infestatio ...	1996	8686177
viability after thawing and dilution of simultaneously cryopreserved vaccinal babesia bovis and babesia bigemina strains cultured in vitro.	a live, frozen experimental vaccine containing babesia bovis and babesia bigemina multiplied in vitro was stored in liquid nitrogen after simultaneous cryopreservation using glycerol as cryoprotectant. the viability of the vaccine was tested by inoculating (subcutaneously) three groups of seven steers each, 2, 12 and 24 h after thawing at 40 degrees c and dilution to obtain a dose of 2 x 10(7) of each organism. all vaccinated cattle developed detectable parasitaemia in thin and/or thick blood sm ...	1996	8720572
light microscopy diagnosis of babesia bovis and babesia bigemina kinetes in the haemolymph of artificially infected boophilus microplus engorged female ticks.	the length, width and position of the nucleus of babesia bovis and babesia bigemina kinetes from the haemolymph of boophilus microplus engorged female ticks were recorded. additionally, the shape of babesia bovis kinetes were registered as curved, semi-curved or straight. to this aim boophilus microplus tick larvae from a colony free of babesia were fed on splenectomised calves artificially infected with either babesia bovis or babesia bigemina pathogenic strains. six engorged female ticks showi ...	1996	8750679
conservation of merozoite membrane and apical complex b cell epitopes among babesia bigemina and babesia bovis strains isolated in brazil.	babesia merozoite polypeptides bear surface exposed and neutralization-sensitive b cell epitopes and have been shown to induce partial protection against experimental challenge. variation in these epitopes has been examined in a limited number of strains. in this study, utilizing strains of babesia bovis and babesia begemina from matto grosso do sul in brazil, we examined the conservation of epitopes bound by monoclonal antibodies developed against mexico strains of b. bovis and b. bigemina. api ...	1996	8750680
babesia bovis rhoptry-associated protein 1 is immunodominant for t helper cells of immune cattle and contains t-cell epitopes conserved among geographically distant b. bovis strains.	the ability of rhoptry-associated protein 1 (rap-1) of babesia bovis and babesia bigemina to confer partial protective immunity in cattle has stimulated interest in characterizing both b-cell and t-cell epitopes of these proteins. it was previously shown that b. bovis rap-1 associates with the merozoite surface as well as rhoptries and expresses b-cell epitopes conserved among otherwise antigenically different b. bovis strains. an amino-terminal 307-amino-acid domain of the molecule that is high ...	1996	8757873
comparative sensitivity of two tests for the diagnosis of multiple hemoparasite infection of cattle.	the purpose of this study was to evaluate the efficacy of light microscopy (lm) examination of blood smears and a multiplex polymerase chain reaction (mpcr) assay, in terms of their ability to detect cattle experimentally infected with babesia bovis, babesia bigemina, and anaplasma marginale. blood samples were collected from 32 intact, 1-2 year old, holstein bulls, previous to and after simultaneous inoculation of culture-derived or field isolates of b. bovis- and b. bigemina-infected erythrocy ...	1996	8784493
use of polymerase chain reaction in bovine babesiosis research.	the polymerase chain reaction (pcr) in babesiosis research was originally developed to detect babesia bovis or babesia bigemina in blood samples containing infected erythrocytes. these preliminary studies led to development of a sensitive pcr/dna probe assay to detect the following hemoparasites: b. bigemina and b. bovis in a single sample. this modified procedure, referred to as a duplex pcr/ nonradioactive probe assay, has an analytic sensitivity of 0.00001% for b. bigemina, and 0.00001% infec ...	1996	8784529
piroplasms of domestic animals in the macedonia region of greece. 1. serological cross-reactions.	during a serological survey on haemoparasites in macedonia, serum samples were collected from cattle, sheep and goats. all sera were tested by the indirect immunofluorescence test (ifat); the cattle sera against theileria orientalis, t. annulata, babesia bigemina, b. bovis, b. divergens and b. major antigens; the sheep and goat sera against t. ovis, b. ovis, b. motasi and b. crassa antigens. parallel tests of negative and positive control sera against all the antigens showed the existence of cro ...	1996	8792579
piroplasms of domestic animals in the macedonia region of greece. 2. piroplasms of cattle.	a study was carried out on piroplasms of cattle in the macedonia region of greece. during 1984-1986, 602 serum samples were collected from cattle in 33 localities. blood smears were also prepared from 50 of the animals in 13 localities. the indirect fluorescent antibody (ifa) test revealed that 41.4% of cattle sera were positive to theileria orientalis, 2.0% to theileria annulata, 21.6% to babesia bovis, 15.2% to babesia bigemina, 5.1% to babesia major and 2.7% to babesia divergens. some of the ...	1996	8792580
field observations on the duration of immunity in cattle after vaccination against anaplasma and babesia species.	in an outbreak of babesia bovis in a large herd of friesian x malawi zebu cattle, which occurred after an interruption of intensive dipping, clinical or fatal babesiosis occurred in 54/299 (18.1%) animals which had never been vaccinated, as compared to 9/153 (5.9%) vaccinated animals. eight of the nine affected vaccinates had been vaccinated more than 27 months previously. sera were collected every 3-4 months from 33 friesian x malawi zebu heifers maintained with intensive dipping and vaccinated ...	1996	8848296
dimorphic sequences of rap-1 genes encode b and cd4+ t helper lymphocyte epitopes in the babesia bigemina rhoptry associated protein-1.	the rhoptry-associated protein-1 (rap-1) of babesia bigemina induces protective immune responses in cattle and contains neutralization-sensitive b cell epitopes. rap-1 variants containing blocks of sequence dimorphism in the amino and carboxy terminal ends are encoded by four nonallelic genes in b. bigemina. epitopes recognized by rap-1 specific monoclonal antibodies (mabs) and bovine cd4+ t cell clones were mapped to determine whether these epitopes are localized in the amino and carboxy termin ...	1996	8892308
prospects for subunit vaccines against tick-borne diseases.	tick-borne parasites are a serious impediment to the improvement of live-stock production in the developing world. the major parasites affecting cattle include theileria parva, t. annulata, babesia bigemina, b. bovis, anaplasma marginale and cowdria ruminantium. the control of these infections is dependent on the use of acaricides to decrease transmission by the tick vectors, and immunization of susceptible animals with live vaccines. the use of acaricide is hampered by the development of resist ...	1996	8979421
integrated tick and tick-borne disease control trials in crossbred dairy cattle in malawi.	crossbred dairy heifers on a farm in an east coast fever (ecf) endemic area in malawi were immunised against theileria parva, anaplasma spp., babesia bigemina, babesia bovis and cowdria ruminantium. they were treated at infrequent intervals with chlorfenvinphos to limit infestation with adult ticks, without providing complete tick control. in one trial, which tested a threshold dipping regimen, 20 heifers were dipped only once in 6 months to control a flush of boophilus microplus. unimmunised co ...	1996	8983132
experiments on the transmission of babesia major and babesia bigemina by haemaphysalis punctata.	experiments on the transmission by haemaphysalis punctata of three large babesia strains were carried out. three babesia-free batches of laboratory reared h. punctata ticks were infected with two strains of babesia major, b. major (xingjiang strain), isolated with adult ticks of h punctata and b. major (henan strain), isolated with h. longicornis) and a strain of babesia bigemina by feeding them on the calves infected by inoculation of blood stabilates. h. punctata was shown to be capable of tra ...	1996	9011018
artificial feeding of ixodid ticks.	ixodid ticks are economically important as they cause direct damage to livestock and are vectors of several pathogens that cause diseases in humans and animals. some of the important tick-borne pathogens of livestock are theileria parva, t. annulata, babesia bigemina, b. bovis, anaplasma marginale and cowdria ruminantium. these pathogens are responsible for causing enormous losses in livestock. identification of factors that influence transmission and development of these pathogens in ticks will ...	1996	15275192
comparison of the infectivity of babesia bovis, babesia bigemina and anaplasma centrale for cattle after cryopreservation in either dimethylsulphoxide (dmso) or polyvinylpyrrolidone (pvp).		1997	9034504
immunization with babesia bigemina rhoptry-associated protein 1 induces a type 1 cytokine response.	rhoptry-associated protein-1 (rap-1) homologues of babesia bigemina and babesia bovis are promising candidates for inclusion in subunit vaccines against these hemoprotozoan parasites. partial protection against challenge infection has been achieved with native forms of these antigens, but the mechanism of immunity has not been thoroughly defined. we previously demonstrated that a panel of antigen-specific t helper cell clones derived from b. bigemina rap-1-immunized cattle expressed relatively h ...	1997	9041471
babesial antibody dynamics after cattle immunisation with live vaccines, measured with an indirect immunofluorescence test.	the efficacy of vaccination of argentinean cattle against babesiosis and anaplasmosis using live immunogens was tested to detect specific antibodies in samples obtained about 60 days after vaccination. under these conditions a higher than expected proportion of cattle failed to show antibodies against babesia bigemina. therefore, a study was designed to evaluate if this failure was due to insensitivity of the routine test to detect antibodies to b. bigemina or to lack of infectivity of the live ...	1997	9195707
immunisation of smallholder dairy cattle against anaplasmosis and babesiosis in malawi.	a field study was conducted in the southern region of malawi to evaluate the possible benefits of immunisation of improved dairy cattle against anaplasma marginale, babesia bigemina and babesia bovis. friesian crossbred heifers were immunised when they were being reared on government farms. they were then issued to smallholder farmers, together with unvaccinated controls, where many of them were exposed to heavy tick infestation. vaccination was shown to provide a significant degree of protectio ...	1997	9203307
the prevalence of serum antibodies to tick-borne infections in cattle in smallholder dairy farms in murang'a district, kenya; a cross-sectional study.	the most important tick-borne disease of cattle in eastern, central and southern africa is east coast fever (ecf) caused by theileria parva and transmitted by the tick rhipicephalus appendiculatus. other less-important tick-borne diseases in cattle are benign theileriosis caused by theileria mutans, babesiosis caused by babesia bigemina, anaplasmosis caused by anaplasma marginale and cowdriosis caused by cowdria ruminatum. in murang's district, central province of kenya, five agroecological zone ...	1997	9234414
comparison of indirect immunofluorescence (iif) and enzyme-linked immunosorbent assay (elisa) in detecting babesia bigemina infection in cattle.	an indirect immunofluorescence test (iif) and an enzyme-linked immuno-sorbent assay (elisa) were standardised to investigate the prevalence of bovine babesiosis caused by babesia bigemina in experimentally and naturally infected bovids. both iif and elisa detected antibodies to b. bigemina 7 days after experimental infection with 87.5% and 100% sensitivity, respectively. the iif results indicated that a titre greater than 1:64 was a reliable indicator of b. bigemina infection. serological study ...	1997	9270130
pcr methods for the discrimination of babesia bovis isolates.	three different polymerase chain reaction assays for the typing of isolates of babesia bovis have been developed and compared with a hybridisation based method. primers were designed within conserved regions flanking the variable length tandem repeats of the bv80 and bvva1 genes. for the long array of repeats in bvva1, up to 7.5 kb, a modified long template pcr method was developed. the assays were compared using ten independent isolates of babesia bovis. using the bvva1 and bv80 pcr assays, 13 ...	1997	9299692
genetic variation in the dimorphic regions of rap-1 genes and rap-1 loci of babesia bigemina.	the rhoptry-associated protein-1 (rap-1) of babesia bigemina induces protective immune responses in cattle. rap-1 has two regions of sequence dimorphism at the carboxy and amino terminal ends, respectively. neutralization-sensitive, surface-exposed b-cell epitopes are present in the amino terminal variant type 1 (nt-1), and cd4+ t-cell epitopes in the carboxy terminal variant type 1 (ct-1). importantly, antibodies recognizing nt-1 epitopes do not cross react with nt-2 and cd4+ t-cells recognizin ...	1997	9476795
babesiasis in nanjing area, china.	this article discusses the tick-borne babesiases which harm dairy cattle, buffaloes and dogs. in addition, the pathogen, vector, seasonal occurrence, hosts, symptoms, pathological changes and treatment are summarized and analysed. the pathogens in this area were identified as babesia bigemina, b. bovis and b. gibsoni; the vectors as boophilus microplus, rhipicephalus haemaphysaloides, haemaphysalis longicornis. affected buffaloes were found from april to september, peak numbers occurred between ...	1997	9512739
observations on the treatment of natural haemosporidia infections by total alkaloid of peganum harmala l. in cattle.	eighty two cattle naturally infected with haemosporidians were treated with total alkaloid hydrochloride of peganum harmale l. (0.5 mg/kg/day). fifty eight cases with theileria sergenti showed a cure rate of 86%; thirteen cases with theileria annulata showed a cure rate of 85%; eight cattle infected with babesia bigemina showed a cure rate of 88% and three cases of anaplasma marginale were completely cured. the results suggested that the curative effect of total alkaloid of p. harmale was better ...	1997	9512749
effect of total alkaloid of peganum harmala l. in the treatment of experimental haemosporidian infections in cattle.	cattle experimentally infected with babesia bigemina or theileria sergenti or mixed infestations of the two parasites were treated with total alkaloid of peganum harmala l. the results showed that treatment was effective against b. bigemina infection, had a marked effect on the course of infection with t. sergenti and some effect on the course of the mixed infection.	1997	9512750
vaccines against hemoparasitic diseases in israel with special reference to quality assurance.	four vaccines against hemoparasitic diseases (anaplasmosis, babesiosis and theileriosis) and a vaccine against besnoitiosis are currently used in israel. these vaccines contain live attenuated parasites derived from cell culture (theileria annulata and besnoitia besnoiti) or from blood of infected, splenectomized calves (babesia bigemina, b. bovis and anaplasma centrale). cryopreserved master seed is used to initiate production of the vaccines. quality control performed during the preproduction ...	1997	9512751
an immunisation trial with in vitro produced babesia bigemina exoantigens.	bovine babesiosis, caused by babesia bigemina, is an important tick-transmitted haemoprotozoan disease in the tropics. this study evaluated the immunoprotective efficacy of in vitro produced b. bigemina exoantigens in bovine calves. the calves inoculated with b. bigemina exoantigens did not show any clinical, parasitological or hypersensitivity reactions after inoculation. they withstood challenge without showing any clinical symptoms except a transient thermal reaction. in contrast, two out of ...	1997	9512758
some quantitative aspects of natural babesial infection in the haemolymph of boophilus microplus engorged female ticks.	quantitative aspects of the natural babesial (babesia bovis and babesia bigemina) infection in boophilus microplus engorged female ticks obtained from two herds of holstein heifers positive by the immunofluorescent antibody test to both protozoan were evaluated. the number of kinetes/microscope field of haemolymph was determined for each tick from day 5 to 10 post-collection. a close relationship between daily and cumulative babesial infection was detected. correlation and determination coeffici ...	1997	9587602
[investigation of babesia in farm workers and blood donors in the province of ciego de avila].	a descriptive study of cases was conducted in which 781 sera were investigated using the indirect immunofluorescent technique with antigens of babesia bovis and babesia bigemina at the national center for agricultural health. of them, 371 came from agricultural workers and 410 from donors in the province of ciego de avila. it was started from dilutions of 1/64. an epidemiological survey was done to each seropositive so as to know the risk factors. the test of difference of proportions was used t ...	1997	9685976
subunit vaccines for the control of tick-borne diseases: implications for the future.	tick-borne parasites are a major constraint to the improvement of livestock productivity in the developing world. these parasites include theileria parva, t. annulata, babesia bigemina, b. bovis, anaplasma marginale and cowdria ruminantium. the impact of these diseases is currently limited by the use of acaricides to decrease transmission by the tick vectors and immunization of the host animals using live vaccines. the use of acaricide is hampered by the development of acaricide resistance and l ...	1997	9530697
in vitro cultivation of an african strain of babesia bigemina, its characterisation and infectivity in cattle.	an african (kenyan) strain of babesia bigemina, muguga (b(2-1)), was inoculated into a calf from a stabilate and blood from the calf was used to establish the parasite in vitro. the strain has been cultured continuously for 20 months, initially in bovine erythrocytes with 60% adult bovine serum, later, with 50%. cultures were incubated at 37 degrees c in rpmi 1640 medium with a gas mixture of 1% o2, 5% co2, 94% n2. adaptation in vitro was demonstrated when serum from a calf which had recovered f ...	1998	9569096
[serum monitoring of igg and igm babesia bigemina (haemosporidia: babesiidae) antibodies in calves from the mexican tropics].	antibody dynamics (igg and igm) against babesia bigemina was studied on 41 under 15 days of age from three ranches (r1, r2 and r3) in yucatan, mexico. blood samples were collected every 30 days, for eight months. sera were tested by the indirect fluorescent antibody method to detect igg and igm. overall igm seroprevalence during the calves first eight months of life was 17.1% without relation to age. overall igg seroprevalence was 66.8%, increasing with age. seroprevalence in r1, r2 and r3 were ...	1998	10751937
use of a duplex pcr/dna probe assay to monitor babesia bovis and babesia bigemina in cattle during a vaccination trial.	a duplex polymerase chain reaction (dpcr)/dna probe assay was used to detect babesia bovis and b. bigemina dna in cattle undergoing immunization trials. blood samples were collected from 15 non-splenectomized, 1-2 years old bulls, inoculated with 1 x 10(7) each of culture-derived b. bovis- and b. bigemina-infected erythrocytes. 15 bulls inoculated with normal erythrocytes served as a control group. all cattle were field exposed to tick-transmitted babesia 21 days (20 animals, group i) and 60 day ...	1998	10932733
isolation and characterization of a babesia species from rhipicephalus evertsi evertsi ticks picked off a sable antelope (hippotragus niger) which died of acute babesiosis.	transmission of a babesia species to susceptible cattle by rhipicephalus evertsi evertsi ticks picked off a sable which died of acute babesiosis is described. the parasite was initially isolated by feeding r. e. evertsi ticks on a susceptible, splenectomised bovine which developed parasitaemia. blood stabilate from the parasitaemic bovine produced a fatal babesiosis in a spleen--intact bovine. clinical signs shown by the affected animals corresponded with those of acute babesiosis. parasitologic ...	1998	9741050
development of an enzyme-linked immunosorbent assay for detection of antibodies to babesia bigemina in cattle.	monoclonal antibodies, directed against a 58-kda babesia bigemina merozoite antigen that reacted strongly with immune sera from experimentally and naturally infected cattle in western blots, were used to develop a competitive-inhibition enzyme-linked immunosorbent assay (elisa). as based on the testing of 70 antibody-positive sera from experimentally infected cattle and 166 antibody-negative sera collected in non-endemic areas of australia, the sensitivity and specificity of the elisa were 95.7% ...	1998	9747938
babesia bigemina: in vitro and in vivo effects of curdlan sulfate on growth of parasites.		1998	9806875
the absence of clinical disease in cattle in communal grazing areas where farmers are changing from an intensive dipping programme to one of endemic stability to tick-borne diseases.	a two-year field study was conducted in four communal grazing areas in south africa. sera were collected from young cattle (6-18 months old) in these areas during the winters of 1991 to 1993. the sera were tested for antibodies to babesia bovis, babesia bigemina, anaplasma marginale and cowdria ruminantium. in two of the four areas, treatment with acaricide was erratic and dependent on the discretion of individual owners. in these areas the drought of 1992 had a major impact on tick burdens and ...	1998	9809321
the efficacy of used engine oil against ticks on cattle.	the study was conducted in a peri-urban agricultural system at botshabelo, a city in the south-eastern free state. a questionnaire survey revealed that 88.5% of cattle farmers in the area experienced problems related to ticks and tick-borne diseases. because of the cost of commercial acaricides the botshabelo farmers use alternative, cheaper methods of tick control, including the application of used engine oil. the specific aim of the study was to determine whether used engine oil can effectivel ...	1998	10192839
epidemiology of tick-borne diseases of cattle in botshabelo and thaba nchu in the free state province.	a seroepidemiological study was conducted on 151 cattle from the botshabelo and thaba nchu areas in the central free state province of south africa, two areas where small scale, peri-urban cattle farming is practised. an indirect fluorescent antibody test was used to test for babesia bigemina and b. bovis antibodies. to test for anaplasma marginale antibodies a competitive inhibition enzyme-linked immunosorbent assay method was used. there were no significant differences in serological test resu ...	1998	10192841
establishment of boophilus microplus infected with babesia bigemina by using in vitro tube feeding technique.	the in vitro tube feeding technique is used to establish a laboratory colony of boophilus microplus infected with babesia bigemina. pre-fed engorged female ticks offered 2 x 10(4) and 2 x 10(5)/ml of b. bigemina infected bovine red blood cells (rbc) showed sporokinetes in the haemolymph smear sample, and positive signals for b. bigemina in polymerase chain reaction (pcr). larvae laid from the ticks offered 2 x 10(5)/ml of b. bigemina infected rbc showed evidence for b. bigemina infection in micr ...	1998	9592726
in vivo binding of immunoglobulin m to the surfaces of babesia bigemina-infected erythrocytes.	babesia bigemina infection of mature bovine erythrocytes results in new proteins specifically exposed on the parasitized cell surface. monoclonal antibody (mab) 64/32 binds a protein, designated p94, on b. bigemina-infected erythrocytes but not on either uninfected or b. bovis-parasitized erythrocytes. however, p94 was not encoded by b. bigemina and was not a parasite-modified erythrocyte membrane protein. in contrast, we showed that p94 could be eluted from the infected erythrocyte surface and ...	1998	9596768
immunochemical characterization of in vitro culture-derived antigens of babesia bovis and babesia bigemina.	cross-reactivity between babesia bovis and b. bigemina becomes a problem in discrimination of the two infections in endemic areas where the two species usually occur in association. with the aim of identifying candidate proteins for use as specific diagnostic tools, culture-derived components of three geographically different stocks of b. bovis (lismore, kwanyanga and mexico) and one of b. bigemina (mexico) were analyzed by immunoprecipitation using acrylamide gel electrophoresis. the approach t ...	1998	9650861
ultrastructure of babesia bigemina gametes obtained in "in vitro" erythrocyte cultures.	propagation of babesia bigemina in "in vitro" erythrocyte cultures resulted in the appearance of the sexual stage of the parasite, characterized by cytoplasmic projections and microtubules. these morphologically distinct parasites were found to adhere to each other, with later fusion of their membranes. no nuclear fusion was observed. the ultrastructure of the sexual stages was described.	1998	9653987
the safety and efficacy of australian tick-borne disease vaccine strains in cattle in paraguay.	glycerol preserved, frozen tick-borne disease vaccine strains developed in australia were imported into paraguay to test their safety in pregnant holando heifers and their efficacy against challenge from inoculated local field strains of babesia bigemina, b. bovis and anaplasma marginale in hereford x criolla heifers. the two babesia strains proved to be safe and the b. bovis k strain was very effective in providing immunity to a local field strain of b. bovis. the b. bigemina efficacy trial was ...	1998	9653988
structure, sequence, and transcriptional analysis of the babesia bovis rap-1 multigene locus.	the complexity of multigene families encoding rhoptry proteins and the generation of new variants in these families are constraints to development of vaccines incorporating rhoptry proteins. for example, the babesia bigemina rhoptry associated protein (rap)-1 locus is composed of tandemly arranged genes including four polymorphic rap-1a genes and two classes of divergent genes, rap-1b and rap-1c. b. bigemina rap-1 polymorphism reflects recombination and gene conversion and results in multiple ra ...	1998	9662706
bovine babesiosis. seroprevalence and ticks associated with cattle from two different regions of morocco.	a total of 475 bovine sera collected in 1995-1996 from 10 areas belonging to two different bioclimatic strata were tested for antibody activity to babesia bigemina and babesia bovis using indirect immunofluorescence (iif). in the gharb, the b. bovis seroprevalence was 21.7% and for b. bigemina, 10.8%. the infection rate for either or both species as determined microscopically with giemsa-stained blood films was 18.9%. the tiflet area was considered an endemic focus, and the seroprevalence was 42 ...	1998	9668467
development of tick gut forms of babesia bigemina in vitro.	development of a laboratory cultured tick-transmissible strain of babesia bigemina was followed in vitro after addition of gut material from engorged female boophilus microplus ticks and incubation at 37 degrees c. sequential development of stages, from intraerythrocytic strahlenkörper through multiplication to the fusion of what is assumed to be two gametes, is described. a change in physical environment (temperature, gas composition) experienced during passage of babesia stages into the in vit ...	1998	9669864
immunodominant t-cell antigens and epitopes of babesia bovis and babesia bigemina.	despite convincing evidence that t cells are critical for both cellular and humoral immunity against haemoprotozoan parasites, the difficulty of performing meaningful experiments in cattle that would define the role of t cells in immunity to babesia spp. has impeded research in this area. however, experiments performed ex vivo with immune t cells can reflect in-vivo events, and provide valuable insight into the nature of immunogenic proteins and the responding lymphocytes. the progress made towa ...	1998	9683898
helper t-cell epitopes encoded by the babesia bigemina rap-1 gene family in the constant and variant domains are conserved among parasite strains.	among important candidates for babesial vaccines are apical complex proteins, including rhoptry-associated protein 1 (rap-1) from babesia bovis and b. bigemina, which have been shown to induce partial immunity. four variant b. bigemina rap-1 transcripts identified in a clone of the mexico strain have highly conserved sequence in the central region but vary in sequence at the amino and carboxy termini (nt and ct) of the predicted proteins, resulting in different combinations of nt and ct domains ...	1998	9529082
development and evaluation of an extra chromosomal dna-based pcr test for diagnosing bovine babesiosis.	subclinical infections of bovine babesiosis, caused primarily by babesia bigemina or babesia bovis are a challenge to current diagnostic methods. in this study, the development and evaluation of a pcr test for sensitive and specific detection of b. bigemina or b. bovis is described. the target selected for amplification is part of the apocytochrome b gene, conserved in both babesia spp. and located on the linear approximately 6.0 kb extra chromosomal dna. the test was evaluated to detect the par ...	1999	10208801
comparison of cattle responses to mono-specific or combined inoculations with babesia bigemina and babesia bovis vaccine strains.	combined inoculation of cattle with vaccine strains of babesia bigemina and babesia bovis induced lower antibody titers to b. bigemina than to b. bovis (previous study). three groups of heifers were used to detect if the low antibody level was due to competition between babesia species: individuals of g1 and g2 were inoculated with 10 million b. bigemina and b. bovis, respectively, and those of g3 with 10 million of each parasite. the prepatent periods, maximum parasitaemias and antibody titers ...	1999	10229940
effect of cattle breed on innate resistance to inoculations of babesia bigemina.		1999	10451734
comparative effects of interleukin-12 and interleukin-4 on cytokine responses by antigen-stimulated memory cd4+ t cells of cattle: il-12 enhances ifn-gamma production, whereas il-4 has marginal effects on cytokine expression.	interleukin-12 (il-12) and il-4 are important immunoregulatory cytokines that determine the fate of naive t cells during antigen priming in mice and also influence cytokine synthesis by differentiated murine and human t cells. the roles of these cytokines in regulating the differentiation and effector function of bovine t cells are less well studied. we investigated the ability of human il-12 and bovine il-4 to modify cytokine expression by antigen-stimulated t cells from cattle immune to the pr ...	1999	10454344
direct and sensitive detection of trypanosoma evansi by polymerase chain reaction.	the mechanically transmitted haemoflagellate, trypanosoma evansi causes 'surra', a wasting disease of domestic animals and is highly endemic in distribution in southeast asia. the detection of t. evansi is important for improving the epizootiological and animal health status of the region. the specificity and sensitivity of polymerase chain reaction (pcr) using oligonucleotide primers constructed from t. evansi repetitive dna sequences were studied in the present investigation. using the assay, ...	1999	10497829
babesia bigemina: immunization with purified rhoptries induces protection against acute parasitemia.		1999	10502474