| progress towards a vaccine against theileria parva: relevance for heartwater research. | such progress has been made in the last decade in the characterization of bovine immunity to theileria parva. the evidence is overwhelming that cattle that become immune through infection can clear subsequent challenge infections by deploying parasite-specific cytotoxic t lymphocytes (ctl). furthermore, high titres of neutralising antibodies are generated against the sporozoite surface after multiple exposure to the parasite, and these can neutralise infection in vitro. although unlikely to be o ... | 1993 | 8134638 |
| the tick vectors of cowdriosis in angola. | amongst the amblyomma species presently known to be capable of transmitting cowdria ruminantium six have been recorded in angola. a. pomposum is the most important and widely distributed. of secondary importance are a. variegatum, which prevails in cabinda and moxico provinces, and a. astrion which occurs in the littoral and transition strips and on camabatela plateau. a. sparsum and a. tholloni which are specific parasites of wild hosts are considered accidental vectors. a. hebraeum was introdu ... | 1993 | 8134639 |
| production of alpha interferon in cowdria ruminantium-infected cattle and its effect on infected endothelial cell cultures. | cattle that resisted experimental heartwater infection caused by the rickettsia cowdria ruminantium produced significant levels of circulating alpha interferon (ifn-alpha), whereas animals that died from heartwater did not. in vitro, recombinant bovine ifn-alpha was found to significantly reduce the yield of cowdria organisms in bovine endothelial cells, but even at a high concentration (1,000 u/ml), ifn-alpha did not completely prevent the growth of cowdria organisms in these cells. this limite ... | 1994 | 8188383 |
| [epidemiology of cowdria infection in senegal. i. study of the transmission and infection level in amblyomma variegatum (fabricius, 1794) in the niayes region]. | the authors report the results of research on infection rates of amblyomma variegatum nympha and imago populations by cowdria ruminantium in the niayes region as well as on the transmission rates of a. variegatum by the various stases. the experiments were carried out on sheep from the sahelian zone where the vector tick is not endemic. the infection rate, estimated by inoculating sheep with ground ticks, gave the following prevalences: t = 13.3% for nymphae and t = 1.2% for adults. the transmis ... | 1993 | 8190980 |
| [epidemiology of cowdria infection in senegal. ii. results of sero-epidemiological follow-up studies]. | the authors report the results of sero-epidemiological monitoring of zebu, diakoré and ndama cattle in the sahel, niayes and north guinea zones, respectively. calves aged 0-3 or 3-6 months were subjected to blood sampling every three months for a period of 20 months. in the niayes and north guinea zones, the immunofluorescence test showed that about 70% of 0-1 month old calves reacted positively to the cowdria ruminantium antigen, whereas the prevalence was 92% between 3 and 6 months. after the ... | 1993 | 8190981 |
| serological evidence for antigenic relationships between ehrlichia canis and cowdria ruminantium. | the sera from dogs experimentally infected with ehrlichia canis reacted at very similar titres in indirect fluorescent antibody (ifa) tests with e canis and cowdria ruminantium antigen. in western blots these sera reacted strongly with the immunodominant antigens of e canis (27 kda) and c ruminantium (25 and 32 kda). the dogs experimentally infected with c ruminantium showed no clinical evidence of infection, though the presence of organisms in the blood was demonstrable, for up to two weeks aft ... | 1994 | 8191006 |
| a protein related to brain microtubule-associated protein map1b is a component of the mammalian centrosome. | the centrosome is the main microtubule organizing center of mammalian cells. structurally, it is composed of a pair of centrioles surrounded by a fibro-granular material (the pericentriolar material) from which microtubules are nucleated. however, the nature of centrosomal molecules involved in microtubules nucleation is still obscure. since brain microtubule-associated proteins (maps) lower the critical tubulin concentration required for microtubule nucleation in tubulin solution in vitro, we h ... | 1994 | 8207082 |
| in vitro feeding of instars of the ixodid tick amblyomma variegatum on skin membranes and its application to the transmission of theileria mutans and cowdria ruminatium. | an in vitro feeding method using rabbit or cattle skin membranes, applied successfully to all stages (larvae, nymphae and adults) of the ioxodid tick, amblyomma variegatum, is described. the feeding apparatus consisted of a blood container with a membrane placed on top of a tick containment unit. a carbon dioxide atmosphere of between 5 and 10% and a temperature of 37 degrees c were used as stimulants for the attachment of the ticks. high co2 concentrations in the atmosphere improved the feeding ... | 1993 | 8233589 |
| in vitro infection of bovine brain endothelial cells by cowdria ruminantium. | endothelial cells from bovine brain capillaries (bbec) were successfully infected with the gardel stock of cowdria ruminantium. growth conditions of cowdria in bbec and bovine umbilical endothelial cells (bue) were identical with average intervals between passages of 8.6 and 8.9 days in bbec (17 passages) and bue (28 passages), respectively. the time required to complete the life cycle and the morphology of the parasite were identical in both types of cells. the demonstration that bbec may be in ... | 1993 | 8235096 |
| serosurvey for cowdria ruminantium, coxiella burnetii, and spotted fever group rickettsiae in ostriches (struthio camelus) from zimbabwe. | sera from 216 ostriches on nine farms around zimbabwe were examined by indirect fluorescent antibody (ifa) testing for the presence of antibodies reactive with cowdria ruminantium, coxiella burnetii, and rickettsia africae, a spotted fever group rickettsia. although no reactive antibodies could be detected to c. ruminantium or c. burnetii, 51/216 (35%) sera reacted with r. africae. the seroprevalence in ostriches from the south of zimbabwe was significantly higher than in birds from the north (p ... | 1996 | 8790897 |
| antibodies to cowdria ruminantium in mozambican goats and cattle detected by immunofluorescence using endothelial cell culture antigen. | endothelial cell cultures, established from bovine umbilical cord arteries and subsequently infected with cowdria ruminantium, were used as antigen in the indirect fluorescent antibody test. bovine sera (374) and caprine sera (388) collected in 6 provinces of mozambique were tested. overall, 30.4% of goat sera had antibodies to cowdria, and 43% of sera collected from cattle. north of the river save, where the tick amblyomma variegatum is highly prevalent, overall percentages of positive sera wer ... | 1993 | 8236490 |
| heartwater in ghana: implications for control of ticks. | heartwater, an often fatal rickettsial disease of domestic ruminants transmitted by amblyomma variegatum ticks, ranks with the a. variegatum-associated skin disease dermatophilosis as a major constraint to the upgrading of livestock productivity in ghana. an epidemiological survey, using new diagnostic tests, is being carried out to determine the incidence and distribution of heartwater and other tickborne diseases in ghanaian cattle, sheep and goats. preliminary results from a longitudinal surv ... | 1996 | 8809994 |
| the control of heartwater in west africa--present and future. | heartwater (hw) is the name given to the acute, febrile disease of ruminants caused by infection with the obligate intra-cellular rickettsia cowdria ruminantium. the effect of losses associated with hw and dermatophilosis are an important constraint to the sustainable use of non-indigenous breeds, but recent advances in heartwater and dermatophilosis research provide optimism that integrated control of these conditions can be achieved in west africa. the relevant advances in hw research are in m ... | 1996 | 8809995 |
| anthrax and cowdriosis in an african elephant (loxodonta africana). | | 1993 | 8236707 |
| an immunoblotting diagnostic assay for heartwater based on the immunodominant 32-kilodalton protein of cowdria ruminantium detects false positives in field sera. | heartwater, a major constraint to improved livestock production in zimbabwe, threatens to invade areas which have been previously unaffected. to monitor its spread in zimbabwe, an immunoblotting diagnostic assay based on the responses of animals to the immunodominant, conserved 32-kda protein of cowdria ruminantium was evaluated. in this assay, no false reactions were detected with sera known to be positive and negative, but sera from some cattle, sheep, and goats from heartwater-free areas of z ... | 1993 | 8253974 |
| molecular cloning, sequence analysis, and expression of the gene encoding the immunodominant 32-kilodalton protein of cowdria ruminantium. | cowdria ruminatium, the causative agent of heartwater disease, expresses an immunodominant and conserved 32-kilodalton protein (map1; formerly called cr32), which is currently in use for serodiagnosis of the disease. the gene encoding this protein, designated map1, was detected, cloned, and characterized. the gene is conserved between four different stocks of c. ruminantium originating from senegal, sudan, south africa, and zimbabwe. homology searches revealed map1 to be homologous to the anapla ... | 1994 | 8132352 |
| detection of antibodies to cowdria ruminantium in the serum of domestic ruminants by indirect elisa. | a solid phase enzyme immunoassay for the detection of antibodies to cowdria ruminantium in the serum of domestic ruminants was developed by using microorganisms cultivated on bovine umbilical endothelial cells as antigen. when the culture showed 90% lysis, the supernatant was centrifuged, sonicated and coated on polystyrene microtiter plates. antibodies were detected as early as 9 days after experimental immunization of goats. the sensitivity of the elisa calculated with 73 ruminant sera ranged ... | 1993 | 8134621 |
| the sero-diagnosis of heartwater: a comparison of five tests. | five serological tests, the indirect and competitive elisa, the indirect fluorescent antibody (ifa) test with 2 different antigens and the western blot technique were compared and applied to sera that were known to be either negative or positive against cowdria ruminantium or that were collected from animals in heartwater-free regions. no false positive reactions were recorded with any of the tests against the known negative sera. except for minor variations in the sensitivity of the 5 tests, th ... | 1993 | 8134622 |
| cytopathic effect, plaque formation, and lysis of ehrlichia chaffeensis grown on continuous cell lines. | ehrlichiae are strict intracellular bacterial pathogens that parasitize leukocytes or other blood cells. only six agents of the tribe ehrlichieae, namely, cowdria ruminantium, neorickettsia helminthoeca, ehrlichia risticii, ehrlichia sennetsu, ehrlichia canis, and ehrlichia chaffeensis, have been adapted to growth in continuous cell lines. e. chaffeensis, the agent of human ehrlichiosis, has been cultured only in a cell line of canine origin. we adapted purified cell-free e. chaffeensis for grow ... | 1994 | 8300201 |
| conconavalin a-stimulated bovine t-cell supernatants inhibit growth of cowdria ruminantium in bovine endothelial cells in vitro. | conconavalin a-stimulated bovine t-cell supernatants inhibited the growth of cowdria ruminantium in bovine endothelial cells in vitro but did not affect their entry. this finding represents one mechanism by which t cells may control c. ruminantium multiplication and hence affect the severity of disease. | 1994 | 8300237 |
| an in vitro test to demonstrate the inhibitory effect of homologous immune serum on the infectivity of cowdria ruminantium. | homologous immune sheep serum inhibits the infectivity of mice for the kümm stock of cowdria ruminantium in an in vitro test. the presence of complement and an optimal ratio between the reagents are of cardinal importance. with the exception of the ball 3 stock, there is no cross-inhibition between the immune sera of sheep infected with several other heterologous stocks and the kümm stock. the role played by the humoral component of the immune response in naturally acquired heartwater is unknown ... | 1993 | 8332319 |
| progress in research on tick-borne diseases: theileriosis and heartwater. | the rapid population growth in subsaharan africa necessitates a great increase in animal production in the more humid zones. vector-borne diseases occurring in these zones will assume more importance, but are difficult to control. they include theileriosis and heartwater. recent developments in research on these diseases are presented. indigenous animal populations in endemic areas, subjected to natural selection, are far less susceptible than exotic stock. heartwater, caused by the rickettsia c ... | 1993 | 8372422 |
| establishment of the foreign partheonogenetic tick amblyomma rotundatum (acari: ixodidae) in florida. | the parthenogenetic tick amblyomma rotundatum, a central and south american species, has become established in southern florida. the date of introduction is unknown, but it is suspected to be either during the 1930s, when 1 of its natural hosts, the giant or marine toad, bufo marinus, was introduced to southern florida as a potential biological control of pest beetles in sugar cane fields, or between 1955 and 1964 when specimens of b. marinus were accidentally or deliberately released in the gre ... | 1993 | 8410557 |
| characterization of an immunoreactive protein from the agent of human granulocytic ehrlichiosis. | a gene that is homologous to the ehrlichia chaffeensis groel operon was recovered and characterized by broad-range pcr amplification of whole blood from patients with human granulocytic ehrlichiosis (hge) and from infected hl60 cell cultures. sequence analysis of an 820-bp dna fragment recovered directly from human blood showed 76.5 and 76.3% identity with cognate sequences from e. chaffeensis and cowdria ruminantium, respectively. analysis of a 1.6-kb dna fragment derived from an hge agent-infe ... | 1997 | 9114402 |
| detection of cowdria ruminantium by means of a dna probe, pcs20 in infected bont ticks, amblyomma hebraeum, the major vector of heartwater in southern africa. | a dna probe, pcs20, previously described for use in detection of cowdria ruminantium infections in amblyomma variegatum (the principal vector of heartwater) hybridized with c. ruminantium dna in organs of laboratory-infected a. hebraeum adult ticks (the major southern african vector of heartwater). the probe hybridized with c. ruminantium dna in 46/49 midguts from male ticks and 26/29 from females, thus indicating infection. corresponding salivary glands were less heavily infected, but infection ... | 1993 | 8432329 |
| the relationship between tick (amblyomma hebraeum) infestation and immunity to heartwater (cowdria ruminantium infection) in calves in zimbabwe. | the occurrence of endemic stability for heartwater (cowdria ruminantium infection) is a controversial issue, because the means by which young cattle and other neonatal ruminants become infected and acquire immunity to the disease have never been adequately explained. we conducted a study in a heartwater-endemic area in southeastern zimbabwe to investigate the relationships between calf immunity to c. ruminatium, infestations of the tick vector amblyomma hebraeum and dam, colostral and calf antib ... | 1995 | 8533273 |
| reactions to heartwater vaccination in crossbred zebu cattle. | one thousand and ninety-four crossbred zebu cattle were immunized against heartwater with a sheep-blood vaccine containing the ball 3 strain of cowdria ruminantium. animals experiencing febrile reactions were treated at various stages of the reaction with tetracycline. four hundred and sixty-two (42.2%) reacted, six (0.6%) of which died. deaths were significantly less frequent in cattle treated on the first day of reaction (2/323, 0.6%) than those treated at a later stage (4/61, 6,6%). the mean ... | 1995 | 8539030 |
| size variation of the major immunodominant protein of cowdria ruminantium. | an immunodominant response is made to a polypeptide of approximately 32 kda in animals infected with the rickettsial pathogen cowdria ruminantium. we show here using cultured strains of the rickettsia from different geographical areas that the apparent size of this polypeptide varies with strain origin. changes in the primary structure between strains should be considered in the design of vaccines and diagnostic tests based on this antigen. | 1994 | 8556531 |
| immunohistochemical identification of cowdria ruminantium in formalin-fixed tissue sections from mice, sheep, cattle and goats. | an immunohistochemical staining technique in which a monospecific serum was used against the major antigenic protein -1 (map-1) of cowdria ruminantium, was evaluated for the detection of c. ruminantium in formalin-fixed tissues of experimentally infected mice and field cases of heartwater in sheep, cattle and goats. mice were infected with the mouse-pathogenic stocks: mara, kwanyanga, welgevonden, nonile, vosloo, kümm, mali and omatjenne. in all these cases and in the naturally infected cattle, ... | 1995 | 8668326 |
| demonstration of vertical transmission of cowdria ruminantium, the causative agent of heartwater, from cows to their calves. | one of the most important questions about the epidemiology of heartwater in the field is how cowdria ruminatium is transmitted within vertebrate host populations. in this study vertical transmission of c. ruminantium from cows to their calves was demonstrated. twelve mixed-breed calves, born to dams living in a heartwater-endemic area of zimbabwe, were tested post-natally for the presence of c. ruminantium. vertical transmission was demonstrated to occur under natural field conditions using test ... | 1996 | 8750689 |
| colostrum from dams living in a heartwater-endemic area influences calfhood immunity to cowdria ruminantium. | two studies were carried out to determine whether colostrum from dams living in a heartwater-endemic area has an influence on calfhood immunity to cowdria ruminantium infection. the initial study was conducted using friesian calves originating from a heartwater-free herd. experimental groups consisted of calves receiving colostrum from dams living in a heartwater-endemic area and known to be exposed to c. ruminantium (as determined by the indirect fluorescent antibody test) and calves receiving ... | 1996 | 8750690 |
| progress and priorities in research on heartwater. | | 1996 | 8784481 |
| immunodominant major outer membrane proteins of ehrlichia chaffeensis are encoded by a polymorphic multigene family. | several immunodominant major proteins ranging from 23 to 30 kda were identified in the outer membrane fractions of ehrlichia chaffeensis and ehrlichia canis. the n-terminal amino acid sequence of a 28-kda protein of e. chaffeensis (one of the major proteins) was determined. the gene (p28), almost full length, encoding the 28-kda protein was cloned by pcr with primers designed based on the n-terminal sequence of the e. chaffeensis 28-kda protein and the consensus sequence between the c termini of ... | 1998 | 9423849 |
| uncharacterized ehrlichia spp. may contribute to clinical heartwater. | | 1996 | 8784482 |
| amino acid and protein depletion in medium of cell cultures infected with cowdria ruminantium. | cowdria ruminantium (rickettsiales) causes heartwater in ruminants of africa, and some islands off africa and in the caribbean sea. the in vitro culture method for the organism devised in 1985, which provided for the first time a means for production of adequate quantities of live organisms and their products, is erratic and requires improvement. we studied depletion of amino acids (aas) and major proteins in culture medium taken daily from infected and uninfected ovine and bovine vascular endot ... | 1996 | 8784483 |
| recombinant expression and use in serology of a specific fragment from the cowdria ruminantium map1 protein. | the major antigenic protein (map1) of cowdria ruminantium was screened for immunogenic regions by expression of overlapping recombinant dna clones of the gene encoding the map1 protein. two regions, designated map1-a and map1-b, were recognized by all antisera to 9 different isolates of c. ruminantium. map1-a contained one or more epitopes responsible for false-positive reactions with ehrlichia antisera in several serological tests for cowdriosis. cross-reactivity with map1-b was limited to anti ... | 1996 | 8784484 |
| genetic resistance of creole goats to cowdriosis in guadeloupe. status in 1995. | a genetic predisposition to resistance (r)/susceptibility (s) has been demonstrated for cowdriosis in certain goal lines. in order to identify genetic markers of r/s and to follow their transmission to the offspring, 4 groups of sires and dams were crossbred in 1991, 1992, and 1993: rr, rs, sr, and ss. the offspring were challenged at the age of six months with subsequent challenge of the s parent. from 28 presumed s dams, 7 turned out r and from 2 presumed s sires, 1 was r and the other undefin ... | 1996 | 8784485 |
| artificial feeding systems for ixodid ticks as a tool for study of pathogen transmission. | | 1996 | 8784502 |
| sequence heterogeneity of the major antigenic protein 1 genes from cowdria ruminantium isolates from different geographical areas. | the genes for the immunodominant major antigenic protein 1 (map1) of cowdria ruminantium from four african and two caribbean isolates were cloned, restriction mapped, and sequenced to identify conserved epitopes for development of serodiagnostic tools for heartwater. restriction length polymorphisms were observed among the respective map1 genes analyzed and were confirmed by sequencing. the sequence data generated for these isolates were compared with data for the previously reported senegal iso ... | 1996 | 8807206 |
| a dna vaccine protects mice against the rickettsial agent cowdria ruminantium. | a dna vaccine (vcl1010/map1) containing the major antigenic protein 1 (map1) gene of cowdria ruminantium, driven by the human cytomegalovirus (hcmv) enhancer-promoter, was injected intramuscularly into 8-10 week-old female dba/2 mice after treating them with 50 microliters/muscle of 0.5% bupivacaine three days previously. up to 75% of the immunized mice seroconverted and reacted with c. ruminantium antigen blots. splenocytes from immunized mice, but not from control mice, proliferated in respons ... | 1998 | 9568614 |
| a recombinant antigen from the heartwater agent (cowdria ruminatium) reactive with antibodies in some southeastern united states white-tailed deer (odocoileus virginianus), but not cattle, sera. | recombinant baculovirus techniques were used to express the 260 amino acid carboxyterminal portion of the 32 kilodalton (kda) major antigenic protein (map 1) of cowdria ruminantium, the heartwater agent, as a fusion protein. the recombinant map 1 was fused to an aminoterminal independently antigenic octapeptide sequence (flag peptide). recombinant map 1 was used as an immunoblotting antigen to evaluate numerous reference antisera against organisms of the tribe ehrlichieae. monoclonal and polyclo ... | 1996 | 8827667 |
| 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 |
| growth of cowdria ruminantium in tissue culture endothelial cell lines from wild african mammals. | endothelial cell cultures were established from several wild african mammalian species. long-term cultures were established from three ruminants, stable antelope (hippotragus niger), buffalo (syncerus caffer), and eland (tragelaphus oryx), and from an omnivore, the bushpig (potamochoerus porcus). cowdria ruminanntium was isolated from plasma of clinically affected animals in these four cell lines and in bovine endothelial cells used routinely for c. ruminantium propagation. nineteen different st ... | 1998 | 9577776 |
| isolation of the causative agent of heartwater (cowdria ruminantium) from three amblyomma species in eight districts of kenya. | thirteen isolates of cowdria ruminantium were made from eight different districts of kenya by four different isolation methods. feeding adult amblyomma species ticks derived from nymphs collected in the field and the inoculation of homogenates prepared from adult field ticks had the highest success rate. the reattachment of adult ticks collected in the field was successful on only one of five attempts, and the subinoculation of blood from suspected heartwater carriers was unsuccessful. seven of ... | 1997 | 9004475 |
| comparative efficacy of freund's and montanide isa50 adjuvants for the immunisation of goats against heartwater with inactivated cowdria ruminantium. | two vaccines, based on inactivated elementary bodies of cowdria ruminantium, one formulated in montanide isa50, the other in freund's adjuvant, were compared in goats. administered twice subcutaneously with an interval of 81 days, both protected three out of five goats against a very severe challenge, lethal for all 14 control goats, 3.5 months after the second injection. both vaccines elicited similar antibody levels. the protection afforded by the montanide isa50 vaccine was tested 15 and 17 m ... | 1996 | 9017866 |
| serological survey of heartwater relative to the distribution of the vector amblyomma variegatum and other tick species in north cameroon. | a study was carried out on the spatial and temporal distribution of amblyomma variegatum and other ticks infesting sheep and goats in northern cameroon. a serological survey of heartwater (cowdriosis) using a competitive elisa was concurrently carried out in the same flocks. a. variegatum was found to be the most predominant species accounting for 48.3% of all the ticks collected. other species identified included rhipicephalus sulcatus, r. lunulatus, r. turanicus, boophilus decoloratus, b. annu ... | 1997 | 9066062 |
| abortion in a heifer associated with the intra-uterine transmission of cowdria ruminantium-like organisms following heartwater vaccination. | a nguni heifer aborted a 6-month-old foetus 35 days after intravenous inoculation with onderstepoort heartwater vaccine. histopathological examination of the brain revealed numerous suspected cowdria ruminantium organisms in the endothelial cells of the blood vessels. the organisms were ultrastructurally and immunohistochemically compatible with cowdria ruminantium, although, owing to autolysis and cross-reactions, the possibility that they represent another rickettsial or related organism could ... | 1996 | 9120863 |
| development and evaluation of a recombinant antigen, monoclonal antibody-based competitive elisa for heartwater serodiagnosis. | cowdria ruminantium is the etiologic agent of heartwater, a tick-transmitted foreign animal disease with considerable potential for entrance into the usa. a competitive enzyme-linked immunosorbent assay (celisa) was developed to detect serologic responses to c. ruminantium infection. the celisa utilized a recombinant form of the c. ruminantium major antigenic protein (map-1) as the antigen and an anti-map-1 monoclonal antibody as the competing indicator reagent. experimental antisera to c. rumin ... | 1997 | 9211230 |
| neutralization of bovine concanavalin-a t cell supernatant-mediated anti-cowdria ruminantium activity with antibodies specific to interferon gamma but not to tumor necrosis factor. | in an earlier study we demonstrated that concanavalin-a stimulated bovine t cell supernatants inhibited the growth of cowdria ruminantium in bovine endothelial cells in vitro. an investigation was conducted to identify the cytokines which were responsible for this growth inhibition. addition of antiserum against bovine interferon gamma (ifn gamma) reproducibly neutralized the inhibitory effect of the t cell supernatants, whereas addition of antisera against bovine tumor necrosis factor alpha (tn ... | 1996 | 9229384 |
| 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 |
| detection of genomic polymorphisms among isolates of the intracellular bacterium cowdria ruminantium by random amplified polymorphic dna and southern blotting. | sixteen primers were successfully used in a rapd assay to generate reproducible fingerprints for six isolates of cowdria ruminantium, a tick-transmitted rickettsia of ruminants. distinction between stocks was possible by using one or at most two primers. two stocks were very similar although originating from widely distant geographical regions. a genetic distance tree was constructed by analysing 108 fragments in pairwise comparison between stocks. three amplification fragments probed with c. ru ... | 1997 | 9297823 |
| different organisms associated with heartwater as shown by analysis of 16s ribosomal rna gene sequences. | cowdria ruminantium is a rickettsial parasite which causes heartwater, a economically important disease of domestic and wild ruminants in tropical and subtropical africa and parts of the caribbean. because existing diagnostic methods are unreliable, we investigated the small-subunit ribosomal rna (srrna) gene from heartwater-infected material to characterise the organisms present and to develop specific oligonucleotide probes for polymerase chain reaction (pcr) based diagnosis. dna was obtained ... | 1997 | 9299697 |
| development of an in vitro cloning method for cowdria ruminantium. | cowdria ruminantium is a tick-borne rickettsia which causes severe disease in ruminants. all studies with c. ruminantium reported so far were carried out with stocks consisting of infective blood collected from reacting animals or from the same stocks propagated in vitro. cloned isolates are needed to conduct studies on immune response of the host, on genetic diversity of the parasite, and on mechanisms of attenuation and the development of vaccines. a method of cloning based on the particular c ... | 1997 | 9302217 |
| construction and initial analysis of a representative lambda zapii expression library of the intracellular rickettsia cowdria ruminantium: cloning of map1 and three other cowdria genes. | the causative agent of heartwater, the rickettsia cowdria ruminantium, is very poorly understood at the molecular level owing to a profound lack of suitable tools. we have developed an immunoaffinity chromatographic method to purify c. ruminantium from host cell components and the purified rickettsial cells have been used to prepare substantially pure cowdria dna. this dna has been used to construct what we believe to be the first fully representative c. ruminantium expression library. a clone c ... | 1997 | 9404845 |
| dna sequence of a cosmid clone of cowdria ruminantium. | | 1998 | 9668487 |
| expression library immunization to identify protective antigens from cowdria ruminantium. | | 1998 | 9668488 |
| in vitro isolation and cultivation of cowdria ruminantium under serum-free culture conditions. | three stocks of cowdria ruminantium, the causative agent of heartwater in domestic ruminants, were propagated in bovine endothelial cells in a serum-free culture medium. the vosloo, welgevonden and senegal stocks were propagated for a period of more than 203, 134, and 43 days, respectively. two of the c ruminantium stocks (vosloo and senegal) were also successfully initiated under serum-free culture conditions. the serum-free medium consisted of a modified hl-1 medium. the senegal stock was succ ... | 1997 | 9429251 |
| evidence to show that an agent that cross-reacts serologically with cowdria ruminantium in zimbabwe is transmitted by ticks. | the serological diagnosis of heartwater based on reactions to the immunodominant cowdria ruminantium major antigen protein-1 (map-1) is impaired by the detection of false-positive reactions. in this study, the prevalence of false-positive reactions on seven heartwater-free farms in zimbabwe was determined to be 8-94% by immunoblotting against c. ruminantium antigens. the highest prevalence of false-positives on spring valley farm correlated with the presence of rhipicephalus evertsi evertsi tick ... | 1998 | 9493330 |
| suppression of interleukin-5 prevents mortality in balb/c mice infected with cowdria ruminantium. | | 1998 | 9668491 |
| attempts to feed amblyomma variegatum ticks on artificial membranes. | feeding jars were used to feed nymphs of amblyomma variegatum on blood of goats or cattle. sterile blood was collected daily or weekly (kept at 4 degrees c or frozen until use), with addition either of heparin alone or of heparin and antibiotics/fungicide or of heparin, adenosine triphosphate and glutathione. membranes were made of a thin (0.12-0.32 mm) film of silicone mastic. blood in the jars was replaced twice a day, and reached a temperature of 39 degrees c in a waterbath before it became a ... | 1998 | 9668493 |
| conventional vaccines for tick-borne haemoparasitic diseases of sheep and goats. | of the many tick-borne haemoparasites of sheep and goats, three may be controlled by vaccination. a live virulent blood vaccine for cowdria ruminantium infection (heartwater) is used widely in southern africa in an infection and treatment procedure. a live vaccine for babesia ovis attenuated by passage in splenectomised sheep has been used extensively in bulgaria with good results. a live vaccine for theileria hirci, consisting of schizonts propagated in a lymphoid cell culture and attenuated by ... | 1997 | 9530695 |
| 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 |
| choline availability modulates the expression of tgfbeta1 and cytoskeletal proteins in the hippocampus of developing rat brain. | choline availability influences long-term memory in concert with changes in the spatial organization and morphology of septal neurons, however little is known concerning the effects of choline on the hippocampus, a region of the brain also important for memory performance. pregnant rats on gestational day 12 were fed a choline control (ct), choline supplemented (cs), or choline deficient (cd) diet for 6 days and fetal brain slices were prepared on embryonic day 18 (e18). the hippocampus in these ... | 1998 | 9566615 |
| demonstration of a carrier state for cowdria ruminantium in wild ruminants from africa. | four wild african ruminants, eland (taurotragus oryx), giraffe (giraffa camelopardalis), kudu (tragephalus strepsiceros strepsiceros), and blue wildebeest (connochaetes taurinus), were experimentally infected with the rickettsia cowdria ruminantium, the tickborne agent causing heartwater in domestic ruminants. the infections were established, and c. ruminantium was transmitted to naive small ruminants by the vector amblyomma hebraeum when transmission attempts were made at days 128 (eland and wi ... | 1998 | 9706566 |
| heartwater in sheep and goats: a review. | heartwater (cowdriosis) is an important, often fatal, tick-borne disease of domestic and wild ruminants in sub-saharan africa and some indian ocean and caribbean islands. the causal agent, cowdria ruminantium (cowdry 1925), is a rickettsia closely related to members of the genus ehrlichia, and is probably a part of a complex of genomic species. imported breeds of sheep and goats (especially angoras) are highly susceptible, but indigenous populations of endemic areas may be resistant to infection ... | 1996 | 8856765 |
| recombinant bovine interferon gamma inhibits the growth of cowdria ruminantium but fails to induce major histocompatibility complex class ii following infection of endothelial cells. | recombinant bovine ifn gamma is a potent inhibitor of cowdria ruminantium growth in vitro irrespective of the rickettsial stock, or the origin of the endothelial cells. these results suggest an important role for ifn gamma in protective immune responses against c. ruminantium infections. here we also show that ifn gamma can induce the expression of mhc class ii molecules on the surface of endothelial cells. however, treatment of endothelial cells with ifn gamma following infection with cowdria f ... | 1996 | 8941969 |
| the distribution of heartwater in the highveld of zimbabwe, 1980-1997. | heartwater, the tick-borne disease caused by the rickettsia cowdria ruminantium has historically been confined to the southern and western lowvelds of zimbabwe. since 1986, however, cases of heartwater have been diagnosed with increasing frequency in the central and eastern regions of the previously heartwater-free highveld plateau. during the same period, collections of the two major tick vectors of heartwater in zimbabwe, amblyomma hebraeum and amblyomma variegatum, were made for the first tim ... | 1998 | 9809322 |
| validation of the indirect map1-b enzyme-linked immunosorbent assay for diagnosis of experimental cowdria ruminantium infection in small ruminants. | the major antigenic protein 1 fragment b (map1-b) enzyme-linked immunosorbent assay (elisa) for the diagnosis of cowdria ruminantium infections was validated to determine cutoff values and evaluate its diagnostic performance with sheep and goat sera. cowdria-infected populations consisted of 48 sheep and 44 goats, while the noninfected populations consisted of 64 sheep and 107 goats. cutoff values were determined by two-graph receiver-operating characteristic (tg-roc) curves. the cutoff value wa ... | 1999 | 9874666 |
| epitope mapping by expression of restriction enzyme or pcr fragments in bacterial plasmids. | | 1996 | 8959723 |
| analysis of t-cell responses in cattle immunized against heartwater by vaccination with killed elementary bodies of cowdria ruminantium. | cattle were successfully immunized against heartwater with a lysate of cowdria ruminantium formulated in freund's adjuvant. vaccinated animals proved fully resistant to virulent challenge 3 and 10 months after vaccination. for the first time a helper t lymphocyte response to cowdria antigens was observed and characterized. cowdria-specific t-cell lines generated from vaccinated animals by in vitro restimulation with cowdria lysates are 95 to 100% cd4+, are mhc class ii restricted, and produce ga ... | 1997 | 8975917 |
| potential value of major antigenic protein 2 for serological diagnosis of heartwater and related ehrlichial infections. | cowdria ruminantium is the etiologic agent of heartwater, a disease causing major economic loss in ruminants in sub-saharan africa and the caribbean. development of a serodiagnostic test is essential for determining the carrier status of animals from regions where heartwater is endemic, but most available tests give false-positive reactions with sera against related erhlichia species. current approaches rely on molecular methods to define proteins and epitopes that may allow specific diagnosis. ... | 1999 | 10066656 |
| models for heartwater epidemiology: practical implications and suggestions for future research. | we present a simple model of the dynamics of heartwater that we use to explore and better understand various aspects of this disease. we adapted the ross-macdonald model for malaria epidemiology so that we could consider both host and vector populations, and evaluate the interactions between the two. we then use two more biologically detailed models to examine heartwater epidemiology. the first includes a carrier state and host mortality, and the second includes density dependence. the results f ... | 1998 | 10192838 |
| 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 |
| inhibition of mhc class i and class ii cell surface expression on bovine endothelial cells upon infection with cowdria ruminantium. | endothelial cells constitute a main target for cowdria ruminantium (cr) and can potentially play a role as antigen presenting cells (apc). therefore, we measured, in vitro, the effect of cr infections on the expression of mhc class i and class ii molecules on bovine umbilical endothelial cells (buec) and on bovine brain endothelial cells (bbec). a dramatic inhibition of the expression of ifngamma induced mhc class ii molecules was observed on buec and to a lesser extent on bbec upon cr infection ... | 1998 | 9613471 |
| molecular characterization of a 28 kda surface antigen gene family of the tribe ehrlichiae. | antisera against different ehrlichiae recognize an immunodominant, cross-reacting approximately 28 kda surface antigen defined as the map1 in cowdria ruminantium. these antigens are considered valuable in developing serodiagnostic tests and recombinant vaccines for ehrlichiae infections. to evaluate the relationship in three closely related ehrlichiae, ehrlichia chaffeensis, ehrlichia canis, and c. ruminantium, the structure of the 28 kda antigen genes was analyzed. we describe the cloning and c ... | 1998 | 9647746 |
| simultaneous detection of bovine theileria and babesia species by reverse line blot hybridization. | a reverse line blot (rlb) assay was developed for the identification of cattle carrying different species of theileria and babesia simultaneously. we included theileria annulata, t. parva, t. mutans, t. taurotragi, and t. velifera in the assay, as well as parasites belonging to the t. sergenti-t. buffeli-t. orientalis group. the babesia species included were babesia bovis, b. bigemina, and b. divergens. the assay employs one set of primers for specific amplification of the rrna gene v4 hypervari ... | 1999 | 10325324 |
| comparative evaluation of 16s, map1 and pcs20 probes for the detection of cowdria and ehrlichia species in ticks. | we have developed a panel of 16s ribosomal rna gene probes for heartwater epidemiology; five of these detect different cowdria genotypes (ball3, senegal, omatjenne, crystal springs, and mara 87/7); one detects all five of these genotypes; one detects any group iii ehrlichia species other than cowdria; one detects any group ii ehrlichia species. we have used these probes on pcr-amplified rickettsial 16s rrna genes from over 200 amblyomma ticks. control ticks were laboratory-reared and either unin ... | 1998 | 9668452 |
| pcr detection of cowdria ruminantium infection in ticks and animals from heartwater-endemic regions of zimbabwe. | the development of a pcr assay for the detection of cowdria ruminantium infection in ticks has been previously described. here we report a further evaluation of this assay by comparison with a dna probe and with the mouse inoculation assay (mia). application of the pcr assay in determining the prevalence of infection in ruminants and ticks from heartwater-endemic areas of zimbabwe is also described. one hundred uninfected and 120 infected amblyomma hebraeum ticks were analyzed by pcr, dna probe ... | 1998 | 9668453 |
| analysis of cellular responses to native and recombinant proteins of cowdria ruminantium. | the response of pbmc collected from cattle immunized with killed cowdria to map1, map1-b, map2 and to a lysate of cowdria was characterized in vitro. cd4+ t lymphocytes responded strongly to cowdria lysates while b cells and gamma delta t cells proliferated in response to recombinant proteins. short-term cell lines derived from pbmc using cowdria lysates were more than 90% cd4+ and did not respond to any of the recombinant proteins. restimulation of pbmc with map1, map1-b, and map2 proved diffic ... | 1998 | 9668461 |
| inhibitory effect of cowdria ruminantium on the expression of mhc class i and class ii molecules on bovine endothelial cells. | bovine endothelial cells constitutively express mhc class i molecules, whereas mhc class ii molecules can be induced by interferon gamma (ifn gamma) treatment. endothelial cells may play a role as antigen presenting cells (apc), but their role in the immune response against cowdria ruminantium is unknown. we have studied the effect of c. ruminantium infection on the expression of mhc class i and class ii molecules on the surface of bovine endothelial cells. bovine brain endothelial cells (bbec) ... | 1998 | 9668463 |
| a partially protective clone from cowdria ruminantium identified by using a salmonella vaccine delivery system. | a strategy has been developed to screen the cowdria genome, using a salmonella vaccine delivery system, to identify genes that code for protection-stimulating proteins. we have cloned mini-libraries of cowdria into this salmonella system, used the recombinant bacteria to immunize outbred mice, and then challenged them after two weeks with a lethal dose of cowdria. when one of these mini-libraries was tested in a group of 5 mice, one mouse lived much longer than the others. the experiment was rep ... | 1998 | 9668471 |
| evaluation of the map-1b elisa for cowdriosis with field sera from livestock in zimbabwe. | the map 1b (senegal) antigen-based indirect elisa was evaluated in zimbabwe with field sera from heartwater-free and heartwater-endemic areas. of 205 sheep sera samples from a heartwater-free area, 34 were negative and 171 were positive by immunoblotting. these 171 samples were classified as false positives. of the same 205 samples, 199 were negative and only 6 were positive by the map 1b elisa. of 72 cattle samples tested from a similar area, 71 were negative, with only 1 sample positive by map ... | 1998 | 9668473 |
| electron microscopy of cowdria-infected macrophages suggests that in the absence of binary fission a mosaic of organisms develops from an amorphous electron dense matrix. | electron microscopy of mouse peritoneal macrophages infected with the kümm stock of cowdria ruminantium suggests that in the final stage of intracellular growth, a mosaic of organisms develops from an amorphous matrix of varying electron density by a process in which double unit membranes portion off the cowdria particles. this stage is preceded by inclusions consisting of a network of aggregated electron dense granules and these in turn by homogeneous dense bodies. the study failed to show how ... | 1999 | 10396761 |
| validation and comparison of three enzyme-linked immunosorbent assays for the detection of antibodies to cowdria ruminantium infection. | serological tests for cowdria ruminantium infection have been hampered by low specificity. here, an indirect elisa based on purified antigen, a competitive elisa using a recombinant major antigenic protein (map-1) and an indirect elisa based on the map-1b region of the recombinant map-1 were compared. the tests were validated using 3000 sera of ruminants from 14 islands of the lesser antilles as well as sequential serum samples from 10 cattle, 17 goats and 10 sheep vaccinated with inactivated c. ... | 1998 | 9668474 |
| serum-free media for the in vitro cultivation of cowdria ruminantium. | the in vitro culture of cowdria ruminantium, the causative agent of heartwater in domestic ruminants, was first achieved in 1985; since then, most groups working with this culture system have used media which were supplemented with serum and, in addition, most of them contained tryptose phosphate broth. these undefined products vary from batch to batch and often fail to support the growth of c. ruminantium. we are therefore working towards the development of a completely chemically defined mediu ... | 1998 | 9668479 |
| purification of cowdria ruminantium organisms for use in genome analysis by pulsed-field gel electrophoresis. | cowdria ruminantium is an obligate intracellular rickettsial pathogen which is responsible for a tick-borne disease of domestic and wild ruminants called heartwater or cowdriosis. although several genes have been cloned and partially sequenced, the genome size, gross structure, and organization of the c. ruminantium genome is unknown. genome analysis of the organism has been hindered because it is difficult to obtain c. ruminantium dna free from contaminating host cell dna, and this probably acc ... | 1998 | 9668480 |
| major antigenic proteins 1 and 2 of cowdria ruminantium are targets for t-lymphocyte responses of immune cattle. | | 1998 | 9668489 |
| cellular immune responses of cattle to cowdria ruminantium. | peripheral blood mononuclear cells (pbm) from cattle immunised against cowdria ruminantium infection (heartwater), proliferated in vitro in the presence of either infected autologous endothelial cells pre-treated with t cell growth factors to induce mhc class ii expression, or infected autologous monocytes. proliferation was not observed in pbm cultured with a soluble extract of the agent, but pbm responded to two recombinant antigens of c. ruminantium, namely a 32 kda (map1) and a 21 kda antige ... | 1998 | 9554286 |
| immunization of cattle by infection with cowdria ruminantium elicits t lymphocytes that recognize autologous, infected endothelial cells and monocytes. | peripheral blood mononuclear cells (pbmc) from immune cattle proliferate in the presence of autologous cowdria ruminantium-infected endothelial cells and monocytes. endothelial cells required treatment with t-cell growth factors to induce class ii major histocompatibility complex expression prior to infection and use as stimulators. proliferative responses to both infected autologous endothelial cells and monocytes were characterized by expansion of a mixture of cd4+, cd8+, and gammadelta t cell ... | 1998 | 9573061 |
| nitric oxide is produced by cowdria ruminantium-infected bovine pulmonary endothelial cells in vitro and is stimulated by gamma interferon. | nitric oxide (no) is a labile inorganic free radical produced by no synthase from the substrate l-arginine in various cells and tissues including endothelial cells. a substantial elevation of nitrite levels indicative of no production occurred in cultures of cowdria ruminantium-infected bovine pulmonary endothelial cells (bpec) incubated in medium alone. exposure of the infected cultures to recombinant bovine gamma interferon (borifn-gamma) resulted in more rapid production of no, reduced viabil ... | 1998 | 9573097 |
| the use of cd4+ t-cell lines to screen for immunogenic proteins of cowdria ruminantium. | | 1998 | 9668490 |
| the inactivated cowdria ruminantium vaccine for heartwater protects against heterologous strains and against laboratory and field tick challenge. | we previously described that an inactivated vaccine against heartwater prepared from cowdria ruminantium (crystal springs strain) organisms and administered in complete freund's adjuvant (cfa) protected sheep against homologous needle challenge. further studies, described herein, demonstrated that this vaccine protected 100% of sheep against death on challenge with laboratory-infected ticks and with field ticks in a heartwater endemic farm, whereas a mortality rate of 44% and 62%, respectively, ... | 1998 | 9682380 |
| investigating the epidemiology of heartwater (cowdria ruminantium infection) by means of a transmission dynamics model. | a mathematical model of the transmission dynamics of cowdria ruminantium by the ixodid tick amblyomma hebraeum in the bovine host is developed and used to investigate the epidemiology of heartwater across a range of vector challenge. the processes described are supported by empirical data. the pattern of outcome measures (incidence, case-fatality and proportion of infected hosts) predicted agrees with those described anecdotally from field experience and empirical observation, and demonstrates t ... | 1998 | 9695100 |
| cloning and characterization of multigenes encoding the immunodominant 30-kilodalton major outer membrane proteins of ehrlichia canis and application of the recombinant protein for serodiagnosis. | a 30-kda major outer membrane protein of ehrlichia canis, the agent of canine ehrlichiosis, is the major antigen recognized by both naturally and experimentally infected dog sera. the protein cross-reacts with a serum against a recombinant 28-kda protein (rp28), one of the outer membrane proteins of a gene (omp-1) family of ehrlichia chaffeensis. two dna fragments of e. canis were amplified by pcr with two primer pairs based on the sequences of e. chaffeensis omp-1 genes, cloned, and sequenced. ... | 1998 | 9705412 |
| a review of heartwater and the threat of introduction of cowdria ruminantium and amblyomma spp. ticks to the american mainland. | heartwater, caused by the rickettsial agent cowdria ruminantium, is one of the most devastating livestock diseases in sub-saharan africa. in addition to domestic cattle, sheep, and goats, a variety of nondomestic species can acquire subclinical and clinical infections. recent epidemiologic findings that demonstrate a long-term host carrier state in domestic and wild ruminants, intrastadial transmission by the tick vectors (amblyomma spp.), vertical transmission of the agent from cows to their ca ... | 1998 | 9732023 |
| 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 |
| characterization of variable immunodominant antigens of cowdria ruminantium by elisa and immunoblots. | cross-immunization experiments have revealed a significant antigenic diversity of the isolate of cowdria ruminantium which needs to be characterized for the development of vaccines. we identified polymorphic immunodominant antigens by elisa and immunoblot. using serum from a goat immune to the gardel stock of cowdria (isolated in guadeloupe) adsorbed on antigen of the senegal stock of this pathogen, distinct serogroups were revealed by elisa among six isolates from different geographical origins ... | 1998 | 9990646 |
| distributions of the vectors of heartwater, amblyomma hebraeum and amblyomma variegatum (acari: ixodidae), in zimbabwe. | the tick vectors of heartwater (cowdria ruminantium infection) in zimbabwe, amblyomma hebraeum and amblyomma variegatum, historically were believed to be confined to the low-lying regions of the south and north-west of the country. however, country-wide surveys performed in 1975-1980 and 1988-1991 demonstrated that both species were also established in western parts of the highveld plateau and had started to encroach on the predominantly heartwater-free central and eastern highveld regions. to d ... | 1998 | 10030008 |
| the map1 gene of cowdria ruminantium is a member of a multigene family containing both conserved and variable genes. | heartwater is an economically important disease of ruminants caused by the tick-transmitted rickettsia cowdria ruminantium. the disease is present in africa and the caribbean and there is a risk of spread to the americas, particularly because of a clinically asymptomatic carrier state in infected livestock and imported wild animals. the causative agent is closely related taxonomically to the human and animal pathogens ehrlichia chaffeensis and ehrlichia canis. a dominant immune response of infec ... | 1999 | 10198207 |
| molecular cloning of the gene for a conserved major immunoreactive 28-kilodalton protein of ehrlichia canis: a potential serodiagnostic antigen. | a gene encoding a 28-kda protein of ehrlichia canis was cloned, sequenced, and expressed, and a comparative molecular analysis with homologous genes of e. canis, cowdria ruminantium, and ehrlichia chaffeensis was performed. the complete gene has an 834-bp open reading frame encoding a protein of 278 amino acids with a predicted molecular mass of 30.5 kda. an n-terminal signal sequence was identified, suggesting that the protein undergoes posttranslational modification to a mature 27.7-kda protei ... | 1999 | 10225842 |