Publications

TitleAbstractYear
Filter
PMID
Filter
in vitro isolation of neospora caninum from a stillborn calf in the uk.neospora caninum was isolated in vero cell culture from the brain of a stillborn calf. this isolate (designated nc-livb1) is the first to be obtained from cattle in the united kingdom and was confirmed as n. caninum by immunofluorescence with specific antibodies and by internal transcribed spacer 1 (its1) sequence analysis. differences were found between nc-livb1, other bovine isolates and canine isolates of n. caninum and closely related protozoal parasites, using random amplified polymorphic d ...199910425249
neospora caninum continues to be implicated in bovine abortion cases. 199910452389
recent advances in neospora and neosporosis.neospora caninum has emerged as a major cause of abortion in cattle in many countries. this paper reviews recent advances in the life cycle and biology of neospora with the emphasis on bovine neosporosis. the role of the recently discovered oocyst stage of n. caninum in the epidemiology of neosporosis is discussed. progress made in serologic diagnosis of n. caninum infection is discussed. there is no vaccine for preventing neospora-induced abortions in cattle or to prevent oocyst shedding in dog ...199910456423
seroprevalence of neospora caninum and abortion in dairy cows in northern spain.the seroprevalence of neospora caninum infection was estimated from a sample of 889 cattle from 43 dairy herds in three counties in the asturias region of spain. the true prevalence of infection was estimated to be 30.6 per cent (95 per cent confidence interval (ci) 27.6 to 33.6). seropositivity was associated with abortion during the previous year (odds ratio (or)=3.31, p<0.001) and was slightly higher among purchased cattle (37.6 per cent), than among cattle raised on the farm (29.1 per cent) ...199910460027
identification of neospora antigens recognized by cd4+ t cells and immune sera from experimentally infected cattle.neospora caninum is recognized as a major cause of infectious abortion in cattle. very little is known about immunity to neospora. cell mediated responses have previously been shown to be important in the development of protective immunity to the closely related parasite toxoplasma gondii, and may therefore be an important component in the immune response to neospora. in this paper we report that a group of low molecular weight nci strain tachyzoite antigens (< or = 30 kda) separated by sds page ...19989717191
polymerase chain reaction approaches for the detection of neospora caninum and toxoplasma gondii.this review summarizes existing knowledge on the development and use of the polymerase chain reaction for the detection of dna from neospora and toxoplasma. several strategies which utilise the polymerase chain reaction for the diagnosis of toxoplasmosis in humans and livestock have been described and they principally target the b1 repetitive sequence, the p30 gene or ribosomal dna. experience has shown that the polymerase chain reaction has proven insufficiently robust to serve as a diagnostic ...19989724876
neospora caninum identification in an aborted bovine fetus in spain.neospora caninum tachyzoites were identified in areas of the cerebrum with lesions of non-suppurative encephalitis in an aborted bovine fetus in spain.19989746288
canine neosporosis: clinical signs, diagnosis, treatment and isolation of neospora caninum in mice and cell culture.clinical signs, diagnosis, treatment and isolation of neospora caninum from two littermate dogs are described. three of six pups from a labrador bitch developed paralysis. neosporosis was diagnosed ante mortem by serological examination in two of the affected pups. at necropsy, tissue cysts were seen in unstained smears and in histologic sections of their brains. tissue cysts were often thin-walled (approximately 1 micron) but antigenically and ultrastructurally identified as n. caninum. further ...19989762578
serum antibody profile and reproductive performance during two consecutive pregnancies of cows naturally infected with neospora caninum.the objective of this study was to record how the antibody levels change over time during pregnancy in dairy cows naturally infected with the protozoan parasite neospora caninum, and relate this to the reproductive performance. eighteen cows with antibodies to n. caninum were serum sampled monthly during their first pregnancy and 13 of them were also followed for a second pregnancy. in all, five pregnancies ended in abortion and two in stillbirth. antibodies to n. caninum in serum were demonstra ...199910488725
oral neospora caninum inoculation of neonatal calves.four calves born to cows seronegative for neospora caninum were dosed orally within 6 h after birth with tachyzoites of the bovine n. caninum nc-sweb1 isolate added to colostrum. two of the calves were dosed via stomach tube and two by feeding bottle. the latter two calves showed transient fever and passed blood-stained diarrhoea 1-2 weeks after inoculation. from 5 weeks after inoculation they developed a significant antibody response which remained high until the calves were euthanised and necr ...19989770634
vaccination of mice with neospora caninum: response to oral challenge with toxoplasma gondii oocysts.neospora caninum is a protozoan parasite that can cause severe disease in mammals. two experiments were conducted to examine the effects of subcutaneous (s.c.) vaccination with hank's balanced salt solution (hbss), 1 x 10(5) n. caninum nc-1 strain tachyzoites or 1 x 10(5) toxoplasma gondii ts-4 strain tachyzoites on challenge oral infections in mice with sporulated veg strain t. gondii oocysts (1 x 10(3) oocysts exp. 1 and 5 x 10(3) oocysts exp. 2). an additional study, experiment 3, evaluated s ...19989576504
examination of red foxes (vulpes vulpes) from belgium for antibody to neospora caninum and toxoplasma gondii. 19979330477
identification and partial characterization of a 36 kda surface protein on neospora caninum tachyzoites.neospora caninum, the causative agent of neosporosis, is a recently identified apicomplexan parasite which is structurally and biologically closely related to, but antigenically distinct from, toxoplasma gondii. molecules associated with the surfaces of n. caninum tachyzoites are likely to participate in the host cell entry process, could be involved in the interaction of the parasite with the immune system, and they could influence the pathogenesis of neosporosis. isolated n. caninum tachyzoite ...19979364563
the p29 and p35 immunodominant antigens of neospora caninum tachyzoites are homologous to the family of surface antigens of toxoplasma gondii.neospora caninum is an apicomplexan parasite that is closely related to toxoplasma gondii and has been found to be associated with neurological disorders in dogs and congenital infections and abortions in cattle. we have identified two surface proteins of 29 and 35 kda (designated ncp29 and ncp35, respectively) from n. caninum tachyzoites that are the predominant antigens recognized by antisera from neospora-infected animals. monoclonal antibodies against ncp29 and ncp35 were used to analyze sev ...19989784539
estimation of neospora caninum seroprevalence in dairy cattle from normandy, france.an epidemiological study was conducted in orne (france) on randomly selected dairy herds (42 herds including 1,924 cows and heifers, which were at least 15 months old). the aim was primarily to estimate the seroprevalence of neospora caninum infection from two blood samples per cow, using an enzyme-linked immunosorbent assay (elisa) for n. caninum (one positive result indicating infection). the second aim was to test the association between some individual and herd factors and n. caninum seropos ...199910543387
characterization of a cdna encoding a subtilisin-like serine protease (nc-p65) of neospora caninum.the nc-p65 cdna is the first protease sequence cloned and described for neospora caninum. the full length cdna was isolated by 5'- and 3'-rapid amplification of cdna ends (race). nc-p65 was composed of 865 amino acids with a predicted signal sequence, a proposed pro-domain, and an internal region of conserved repeats. analysis of the deduced amino acid sequence revealed that this protein had homology to the serine proteases of the subtilisin-like superfamily (subtilases) and had a predicted acti ...199910551364
detection by pcr of neospora caninum in fetal tissues from spontaneous bovine abortions.the routine diagnosis of neospora caninum abortion is based upon histopathologic changes in fetal tissues and identification of tissue parasites by immunohistochemistry. confirmation of n. caninum infection by immunohistochemistry has low sensitivity. in the present study, we examined the utility of pcr in detecting n. caninum infection in fetal tissues from spontaneous bovine abortion. dna was obtained from fresh and formalin-fixed tissues from 61 bovine fetuses submitted for abortion diagnosis ...199910565932
the expression of toxoplasma proteins in neospora caninum and the identification of a gene encoding a novel rhoptry protein.genes for the toxoplasma gondii dense granule and rhoptry proteins nucleoside triphosphate hydrolase 3 and rop2 were expressed at high levels in the closely related parasite n. caninum. the protein products were processed appropriately and were targeted to their correct secretory organelles. ntpase 3 was secreted into the parasitophorous vacuole. the utility of this system was demonstrated in the analysis of a new open reading frame identified upstream of two identical copies of the rop2 gene. t ...19979364966
neospora caninum: tachyzoites express a potent type-i nucleoside triphosphate hydrolase.we have identified type i nucleoside triphosphate hydrolase (ntpase; ec 3.6. 1.3) activity, previously thought to be restricted to the virulent strains of toxoplasma gondii, in the cell extracts of neospora caninum tachyzoites. sequence analysis of a complete cdna from nc-1 strain indicated that n. caninum ntpases shared approximately 69% identity to the ntpases of t. gondii and are most similar to the ntpase-i isozyme. southern blot analysis of genomic dna and sequence analysis of two independe ...19989806873
significance of neospora caninum in british dairy cattle determined by estimation of seroprevalence in normally calving cattle and aborting cattle.a case control study was conducted to evaluate the significance of neospora caninum infections in cattle in england and wales. the prevalence of n. caninum in normally calving cattle (the control group; n = 418) and aborting cattle (n = 633) was estimated using a commercial antibody-detection elisa. prevalence estimates for bovine virus diarrhoea virus, infectious bovine rhinotracheitis virus and leptospira hardjo were also obtained by serology. the prevalence of n. caninum was significantly hig ...199910576570
towards evaluating the economic impact of bovine neosporosis.in spite of the global importance of neosporosis as a cause of bovine abortion, there is very little information about its economic consequences. the economic costs are a product of estimations of the quantity of the effects attributable to neospora infection, and the particular unit costs of those effects. in this brief review, which arose from a workshop on the economics of coccidiosis held at the cost 820 meeting, toledo 1998, we discuss the possible effects of neosporosis which are of econom ...199910576571
seroprevalence of neospora caninum infection in dairy and beef cattle in spain.in recent years, neosporosis has been identified as a major cause of abortion in dairy and beef cattle. although the disease has been described worldwide, there is a jack of information concerning the prevalence of this infection in different cattle production systems. the aim of this study was to investigate the seroprevalence of neospora caninum infection in a representative area of beef and dairy cattle production in spain. a cross-sectional study was undertaken in which herds constituted the ...199910576572
prevalence of neospora caninum and toxoplasma gondii antibodies in coyotes (canis latrans) and experimental infections of coyotes with neospora caninum.antibodies to neospora caninum were detected in 5 (10%) of 52 coyotes from texas. antibodies to toxoplasma gondii were detected in 32 (62%) of 52 samples from these same coyotes. four (80%) of the 5 coyotes that were seropositive for n. caninum also had antibodies to t. gondii. nineteen (37%) of the coyotes did not have antibodies to either parasite. three coyote pups were inoculated with the brains from mice infected with 3 strains of n. caninum originally isolated from dogs. none of the pups d ...19968691381
application of iscom antigen preparations in elisas for diagnosis of neospora and toxoplasma infections.immunostimulating complexes (iscoms) are cage-like structures of about 40 nm composed of quil a, cholesterol, phospholipids and antigen. their main area of use has been as adjuvants and carriers of immunogens in vaccines. iscoms can also be used for selection of surface membrane proteins of micro-organisms for use in immunoassays, thus decreasing the number of internal proteins that might cause problems with non-specific binding and cross-reactivity. enzyme-linked immunoassays (elisas) utilising ...19989504345
associations of neospora caninum seropositivity with gestation number and pregnancy outcome in danish dairy herds.the prevalence and distribution of seropositivity towards the protozoan parasite neospora caninum were studied in single blood samples from 1561 cows from 31 danish dairy herds. blood samples were analysed by an indirect enzyme-linked immunoassay and an indirect fluorescent-antibody test. seroprevalence in 15 herds with previous abortions assigned to neosporosis ranged from 1% to 58%, with a mean frequency of 22%. in eight out of 16 herds without a history of n.caninum related abortions, no sero ...199910423771
outbreak of abortion associated with neospora caninum infection in a beef herd.abortion outbreaks caused by infection with neospora caninum in beef cattle have not been well documented. neospora caninum infection was confirmed in 4 fetuses that were aborted by cattle in a 350-head beef herd; an additional 58 cattle aborted during the next 2.5 months. overall, 44.4% (157/354) of the cattle in the herd did not become pregnant or experienced fetal loss during this period. initially, 81.3% (282/347) of the herd was seropositive for antibodies to n caninum, and seropositive cow ...199910579048
effect of polyclonal antisera developed against dense granule-associated neospora caninum proteins on cell invasion and development in vitro by n. caninum tachyzoites.the effects of polyclonal antisera to 2 recombinant dense granule (dg) antigens of neospora caninum on invasion and development by n. caninum tachyzoites in baby hamster kidney cell cultures were examined. in immunofluorescent antibody tests, the anti-dg sera, at dilutions of 1:100 to 1:500, reacted intensely with individual intracellular tachyzoites and groups of tachyzoites enclosed in parasitophorous vacuoles at 2 and 52 h p.i., respectively. tachyzoites suspended in diluted anti-dg sera and ...199910599076
evaluation of a commercial elisa for detecting serum antibody to neospora caninum in cattle.a commercially available serum antibody detection enzyme-linked immunosorbent assay for neospora caninum in cattle was evaluated against an immunofluorescent antibody test (ifat) by applying it to 397 sera from normal adult cattle, 352 sera from cattle which had recently aborted, and 422 sera from two herds which had a history of n caninum-associated abortions. it was evaluated in two laboratories and showed high reproducibility, repeatability and almost perfect or substantial agreement with the ...199910606017
serological evidence of human infection with the protozoan neospora caninum.neospora caninum is a protozoan parasite that is closely related to toxoplasma gondii. dogs are a definitive host. prior to its discovery in 1988, n. caninum infection in animals was often mistakenly diagnosed as toxoplasmosis. neosporosis in animals is characterized by encephalitis, abortion, and other conditions that clinically and pathologically resemble toxoplasmosis. the potential of n. caninum to infect humans is unknown. therefore, evidence of human exposure to this parasite was sought by ...199910473533
the major 36 kda neospora caninum tachyzoite surface protein is closely related to the major toxoplasma gondii surface antigen.the tachyzoites and the tissue cysts containing bradyzoites of neospora caninum and toxoplasma gondii, respectively, are difficult to distinguish morphologically. specific antigens have been identified in t. gondii tachyzoites and bradyzoites, some of which are stage-specifically expressed, and different functions have been attributed to some of them. a tachyzoite stage-specifically expressed surface protein is the major surface antigen 1 (sag1) which has been shown to be involved in host cell a ...19989879890
cellular immune responses in cattle experimentally infected with neospora caninum.neospora caninum has recently been identified as an important cause of infectious abortion in cattle. the parasite is closely related to toxoplasma gondii, but the two species are antigenically distinct. to examine cell proliferative responses and the induction of ifn-gamma in experimentally infected cattle, four 2-4 months old calves were subcutaneously inoculated with n. caninum tachyzoites. peripheral blood mononuclear cells were collected regularly and stimulated in vitro with a crude lysate ...19989988308
sequence and pcr-rflp analysis of the internal transcribed spacers of the rdna repeat unit in isolates of cryptosporidium from different hosts.the cryptosporidium its1, 5.8s and its2 rdna regions from a number of cryptosporidium isolates from different hosts and geographical areas were cloned and sequenced in order to investigate the extent of sequence heterogeneity between human and cattle-derived isolates from different geographical locations and also between isolates of cryptosporidium from different hosts such as cats, pigs, mice and a koala. calf-derived isolates from different continents were virtually identical as were human-der ...199910070661
the host-parasite relationship in neosporosis.neospora caninum is an apicomplexan parasite which invades many different cell types and tissues. it causes neosporosis, namely stillbirth and abortion in cattle and neuromuscular disease in dogs, and has been found in several other animal species. n. caninum is closely related to toxoplasma gondii, and controversial opinions exist with respect to its phylogenetical status. initially, two stages of n. caninum had been identified, namely asexually proliferating tachyzoites and bradyzoites. the se ...199910214690
experimental inoculation of domestic pigeons (columbia livia) and zebra finches (poephila guttata) with neospora caninum tachyzoites.dogs are a definitive host of neospora caninum and cattle are intermediate hosts. alternative life-cycles have not been investigated. foxes are frequently seropositive, but may not commonly prey upon cattle; therefore, other intermediate hosts may exist that are frequent prey of foxes. three domestic pigeons (columbia livia) and three zebra finches (poephila guttata) were inoculated with n. caninum tachyzoites, to determine if they could serve as intermediate hosts. tissue culture, pcr, serology ...199910608438
ingestion of neospora caninum tissue cysts by mustela species.dogs are a definitive host of neospora caninum, a protozoal parasite that causes abortion in cattle. mustelids were tested to determine if they could also be definitive hosts. the procedures used were the same as those previously used to test dogs. ermine (mustela erminea), weasels (mustela frenata) and ferrets (mustela putorius) were fed n. caninum-infected mice. neospora caninum oocysts were not observed. mustelid faeces were fed to mice. the mice did not seroconvert and n. caninum was not det ...199910608439
comparison of the biological characteristics of two isolates of neospora caninum.this study compared the biological and genetic properties of a bovine (nc-sweb1) and a canine (nc-liverpool) isolate of neospora caninum. a mouse model for cns infection demonstrated marked differences in pathogenicity between the isolates. nc-liverpool induced severe clinical signs of neosporosis in 57/58 mice including discoordinated movement, hindlimb paralysis and coat ruffling with severe weight loss. in contrast nc-sweb1 induced similar but less severe symptoms in a much smaller proportion ...199910340326
[diagnosis and epidemiology of neospora caninum-associated abortions in cattle].neospora caninum, a recently discovered protozoan parasite closely related to toxoplasma gondii, has world-wide been recognized as an important cause of bovine abortion. n. caninum possesses a wide host range. the dog can be a definitive host for n. caninum. in cattle, the infection is transmitted transplacentally with high efficiency, while the majority of congenitally infected calves is clinically normal at birth and thereafter. whether horizontal transmission occurs in cattle and whether this ...199910384703
vertical transmission of neospora caninum in balb/c mice determined by polymerase chain reaction detection.vertical transmission of neospora caninum was evaluated in balb/c mice using an n. caninum-specific polymerase chain reaction (pcr) assay as a means of detecting parasite transmission to offspring. balb/c mice were infected with the nc-1 isolate of n. caninum during pregnancy (days 8-15 gestation). transmission of parasite, detected by pcr, was determined in 2- to 23-day-old offspring. when dams were infected on days 13-15 of gestation, transfer of parasites was detected in only a proportion of ...199910386452
differentiation of neospora hughesi from neospora caninum based on their immunodominant surface antigen, sag1 and srs2.neospora hughesi is a newly recognised parasite that is closely related to neospora caninum, and is a cause of equine protozoal myeloencephalitis. we have characterised two n. hughesi immunodominant tachyzoite antigens which exhibit antigenic and molecular differences from the homologous tachyzoite antigens on n. caninum. these antigens on n. hughesi are referred to as nhsag1 and nhsrs2, using the same mnemonics as used for the n. caninum antigens (ncsag1 and ncsrs2), and are homologous to toxop ...199910608444
a competitive pcr assay for quantitative detection of neospora caninum.a quantitative-competitive pcr (qc-pcr) assay was developed for measurement of neospora caninum levels in the tissues of infected animals. a molecule was synthesised for use in pcr as a competitor to the target neospora-specific nc5 genomic sequence. the assay was used to evaluate the relative level of parasites in the brain and lungs of mouse pups in a model of vertical transmission of n. caninum. infection on day 11 of gestation resulted in similar levels of parasites in all offspring. the ass ...199910608445
a modified agglutination test for neospora caninum: development, optimization, and comparison to the indirect fluorescent-antibody test and enzyme-linked immunosorbent assay.current serologic tests used to detect antibodies to neospora caninum require species-specific secondary antibodies, limiting the number of species that can be tested. in order to examine a wide variety of animal species that may be infected with n. caninum, a modified direct agglutination test (n-mat) similar to the toxoplasma gondii modified direct agglutination test (t-mat) was developed. this test measures the direct agglutination of parasites by n. caninum-specific antibodies in serum, thus ...19989665950
pathological and immunological findings of athymic nude and congenic wild type balb/c mice experimentally infected with neospora caninum.neospora is a cyst-forming coccidian parasite that causes abortions and neuromuscular disorders in a wide variety of mammals. japanese bovine isolate jpa1 was inoculated intraperitoneally into balb/c nu/ nu (athymic nude) and balb/c (congenic wild type) female mice to examine the distribution of parasites and resistance mechanisms to neospora infection. all the athymic nude mice died within 28 days after intraperitoneal injection of 2 x 10(5) jpa1 tachyzoites, whereas all the congenic wild type ...199910421099
immunogenicity of a killed whole neospora caninum tachyzoite preparation formulated with different adjuvants.a killed whole neospora caninum tachyzoite preparation was formulated with various adjuvants and tested for its immunogenicity in cattle. the adjuvants used were: havlogen, a polymer of acrylic acid cross-linked with polyallylsucrose; polygen, a non-particulate copolymer; a mixture of havlogen and bay r-1005, which is a preparation of free base synthetic glycolipids; and montanide isa 773, a water-in-oil emulsion made with a mixture of metabolisable and mineral oils. immune responses in immunise ...199910608448
phenotypic characterisation of a neospora caninum temperature-sensitive strain in normal and immunodeficient mice.the in vivo persistence, immunogenicity and pathogenicity of a recently described temperature-sensitive (ts) strain from neospora caninum, ncts-8, was investigated in normal and immunodeficient mice. groups of balb/c and scid/bg mice were infected s.c. with 5 x 10(6) wild-type nc-1, control ncts-8 (pass 0) or ncts-8 tachyzoites prepared at four in vitro passage levels (pass 7, 13, 21 and 28). for persistence and immunogenicity studies, balb/c mice were bled and sacrificed at 4, 6 or 8 weeks p.i. ...199910608449
seroepidemiologic study of neospora caninum in dairy herds.to identify risk factors associated with neospora caninum infection in dairy herds in québec and to estimate seroprevalence in case and control herds.19989838960
epizootic disseminated toxoplasmosis in captive slender-tailed meerkats (suricata suricatta).fatal disseminated toxoplasmosis was diagnosed in seven captive slender-tailed meerkats (suricata suricatta) according to clinicopathologic findings and immunohistochemistry. five of nine meerkats died during an outbreak in late 1994. these included four kits (2.5 to 4.5 months old) and a 4-year-old meerkat. two other meerkats, both adults, died in 1992 and 1995. respiratory insufficiency (4/7) and incoordination (3/7) were the most consistent clinical signs. although two of seven meerkats died ...19979150539
a multiple antigen elisa to detect neospora-specific antibodies in bovine sera, bovine foetal fluids, ovine and caprine sera.neospora caninum is a cyst-forming coccidian parasite recently identified as a cause of abortion in cattle. the epidemiology of neosporosis is poorly understood, partly because accurate diagnosis of infection is difficult. in this paper we describe the development of a multiple antigen-based enzyme-linked immunosorbent assay (elisa) to detect antibodies to n. caninum in sera from cattle, sheep and goats as well as from bovine foetal fluids. a water-soluble fraction (wsf) of sonicated nc-1 strain ...19989777723
interferon-gamma and interleukin-12 mediate protection to acute neospora caninum infection in balb/c mice.the type of immune response required to protect mice against clinical disease during acute neospora caninum challenge was investigated in balb/c mice. groups of female balb/c mice were infected i.p. with n. caninum tachyzoites concomitant with either: (1) antibody to interferon-gamma; (2) recombinant murine interleukin-12; or (3) recombinant murine interleukin-12 plus antibody to interferon-gamma. mice treated with anti-interferon-gamma alone had increased morbidity/mortality, decreased body wei ...199910608450
oral infection of calves with neospora caninum oocysts from dogs: humoral and cellular immune responses.neospora caninum has been identified as a major cause of abortion in cattle in a number of countries throughout the world. until the recent demonstration that dogs can serve as a definitive host of this parasite, it was not possible to study the infection in cattle orally exposed to oocysts. the aim of this study was to investigate the potential of n. caninum oocysts to infect calves, and to define initial immune responses that arise after oral infection. seven calves were fed approximately 10(4 ...199910608451
bovine neosporosis: comparison of serological methods using outbreak sera from a dairy herd in new zealand.serological methods developed to detect neospora caninum specific bovine antibodies were compared using sera from an abortion outbreak on a dairy farm in new zealand. these methods included four elisas, ifat and immunoblot. the abortions (n = 16) on the farm were restricted to one of two groups of the herd which consisted of 194 adult dairy cows. all elisas, ifat and immunoblot (applying stringent cut-off levels) revealed a statistically significant association between seropositivity and abortio ...199910608452
postnatal neospora caninum transmission and transient serologic responses in two dairies.cattle on two typically managed drylot dairies were serologically monitored from birth through year 1 to year 4 of life to characterise congenital and postnatal neospora caninum transmission. of the 456 calves enrolled, 284 were classified as n. caninum negative and 172 were classified as n. caninum positive. ninety-six percent of congenitally infected calves were seropositive for all samples tested. seven (4%) of the 172 congenitally infected animals had a period that persisted for 9 to 18 mont ...199910608453
seroepidemiological evidence for a relationship between neospora caninum infections in dogs and cattle.dogs from dairy farms with a known prevalence of neospora caninum antibodies in the cattle were examined for the presence of n. caninum antibodies using an elisa. data of farm dogs were compared with those of dogs examined at a university clinic, which originated mainly in urban areas. of the 152 farm dogs, 36 (23.6%) were seropositive to n. caninum, which was significantly higher than the proportion of seropositives in the clinic dog population (19 of 344, 5.5%). seroprevalence was significantl ...199910608454
estimation of vertical and horizontal transmission parameters of neospora caninum infections in dairy cattle.transmission parameters of neospora caninum infections in dairy cattle were determined in six herds with a history of neospora-associated abortions, using an antibody-detection elisa to detect evidence of infection. a total of 124 seropositive dams and their calves were tested at calving to estimate vertical transmission, and 154 seronegative heifers were monitored prospectively from birth for evidence of post-natal infection. the probability of vertical transmission was very high; 95.2% (95% co ...199910608455
mathematical models of neospora caninum infection in dairy cattle: transmission and options for control.the transmission and control of neospora caninum infection in dairy cattle was examined using deterministic and stochastic models. parameter estimates were derived from recent studies conducted in the uk and from the published literature. three routes of transmission were considered: maternal vertical transmission with a high probability (0.95), horizontal transmission from infected cattle within the herd, and horizontal transmission from an independent external source. putative infection via po ...199910608456
neospora caninum infections in bovine foetuses and dairy cows with abortions in argentina.antibodies to neospora caninum were measured in bovine foetuses, dairy cows and beef cows in argentina using the ifat, the n. caninum agglutination test, and the recombinant ncdg1 and ncdg2 elisa. serum antibodies (ifat titre 1:80) were found in 20 of 82 (24.4%) dairy cow foetuses and one of 22 (4.5%) beef cow foetuses. microscopic lesions suggestive of neosporosis were seen in brains of seven of eight foetuses with ifat titres of 1:80. antibodies (ifat) were found in 122 of 189 (64.5%) dairy co ...199910608457
neosporosis--the first decade of research.this paper reviews the history of neospora caninum for the past decade, and provides a prospective for research for the next decade.199910608433
serological differences in neospora caninum-associated epidemic and endemic abortions.a sandwich enzyme-linked immunosorbent assay (elisa) for the sensitive and specific detection of bovine antibodies to neospora caninum was developed and evaluated using sera from cattle experimentally infected with n. caninum, toxoplasma gondii, sarcocystis cruzi, sarcocystis hominis, sarcocystis hirsuta, eimeria bovis, cryptosporidium parvum, babesia divergens, and field sera from naturally exposed animals. field sera were classified using a gold standard that included the results from an indir ...199910461950
growth of and competition between neospora caninum and toxoplasma gondii in vitro.competitive interactions between neospora caninum and toxoplasma gondii were studied because both species appear to have identical ecological niches in vitro. tachyzoites of n. caninum (nc-1 isolate) and t. gondii (rh isolate) were compared in three in vitro studies: (1) rate of penetration of host cells; (2) generation time; and (3) competition between the two species when grown together in the same flask and allowed to compete for space. when tachyzoites of the two species were inoculated onto ...199910608460
structural analysis of free and protein-bound glycosyl-phosphatidylinositols of neospora caninum. 200010613708
the relationship of hammondia hammondi and sarcocystis mucosa to other heteroxenous cyst-forming coccidia as inferred by phylogenetic analysis of the 18s ssu ribosomal dna sequence.the complete sequence of the 18s small subunit (ssu) ribosomal dna of hammondia hammondi and sarcocystis mucosa was obtained and compared to ssu rdna sequences of neospora caninum, toxoplasma gondii, besnoitia besnoiti, 2 species of frenkelia, 3 species of isospora, and 13 species of sarcocystis. analyses showed that h. hammondi and t. gondii are monophyletic and that these taxa shared a common ancestor with n. caninum and b. besnoiti. the weight of evidence shows that s. mucosa, s. neurona, and ...199910466120
comparison of the major antigens of neospora caninum and toxoplasma gondii.the apicomplexa are a diverse group of parasitic protozoa with very ancient phylogenetic roots. consistent with their phylogeny, the extant species share conserved proteins and traits that were found in their apicomplexan progenitor, but at the same time they have diverged to occupy different biological niches (e.g. host-range and cell type). characterisation of gene and protein diversity is important for distinguishing between related parasites, for determining their phylogeny, and for providin ...199910608434
monoclonal antibody inhibition of neospora caninum tachyzoite invasion into host cells.monoclonal antibodies were produced against neospora caninum tachyzoites to identify antigens which may play a role during invasion of host cells. confocal laser microscopy showed that most antigens recognised by the mab were located on the surface, but one mab, 1a5, reacted to the apical end of the parasite. some mabs, which recognised 70, 42 and 36kda parasite proteins, significantly inhibited the invasion of the parasite in vitro. the mabs which recognised 42 and 36kda parasite protein, react ...200010675744
seroprevalences of neospora caninum and toxoplasma gondii in nondomestic felids from southern africa.sera from 68 nondomestic captive and free-ranging felids from southern africa were tested for antibodies to neospora caninum and toxoplasma gondii by the indirect fluorescent antibody test. four of the 68 (5.9%) serum samples were positive for antibodies to n. caninum, with titers ranging from 1:50 to 1:200. all other animals were negative for antibodies to n. caninum at a dilution of 1:50. fifty of the 68 (74%) serum samples tested positive for antibodies to t. gondii, with titers ranging from ...199910484140
prevalence of antibodies to neospora caninum in dogs.serum samples from 1077 dogs suspected of having neospora caninum infections from 35 states in the united states and 3 provinces in canada were tested for n. caninum igg antibodies by the indirect fluorescent antibody test. antibodies to n. caninum were found in 75 of 1077 (7%) of the samples. twenty of the positive dogs were females, 17 were males and the sex was not recorded on 38 dogs. chi square analysis indicated no differences (p > 0.05) based on sex were present. dogs from the southeast a ...199910488735
seroprevalence of antibodies to neospora caninum and associated abortion in dairy cattle from central thailand.a total of 904 sera from dairy cattle in 11 provinces of central thailand were tested for antibodies to neospora caninum employing the indirect fluorescent antibody test (ifat). fifty four (6%) cattle were positive in ifat, titres of 1:200 (16 cattle), 1:400 (9 cattle), 1:800 (14 cattle), 1:1600 (7 cattle), 1:3200 (6 cattle) and two positives. no significant difference was observed among the provinces. the seropositivity for toxoplasma gondii by a commercial latex agglutination test was 4% (2 ou ...199910489202
prevalence of antibodies to sarcocystis neurona, toxoplasma gondii and neospora caninum in horses from argentina.sera from 76 horses from argentina were examined for antibodies to sarcocystis neurona, toxoplasma gondii and neospora caninum. antibodies to s. neurona were found in 27 (35.5%) of 76 horses using immunoblots with culture derived merozoites as antigen. antibodies to t. gondii were found in 10 (13.1%) of 76 horses by using the modified agglutination test with formalin-fixed tachyzoites and mercaptoethanol; titers were 1:25 (two horses), 1:50 (six horses), 1:100 (two horses), and 1:200 (one horse) ...199910489203
neospora caninum and bovine virus diarrhoea virus infections in swedish dairy cows in relation to abortion.the protozoan parasite neospora caninum and bovine virus diarrhoea virus (bvdv) are recognized as important causes of bovine abortion and congenital disease worldwide. in this study, serological investigations were performed to estimate the prevalence of n. caninum infection in swedish dairy cattle, to assess to what extent it may affect abortion rates, and to determine possible effects of coinfection with bvdv. the overall n. caninum seroprevalence in swedish dairy cows was estimated at 2% (16/ ...200010712809
seroprevalence of neospora caninum in dairy cattle in bahia, brazil.sera collected from 447 dairy cattle on 14 dairy farms were tested for neospora caninum antibodies by use of an immunofluorescent antibody technique. positive reactions with titres > or =1:200 were found in 63 (14.09%) of animals. neospora positive sera were also tested for toxoplasma gondii antibodies by using a commercial latex agglutination test. antibodies to t. gondii were detected in 3 (4.76%) of 63 n. caninum positive sera. these results indicate that n. caninum infection is widespread am ...199910489205
increased risk of abortion following neospora caninum abortion outbreaks: a retrospective and prospective cohort study in four dairy herds.explosive abortion outbreaks in 4 dutch dairy herds during 1992 to 1994 are reported. in 50 of 51 fetuses submitted during the first 3 wk of the outbreaks characteristic histological lesions compatible for infection with neospora caninum were seen. diagnosis of infection was confirmed by immunohistochemistry in 40 fetuses (78%). no evidence for other abortifacients was found. the abortion risk of the herds was investigated in a prospective and retrospective cohort study. the prospective study sh ...199810732067
abortion risk in progeny of cows after a neospora caninum epidemic.a study was done of the descendants of cows from 4 dairy herds in which there had been n. caninum abortion outbreaks. precolostral antibodies to n. caninum were demonstrated in 34 of 50 (68%) f1 calves and in 14 of 17 (82%) f2 calves from cows that aborted during the outbreaks. in 214 f1 progeny, n. caninum seroprevalence was nearly 50%, and there was a significant association between serostatus of the offspring and serostatus of dams. these observations indicated that congenital infection was a ...199810732068
characteristics of neospora caninum-associated abortion storms in diary herds in the netherlands (1995 to 1997).abortion storms in 50 dairy herds in the netherlands were reported in which there was a strong association with neospora caninum-infection. the duration of the abortion storms ranged from 6 to 65 d (mean 41.5 d). the cumulative proportion of aborting cows ranged from 0.11 to 0.57 (mean 0.26) of the animals at risk. an apparent seasonal influence was noted as most abortion storms occurred during the summer and early autumn. the prevalence of antibodies to n. caninum in 50 herds which had had an a ...199910734391
risk factors for neospora caninum-associated abortion storms in dairy herds in the netherlands (1995 to 1997).a 2 to 1 matched case control study design was used to analyze herd level risk factors for neospora caninum-associated abortion storms in 47 dairy herds. data were obtained using a questionnaire regarding the state of affairs at the farms over the 2 years prior to the abortion storm. the questionnaire included 120 variables considered to be potential risk factors for either introduction of infection or recrudescence of chronic infection. the relationship between risk factors and case control pai ...199910734392
[the occurrence of toxoplasma gondii and neospora caninum as regards meat hygiene].toxoplasma gondii and neospora caninum are phenotypically and phylogenetically closely related cyst-forming coccidia, both of which may cause abortion in livestock animals. t. gondii exhibits also zoonotic potential by causing diaplacental infections in the human fetus and harmful infections in immunosuppressed individuals. humans get infected either by consuming inappropriately prepared cyst-containing meat or by ingesting oocysts originating from cat feces. therefore, in order to assess infect ...200010748708
the inhibitory effect of interferon gamma and tumor necrosis factor alpha on intracellular multiplication of neospora caninum in primary bovine brain cells.primary culture of bovine brain cells was examined for its susceptibility to neospora caninum infections, and this model was used to investigate the effects of bovine interferon gamma (ifn-gamma) and tumor necrosis factors alpha (tnf-alpha) on tachyzoite growth. tachyzoites of n. caninum grew well in this culture, and tachyzoite growth in astroglia and microglia were confirmed by immunocytochemical staining. ifn-gamma inhibited the tachyzoite growth, and this inhibition was not reversed by the a ...200010770613
serologic prevalence of sarcocystis neurona, toxoplasma gondii, and neospora caninum in horses in brazil.to determine serologic prevalence of sarcocystis neurona, toxoplasma gondii, and neospora caninum in horses in brazil.199910511862
neutralization of maternal il-4 modulates congenital protozoal transmission: comparison of innate versus acquired immune responses.il-4 levels were modulated in mice to test the hypothesis that induction of a maternal type 1 response would decrease the frequency of congenital neospora caninum transmission. this hypothesis tested the relationship between il-4 and both innate and adaptive immunity utilizing two basic experimental designs. in the first, maternal il-4 was neutralized with mab during pregnancy in naive mice concomitant with initial, virulent infection. in the second, maternal il-4 was neutralized before pregnanc ...200010779783
neospora caninum infection in a clinically healthy calf: parasitological study and serological follow-up.in this study a case of congenital infection in a clinically healthy calf is reported. the mother showed high antibody levels (ifat) at 230 days of gestation (igg titres > or = 1:1600, igm titres > or = 1:320) and the parasite was isolated from placental cotyledonary villi at calving. the igm values are indicative of a recent infection in the third trimester of gestation. the calf was monitored serologically for igm and igg from birth until slaughtering, at 8 months of age. igm titre showed a pe ...200010780172
diagnosis and epidemiology of bovine neosporosis: a review.neospora caninum is a protozoan parasite that was first described in dogs in 1988. subsequently the parasite has been associated with abortion in cattle. evidence is accumulating that neosporosis is a major cause of reproductive failure in cattle all over the world. recent knowledge of neosporosis is reviewed with emphasis on the diagnosis and epidemiology of the disease in cattle. in addition, attention is paid to strategies for disease control and prevention.200010789513
comparison of the ifat and iscom-elisa response in bovine foetuses with neospora caninum infection.the study was carried out to evaluate the efficacy of foetal serology in the diagnosis of neospora-associated bovine abortions. fluids from 14 foetuses of cows with confirmed neosporosis (group a), seven foetuses with confirmed bovine viral diarrhoea virus (bvd infection) (group b) and 11 aborted foetuses without demonstrable infection (group c) were examined. the age of the foetuses ranged from 4.5 months to 9 months. albumin concentration (measured by rocket immunoelectrophoresis) was not sign ...199910576568
the antigenic composition of neospora caninum.neospora caninum is an apicomplexan parasite which causes neosporosis, namely stillbirth and abortion in cattle, and neuromuscular disease in dogs. although n. caninum is phylogenetically and biologically closely related to toxoplasma gondii, it is antigenically clearly distinct. in analogy to t. gondii, three stages have been identified. these are: (i) asexually proliferating tachyzoites; (ii) tissue cysts harbouring slowly dividing bradyzoites; and (iii) oocysts containing sporozoites. the sex ...199910576569
neospora caninum seroprevalence and associated risk factors in beef cattle in the northwestern united states.a neospora caninum seroprevalence and risk factor survey of 2585 cows was conducted in 55 beef cow-calf herds located in five northwestern states of the usa. blood samples were collected by private veterinary practitioners and management practices were surveyed using a mail questionnaire. producers were randomly selected from those that employed these veterinarians to perform annual herd pregnancy examinations. questions were asked about animal management, grazing and feeding, immunization and r ...200010828508
development and validation of species-specific nested pcrs for diagnosis of acute sarcocystiosis in sheep.sheep may be infected by four species of sarcocystis. two of these species, sarcocystis tenella and sarcocystis arieticanis, are pathogenic. they may cause abortion or acute disease during the early phase of infection, and chronic disease during the late phase of infection. thus far, diagnosis of sarcocystiosis in sheep has been limited, because traditional diagnostic tests based on the detection of sarcocystis-specific antibodies are only genus-specific and, thus, cannot differentiate between p ...199910576582
in vitro isolation and characterization of bovine neospora caninum in korea.the brains of nine aborted bovine fetuses and two newborn calves born from dams suspected to be infected with neospora caninum were homogenized and inoculated into vero cells. all fetuses and calves were from cows determined as seropositive to n. caninum by an ifa test. sera and thoracic fluids of all fetuses and calves also revealed high antibody titer to n. caninum by ifat ranging from 1:800 to 1:3200. n. caninum was isolated from the brains of one aborted fetus and one newborn calf when the b ...200010828521
neospora caninum infections in australia and new zealand.to review the current state of knowledge of neospora caninum infections with particular reference to australia and new zealand.200010840573
seroprevalence of neospora caninum infection following an abortion outbreak in a dairy cattle herd.to investigate the seroprevalence of neospora caninum infection in a commercial dairy cattle herd, 15 months after detection of an abortion outbreak.200010840574
serologic survey of neospora caninum infection in a closed dairy cattle herd in maryland: risk of serologic reactivity by production groups.prevalence of antibodies to neospora caninum was determined in a cross-sectional consensus survey of 1029 bovines in a dairy herd with endemic neospora-induced abortion. sera were screened by indirect fluorescent antibody test (ifat). the prevalence of n. caninum antibody in the ifat was 17.9% in 107 neonates, 26.2% in 233 yearling heifers and steers, 39.07% in 218 mature heifers, and 26.9% in 465 milking cows. serologic reactivity was associated with production grouping on the farm with the gre ...200010841997
the role of cd4(+) or cd8(+) t cells in the protective immune response of balb/c mice to neospora caninum infection.the role of cd4(+) or cd8(+) t cells in the immune response of balb/c mice against neospora caninum infection was examined by using anti-cd4 and/or anti-cd8 monoclonal antibodies (mabs). mice were intraperitoneally inoculated with anti-cd4 and/or anti-cd8 mabs before and after infection with n. caninum and observed for 30 days after infection. most of the anti-cd4 mab-treated mice and all of the anti-cd4 and anti-cd8 mabs-treated mice died within 30 days post-infection (p.i.). in contrast, 100% ...200010841998
isolation of neospora caninum from the brain of a naturally infected adult dairy cow.neospora caninum was isolated from the brain of a 2-year-old dairy cow that had aborted confirmed n. caninum-infected fetuses on two occasions. the cow had an indirect fluorescent antibody titer of 1:1600 to n. caninum. the cow was killed 24 days after its second abortion and the brain was bioassayed for n. caninum in nude mice. multifocal areas of perivascular cuffing and glial nodules were observed in the cerebrum and mesencephalon of the cow, but n. caninum was not identified in histological ...200010842005
neosporosis in cattle.during the past decade, neospora caninum infection has emerged as an important reproductive disease in cattle throughout the world. abortion, occurring during the middle of gestation, is the primary clinical sign of the infection in cattle. surveys in several countries from three continents have identified n. caninum infection as the major diagnosed cause of bovine abortion. both endemic and epidemic patterns of abortion may occur in herds. an important feature of this disease is that the protoz ...200010844212
[neospora caninum and neosporosis--basic science at the institute of parasitology and possible implications]. 200010850161
neospora caninum infected the alimentary tract of nude mice and was transmitted to other mice by intraperitoneal inoculation with the intestinal contents.neospora caninum (bt-2 strain) that originated from the brain of a holstein calf was serially passaged through 10 generations of balb/c nude mice by intraperitoneal inoculation. histological examination of the mice revealed that numerous clusters of tachyzoites appeared in the pancreas, stomach and small intestine as well as in the central nervous system (cns) and skeletal muscles. intestinal contents of the infected mice were inoculated intraperitoneally into uninfected nude mice and 3 of the 1 ...200010852403
vertical and horizontal transmission of neospora caninum in dairy herds in québec.neospora caninum is an important cause of abortion in dairy cattle. the objective of this observational study was to estimate the rate of vertical transmission of n. caninum in dairy herds in québec and to investigate horizontal transmission in the same herds. the genealogy of cows from 23 dairy herds were examined. prevalence of seropositive animals in herds studied varied from 4.3% to 61.8% (average, 21.9%). the overall rate of vertical transmission was estimated to be 44.4%, varying from 0% t ...200010857030
seroprevalence of neospora caninum infection in domestic dogs in turkey. 200010872789
serological diagnosis of neospora caninum infection.since the first isolation of the apicomplexan parasite neospora caninum, a range of serological assays have been developed for use in dogs, cattle and a variety of other potential host species. the tests include the indirect fluorescent antibody test, the direct agglutination test and different enzyme-linked immunosorbent assays. this article reviews the principles and properties of the available tests which are discussed in relation to different applications.199910608435
hepatic sarcocystosis in a horse.hepatic sarcocystosis was diagnosed in a horse in association with refractory bacterial osteomyelitis and plasma cell tumor of the maxilla and hepatic salmonellosis. gross lesions included pleural, pericardial, and peritoneal effusions, hepatomegaly, gastric ulceration, colonic edema, and proliferative tissues filling 2 maxillary dental alveoli. histologically, liver was characterized by severe suppurative, necrotizing, periportal hepatitis, and severe periacinar necrosis. hepatocytes frequently ...199910577737
neospora hughesi: experimental infections in mice, gerbils, and dogs.neospora hughesi is a recently described cause of equine protozoal myeloencephalitis (epm). a rodent model for pathogenicity would facilitate development of therapies to be used in horses. in the present study, we examined the susceptibility of balb/c gamma-interferon gene knockout (gamma-infko), balb/c, cd-1, and c57bl/6 strains of mice and gerbils to infection with tachyzoites of the nh-a1 strain of n. hughesi isolated from a horse from al, usa. only the gamma-ifnko mice developed severe clini ...200010946135
an igg avidity elisa to discriminate between recent and chronic neospora caninum infection.the avidity of igg antibodies directed to neospora caninum was measured using an igg avidity enzyme-linked immunosorbent assay (elisa) employing n. caninum proteins incorporated into immunostimulating complexes as antigen. in this elisa, low-affinity antibodies were eluted by adding an incubation step with urea after the serum incubation. the antibody titers obtained with and without incubation with urea were then used to calculate the igg avidity values. analysis of sequential sera collected fr ...19999925210
a polygen-adjuvanted killed neospora caninum tachyzoite preparation failed to prevent foetal infection in pregnant cattle following i.v./i.m. experimental tachyzoite challenge.cattle immunised with a polygen-adjuvanted killed neospora caninum tachyzoite preparation were previously shown to produce interferon (ifn)-gamma at levels similar to those of tachyzoite-infected cattle. in view of the critical role of ifn-gamma in resistance of mice to n. caninum infection, these results prompted us to test the polygen-adjuvanted preparation in pregnant cattle to determine whether it will be able to prevent foetal infection following an experimental tachyzoite challenge. seven ...200010980287
prevalence of antibodies to neospora caninum in horses in north america.serum samples from 296 horses slaughtered for food in the united states were tested for antibodies to neospora caninum by the neospora-agglutination test (nat). antibodies were found in 69 (23.3%) horses with titers of 1:40 (19 horses), 1:80 (19 horses), 1:100 (3 horses), 1:200 (7 horses), 1:400 (4 horses), and 1:800 (17 horses). this is the first serologic survey for n. caninum antibodies in horses.199910577738
use of purified tachyzoite surface antigen p38 in an elisa to diagnose bovine neosporosis.affinity-purified 38 kda surface antigen of neospora caninum tachyzoites was used to develop an enzyme-linked immunosorbent assay (elisa) to diagnose n. caninum-associated abortion in cattle. the specificity of this antigen was demonstrated by using sera from cattle experimentally infected with other apicomplexan parasites. in a panel of field sera, serological differences could be demonstrated between herds with epidemic and endemic abortions. optimal elisa cut-offs were determined for the dete ...200010996331
Displaying items 201 - 300 of 1864