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At least 19 recordsLinked to original sources
PubMed1993

Congenital Neospora infection in calves born from cows that had previously aborted Neospora-infected fetuses: four cases (1990-1992).

Four dairy cows that had been successfully rebred following fetal Neospora infection and abortion were identified from 2 drylot dairies. All 4 cows had uncomplicated pregnancies with the birth of 5 full-term calves. The calves all had high precolostral serum IgG antibodies. The precolostral antibodies to Neospora sp as determined by indirect fluorescent antibody test ranged from 5,120 to 20,480, compared with maternal serum and colostral antibody titers from 320 to 1,280. Two calves had mild neurologic limb deficits. Three calves had mild nonsuppurative encephalomyelitis and Neospora organisms were found in the CNS of 3 calves. Findings indicate that repeat transplacental Neospora infections occur in cows. Additionally, calves born from cows with a history of Neospora fetal infection and abortion may have congenital Neospora infections and/or neurologic dysfunctions at birth. The Neospora indirect fluorescent antibody test appears to be a useful antemortem test for detection of calves exposed in utero to Neospora organisms.

Abortion, Veterinary↗
PubMed1994

Experimental reproduction of bovine fetal Neospora infection and death with a bovine Neospora isolate.

Studies were conducted to determine the pathogenic potential of the recently isolated bovine Neospora protozoa (BPA-1) for the bovine fetus. Cows chosen for study had Neospora titers < 160 using an indirect immunofluorescent antibody (IFA) test. Four experimental groups were studied. In group 1, 2 fetuses were inoculated in utero at 118 days gestation with culture-derived Neospora tachyzoites. A pregnant control cow was housed in the same pen, observed daily and screened serologically for evidence of exposure to Neospora. In group 2, 2 cows were infected with Neospora tachyzoites at 138 or 161 days gestation, and 1 control cow was given uninfected cell culture suspension simultaneously at 154 days gestation. Groups 3 (85 days gestation) and 4 (120 days gestation) each consisted of 2 cows infected with Neospora tachyzoites and 1 control cow given uninfected material at the same stage of gestation. Dead fetuses were surgically removed from the infected cows in group 1 on postinfection day (PID) 17. The histopathology was compatible with protozoal fetal infection, and protozoa were identified by immunohistochemistry. Viable fetuses were removed surgically from cows in group 2 on PID 28-30. The histopathology was compatible with protozoal fetal infection, protozoa were identified by immunoperoxidase techniques, and Neospora tachyzoites were reisolated in vitro from tissues of the 2 infected fetuses. In groups 3 and 4, the control fetus and 1 infected fetus were removed surgically between PID 26 and PID 33. The remaining infected cows were observed until fetal death or abortion occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗
PubMed1999

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 Toxoplasma gondii surface antigen 1 (SAG1) and SAG1-related sequence 2 (SRS2). The NcSAG1 and NcSRS2 were antigenically conserved in six different N. caninum isolates from cattle and dogs. The two equine-derived Neospora isolates, one designated as N. hughesi, were similar to each other but different from N. caninum. There was 6% difference in amino acid identity between NcSAG1 and NhSAG1, whereas there was a 9% difference when NcSRS2 and NhSRS2 were compared. The polymorphism of these genes and their corresponding proteins provide additional markers which can be used to distinguish N. caninum from N. hughesi.

Amino Acid Sequence↗
PubMed2001

Molecular comparison of the dense granule proteins GRA6 and GRA7 of Neospora hughesi and Neospora caninum.

Neospora hughesi is a recently described apicomplexan parasite that has been associated with several cases of equine protozoal myeloencephalitis. The biology of this new parasite is just beginning to be defined. Towards this understanding, we report important differences between the nucleotide and deduced amino acid sequences of the dense granule proteins GRA6 and GRA7 of N. hughesi and Neospora caninum. This information can be used to differentiate the two species and contribute to further understanding of the prevalence and biology of N. hughesi. The newly defined proteins of N. hughesi are referred to as NhGRA6 and NhGRA7 in keeping with the protocol for naming homologous proteins of the Apicomplexa. Genes of the two dense granule proteins of N. hughesi (isolate Nh-A1) and four different isolates of N. caninum were isolated via PCR and their DNA sequences were determined. Computer analysis indicated that the two gene sequences were identical among all four N. caninum isolates. However, the gene for NhGRA6 was found to be 96 nucleotides longer at the 3' end than that of NcGRA6, resulting in a protein product that is 32 amino acids larger than NcGRA6. Two tandem repeat sequences were identified at the 3' end of the NhGRA6 gene. These repeat sequences contributed to the lengthening of the carboxy terminus of NhGRA6 in comparison with that of NcGRA6. The larger size of NhGRA6 was further confirmed by Western blot analysis in which NcGRA6 monospecific antibodies recognised a protein of approximately 42 kDa in N. hughesi whole tachyzoite preparation but a protein of 37 kDa in N. caninum whole tachyzoite preparation. Analysis of GRA7 gene sequences indicated a 6 and 14.8% difference at nucleotide and amino acid sequence level, respectively, between NcGRA7 and NhGRA7. Despite the same number of residues in the deduced amino acid sequences of all the GRA7 proteins, Western blot analysis indicated a difference in the migration pattern of NhGRA7 in comparison with NcGRA7. Results of our study indicate that diagnostic tests based on differences in dense granule sequences and antigenicity may have potential to differentiate between N. hughesi and N. caninum. Such diagnostic tests would be valuable tools to aid in our understanding of the epidemiology of these parasites. Additionally, dense granule proteins are immunogenic and they may have potential as use in recombinant vaccines against neosporosis.

Amino Acid Sequence↗
PubMed2001

Characterization of Neospora caninum surface protein NcSRS2 based on baculovirus expression system and its application for serodiagnosis of Neospora infection.

The baculovirus expression system has proved to be a useful tool for the production of recombinant proteins. Here we have characterized the Neospora caninum surface protein NcSRS2 produced by two types of the recombinant virus and also have developed an enzyme-linked immunosorbent assay (ELISA) using recombinant NcSRS2 for the serologic diagnosis of Neospora infection. Western blot analysis showed two major protein bands that were detectable in insect cells infected with each recombinant baculovirus, and a lower-molecular-weight protein was detected in culture supernatants from a cell infected with the recombinant virus lacking the hydrophobic C-terminal tail. Analysis of the N-terminal amino acids showed that the secreted NcSRS2 lacked 6 kDa of the N-terminal signal peptide. Moreover, the detergent-soluble protein of insect cells infected with the recombinant baculovirus expressing the full-length NcSRS2 gene was used to develop an ELISA system based on specificity and reactivity to antisera against Toxoplasma gondii, Hammondia heydorni, or N. caninum. Anti-N. caninum mouse, dog, and bovine sera recognized the recombinant NcSRS2 on Western blots. Furthermore, we have shown that the developed ELISA system consistently discriminates indirect fluorescent-antibody test (IFAT)-positive bovine sera against N. caninum from IFAT-negative sera. These results indicate that the ELISA using baculovirus-expressed NcSRS2 can be useful for effective and reliable serodiagnosis of N. caninum infection.

Animals↗
PubMed2006

Effect of Neospora caninum-serostatus on culling, reproductive performance and milk production in Dutch dairy herds with and without a history of Neospora caninum-associated abortion epidemics.

We quantified the effect of Neospora caninum (NC)-serostatus on culling and (re)production in 83 herds randomly selected from the Dutch dairy herd population (random group) and in 17 herds that had experienced an abortion epidemic associated with NC infection (epidemic-abortion group). In the random group, a single whole-herd blood sampling was done during the spring of 2003, while in the epidemic-abortion group whole-herd blood sampling was done repeatedly at least once a year starting after the abortion epidemic during the period 1997-2000 until the summer of 2004. Serological test-results for NC were given as 'negative' (N), 'low-positive' (LP) and 'high-positive' (HP). For analysing the time to culling, calving interval and age of first calving, survival analysis was used. For categorical reproduction parameters either a logistic-regression model (abortion, non-return after 1st insemination) or a Poisson-regression model (number of inseminations per pregnancy) was used. For milk production a linear-mixed model was used. All models were controlled, if applicable, for confounding variables like parity, production, season, year and abortion and adjusted for within-herd clustering. In random herds, HP serostatus increased the hazard for culling 1.73-fold (95% CI: 1.37-2.19) compared to N and LP serostatus. Compared to N serostatus, LP and HP serostatus in epidemic-abortion herds increased the odds for abortion 1.88-fold (95% CI: 1.41-2.52) and 1.72-fold (95% CI: 1.38-2.14), respectively. No other reproduction parameters were associated with NC-serostatus in the random or epidemic-abortion herds. We found no effect of serostatus on milk production in the random group. In contrast, milk production of LP and HP serostatus in the epidemic-abortion group was respectively, 0.72kgmilk/day (95% CI: 0.15-1.03) and 0.59kgmilk/day (95% CI: 0.13-1.30), less during the first 100 days of lactation in the first year after the abortion epidemic compared with N serostatus.

Abortion, Veterinary↗
PubMed2001

Dogs shed Neospora caninum oocysts after ingestion of naturally infected bovine placenta but not after ingestion of colostrum spiked with Neospora caninum tachyzoites.

An experiment was carried out to determine whether bovine colostrum or placenta could be a source of infection of Neospora caninum for dogs. For this purpose, two dogs were fed bovine colostrum to which culture-derived N. caninum tachyzoites were added and two other dogs were fed placental cotyledonary tissue from N. caninum seropositive cows. One dog served as a negative control during the start of the experiment but this control dog was fed cotyledonary tissue later on. None of the dogs did produce serum antibodies to N. caninum. All three dogs that were fed cotyledonary tissue did shed N. caninum oocysts, but no oocyst shedding was seen in the two dogs that were fed colostrum with N. caninum tachyzoites. Oocyst excretion did not resume in two dogs after repeated feeding of N. caninum infected placenta. The identity of the oocysts was confirmed by a bioassay in gerbils. It is concluded that ingestion of bovine placenta by dogs is an effective mode of transmission of N. caninum from cattle to dogs.

Animals↗
PubMed2005

[First documentation of a neospora-induced "abortion storm" (exogenous transplacental transmission of neospora caninum) in a Swiss dairy farm].

In a Swiss dairy farm (canton of Geneva) consisting of 73 animals 8 abortions were observed within 2 weeks. Serological and molecular biological analyses (PCR) on aborting dams, and abortion materials, respectively, revealed that the protozoan parasite Neospora caninum was the causative agent. Besides the 8 aborting animals, 12 other non-aborting heifers were found to be serologically positive for this parasite. All positive sera were further tested in an avidity-ELISA to elucidate the recency of infection. All seropositive animals but one showed low avidities at the time the abortion storm started. This indicated at a recent N. caninum-infection within the herd. Thus, the animals most probably were exposed to N. caninum-oocysts (e.g. by dog feces-contaminated forage) and the resulting abortion storm was due to an exogenous (formerly known as "horizontal") parasite transmission into a naive herd. This is the first documented record of such an event in Switzerland.

Abortion, Veterinary↗
PubMed2005

Neospora caninum infection does not affect the fertility of dairy cows in herds with high incidence of Neospora-associated abortions.

This present study, was designed to establish whether Neospora caninum infection affects the fertility of high-producing dairy cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection in aborted foetuses. Assessment was made of 7518 artificial inseminations (AI) (applied to parous cows) performed in three herds. Of these inseminations, 2540 (33.8%) resulted in pregnancy; 34% of which corresponded to seronegative cows (2226 of 6556 AI performed in seronegative cows) and 32.6% to seropositive animals (314 of 962). Abortion occurred in 97 (30.1%) of the 314 pregnancies recorded in dams seropositive for N. caninum, while only 93 (4.2%) of the 2226 pregnancies in seronegative animals ended in abortion. Logistic regression analysis indicated no significant effects of N. caninum antibody titre, days in milk and milk production at insemination on fertility. Factors found to affect fertility were herd, season of insemination, lactation and insemination number, semen-providing bull and AI technician. Our results indicate that N. caninum infection does not affect the fertility of high-producing dairy cows.

Abortion, Veterinary↗
PubMed2005

Protective efficacy of vaccination with Neospora caninum multiple recombinant antigens against experimental Neospora caninum infection.

Protective efficacy of vaccination with Neospora caninum multiple recombinant antigens against N. caninum infection was evaluated in vitro and in vivo. Two major immunodominant surface antigens (NcSAG1 and NcSRS2) and two dense granule proteins (NcDG1 and NcDG2) of N. caninum tachyzoites were expressed in E. coli, respectively. An in vitro neutralization assay using polyclonal antisera raised against each recombinant antigen showed inhibitory effects on the invasion of N. caninum tachyzoites into host cells. Separate groups of gerbils were immunized with the purified recombinant proteins singly or in combinations and animals were then challenged with N. caninum. Following these experimental challenges, the protective efficacy of each vaccination was determined by assessing animal survival rate. All experimental groups showed protective effects of different degrees against experimental infection. The highest protection efficacy was observed for combined vaccination with NcSRS2 and NcDG1. Our results indicate that combined vaccination with the N. caninum recombinant antigens, NcSRS2 and NcDG1, induces the highest protective effect against N. caninum infection in vitro and in vivo.

Animals↗
PubMed1996

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 developed neosporosis or excreted N. caninum oocysts in their feces. The pups developed anti-N. caninum antibody titers of > or = 1:800 but did not develop antibodies to T. gondii. Results of this study indicate that antibodies to T. gondii are more common than antibodies to N. caninum in coyotes. Additionally, young coyotes appear to be resistant to experimental N. caninum infection.

Agglutination Tests↗
PubMed1994

Experimental fetal and transplacental Neospora infection in the nonhuman primate.

BACKGROUND: Neospora is a newly recognized Toxoplasma-like protozoan that causes spontaneous abortion and/or neonatal disease in a wide range of animals. The purpose of this study was to determine the susceptibility of primates to Neospora infection. EXPERIMENTAL DESIGN: In experiment 1, two rhesus macaque fetuses were inoculated in utero at gestational day 65 with 1 x 10(6) culture-derived Neospora tachyzoites. A control fetus was given uninfected vehicle. The fetuses were removed by hysterotomy between 13 and 22 days postinoculation. In experiment 2, two pregnant macaques were inoculated intramuscularly and intravenously on gestational day 43 with a total of 1.6 x 10(7) culture-derived tachyzoites. A pregnant control macaque was given uninfected vehicle. The fetuses were removed by hysterotomy between 67 to 70 days postinoculation. Fetal tissues were collected for in vitro parasite isolation, histopathology, and Neospora immunohistochemistry. Fetal blood was examined for Neospora-specific antibody titers using an indirect fluorescent antibody test. RESULTS: Neospora infections were confirmed in all fetuses that received tachyzoites either directly or via transplacental infection. In experiment 1, infected fetuses had reduced amniotic fluid volumes, marked protozoal amnionitis and dermatitis, and a mild multifocal encephalitis. Infected fetuses from experiment 2 had a chronic multifocal necrotizing nonsuppurative meningoencephalitis with microcavitation, that was confined to the cerebrum, and a mild multifocal necrotizing amnionitis. In both experiments, Neospora tachyzoites were detected in association with lesions in fetal tissues by immunohistochemistry, and the parasites were reisolated in vitro. IgG Neospora antibody titers were detected in blood from all infected fetuses, whereas Neospora-specific IgM and IgA titers were found in one and three fetuses, respectively. CONCLUSIONS: Results indicate that nonhuman primates are susceptible to transplacental Neospora infection. The fetal lesions after transplacental infection are similar to those induced by transplacental Toxoplasma infections in primates.

Animal Diseases↗
PubMed1996

Identification of bovine Neospora parasites by PCR amplification and specific small-subunit rRNA sequence probe hybridization.

Neospora is a newly recognized genus of pathogenic coccidia, closely related to Toxoplasma gondii, that can cause abortion or congenital disease in a variety of domestic animal hosts. On the basis of the small-subunit rRNA gene sequences of Neospora spp. and other apicomplexa coccidia, oligonucleotide primers COC-1 and COC-2 were used for PCR amplification of conserved sequences of approximately 300 bp in size. A Neospora-specific chemiluminescent probe hybridized to Southern blots of amplification products from Neospora DNA but not to Southern blots with amplified DNA from the other coccidian parasites tested. A Toxoplasma-specific probe whose sequence differed from that of the probe for Neospora spp. by a single base pair was used to distinguish these parasites by specific Southern blot hybridization. The PCR system detected as few as one Neospora tachyzoite in the culture medium or five tachyzoites in samples of whole blood or amniotic fluid spiked with Neospora parasites. In addition, Neospora PCR products were successfully amplified from whole blood and amniotic fluid samples of experimentally infected bovine and rhesus macaque fetuses. These results indicate that this PCR and probe hybridization system could be a valuable adjunct to serology and immunohistochemistry for the diagnosis of Neospora infections in bovine or primate fetuses.

Abortion, Veterinary↗
PubMed1997

Evidence of vertical transmission of Neospora sp infection in dairy cattle.

OBJECTIVE: To determine whether heifers with naturally acquired congenital exposure to Neospora sp would transmit the infection to their offspring during gestation. DESIGN: Prospective cohort study. ANIMALS: Neonatal heifers on a dairy with a history of Neospora sp infections were selected for the study on the basis of their serum titers to Neospora sp, as determined by the use of indirect fluorescent antibody testing. Seropositive heifers (n = 25) had titers > or = 1:5,120 and seronegative heifers (25) had titers < or = 1:80. All heifers were raised and bred on the dairy, and samples were obtained from heifers and their calves at the time of calving. PROCEDURE: Blood samples were tested for Neospora sp antibodies. Histologic evaluations, Neospora sp immunohistochemical examinations, and protozoal culturing were performed on samples obtained from selected offspring (second-generation calves). RESULTS: Seropositive heifers gave birth to calves with titers > or = 1:1,280 to Neospora sp. All offspring from seropositive heifers that were necropsied had evidence of Neospora sp infection. All seronegative heifers and their offspring had titers < 1:80 to Neospora sp. CLINICAL IMPLICATIONS: Congenitally acquired Neospora sp infection can persist in clinically normal heifers and be transmitted transplacentally to their offspring. Vertical transmission can be a way by which neosporosis is maintained in herds.

Animals↗
PubMed2002

Pattern of recognition of Neospora caninum tachyzoite antigens by naturally infected pregnant cattle and aborted foetuses.

Different aspects of Neospora tachyzoite antigen recognition by Neospora-infected heifers and cows and aborted foetuses were studied. The pattern of antigen recognition and the relationship between IFAT titres and number of Neospora antigens detected, were evaluated. In addition, the tachyzoite antigens involved in the humoral immune response developed against infection in normal cows and cows that aborted were also characterised throughout pregnancy. Comparison of tachyzoite antigen recognition was carried out in 13 thoracic and/or abdominal fluids from Neospora aborted foetuses and 33 sera from Neospora infected cows that had aborted. The kinetics of Neospora-antigen recognition was studied in Neospora-infected heifers and cows that had aborted foetuses (7) or not (14) during pregnancy. Based on the frequency and intensity of recognition, four IDAs-17-18, 34-35, 37 and 60-62kDa antigens-have been described. Moreover, a correlation was found between Western blot results and IFAT titres in both age groups. In relation to antigen recognition throughout pregnancy by seropositive cows that had aborted or not, the antibody fluctuations throughout pregnancy described in the literature could be due to differences in the intensity and frequency of recognition of particular antigens, especially the 17-18kDa antigen. We emphasize the important role that the 17-18kDa antigen could play in the serological diagnosis of Neospora infection in cattle as this was intensely detected in 100% of the animals.

Aborted Fetus↗