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Gereon Schares - One of the best experts on this subject based on the ideXlab platform.
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Hammondia heydorni: Oocyst shedding by dogs fed in vitro generated tissue cysts, and evaluation of cross-immunity between H. heydorni and Neospora caninum in mice.
Veterinary parasitology, 2017Co-Authors: I.d.s. Meneses, Gereon Schares, M.m. Rezende-gondim, G.s. Galvão, Luis Fernando Pita GondimAbstract:Abstract Hammondia heydorni is a coccidian parasite believed to be nonpathogenic for naturally-infected animals, but it is biologically and genetically related to Neospora caninum, a worldwide cause of abortion in cattle. The major aim of the present work was to determine whether dogs shed H. heydorni oocysts after consuming in vitro generated tissue cysts of the parasite. In addition, we investigated cross-immunity between H. heydorni and N. caninum in mice. Two dogs were fed cultured cells containing tissue cysts of H. heydorni mixed with canned dog food, and a third dog (negative control) received only non-infected cells mixed with canned food. The two dogs that consumed in vitro produced tissue cysts shed high numbers of oocysts, which were induced to sporulate and tested positive for H. heydorni by a species-specific PCR. The third uninfected dog did not shed H. heydorni oocysts in the feces. Oocysts shed by the dogs induced the formation of encysted bradyzoites of H. heydorni on KH-R cells. Nineteen BALB/c mice were employed in the cross-immunity study. Nine mice were orally inoculated with 1 × 105 sporulated oocysts of H. heydorni and challenged with N. caninum tachyzoites 30 days after infection with H. heydorni. Other ten mice, which did not receive H. heydorni oocysts, were infected with 2 × 105 N. caninum tachyzoites. Thirty days after challenging with N. caninum, all mice were euthanized and N. caninum DNA in their tissues was quantified by real time PCR. No statistically significant difference in N. caninum DNA concentrations were observed between the two groups. We concluded that in vitro generated cysts of H. heydorni are biologically active, because they induced oocyst shedding in dogs. As no cross-protection occurred in mice inoculated with H. heydorni and challenged with N. caninum, it is suspected that these parasites do not express significant numbers of homologous proteins during infection, or the immune response of BALB/c mice after H. heydorni infection was not sufficient.
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in vitro cultivation of Hammondia heydorni generation of tachyzoites stage conversion into bradyzoites and evaluation of serologic cross reaction with neospora caninum
Veterinary Parasitology, 2015Co-Authors: Luis Fernando Pita Gondim, Majda Globokar Vrhovec, Nikola Pantchev, C Bauer, Franz Josef Conraths, J Meyer, Martin Peters, M M Rezendegondim, Gereon ScharesAbstract:Abstract Hammondia heydorni was in vitro isolated from oocysts shed by three dogs using a finite cell line from embryonal bovine heart (KH-R). The oocysts were purified and suspended in 2% potassium dichromate or 2% sulphuric acid for sporulation for 2–5 days at room temperature. The parasites were confirmed as H. heydorni by PCR using specific primers (JS4/JS5) and by negative reaction for Neospora caninum employing the primers Np6+/Np21+. H. heydorni sporulated oocysts (1 × 10 6 ) from each dog were initially treated with sodium hypochlorite. For excystation of sporozoites, oocysts from one dog were lysed by ultrasound followed by incubation with 0.75% taurocholate. Excystation of sporozoites from the other two dogs was achieved by oocyst fragmentation with glass beads with no further chemical treatment. Tachyzoites were clearly seen in the cultures at three days post inoculation (dpi). Bradyzoite conversion and cyst formation were evaluated at different time points by using a polyclonal rabbit serum against a bradyzoite-specific antigen (anti-BAG1), and a rat monoclonal antibody (mAbCC2) against a cyst wall protein. Bradyzoites were firstly detected at 7 dpi. Between 18 and 21 dpi most of cultured parasites consisted of encysted bradyzoites. The H. heydorni cysts increased in size during cultivation and reached a length of up to 135 μm. The parasite was maintained in the bovine heart cells up to 4.5 months. Sera from mice and sheep experimentally infected with H. heydorni oocysts reacted with H. heydorni by IFAT, but did not cross-react with N. caninum antigens using IFAT or immunoblot. These findings suggest that serological cross-reactivity between H. heydorni and N. caninum seems to be of minor importance.
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quantitative real time polymerase chain reaction assays for the sensitive detection of besnoitia besnoiti infection in cattle
Veterinary Parasitology, 2011Co-Authors: Gereon Schares, Aline Maksimov, Gaston More, Ana Rostaher, M Majzoub, Benjamin M Rosenthal, Walter Basso, J P Dubey, Josef SelmairAbstract:Bovine besnoitiosis, an economically important disease in cattle in some countries of Africa and Asia, is emerging in Europe. The definitive host of Besnoitia besnoiti, the causative agent of bovine besnoitiosis, is unknown and the transmission of the parasite is not completely understood. Sensitive and quantitative DNA detection methods are needed to determine whether serologically positive animals are infectious and to examine the role of vectors (e.g. haematophagous insects) in the transmission of the parasite. To this end, we established two different 5'-nuclease quantitative assays to detect B. besnoiti infection in cattle and to estimate the parasite load in samples (BbRT1 and BbRT2). These PCRs are based on the sequence of the internal transcribed spacer region 1 (ITS-1) of the ribosomal RNA gene. Tests with serial dilutions of B. besnoiti genomic DNA in a buffer containing 100 ng/µl bovine DNA revealed a detection limit of 0.01 pg genomic B. besnoiti DNA. Reliable quantification was possible in samples containing =1 pg B. besnoiti genomic DNA with a coefficient of variation of =2%. To estimate the diagnostic sensitivity of the tests, skin biopsies and scrapings from the mucous membrane of the vestibulum vaginae (vaginal scrapings) were taken from cattle with clinical signs of chronic besnoitiosis. Regardless of the real time PCR assay used, 90.7% (39/43) of these animals were positive in at least one of two samples (skin or vaginal scrapings). Antibody titers, as determined by an immunofluorescent antibody test, and the threshold cycle values of the real time PCR obtained for skin samples and vaginal scrapings, were significantly correlated. The specificity of the PCRs was confirmed using genomic DNA from related parasites, including genomic DNA of Besnoitia spp., Neospora caninum, Toxoplasma gondii, Hammondia hammondi, Hammondia heydorni, Isospora spp., Sarcocystis spp., Eimeria bovis, Cryptosporidium parvum, and Trypanosoma brucei brucei. Since the sequence of the ITS-1 region of B. besnoiti is identical with that of Besnoitia species isolated from donkeys (Besnoitia bennetti), and reindeer (Besnoitia tarandi), both real time PCRs detected also DNA of these parasites. One of the B. besnoiti real time PCRs, BbRT1, but not BbRT2, cross-reacted with Besnoitia darlingi, Besnoitia oryctofelisi, and Besnoitia neotomofelis when large amounts of genomic DNA (10 ng) were used. The other B. besnoiti real time PCR assay (BbRT2) was specific for B. besnoiti, B. bennetti and B. tarandi, but did not react when 10 ng DNA of other related parasite species from the genus Besnoitia or other genera were subjected to analysis.
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Occurrence of Toxoplasma gondii and Hammondia hammondi oocysts in the faeces of cats from Germany and other European countries
Veterinary Parasitology, 2007Co-Authors: Gereon Schares, Majda Globokar Vrhovec, Nikola Pantchev, Daland Herrmann, Franz Josef ConrathsAbstract:Faecal samples of 24,106 cats from Germany and other European countries were examined microscopically in a veterinary laboratory in Germany between October 2004 and November 2006 to estimate the prevalence of animals shedding Toxoplasma gondii or Hammondia hammondi oocysts. Oocysts of 9-15 mu m size with a morphology similar to that of H. hammondi and T. gondii were found in 74 samples (0.31%). A total of 54 samples were further characterised to achieve a species diagnosis and to determine the genotype of T. gondii isolates by PCR and PCR-RFLP. From these samples, 48 isolates were obtained: 26 (0.11%) were finally identified as T. gondii and 22 (0.09%) as H. hammondi. T. gondii-positive samples came from Germany, Austria, France and Switzerland while H. hammondi was detected in samples from Germany, Austria and Italy. In two samples (one T. gondii and one H. hammondi), PCR indicated the presence of Hammondia heydorni DNA. No Neospora caninum DNA was detected in any of the feline faecal samples. Twenty-two of the 26 T. gondii isolates could be genotyped. A PCR-RFLP analysis for the SAG2, SAG3, GRA6 and BTUB genes revealed T. gondii genotype II in all cases. Morphologically, H. hammondi oocysts exhibited a statistically significantly smaller Length-Width-Ratio than T. gondii oocysts. (C) 2007 Elsevier B.V. All rights reserved
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Incidence of Neospora caninum and other intestinal protozoan parasites in populations of Swiss dogs.
Veterinary Parasitology, 2006Co-Authors: Heinz Sager, Gereon Schares, C. Steiner Moret, Norbert Müller, Daniela Staubli, M. Esposito, Michael Hässig, Katharina D.c. Stärk, Bruno GottsteinAbstract:The protozoan parasite Neospora caninum is one of the most important abortifacient organisms in cattle worldwide. The dog is known to act as definitive host although its potential role as infection source for bovines still remains unelucidated. The aim of the present study was to compile initial epidemiological data on the prevalence and incidence of N. caninum in Swiss dogs acting as definitive hosts. Thus, 249 Swiss dogs were investigated coproscopically in monthly intervals over a period of 1 year. A total of 3289 fecal samples was tested by the flotation technique. Among these, 202 were shown to contain Sarcocystis sp. (6.1%), 149 Cystoisospora sp. (=Isospora sp.; 4.5%) and 25 Hammondia/Neospora-like oocysts (HNlO) (0.7%). All but one sample containing HNlO were from different dogs; one dog shed HNlO at two subsequent time points. Calculation of the yearly incidence for HNlO resulted in the surprisingly high value of 9.2%. Farm dogs exhibited a higher incidence for HNlO than urban family dogs. Thirteen out of the 25 HNlO-samples showed sporulation after 5 days incubation at room temperature. HNlO were further differentiated by species-specific PCR. However, all HNlO-samples were negative for N. caninum, Hammondia heydorni and Toxoplasma gondii. One reason may be the low oocyst density found in most fecal samples, which did not permit us to carry out PCR under optimal conditions. Three out of the 25 HNlO-cases contained enough oocysts to allow further enrichment and purification by the flotation technique. Subsequently, twenty to fifty sporulated HNlO-oocysts were orally administered to Meriones unguiculatus. All gerbils were seronegative for N. caninum at 5 weeks p.i. A N. caninum-seroprevalence of 7.8% was determined by ELISA upon 1132 serum samples collected from dogs randomly selected by veterinarians among their clinical patients.
Luis Fernando Pita Gondim - One of the best experts on this subject based on the ideXlab platform.
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Hammondia heydorni: Oocyst shedding by dogs fed in vitro generated tissue cysts, and evaluation of cross-immunity between H. heydorni and Neospora caninum in mice.
Veterinary parasitology, 2017Co-Authors: I.d.s. Meneses, Gereon Schares, M.m. Rezende-gondim, G.s. Galvão, Luis Fernando Pita GondimAbstract:Abstract Hammondia heydorni is a coccidian parasite believed to be nonpathogenic for naturally-infected animals, but it is biologically and genetically related to Neospora caninum, a worldwide cause of abortion in cattle. The major aim of the present work was to determine whether dogs shed H. heydorni oocysts after consuming in vitro generated tissue cysts of the parasite. In addition, we investigated cross-immunity between H. heydorni and N. caninum in mice. Two dogs were fed cultured cells containing tissue cysts of H. heydorni mixed with canned dog food, and a third dog (negative control) received only non-infected cells mixed with canned food. The two dogs that consumed in vitro produced tissue cysts shed high numbers of oocysts, which were induced to sporulate and tested positive for H. heydorni by a species-specific PCR. The third uninfected dog did not shed H. heydorni oocysts in the feces. Oocysts shed by the dogs induced the formation of encysted bradyzoites of H. heydorni on KH-R cells. Nineteen BALB/c mice were employed in the cross-immunity study. Nine mice were orally inoculated with 1 × 105 sporulated oocysts of H. heydorni and challenged with N. caninum tachyzoites 30 days after infection with H. heydorni. Other ten mice, which did not receive H. heydorni oocysts, were infected with 2 × 105 N. caninum tachyzoites. Thirty days after challenging with N. caninum, all mice were euthanized and N. caninum DNA in their tissues was quantified by real time PCR. No statistically significant difference in N. caninum DNA concentrations were observed between the two groups. We concluded that in vitro generated cysts of H. heydorni are biologically active, because they induced oocyst shedding in dogs. As no cross-protection occurred in mice inoculated with H. heydorni and challenged with N. caninum, it is suspected that these parasites do not express significant numbers of homologous proteins during infection, or the immune response of BALB/c mice after H. heydorni infection was not sufficient.
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characterization of an igg monoclonal antibody targeted to both tissue cyst and sporocyst walls of toxoplasma gondii
Experimental Parasitology, 2016Co-Authors: Luis Fernando Pita Gondim, J P Dubey, Alexander Wolf, Majda Globokar Vrhovec, Nikola Pantchev, C Bauer, M C Langenmayer, Wolfgang Bohne, Jens Peter Teifke, Franz Josef ConrathsAbstract:Toxoplasma gondii infects animals habiting terrestrial and aquatic environments. Its oocysts and tissue cysts are important for the horizontal transmission of this parasite. The oocyst and tissue cyst walls are crucial for the ability of the parasite to persist in the environment or in animal tissues, respectively. However, the composition of these walls is not well understood. We report the generation of monoclonal antibodies directed against wall components using mice immunized with oocyst antigens of T. gondii. One monoclonal antibody (mAb) G1/19 reacted solely with T. gondii sporozoites. The respective antigen had a relative molecular weight (Mr) of 30 kDa. MAb G1/19 failed to react with sporozoites of any other coccidian parasite species tested (Hammondia hammondi, Hammondia heydorni, Cystoisospora felis, Eimeria bovis, Sarcocystis sp.). Another mAb, designated K8/15-15, recognized antigens in sporocyst walls of the parasite and in the walls of in vivo or in vitro produced tissue cysts, as demonstrated by immunofluorescence and immunoblot assays. Antigens of 80 to a high molecular weight protein of about 350 kDa Mr were recognized by this antibody using antigen extracts from sporocysts, and from in vitro or in vivo generated tissue cysts of the parasite. Tissue cyst and sporocyst walls of H. hammondi and H. heydorni, and tissue cysts of Neospora caninum were also recognized by mAb K8/15-15. Sporocyst walls of C. felis also reacted to this mAb. The cyst walls of Sarcocystis sp. and Besnoitia besnoiti were not recognized by mAb K8/15-15. Reactivity by a single mAb against T. gondii antigens in tissue cysts and sporocysts had not been reported previously. MAb K8/15-15 may be a practical tool for the identification of both cysts and sporocysts of the parasite, and may also be potentially employed in proteomic studies on the identification of new components of the cyst and sporocyst walls of T. gondii.
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in vitro cultivation of Hammondia heydorni generation of tachyzoites stage conversion into bradyzoites and evaluation of serologic cross reaction with neospora caninum
Veterinary Parasitology, 2015Co-Authors: Luis Fernando Pita Gondim, Majda Globokar Vrhovec, Nikola Pantchev, C Bauer, Franz Josef Conraths, J Meyer, Martin Peters, M M Rezendegondim, Gereon ScharesAbstract:Abstract Hammondia heydorni was in vitro isolated from oocysts shed by three dogs using a finite cell line from embryonal bovine heart (KH-R). The oocysts were purified and suspended in 2% potassium dichromate or 2% sulphuric acid for sporulation for 2–5 days at room temperature. The parasites were confirmed as H. heydorni by PCR using specific primers (JS4/JS5) and by negative reaction for Neospora caninum employing the primers Np6+/Np21+. H. heydorni sporulated oocysts (1 × 10 6 ) from each dog were initially treated with sodium hypochlorite. For excystation of sporozoites, oocysts from one dog were lysed by ultrasound followed by incubation with 0.75% taurocholate. Excystation of sporozoites from the other two dogs was achieved by oocyst fragmentation with glass beads with no further chemical treatment. Tachyzoites were clearly seen in the cultures at three days post inoculation (dpi). Bradyzoite conversion and cyst formation were evaluated at different time points by using a polyclonal rabbit serum against a bradyzoite-specific antigen (anti-BAG1), and a rat monoclonal antibody (mAbCC2) against a cyst wall protein. Bradyzoites were firstly detected at 7 dpi. Between 18 and 21 dpi most of cultured parasites consisted of encysted bradyzoites. The H. heydorni cysts increased in size during cultivation and reached a length of up to 135 μm. The parasite was maintained in the bovine heart cells up to 4.5 months. Sera from mice and sheep experimentally infected with H. heydorni oocysts reacted with H. heydorni by IFAT, but did not cross-react with N. caninum antigens using IFAT or immunoblot. These findings suggest that serological cross-reactivity between H. heydorni and N. caninum seems to be of minor importance.
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Investigation of Neospora caninum, Hammondia sp., and Toxoplasma gondii in tissues from slaughtered beef cattle in Bahia, Brazil
Parasitology Research, 2009Co-Authors: Sara Lima Santos, Mariana S A Silva, Kattyanne De Souza Costa, Rosângela Soares Uzeda, Luis Fernando Pita Gondim, Kiyoko Abe-sandesAbstract:Neospora caninum , Hammondia sp., and Toxoplasma gondii are parasites with morphological and genetic similarities. N. caninum and T. gondii are important abortive agents of cattle and sheep, respectively, and may infect numerous animal species. Hammondia sp. is not known to induce disease in animals, but may cause confusion in the identification of closely related coccidia. The aim of this study was to investigate infection rates caused by N. caninum , Hammondia sp., and T. gondii in beef cattle using a nested PCR for Toxoplasmatinae rDNA, followed by sequencing of the PCR products. Antibodies to N. caninum and T. gondii were also investigated in the tested animals. Brains and hearts were obtained from 100 beef cattle in a slaughterhouse in Bahia. Seven samples from brain tested positive for Toxoplasmatinae DNA. No positive reactions were found in heart tissues. After sequencing of the PCR products from all positive tissues, five sequences matched with N. caninum and two matched with T. gondii. Antibodies to N. caninum and T. gondii were found in 20% and 26% of the animals, respectively. The confirmation of N. caninum and the absence of Hammondia heydorni in the tested animals is suggestive that cattle are not efficient intermediate hosts of H. heydorni ; however further studies need to be performed using a greater variety of tissues and a higher sample size. The detection of T. gondii DNA in bovine tissues reinforces the potential risk of transmission of this parasite to humans and other animals through the consumption of bovine meat.
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detection of Hammondia heydorni and related coccidia neospora caninum and toxoplasma gondii in goats slaughtered in bahia brazil
Veterinary Parasitology, 2009Co-Authors: Mariana S A Silva, Kattyanne De Souza Costa, Sara Lima Santos, Alan C C Macedo, Kiyoko Abesandes, Rosângela Soares Uzeda, Luis Fernando Pita GondimAbstract:Hammondia heydorni is a coccidian parasite with an obligatory two host life cycle, with dogs and foxes as definitive hosts, and a number of intermediate hosts, including goats. While infection by this parasite seems to be unassociated with any clinical signs, infection by the closely related parasites Neospora caninum and Toxoplasma gondii can result in abortion, stillbirths and low yielding in caprine herds. The aim of this work was to investigate the frequency of goats infected with H. heydorni using a nested PCR, specific to Toxoplasmatinae internal transcribed spacer 1 (ITS1) of the rDNA, followed by sequencing of the purified PCR fragments. The same molecular techniques were used to determine the frequencies of N. caninum and T. gondii-infected animals. A total frequency of 13.72% (14/102) was obtained for Toxoplasmatinae DNA in goat tissues. After sequencing the PCR products from all positive tissues, a frequency of 3.92% (4/102), 1.96% (2/102) and 7.84% (8/102) were obtained for H. heydorni, N. caninum and T. gondii, respectively. All sequences shared 98–100% identity with sequences from other strains of these coccidia present in GenBank. To the authors’ knowledge, this is the first report of H. heydorni DNA in tissues from naturally infected intermediate hosts.
Alfred Otto Heydorn - One of the best experts on this subject based on the ideXlab platform.
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oocysts of neospora caninum Hammondia heydorni toxoplasma gondii and Hammondia hammondi in faeces collected from dogs in germany
International Journal for Parasitology, 2005Co-Authors: Gereon Schares, Alfred Otto Heydorn, Nikola Pantchev, C Bauer, D Barutzki, Franz Josef ConrathsAbstract:Abstract Faecal samples of 24,089 dogs were examined coproscopically in two veterinary laboratories in Germany between March 2001 and October 2004. In 47 dogs, oocysts of 9–14 μm size were found. Their morphology was similar to those of Hammondia heydorni and Neospora caninum. Samples of 28 of these dogs were further examined by inoculation into gerbils: seven isolates induced a specific antibody response against antigens of N. caninum NC-1 tachyzoites. This response suggests that the isolates contained N. caninum. In addition to H. heydorni (12 times isolated), Toxoplasma gondii occysts (twice) and Hammondia hammondi oocysts (twice) were observed in dog faeces. The latter findings suggest that coprophagia with a subsequent intestinal passage by dogs plays a role in the dissemination of coccidian parasites for which cats are definitive hosts. Five of the seven N. caninum (NC-GER2, NC-GER3, NC-GER4, NC-GER5, NC-GER6) and the two T. gondii isolates (TG-dgGER1, TG-dgGER2) were successfully passaged into cell culture and are now available for detailed characterization. In contrast to oocysts of other parasites, N. caninum oocysts were predominantly found between January and April (Fisher exact; P=0.038). In the sera of dogs shedding N. caninum, no reactions against the immunodominant antigens with apparent molecular weights of 19, 29, 30, 33 and 37 kDa of N. caninum tachyzoites were observed 3–5 weeks after shedding. However, the animals recognized a 152-kDa N. caninum antigen. Compared with those identified as H. heydorni, T. gondii or H. hammondi, N. caninum oocyst isolates were significantly smaller in length with the 75th percentiles ≤10.7 μm when measured in concentrated sucrose solution and smaller length–width ratios with the 75th percentiles ≤1.06. It may thus be possible to develop criteria for a preliminary identification of N. caninum in dog faeces based on the oocyst morphology.
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Effects of toltrazuril and ponazuril on the fine structure and multiplication of tachyzoites of the NC-1 strain of Neospora caninum (a synonym of Hammondia heydorni) in cell cultures
Parasitology Research, 2004Co-Authors: Anne Kathrin Darius, Heinz Mehlhorn, Alfred Otto HeydornAbstract:Rhesus monkey kidney cell cultures were used to propagate tachyzoites of the NC-1 strain of Neospora caninum (syn . Hammondia heydorni ). The infected cell cultures were incubated for 4–12 h in media containing 0, 1, 10 or 100 µg/ml of either toltrazuril or ponazuril. The effects were studied by light and electron microscopy. Drug dosages of at least 30 µg/ml were needed to eliminate the parasites. Ponazuril was found (with respect to the reduction of the number of parasites) to be less effective at dosages of 30 µg/ml compared to toltrazuril. However, the damage to the tachyzoites being incubated in 30 µg toltrazuril or ponazuril seen by electron microscopy was so significant that it was surely lethal. The initial damage occurred within the apicoplast and the tubular mitochondrion in all cases,thus destroying two of the most important cell organelles.
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effects of toltrazuril and ponazuril on Hammondia heydorni syn neospora caninum infections in mice
Parasitology Research, 2004Co-Authors: Anne Kathrin Darius, Heinz Mehlhorn, Alfred Otto HeydornAbstract:Mice infected with tachyzoites of Neospora caninum (syn.: Hammondia heydorni) must be pretreated with cortisone in order to show disease symptoms. This indicates the status of an opportunistic agent of disease. Toltrazuril was an effective curative agent.
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A re-evaluation of Neospora and Hammondia spp.
Trends in Parasitology, 2002Co-Authors: Alfred Otto Heydorn, Heinz MehlhornAbstract:With respect to a recent article by J.P. Dubey et al. [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1], we recommend the content of our recent article [2xNeospora caninum is an invalid species name: an evaluation of facts and statements. Heydorn, A.O. and Mehlhorn, H. Parasitol. Res. 2002; 88: 175–184Crossref | PubMed | Scopus (21)See all References[2], wherein we show by citations from Dubey's original descriptions [3xNewly recognized fatal protozoan disease of dogs. Dubey, J.P. et al. J. Am. Vet. Med. Assoc. 1988; 192: 1269–1285PubMedSee all References[3] that, from the start of the Neospora story, the basic rules of the Code of Zoological Nomenclature have been violated. This is not only Dubey et al.'s error, but also that of the editors of J. Am. Vet. Med. Assoc., who accepted the launch of the new genus and a new species based on a single criterion: the presence or absence of a parasitophorous vacuole. Dubey, himself, however, subsequently described the existence of a parasitophorous vacuole in both genera. Now Dubey et al. [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1] repeat a nomenclatural mistake. They took one or several oocysts of the established ‘small Isospora bigemina’, such as the coccidian species of dogs, and claim that this material is Hammondia heydorni, although they have no further life cycle stages than oocysts.Furthermore, the claimed (but not done) oral transmission of ‘Neospora-material’ to dogs postponed the elucidation of the life cycle of this coccidian parasite for nearly 10 years (established by McAllister et al. [4xDogs are definitive hosts of Neospora caninum. McAllister, M. et al. Int. J. Parasitol. 1998; 28: 1473–1478Crossref | PubMed | Scopus (731)See all References[4]) that is thought to cause high economic losses in cattle breeding. In addition, the differences seen in PCR when using a single random primer are not necessarily genus- or species-specific [e.g. when using the random primer R74, we found larger differences among eight isolates of the same species (the cat flea) did Dubey et al. between Hammondia and Neospora]. Figure 2 in Ref. [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1] also showed larger differences between N. caninum and Neospora hughesi than between N. caninum and Hammondia.Finally, we criticize in Dubey et al.'s paper [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1] the incorrect quotation of the relevant literature (e.g. Refs [5.xStudies on the life cycle of the small race of Isospora bigemina of the dog. I. Cattle and dog as possible intermediate hosts. Heydorn, A.O. Berl. Munch. Tieraztl. Wschr. 1973; 86: 323–329PubMedSee all References, 6.xDevelopment of Isospora bigemina in dogs and other mammals. Dubey, J.P. and Fayer, R. Parasitology. 1976; 73: 371–380Crossref | PubMed | Scopus (26)See all References, 7.xThe roe deer intermediate host of different coccidia. Entzeroth, R. et al. Naturwissenschaften. 1978; 65: 395–396Crossref | PubMed | Scopus (18)See all References, 8.xShedding of Hammondia heydorni-like oocysts by foxes fed muscular tissue of reindeer (Rangifer tarandus). Gjerde, B. Acta Vet. Scand. 1983; 24: 241–243PubMedSee all References, 9.xThe fox, Vulpes vulpes, as a final host for Sarcocystis of sheep. Ashford, R.W. Ann. Trop. Med. Parasitol. 1977; 71: 29–34PubMedSee all References]).
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Neospora caninum: is it really different from Hammondia heydorni or is it a strain of Toxoplasma gondii? An opinion.
Parasitology research, 2000Co-Authors: Heinz Mehlhorn, Alfred Otto HeydornAbstract:The published data concerning Toxoplasma gondii, Hammondia hammondi, H. heydorni and Neospora caninum on one side and between T. gondii on the other were neglected by most authors. As conclusion we are convinced that there are only two valid species: Isospora (Toxoplasma) gondii and Hammondia heydorni. The first includes as a strain H. hammondi and the latter N. caninum. In any case there is absolutely no reason (with respect to general Zoological nomenclature) to create new genera!
Heinz Mehlhorn - One of the best experts on this subject based on the ideXlab platform.
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Effects of toltrazuril and ponazuril on the fine structure and multiplication of tachyzoites of the NC-1 strain of Neospora caninum (a synonym of Hammondia heydorni) in cell cultures
Parasitology Research, 2004Co-Authors: Anne Kathrin Darius, Heinz Mehlhorn, Alfred Otto HeydornAbstract:Rhesus monkey kidney cell cultures were used to propagate tachyzoites of the NC-1 strain of Neospora caninum (syn . Hammondia heydorni ). The infected cell cultures were incubated for 4–12 h in media containing 0, 1, 10 or 100 µg/ml of either toltrazuril or ponazuril. The effects were studied by light and electron microscopy. Drug dosages of at least 30 µg/ml were needed to eliminate the parasites. Ponazuril was found (with respect to the reduction of the number of parasites) to be less effective at dosages of 30 µg/ml compared to toltrazuril. However, the damage to the tachyzoites being incubated in 30 µg toltrazuril or ponazuril seen by electron microscopy was so significant that it was surely lethal. The initial damage occurred within the apicoplast and the tubular mitochondrion in all cases,thus destroying two of the most important cell organelles.
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effects of toltrazuril and ponazuril on Hammondia heydorni syn neospora caninum infections in mice
Parasitology Research, 2004Co-Authors: Anne Kathrin Darius, Heinz Mehlhorn, Alfred Otto HeydornAbstract:Mice infected with tachyzoites of Neospora caninum (syn.: Hammondia heydorni) must be pretreated with cortisone in order to show disease symptoms. This indicates the status of an opportunistic agent of disease. Toltrazuril was an effective curative agent.
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A re-evaluation of Neospora and Hammondia spp.
Trends in Parasitology, 2002Co-Authors: Alfred Otto Heydorn, Heinz MehlhornAbstract:With respect to a recent article by J.P. Dubey et al. [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1], we recommend the content of our recent article [2xNeospora caninum is an invalid species name: an evaluation of facts and statements. Heydorn, A.O. and Mehlhorn, H. Parasitol. Res. 2002; 88: 175–184Crossref | PubMed | Scopus (21)See all References[2], wherein we show by citations from Dubey's original descriptions [3xNewly recognized fatal protozoan disease of dogs. Dubey, J.P. et al. J. Am. Vet. Med. Assoc. 1988; 192: 1269–1285PubMedSee all References[3] that, from the start of the Neospora story, the basic rules of the Code of Zoological Nomenclature have been violated. This is not only Dubey et al.'s error, but also that of the editors of J. Am. Vet. Med. Assoc., who accepted the launch of the new genus and a new species based on a single criterion: the presence or absence of a parasitophorous vacuole. Dubey, himself, however, subsequently described the existence of a parasitophorous vacuole in both genera. Now Dubey et al. [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1] repeat a nomenclatural mistake. They took one or several oocysts of the established ‘small Isospora bigemina’, such as the coccidian species of dogs, and claim that this material is Hammondia heydorni, although they have no further life cycle stages than oocysts.Furthermore, the claimed (but not done) oral transmission of ‘Neospora-material’ to dogs postponed the elucidation of the life cycle of this coccidian parasite for nearly 10 years (established by McAllister et al. [4xDogs are definitive hosts of Neospora caninum. McAllister, M. et al. Int. J. Parasitol. 1998; 28: 1473–1478Crossref | PubMed | Scopus (731)See all References[4]) that is thought to cause high economic losses in cattle breeding. In addition, the differences seen in PCR when using a single random primer are not necessarily genus- or species-specific [e.g. when using the random primer R74, we found larger differences among eight isolates of the same species (the cat flea) did Dubey et al. between Hammondia and Neospora]. Figure 2 in Ref. [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1] also showed larger differences between N. caninum and Neospora hughesi than between N. caninum and Hammondia.Finally, we criticize in Dubey et al.'s paper [1xNeospora caninum and Hammondia heydorni are separate species. Dubey, J.P. et al. Trends Parasitol. 2002; 18: 66–69Abstract | Full Text | Full Text PDF | PubMed | Scopus (23)See all References[1] the incorrect quotation of the relevant literature (e.g. Refs [5.xStudies on the life cycle of the small race of Isospora bigemina of the dog. I. Cattle and dog as possible intermediate hosts. Heydorn, A.O. Berl. Munch. Tieraztl. Wschr. 1973; 86: 323–329PubMedSee all References, 6.xDevelopment of Isospora bigemina in dogs and other mammals. Dubey, J.P. and Fayer, R. Parasitology. 1976; 73: 371–380Crossref | PubMed | Scopus (26)See all References, 7.xThe roe deer intermediate host of different coccidia. Entzeroth, R. et al. Naturwissenschaften. 1978; 65: 395–396Crossref | PubMed | Scopus (18)See all References, 8.xShedding of Hammondia heydorni-like oocysts by foxes fed muscular tissue of reindeer (Rangifer tarandus). Gjerde, B. Acta Vet. Scand. 1983; 24: 241–243PubMedSee all References, 9.xThe fox, Vulpes vulpes, as a final host for Sarcocystis of sheep. Ashford, R.W. Ann. Trop. Med. Parasitol. 1977; 71: 29–34PubMedSee all References]).
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Neospora caninum is an invalid species name: an evaluation of facts and statements
Parasitology Research, 2002Co-Authors: Alfred Heydorn, Heinz MehlhornAbstract:An evaluation of both the formal requirements of the International Rules of Zoological Nomenclature and the scientific reasons for the description of new genera and species shows that the name Neospora caninum is a nomen nudum . The only characteristic criteria for discriminating between the previously described species Hammondia heydorni and the proposed new species N. caninum (i.e. the lack of a parasitophorous vacuole) has been shown to be wrong in many publications. Furthermore, absolutely no criteria were presented as to why a new genus (i.e. Neospora ) should be established besides the already existing genera Hammondia , Toxoplasma and Isospora . In addition, recent transmission experiments show that an oocyst isolate (from the faeces of dogs) is morphologically indistinguishable from H. heydorni [synonymous with Isospora bigemina – small form, Isospora heydorni (Tadros and Laarman 1976) and H. heydorni (Tadros and Laarman 1976) Dubey 1977] and is almost identical with respect to molecular biological features with the NC-1 strain of N. caninum .
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Hammondia heydorni-like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished
Parasitology Research, 2001Co-Authors: Gereon Schares, Alfred Heydorn, Arnd Cüppers, Franz Conraths, Heinz MehlhornAbstract:This study describes transmission experiments using Hammondia heydorni -like oocysts isolated in 1996 from a naturally infected dog. The isolate was designated as H. heydorni -Berlin-1996. Examination of sera from infected intermediate hosts showed immunoblot reactions that resembled patterns observed after Neospora caninum NC-1 infection. Furthermore, N. caninum DNA could be demonstrated in tissue samples (e.g. heart, brain) of experimentally infected intermediate hosts and in oocyst preparations from H. heydorni -Berlin-1996. The isolated oocysts did not induce any detectable disease in any of the inoculated adult intermediate hosts (goats, sheep, gerbils, guinea pigs, multimammate rats, BALB/c mice, SCID mice), even upon immunosuppression. Furthermore, neither histological lesions nor parasite stages could be identified in the tissues of all fetuses recovered from two multimammate rats that had been infected prior to pregnancy. An experiment with one dog fed a second time on infected intermediate host tissue indicated that immunity may prevent repeated oocyst shedding in N. caninum- infected dogs. In addition, the study clearly demonstrates that N. caninum can be readily transmitted by dogs that have ingested exclusively skeletal muscles of infected intermediate hosts. Therefore, the study has consequences for the recommendations for farmers to prevent postnatal transmission of N. caninum to cattle. It indicates that feeding of any tissues of potential intermediate hosts (including sheep, goats, rodents) to final hosts may induce the shedding of oocysts in these hosts and thus pose a risk for post-natal infection of cattle. With respect to oocyst morphology and the infectivity of muscle tissues for final hosts, no differences were seen in comparison with observations made in the past on Isospora bigemina / I. heydorni / H. heydorni . Therefore, earlier studies made on I. bigemina / I. heydorni / H. heydorni have to be re-evaluated critically to determine whether they may have included N. caninum or other protozoan parasites that use dogs as final hosts and have an oocyst morphology resembling that of I. bigemina / I. heydorni / H. heydorni .
Franz Josef Conraths - One of the best experts on this subject based on the ideXlab platform.
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characterization of an igg monoclonal antibody targeted to both tissue cyst and sporocyst walls of toxoplasma gondii
Experimental Parasitology, 2016Co-Authors: Luis Fernando Pita Gondim, J P Dubey, Alexander Wolf, Majda Globokar Vrhovec, Nikola Pantchev, C Bauer, M C Langenmayer, Wolfgang Bohne, Jens Peter Teifke, Franz Josef ConrathsAbstract:Toxoplasma gondii infects animals habiting terrestrial and aquatic environments. Its oocysts and tissue cysts are important for the horizontal transmission of this parasite. The oocyst and tissue cyst walls are crucial for the ability of the parasite to persist in the environment or in animal tissues, respectively. However, the composition of these walls is not well understood. We report the generation of monoclonal antibodies directed against wall components using mice immunized with oocyst antigens of T. gondii. One monoclonal antibody (mAb) G1/19 reacted solely with T. gondii sporozoites. The respective antigen had a relative molecular weight (Mr) of 30 kDa. MAb G1/19 failed to react with sporozoites of any other coccidian parasite species tested (Hammondia hammondi, Hammondia heydorni, Cystoisospora felis, Eimeria bovis, Sarcocystis sp.). Another mAb, designated K8/15-15, recognized antigens in sporocyst walls of the parasite and in the walls of in vivo or in vitro produced tissue cysts, as demonstrated by immunofluorescence and immunoblot assays. Antigens of 80 to a high molecular weight protein of about 350 kDa Mr were recognized by this antibody using antigen extracts from sporocysts, and from in vitro or in vivo generated tissue cysts of the parasite. Tissue cyst and sporocyst walls of H. hammondi and H. heydorni, and tissue cysts of Neospora caninum were also recognized by mAb K8/15-15. Sporocyst walls of C. felis also reacted to this mAb. The cyst walls of Sarcocystis sp. and Besnoitia besnoiti were not recognized by mAb K8/15-15. Reactivity by a single mAb against T. gondii antigens in tissue cysts and sporocysts had not been reported previously. MAb K8/15-15 may be a practical tool for the identification of both cysts and sporocysts of the parasite, and may also be potentially employed in proteomic studies on the identification of new components of the cyst and sporocyst walls of T. gondii.
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in vitro cultivation of Hammondia heydorni generation of tachyzoites stage conversion into bradyzoites and evaluation of serologic cross reaction with neospora caninum
Veterinary Parasitology, 2015Co-Authors: Luis Fernando Pita Gondim, Majda Globokar Vrhovec, Nikola Pantchev, C Bauer, Franz Josef Conraths, J Meyer, Martin Peters, M M Rezendegondim, Gereon ScharesAbstract:Abstract Hammondia heydorni was in vitro isolated from oocysts shed by three dogs using a finite cell line from embryonal bovine heart (KH-R). The oocysts were purified and suspended in 2% potassium dichromate or 2% sulphuric acid for sporulation for 2–5 days at room temperature. The parasites were confirmed as H. heydorni by PCR using specific primers (JS4/JS5) and by negative reaction for Neospora caninum employing the primers Np6+/Np21+. H. heydorni sporulated oocysts (1 × 10 6 ) from each dog were initially treated with sodium hypochlorite. For excystation of sporozoites, oocysts from one dog were lysed by ultrasound followed by incubation with 0.75% taurocholate. Excystation of sporozoites from the other two dogs was achieved by oocyst fragmentation with glass beads with no further chemical treatment. Tachyzoites were clearly seen in the cultures at three days post inoculation (dpi). Bradyzoite conversion and cyst formation were evaluated at different time points by using a polyclonal rabbit serum against a bradyzoite-specific antigen (anti-BAG1), and a rat monoclonal antibody (mAbCC2) against a cyst wall protein. Bradyzoites were firstly detected at 7 dpi. Between 18 and 21 dpi most of cultured parasites consisted of encysted bradyzoites. The H. heydorni cysts increased in size during cultivation and reached a length of up to 135 μm. The parasite was maintained in the bovine heart cells up to 4.5 months. Sera from mice and sheep experimentally infected with H. heydorni oocysts reacted with H. heydorni by IFAT, but did not cross-react with N. caninum antigens using IFAT or immunoblot. These findings suggest that serological cross-reactivity between H. heydorni and N. caninum seems to be of minor importance.
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Occurrence of Toxoplasma gondii and Hammondia hammondi oocysts in the faeces of cats from Germany and other European countries.
Veterinary parasitology, 2007Co-Authors: G. Schares, Majda Globokar Vrhovec, Nikola Pantchev, D C Herrmann, Franz Josef ConrathsAbstract:Faecal samples of 24,106 cats from Germany and other European countries were examined microscopically in a veterinary laboratory in Germany between October 2004 and November 2006 to estimate the prevalence of animals shedding Toxoplasma gondii or Hammondia hammondi oocysts. Oocysts of 9-15 microm size with a morphology similar to that of H. hammondi and T. gondii were found in 74 samples (0.31%). A total of 54 samples were further characterised to achieve a species diagnosis and to determine the genotype of T. gondii isolates by PCR and PCR-RFLP. From these samples, 48 isolates were obtained: 26 (0.11%) were finally identified as T. gondii and 22 (0.09%) as H. hammondi. T. gondii-positive samples came from Germany, Austria, France and Switzerland while H. hammondi was detected in samples from Germany, Austria and Italy. In two samples (one T. gondii and one H. hammondi), PCR indicated the presence of Hammondia heydorni DNA. No Neospora caninum DNA was detected in any of the feline faecal samples. Twenty-two of the 26 T. gondii isolates could be genotyped. A PCR-RFLP analysis for the SAG2, SAG3, GRA6 and BTUB genes revealed T. gondii genotype II in all cases. Morphologically, H. hammondi oocysts exhibited a statistically significantly smaller Length-Width-Ratio than T. gondii oocysts.
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Occurrence of Toxoplasma gondii and Hammondia hammondi oocysts in the faeces of cats from Germany and other European countries
Veterinary Parasitology, 2007Co-Authors: Gereon Schares, Majda Globokar Vrhovec, Nikola Pantchev, Daland Herrmann, Franz Josef ConrathsAbstract:Faecal samples of 24,106 cats from Germany and other European countries were examined microscopically in a veterinary laboratory in Germany between October 2004 and November 2006 to estimate the prevalence of animals shedding Toxoplasma gondii or Hammondia hammondi oocysts. Oocysts of 9-15 mu m size with a morphology similar to that of H. hammondi and T. gondii were found in 74 samples (0.31%). A total of 54 samples were further characterised to achieve a species diagnosis and to determine the genotype of T. gondii isolates by PCR and PCR-RFLP. From these samples, 48 isolates were obtained: 26 (0.11%) were finally identified as T. gondii and 22 (0.09%) as H. hammondi. T. gondii-positive samples came from Germany, Austria, France and Switzerland while H. hammondi was detected in samples from Germany, Austria and Italy. In two samples (one T. gondii and one H. hammondi), PCR indicated the presence of Hammondia heydorni DNA. No Neospora caninum DNA was detected in any of the feline faecal samples. Twenty-two of the 26 T. gondii isolates could be genotyped. A PCR-RFLP analysis for the SAG2, SAG3, GRA6 and BTUB genes revealed T. gondii genotype II in all cases. Morphologically, H. hammondi oocysts exhibited a statistically significantly smaller Length-Width-Ratio than T. gondii oocysts. (C) 2007 Elsevier B.V. All rights reserved
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oocysts of neospora caninum Hammondia heydorni toxoplasma gondii and Hammondia hammondi in faeces collected from dogs in germany
International Journal for Parasitology, 2005Co-Authors: Gereon Schares, Alfred Otto Heydorn, Nikola Pantchev, C Bauer, D Barutzki, Franz Josef ConrathsAbstract:Abstract Faecal samples of 24,089 dogs were examined coproscopically in two veterinary laboratories in Germany between March 2001 and October 2004. In 47 dogs, oocysts of 9–14 μm size were found. Their morphology was similar to those of Hammondia heydorni and Neospora caninum. Samples of 28 of these dogs were further examined by inoculation into gerbils: seven isolates induced a specific antibody response against antigens of N. caninum NC-1 tachyzoites. This response suggests that the isolates contained N. caninum. In addition to H. heydorni (12 times isolated), Toxoplasma gondii occysts (twice) and Hammondia hammondi oocysts (twice) were observed in dog faeces. The latter findings suggest that coprophagia with a subsequent intestinal passage by dogs plays a role in the dissemination of coccidian parasites for which cats are definitive hosts. Five of the seven N. caninum (NC-GER2, NC-GER3, NC-GER4, NC-GER5, NC-GER6) and the two T. gondii isolates (TG-dgGER1, TG-dgGER2) were successfully passaged into cell culture and are now available for detailed characterization. In contrast to oocysts of other parasites, N. caninum oocysts were predominantly found between January and April (Fisher exact; P=0.038). In the sera of dogs shedding N. caninum, no reactions against the immunodominant antigens with apparent molecular weights of 19, 29, 30, 33 and 37 kDa of N. caninum tachyzoites were observed 3–5 weeks after shedding. However, the animals recognized a 152-kDa N. caninum antigen. Compared with those identified as H. heydorni, T. gondii or H. hammondi, N. caninum oocyst isolates were significantly smaller in length with the 75th percentiles ≤10.7 μm when measured in concentrated sucrose solution and smaller length–width ratios with the 75th percentiles ≤1.06. It may thus be possible to develop criteria for a preliminary identification of N. caninum in dog faeces based on the oocyst morphology.
