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1.
Cyclical interactions between intracellular schizonts of the Ankara and Hissar strains of Theileria annulata and the Muguga strain of T. parva and the parasitised host lymphoblasts have been studied autoradiographically by following the incorporation of (3H) thymidine into parasite and host cell nuclei, and also by quantitating the number of schizont nuclei per lymphoblast, at various stages and phases of host cell cycle. The synthesis of DNA by Theileria schizonts and the parasitised host lymphoblasts was found to be asynchronous and to occur at different phases of the host cell interphase stage. While the lymphoblast nuclear DNA incorporates (3H) thymidine during the S phase, schizont nuclei were labelled during the G2 phase of the host lymphoblast interphase stage. The replication of schizont nuclei took place before the metaphase stage of host cell cycle, viz, prometaphase, so that the mean schizont nuclear number at host prometaphase and at anaphase--telophase was consistently more or less double the mean nuclear number at interphase. 相似文献
2.
A C Maritim A S Young A C Lesan S G Ndungu D A Stagg P N Ngumi 《Veterinary parasitology》1992,43(1-2):1-14
A sporozoite stabilate (St. 199) of Theileria parva was obtained by feeding nymphal Rhipicephalus appendiculatus on an African buffalo (Syncerus caffer) and was used to immunize cattle by the infection and treatment method. Nymphal ticks were applied to one of the steers 90 days later and it was shown that the resultant adult tick had become infected. Using tick/cattle passage, two passage lines of T. parva were established. By the fifth tick/cattle passage, the parasite stocks had changed their behaviour to that of T. parva derived from cattle as the parasite produced relatively high schizont parasitosis and piroplasm parasitaemia in cattle, and had become highly infective to ticks. At various passage levels the parasite populations were characterized by behaviour and by monoclonal antibodies against T. parva schizonts using infected cell culture isolates from cattle during acute infections. The monoclonal antibody profile showed little evidence of antigen change of the parasite during passage through cattle, which was confirmed in a two-way cross-immunity experiment using sporozoite stabilate derived from ticks obtained from the buffalo and fourth passage in cattle. The implication of these results, particularly in relationship to immunization of cattle against T. parva derived from buffalo, is discussed. 相似文献
3.
4.
P. van der Meer G. Uilenberg S. G. van den Bergh A. A. M. Spanjer N. M. Perié 《The Veterinary quarterly》2013,33(2):61-65
Summary Bovine blood containing piroplasms of Theileria parva, as well as non‐injected blood, was lysed and subjected to iso‐electric focussing. Staining for 13 different enzymes revealed parasite‐associated bands of glucose phosphate isomerase (GPI) activity, not of any of the other enzymes. There were no variations between individual donor animals in the host cell GPI bands and these bands did not interfere with the recognition of the parasite‐associated bands, so that purification of the piroplasms was unnecessary. Blood from cattle infected with T. mutans also gave parasite‐associated bands of GPI, but no such bands were seen in zymograms of blood from cattle infected with a Theileria sp. from Japan. Depending on the level of parasitaemia, up to four parasite‐associated bands were found in one strain of T. parva and up to three in two other strains. Among the disadvantages of using piroplasm material for the study of isoenzymes of T. parva is the fact that animals often die before their parasitaemia is sufficiently high, and that some strains never give rise to a high parasitaemia. 相似文献
5.
Blood from calves infected with Theileria annulata and T parva was freed from host cell elements and the piroplasms liberated from the red cells by ammonium chloride lysis. Lysates of the purified piroplasms and control host cell material were examined electrophoretically for several enzymes. Zymograms stained for glucose phosphate isomerase showed distinct differences between the host cell enzyme pattern and parasite enzyme patterns. The isoenzyme pattern of T annulata piroplasms differed from the isoenzyme pattern of T parva piroplasms. 相似文献
6.
McKeever DJ 《Research in veterinary science》2001,70(1):77-81
Theileria parva, a tick-borne parasite of African cattle, causes a fatal disease known as East Coast fever. Cattle that recover from the disease develop strong parasite-specific MHC-class I-restricted cytotoxic T-lymphocyte responses. Protection can be transferred between immune and na?ve calves in the CD8+ T cell fraction emanating from a responding lymph node. In vitro studies suggest that this response requires input from activated CD4+ T cells. The T parva life cycle involves developmental stages in mammalian and tick hosts and can lead to a number of different endemic scenarios for the disease. These range from a stable situation with high prevalence of herd infection, but low fatality rates, to a low prevalence/high fatality scenario. The impact on endemic stability is an important consideration for the design of vaccine implementation strategies. For subunit vaccines targeted at T parva schizonts, the principal issue in this regard is whether development of the piroplasm stage is blocked by immunity. 相似文献
7.
Lysates prepared from the salivary glands of uninfected Hyalomma anatolicum anatolicum and Rhipicephalus appendiculatus and from ticks of these species infected with 2 strains of Theileria annulata and 1 strain of T. parva respectively have been examined for enzyme polymorphism using thin layer starch gel electrophoresis. Representative enzymes from 3 of the major metabolic pathways, the tricarboxylic acid cycle, the glycolytic pathway and the pentose phosphate pathway were investigated. Only 1 enzyme, glucose phosphate isomerase, showed differences between the host cell activity and the parasite activity and also inter- and intraspecific differences between the parasites. This technique represents a useful complement to the present histochemical methods for identification of Theileria infections in the salivary glands of ticks. 相似文献
8.
Thirty-one calves born into five Maasai zebu cattle herds over a period of 1 month in the Trans-Mara Division of Kenya, endemic for theileriosis, were recruited for an intensive study of theileriosis. No calves up to 6 months of age died but all developed Theileria infections as judged by slide examination and serology. Parasitosis by T. mutans schizonts in lymph node smears was usually higher than that of T. parva. The T. mutans schizonts usually occurred at an earlier age but persisted at a patent level for a shorter time than those of T. parva. Serological findings using the indirect fluorescent antibody test confirmed the parasitological findings. It was evident that colostral transfer of Theileria antibodies was frequent. Theileria piroplasm parasitaemia had developed in all calves by 111 days of age. The earlier parasitosis by T. mutans reflected the higher infection rates in Amblyomma spp. than in Rhipicephalus appendiculatus. The mean number of R. appendiculatus on the ears of calves during the observations was 9.1 adults and 1.5 nymphs. Clinical episodes of T. mutans and T. parva infection were associated with febrile responses, enlarged lymph nodes, anaemia and other symptoms and about 80% of calves had poor weight gains or weight losses during either clinical infection. It would appear that theileriosis is one of the most important factors in the stunting of calf development in the area. 相似文献
9.
K M Cowan T T Dolan A J Teale A S Young D D Stagg C M Groocock 《Veterinary parasitology》1984,15(3-4):223-237
Peroxidase-labeled antibody procedures were described for detecting bovine antibodies reactive with intracellular Theileria parva schizonts and cell surface membrane antigens of infected lymphoblastoid cells. Indirect tests were performed where the reacting bovine antibodies were localized with affinity purified rabbit-anti-bovine IgG coupled to horseradish peroxidase. A 4- to 8-fold increase in sensitivity for detecting bovine antibodies was obtained with unlabeled rabbit-anti-bovine IgG which in turn was detected with peroxidase labeled goat-anti-rabbit IgG. The T. parva infected cells used as antigen were attached to poly-l-lysine treated glass slides and all reaction steps were performed on the slides. The intracellular schizonts and cell surface staining reactions were dependent upon the status of the cells; acetone-fixed cells were required for schizont reactions and viable unfixed cells for cell surface membrane reactions. Sera from cattle stimulated in various ways with T. parva were examined by the techniques. Cattle infected by stabilate inoculation or inoculated with infected autologous lymphoblastoid cells developed relatively high levels of antibody to schizonts, but no detectable antibody to cell surface membrane antigens. This would indicate that parasite antigens do not occur on the surface of infected lymphoblasts. Cattle inoculated with infected allogeneic lymphoblasts developed low-levels of antibody to schizonts and readily demonstrable antibody to cell surface antigens. The immunoperoxidase procedures have certain advantages over immunofluorescence in that light microscopy is used; therefore, the reactions do not fade which permits a more detailed examination and provides a relatively permanent record, the preparations can be counterstained, and the reagents may be used for immunoelectron-microscopy. The procedures could provide suitable alternatives to immunofluorescence methods for East Coast fever investigations and other systems having intracellular and/or cell surface membrane antigens. 相似文献
10.
B.A. Kimeto 《Veterinary parasitology》1980,7(1):25-32
Ultrastructural studies of Theileria parva in the bovine skin revealed ‘infective particles’ of the parasite. These parasite forms were pleomorphic and were found extracellular or within host lymphoid cells, neutrophils and erythrocytes. The parasites were a product of extracellular schizogony. They were phagocytosed by the host leucocytes but seemed actively to invade the erythrocytes. Several extracellular uninucleate schizonts were also observed. The presence of extracellular infective particles, uninucleate schizonts and multinucleate schizonts, some showing schizogony, suggests an extracellular life cycle of T. parva within bovine tissue. 相似文献
11.
Sibeko KP Oosthuizen MC Collins NE Geysen D Rambritch NE Latif AA Groeneveld HT Potgieter FT Coetzer JA 《Veterinary parasitology》2008,155(1-2):37-48
Corridor disease, caused by the tick-borne protozoan parasite Theileria parva, is a controlled disease in South Africa. The Cape buffalo is the reservoir host and uninfected buffalo have become sought-after by the game industry in South Africa, particularly for introduction into Corridor disease-free areas. A real-time polymerase chain reaction (PCR) test for detection of T. parva DNA in buffalo and cattle was developed to improve the sensitivity and specificity of the official diagnostic test package in South Africa. Oligonucleotide primers and hybridization probes were designed based on the 18S ribosomal RNA (rRNA) gene. Amplification of control DNA using Theileria genus-specific primers resulted in detection of T. taurotragi and T. annulata, in addition to T. parva. A T. parva-specific forward primer was designed which eliminated amplification of all other Theileria species, except for Theileria sp. (buffalo); however only the T. parva product was detected by the T. parva-specific hybridization probe set. The real-time PCR assay requires less time to perform, is more sensitive than the other molecular assays previously used in T. parva diagnostics and can reliably detect the parasite in carrier animals with a piroplasm parasitaemia as low as 8.79 x 10(-4)%. 相似文献
12.
T. R. Melrose C. G. D. Brown S. P. Morzaria J. G. R. Ocama A. D. Irvin 《Tropical animal health and production》1984,16(4):239-245
Six stocks of Theileria annulata isolated from the Sudan and nine stocks of T. parva, isolated in Kenya and Malawi were grown in bovine lymphoblastoid cell lines. Lysates prepared from the infected cultures were examined electrophoretically on thin layer starch gels for evidence of glucose phosphate isomerase polymorphism. The six stocks of T. annulata showed major variations in their parasite enzyme patterns but no variation was detected in nine stocks of T. parva. 相似文献
13.
Five strains of Theileria annulata from three geographically different areas and one strain of T parva were grown in bovine lymphoblastoid cell lines. Lysates of the parasitised cells were examined by thin layer starch gel electrophoresis for multiple forms of the enzyme glucose phosphate isomerase. A reported difference between the glucose phosphate isomerase isoenzyme patterns of T annulata and T parva was confirmed. Cultures of one strain of T annulata grown in cells derived from four different cattle showed similar host and parasite isoenzyme patterns. Two strains of T annulata and one strain of T parva grown in lymphoid cells derived from the same animal showed identical host cell isoenzyme patterns whereas the isoenzyme pattern associated with each parasite was different. Strains of T annulata from different geographical areas showed major differences in their isoenzyme patterns, but no differences were detected between strains from the same geographical area. Meldola blue was found to be superior to phenazine methosulphate as an intermediate electron acceptor in the visualisation of enzyme activity. 相似文献
14.
Madder M Speybroeck N Berkvens D Baudoux V Marcotty T Pita Bah I Geysen D Brandt J 《Veterinary parasitology》2003,114(3):195-203
In vitro studies were focussed on the duration and cessation of merogony in Theileria parva infected blood lymphocyte cell cultures. The cultures were infected using purified tick stabilates as an alternative to in vitro infections, using sporozoites obtained by labour intensive dissections of salivary glands from infected ticks. After establishment of infection in peripheral blood lymphocytes (PBL), merozoites were temporarily produced for about 2 months after which lymphoblasts only contained schizonts. 相似文献
15.
Chaisi ME Sibeko KP Collins NE Potgieter FT Oosthuizen MC 《Veterinary parasitology》2011,182(2-4):150-162
Theileria parva is the causative agent of Corridor disease in cattle in South Africa. The African buffalo (Syncerus caffer) is the reservoir host, and, as these animals are important for eco-tourism in South Africa, it is compulsory to test and certify them disease free prior to translocation. A T. parva-specific real-time polymerase chain reaction (PCR) test based on the small subunit ribosomal RNA (18S rRNA) gene is one of the tests used for the diagnosis of the parasite in buffalo and cattle in South Africa. However, because of the high similarity between the 18S rRNA gene sequences of T. parva and Theileria sp. (buffalo), the latter is also amplified by the real-time PCR primers, although it is not detected by the T. parva-specific hybridization probes. Preliminary sequencing studies have revealed a small number of sequence differences within the 18S rRNA gene in both species but the extent of this sequence variation is unknown. The aim of the current study was to sequence the 18S rRNA genes of T. parva and Theileria sp. (buffalo), and to determine whether all identified genotypes can be correctly detected by the real-time PCR assay. The reverse line blot (RLB) hybridization assay was used to identify T. parva and Theileria sp. (buffalo) positive samples from buffalo blood samples originating from the Kruger National Park, Hluhluwe-iMfolozi Park, the Greater Limpopo Transfrontier Park, and a private game ranch in the Hoedspruit area. T. parva and Theileria sp. (buffalo) were identified in 42% and 28%, respectively, of 252 samples, mainly as mixed infections. The full-length 18S rRNA gene of selected samples was amplified, cloned and sequenced. From a total of 20 sequences obtained, 10 grouped with previously published T. parva sequences from GenBank while 10 sequences grouped with a previously published Theileria sp. (buffalo) sequence. All these formed a monophyletic group with known pathogenic Theileria species. Our phylogenetic analyses confirm the distinction between Theileria sp. (buffalo) and T. parva and indicate the existence of a single group of T. parva and two Theileria sp. (buffalo) 18S rRNA gene variants in the African buffalo. Despite the observed variation in the full-length parasite 18S rRNA gene sequences, the area in the V4 hypervariable region where the RLB and real-time PCR hybridization probes were developed was relatively conserved. The T. parva specific real-time PCR assay was able to successfully detect all T. parva variants and, although amplicons were obtained from Theileria sp. (buffalo) DNA, none of the Theileria sp. (buffalo) 18S rRNA sequence variants were detected by the T. parva-specific hybridization probes. 相似文献
16.
牛中华泰勒虫新种(梨形虫亚目:泰勒虫科)2.分子分类学研究 总被引：6，自引：0，他引：6
分离自我国甘肃中部地区土种黄牛的一种形态特异的泰勒虫，采用传统分类学研究鉴定为新种，被定名为中华泰勒虫（Theileria sinensis sp.nov）。又利用对泰勒虫属特异的PCR引物（92/93）对该种基因组DNA扩增，结果表明该种属泰勒虫属原虫确定无疑，并对代表虫种进化和分类的18S rRNA基因序列进行了测定，对已测出该基因1067bp长片断序列与基因库中9种巴贝斯虫，7种已知牛泰勒虫的相应序列进行比较、分，建立起系统发生树。树图表明，瑟氏泰勒虫和水牛泰勒虫的亲缘关系非常近， 中华泰勒虫与这两个种的亲缘关系较近，与附膜泰勒虫、小泰勒虫、环形泰勒虫、斑羚泰勒虫、突变泰勒虫差异较大。 相似文献
17.
Walker AR Katzer F Ngugi D McKeever D 《The Onderstepoort journal of veterinary research》2006,73(2):157-162
Experimental transmissions of cloned Theileria parva in cattle with Rhipicephalus appendiculatus ticks were compared to transmissions with uncloned T. parva during studies on the potential for genetic recombination during syngamy of Theileria to produce antigenic diversity for evasion of bovine immunity. Prevalence and abundance of T. parva infection in adult ticks, which resulted from the feeding of nymphs on the calves, were significantly higher in the uncloned compared to the cloned T. parva. Development of sporoblasts of T. parva in the ticks to produce infective sporozoites was similar. There was no statistically significant difference in the clinical course of infection in cattle between cloned and uncloned T. parva. It was concluded that cloned T. parva has characteristics that reduce its viability during the tick stages of its life cycle. 相似文献
18.
H T Koch L Kambeva J G Ocama F C Munatswa F F Franssen G Uilenberg T T Dolan R A Norval 《Veterinary parasitology》1990,37(3-4):185-196
Theileria parva bovis isolates were tested for their immunizing capacity under natural field challenge on Willsbridge Farm in the highveld of Zimbabwe. Fifteen susceptible Sussex yearlings were immunized with the Boleni stock and 15 with a mixture of three isolates from the farm, using tick-derived sporozoite stabilates. No chemoprophylaxis was used. A dose of 0.1 ml of stabilate appeared to be safe in preliminary laboratory experiments, but the reactions were severe in the Sussex cattle and one died despite treatment. Twenty-nine immunized animals and 10 controls first experienced a mild infection, starting about 15 days after their arrival at the farm. Ten of the immunized animals and four controls had schizonts in peripheral lymph nodes for variable periods; one third of those had pyrexia. Nymphal Rhipicephalus appendiculatus ticks applied to three of the reacting immunized calves transmitted Theileria taurotragi to two animals and T. parva to a third. A second Theileria infection, due to T. parva bovis, was detected shortly after the first one. Schizonts were detected in seven out of 10 controls. Pyrexia was more severe and prolonged. Two of the controls died of theileriosis. At the same time schizonts were seen in three immune animals and eight of them had short periods of pyrexia. Intercurrent infections with Babesia bigemina, Borrelia theileri and Eperythrozoon were detected and may have contributed to the fever. Tick infestations were low during the exposure. In the second year of exposure, four out of eight new control animals had severe reactions, and one died. None of the immunized animals became ill, but one animal from the first year control group, which had not reacted previously, had clinical theileriosis. It is concluded that immunization provided an effective protection against field challenge. 相似文献
19.
Papli N Landt O Fleischer C Koekemoer JO Mans BJ Pienaar R Josemans A Zweygarth E Potgieter F Latif AA 《Veterinary parasitology》2011,175(3-4):356-359
A real-time PCR assay based on TaqMan probe chemistry was developed for the detection of Theileria parva DNA in blood samples. It uses a Theileria genus-specific PCR primer set and a T. parva-specific probe to amplify and hybridize with a species-specific part of the 18S rRNA gene of the parasite. The test was evaluated using positive and negative reference blood samples and shown to be specific for T. parva. Analytical sensitivity was determined by testing a dilution series of T. parva positive blood. It was shown to be able to detect parasitaemia as low as 2 × 10(-6)%. The Taqman assay results were also compared with that obtained with the real-time hybridization probe PCR assay, which is currently employed as the official test for the diagnosis of T. parva infections in buffalo and cattle and was shown to be equally sensitive. A panel of 1164 field samples was screened using both assays and 164 samples tested positive in both tests, indicating a good correlation. 相似文献
20.
A A Latif T Hove G K Kanhai S Masaka R G Pegram 《The Onderstepoort journal of veterinary research》2001,68(3):187-195
Fifty-nine Hereford cattle susceptible to tick-borne diseases were used as tracer animals to assess the tick challenge and pathogenicity of Theileria parva under field conditions in Zimbabwe. They were moved periodically in groups of five to three commercial farms (one group consisted of four) during seasons of Rhipicephalus appendiculatus nymphal and adult activity. All tracer cattle were herded together with the farm cattle but were not dipped. The nymphal tick counts were high on two of the farms (up to 2000 per animal) but were very low on the third farm (less than ten per animal). On the three farms, 19 out of 24 (76%) tracers had patent Theileria schizonts. There was a range of clinical manifestations of theileriosis with acute and fatal infections occurring on one farm. The adult R. appendiculatus infestations during the wet season numbered 120-800 per animal on the three farms. The disease transmitted by the adults was very pathogenic on the three farms; 30 out of 35 (86%) had severe theileriosis infections. Cattle, which survived the nymphal diseases challenge, showed various degrees of immunity to subsequent T. parva challenge transmitted by adult ticks. Therefore, 13 out of 18 (72%) of these cattle had a second disease episode and the case fatality rate on the three farms was 46%. The factors which determined the epidemiological status of Theileria challenge on the farms, such as the farming systems and presence of wild animals, are discussed. 相似文献