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1.
C F Simpson J W Harvey M J Lawman J Murray A A Kocan J W Carlisle 《American journal of veterinary research》1985,46(2):384-390
Schizonts in the liver of 2 cats with cytauxzoonosis were studied by both light and electron microscopies. By light microscopy, the cytoplasm of macrophages in the sinusoids and small vascular channels contained schizonts with cytomeres or both cytomeres and mature merozoites. By electron microscopy, it was determined that schizogony occurred in 4 stages. The earliest stage was the presence of a multilobed structure containing finely granular protoplasm in the cytoplasm of the macrophage. The 2nd stage was an increase in height and number of the lobulations on the surface of the schizont. The 3rd stage involved the development of cytomeres and the appearance of a polar ring and rhoptries in everted sacculations on the cytomere membrane. Nuclei and mitochondria were incorporated into the sacculations before the release of mature merozoites into the host cell cytoplasm. In the last stage of schizogony, following massive merozoite formation and reduction in size of the schizont, residual nuclei divided by multiple fission. Each nuclear division became incorporated into a developing merozoite having preformed rhoptries, mitochondria, and a polar ring. 相似文献
2.
M Tanaka T Okabe N Sasaki 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(4):813-818
Monoclonal anti-idiotype antibodies against monoclonal antibody (23C11) to intraerythrocytic merozoites of Theileria sergenti were prepared and examined by indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). Three anti-idiotype antibodies containing antibodies against interspecies cross-reactive idiotopes and/or an internal image of Theileria sergenti merozoite were found. The presence of antibody against Theileria sergenti was shown by ELISA in these anti-idiotype antibodies induced anti-anti-idiotype antibodies. 相似文献
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4.
Macrophage activation in Theileria sergenti-infected calves was studied by testing the production of oxygen metabolites in macrophages following specific and non-specific stimulation with T sergenti merozoites or zymosan, respectively. Six calves were inoculated with merozoites and three calves with sporozoites. All showed significant macrophage activation within one month after inoculation (P less than 0.05). Activation of macrophages appeared earlier than parasitaemia or the peak of antibody titre against T sergenti. The highest chemiluminescence response, indicative of macrophage activation, was observed when the merozoites were opsonised with immune sera. 相似文献
5.
The nuclei of merozoites of Sarcocystis neurona and Sarcocystis falcatula were labeled with the fluorescent marker Syto21. It was shown that the marker would label the parasites and that they would retain the marker throughout schizogony. Thus, there was sufficient marker in the daughter merozoites to make them easily visible with fluorescence microscopy. This technique will be helpful in studying the developmental biology of these parasites in vitro. 相似文献
6.
In Boophilus decoloratus infected by transovarian passage with B. bigemina, primary schizogony occurred as a continuous repetitive process in all 3 stages of the tick's life cycle spent on the host. The primary schizonts and the large merozoites (= vermicules) produced by them were observed in the gut epithelium, haemocytes, muscles, ad peritracheal cells. Secondary schizogony which led to the formation of small merozoites (= infective forms) occurred mainly in the salivary glands, but was also observed in the cortex of the synganglion. Mature small merozoites were observed in nymphal and adult ticks only. An infective stabilate was prepared from nymphae collected on Day 14 and Day 15 post larval infestation. The infections resulting from intravenous injection of the stabilate had a prepatent period of 8 days. 相似文献
7.
The role of peripheral blood mononuclear cell (PBMC) in Theileria sergenti-infected calves was studied by various in vitro assay systems. Proliferation of T cells in mixed lymphocyte protozoa culture (MLPC) increased with parasitemia, and the addition of monoclonal antibodies against T. sergenti merozoites in this MLPC enhanced the response. However, the addition of antibody-positive autologous serum resulted in the suppression of the response. Cell-mediated cytotoxicity of PBMC increased after peak parasitemia. This cytotoxicity increased on co-cultivation of PBMC with T. sergenti merozoites, but the addition of autologous serum suppressed the response. 相似文献
8.
N Kajiwara R Kirisawa M Onuma Y Kawakami 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(6):1199-1204
A simple procedure was developed for detection of Theileria sergenti infection on the basis of hybridization of parasite DNA with a specific probe. A genomic DNA library of T. sergenti constructed in pUC-18 was screened to detect clones containing the parasite's DNA sequences by colony and Southern hybridizations. Two positive DNA inserts were purified from the recombinant plasmids and used as probes labelled with 32P or non-isotopic reagent, biotin-11-dUTP. 32P-radiolabelled and non-radioactive probes appear to be sensitive enough to detect 15 pg (equivalent to 1,200 parasites) and 125 pg (equivalent to 10,000 parasites) of purified T. sergenti DNA, and in diluted T. sergenti-infected red blood cells, they are able to detect 8,000 parasites and 16,000 parasites, respectively. 相似文献
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S Shimizu K Suzuki K Nakamura K Kadota K Fujisaki S Ito T Minami 《Research in veterinary science》1988,45(2):206-212
A method of obtaining a pure suspension of Theileria sergenti piroplasms from infected bovine erythrocytes was developed and the resulting parasites used as antigen in an enzyme-linked immunosorbent assay (ELISA). Piroplasms were freed from infected erythrocytes using the nitrogen cavitation technique and then separated from unbroken erythrocytes by centrifugation at 670 gmax. The parasites in the supernatant were then sedimented by centrifugation at 2700 gmax and the purified fraction examined by electron microscopy. This examination showed that the isolated piroplasms were morphologically intact and that there were few contaminants. SDS-PAGE and spectrophotometric analysis showed that this fraction contained little erythrocyte component. The piroplasms thus obtained were sonicated and treated with Triton X-100 then used for ELISA antigen. The ELISA values had a high correlation with titres obtained using the indirect fluorescent antibody test on sera from cattle infected with T sergenti. 相似文献
11.
Uilenberg G 《Veterinary parasitology》2006,138(1-2):3-10
The history of the genus Babesia is briefly outlined. The classical differences with the main other genus of non-pigment-forming hemoparasites, Theileria, are the absence of extra-erythrocytic multiplication (schizogony) in Babesia and the cycle in the vector tick, which includes transovarial transmission in Babesia but only transstadial transmission in Theileria. Also, the multiplication in the red cell of Babesia, by budding, most often results in two daughter cells (merozoites), while that of Theileria gives four merozoites, often as a Maltese cross. In particular this means that what is still commonly called Babesia microti is not a Babesia and that it would be just as logical to speak of human theileriosis as of babesiosis. The small piroplasm of horses, long known as Babesia equi, is already commonly designated as Theileria equi. However, on molecular grounds, it may be necessary to create a new genus for these parasites. The Babesia species of domestic animals are briefly discussed and presented in a table. 相似文献
12.
The morphology and development of Cowdria ruminantium have been studied in Amblyomma hebraeum and A. variegatum. Colonies of C. ruminantium have so far been demonstrated microscopically in gut, salivary gland cells, haemocytes and malphighian tubules of infected Amblyomma ticks. Colonies in gut cells were seen in both unfed and feeding ticks but colonies in salivary gland acini were observed only in nymphs that had fed for 4 days. Although the predominant type seen in both tick stages was the reticulated form that appeared to divide by binary fission, electron dense forms were also present. The latter are similar to those forms documented in endothelial cells of the vertebrate host as well as in cell culture. The presence of colonies of C. ruminantium in salivary glands of feeding ticks, along with the demonstration of different morphologic forms of the organism, suggests that a developmental cycle of the organism occurs in its invertebrate host. It is thought that organisms first infect and develop within gut cells. From there subsequent stages continue their development in haemolymph and salivary glands and are then transferred to the vertebrate host during tick feeding. Further studies are needed to completely understand the development of C. ruminantium in ticks and its subsequent transmission by these parasites. 相似文献
13.
Restriction fragment length polymorphisms of Theileria sergenti DNA from 18 different infections of cattle in 14 locations in Japan were analyzed by Southern blotting using T. sergenti genomic DNA fragments as probes. Probe pTs 2 hybridized with four fragments in BamHI digested piroplasm DNA, at 8.0, 7.3, 6.0 and 3.4 kb. Probe pTs 11-D1 hybridized with multiple fragments. With each probe, polymorphisms were observed among stocks from different locations. However, there was no correlation between the patterns of hybridization bands and the locations where parasites were collected. Analysis of the hybridization patterns of stocks obtained from individual cattle in the same grazing areas showed an almost identical pattern. 相似文献
14.
为研究柔嫩艾美耳球虫不同发育时期Etron2基因的转录水平差异,选取E.tenella生活史中的未孢子化卵囊、孢子化卵囊、子孢子、第二代裂殖子,分别提取总RNA,反转录为cDNA;选择Etactin作为参照基因,Etron2为目的基因,设计实时荧光定量PCR的引物,分析在E.tenella生活史中不同发育阶段Etron2转录水平的差异。结果显示Etron2在未孢子化卵囊中转录水平最高,然后分别是裂殖子、孢子化卵囊和子孢子。在柔嫩艾美耳球虫发育过程中,Etron2基因可能在未孢子化卵囊阶段被转录储备,随着宿主细胞的刺激,得以大量表达,在入侵过程中发挥作用。 相似文献
15.
J L Du Plessis 《The Onderstepoort journal of veterinary research》1999,66(1):39-46
Electron microscopy of mouse peritoneal macrophages infected with the Kümm stock of Cowdria ruminantium suggests that in the final stage of intracellular growth, a mosaic of organisms develops from an amorphous matrix of varying electron density by a process in which double unit membranes portion off the Cowdria particles. This stage is preceded by inclusions consisting of a network of aggregated electron dense granules and these in turn by homogeneous dense bodies. The study failed to show how these dense bodies develop from internalized Cowdria particles introduced in the infective inoculum. The replication of the heartwater agent in macrophages differs from that in vascular endothelial cells in two important respects. First, at no stage during the course of development in macrophages is binary fission in evidence and second, in the absence of a limiting membrane the inclusions and colonies of organisms throughout the cycle of development in macrophages are in intimate contact with the host cell cytoplasm. 相似文献
16.
The growth of Sarcocystis neurona, isolate UCD1, in continuous culture was examined in 10 cell lines to identify growth conditions and methods for the preparation of parasites free of gross host cell contamination for molecular studies. The unpredictable, slow release of merozoites in most cell lines prompted development of a method to synchronously release the parasites from infected host cells. The calcium ionophore A23187 at a concentration of 1 microM was found to release intracellular merozoites with a 40 min treatment at 37 degrees C. The release of merozoites en masse from attached host cells allowed for the rapid collection of relatively pure parasites from the culture supernatant. This release of merozoites occurred in five different host cell lines. The ionophore-released parasites were highly infectious for host cells and appeared to be morphologically identical to naturally released merozoites, except that the treated merozoites had an increased number of micronemes when examined by electron microscopy. The ionophore did not enhance the release of sporozoites from sporocysts, but freezing in the presence of 5% DMSO released sporozoites that were infectious to bovine monocytes in in vitro culture. 相似文献
17.
Globidian parasites infecting the abomasum of sheep in Germany were investigated by means of electron microscopy. The frequency of infection was found to be 93 %. The globidian cyst-like bodies contained multinucleate schizonts, developing merozoites or fully developed merozoites. Among the latter there were two different types, namely short and long forms. The process of merozoite formation was described in detail. The giant schizonts were subdivided into multinucleate cell portions of irregular size and shape. Their nuclei were then arranged at the periphery of the cell portions and underwent their last division which was combined with the differentiation of merozoites. The long form merozoites were elongated cylindrical in shape with terminal nucleus. They measured 7.7 μm in length and 1.0 μm in width. The merozoites of the short type were spindle-shaped with a central nucleus. They were 5.0 μm long and 1.0 μm wide. The globidian parasites were located in a parasitophorous vacuole of an intact host cell. 相似文献
18.
L P Joyner R C Payne K Takahashi D W Brocklesby A D Irvin 《Research in veterinary science》1979,26(3):387-388
A serological comparison between British Theileria mutans and Japanese T sergenti using the indirect fluorescent antibody test, showed that the two parasites were indistinguishable. On the basis of this and previous findings it is suggested that the British parasite is identical with the Japanese one and that its name should therefore be changed to T sergenti. 相似文献
19.
H S Lillehoj 《Veterinary immunology and immunopathology》1986,13(4):321-330
Development of cell-mediated immunity (CMI) and comparative effectiveness of different stage-specific coccidia antigens in T cell activation during avian coccidiosis were evaluated in two inbred strains of chickens using a specific in vitro T cell proliferation assay. Lymphocytes from chickens infected with different Eimeria spp. showed proliferative response to sporozoites, merozoites or Eimeria soluble antigen (Esa) excreted by cultured parasites. Detectable CMI response was observed at 21 day P.I. in chickens infected with E. tenella and E. maxima. Generally lower T cell response was observed in chickens infected with E. acervulina. Merozoites were highly immunogenic compared to sporozoites. Esa prepared from cultured parasites was as effective as whole parasites in evoking a T cell response. Although strain variation in T cell response to parasites or Esa was observed during a primary infection, substantially enhanced T cell response was observed 3 days after a secondary infection in both strains of chickens. The results of the present investigation suggest that Esa may be a major parasite antigen released to the immune system during early stages of infection and relevant to the development of protective immunity. 相似文献
20.
用鹌鹑源火鸡隐孢子虫（Cryptos poridium meleagridis）卵囊分别感染昆明系小白鼠和固始雏鸡，用透射电镜和扫描电镜观察比较了C．meleagridis在两种试验动物体内的内生发育虫体超微结构和致病性的差异。利用扫描电镜观察发现，鹌鹑源火鸡隐孢子虫（C.meleagridis）在小白鼠和雏鸡体内的寄生部位有较大差异，在小白鼠体内寄生于十二指肠，但在雏鸡体内主要寄生于回肠；C．meleagridis深嵌于小白鼠肠微绒毛丛内，微绒毛较为完整；但在雏鸡回肠，C．meleagridis似黏附在肠黏膜表面，微绒毛脱落明显，对雏鸡致病性明显比对小白鼠的致病性强。利用透射电镜在两种试验动物的样品中均观察到不同发育阶段的滋养体、裂殖体和大配子体以及正在孢子化的卵囊。滋养体和裂殖体在发育过程中可明显见到粗面内质网结构，裂殖生殖中期阶段粗面内质网尤其发达；小白鼠体内的C．meleagridis虫体与肠黏膜接触处形成一凹陷，寄生部位较深，而在雏鸡体内无此现象。此外，利用透射和扫描电镜均观察到虫体寄生部位周围微绒毛密度高而且也比其它部位长。形成这些差异的原因有待于进一步探讨。 相似文献