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71.
Tick transmission of Anaplasma centrale 总被引:1,自引:0,他引:1
Anaplasma centrale was isolated from a field collection of Rhipicephalus simus. Transstadial transmission of A. centrale with adult ticks was demonstrated, but the infection was not carried transovarially. Ticks from this collection were subsequently reared as a non-infected, laboratory strain. It was proved that the Onderstepoort live blood vaccine strain of A. centrale, isolated by Theiler in 1911, is still tick transmissible after more than 75 years of needle passage through cattle in the laboratory. Attempts to demonstrate transstadial transmission of the vaccine strain with Boophilus decoloratus and Boophilus microplus failed. 相似文献
72.
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
73.
74.
DNA amplification fingerprinting (DAF) was used to characterize different Cynodon dactylon (L.) Pers. cultivars and accessions and evaluate the genetic diversity among them. DAF analyses of some well known cultivars
used in South Africa, i.e. Sahara, Tifway, Tifgreen, Harrismith, Royal Blue, Silverton Blue, Elliott, Tifdwarf, Gulf Green,
Magennis, Klip, Florida, Oval, Bayview, Bermuda, X Kweek, Natal Kweek and Tifton 78, as well as 23 unknown Cynodon specimens were done. The unknown Cynodon specimens represent invaders of cultivated lands, with considerable morphological variation. The results were used to determine
the genetic distances between the cultivars and unknown accessions, to identify the unknown specimens and to determine the
phylogenetic affinities between the cultivars and accessions. The results obtained from the genetic distance matrices confirmed
the results obtained from the phylogenetic analyses. In this study DAF analyses was successfully used to distinguish between
different C. dactylon cultivars and accessions and could be used to trace the current weed back to its introduction area.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
75.
Moraxella bovis pilus proteins, collected and purified from four strains of M. bovis, were cleaved with cyanogen bromide. Two major fragments were produced. Antisera were produced in rabbits to the pilin protein fragments and to whole uncleaved pili from these strains. Immunoblots of whole and cyanogen bromide-cleaved pilin were reacted with the homologous and heterologous antisera to whole pili and cleaved pilin. Antisera to whole pili reacted strongly with homologous pilin. Weaker and inconsistent reactions were detected with heterologous pilin. Antisera produced to cyanogen bromide-cleaved pilin proteins reacted strongly with homologous and heterologous pilin fragments and uncleaved pilin proteins. These findings demonstrate the presence of conserved antigenic determinants on pili from heterologous strains that are non-immunogenic in the intact pilus but are immunogenic after treatment with cyanogen bromide. Cyanogen bromide-treated pilus preparation might have potential as a vaccine because antibodies are induced against heterologous strains of M. bovis, whether these cross-reactive antibodies are protective remains to be determined. 相似文献
76.
77.
MBS de Brito MAR Feliciano LN Coutinho RR Uscategui APR Simões MC Maronezi VT de Almeida RM Crivelaro B Gasser L Pavan WR Russiano 《Reproduction in domestic animals》2015,50(5):730-734
The objective was to characterize the vascular patterns of testicular blood flow of adult cats, measuring the systolic velocity (SV), diastolic velocity (DV), resistance index (RI), gate time (wash‐in) peak enhancement and output time (wash‐out) of the contrast and addition of tissue fill characteristics. Forty‐five adult cats were selected, and the echotexture, echogenicity, size, contours and margins of testicles were assessed via ultrasound. By Doppler were evaluated the blood flow and determined of vascular index in testicular artery (SV, DV and RI) and via contrast‐enhanced ultrasonography determine the time for phases: wash‐in, wash‐out and peak enhancement. Sonographic findings presented normal. Testicular artery was observed in the spermatic cord with tortuous patter and showed monophasic‐patterned waves and low vascular resistance and with systolic peak evident. Values of indices vascular were as follows: SV = 6.73 cm/s, DV = 2.8 cm/s and RI = 0.54 for left testicles; and SV = 6.23 cm/s, DV = 2.77 cm/s and RI = 0.53 for right testicles. Contrast filled the subcapsular vascular structures and after a few seconds, a homogeneous moderate enhancement of the parenchyma, with parenchymal vessels still distinguishable and after the peak phase, a rapid homogeneous decrease in echogenicity. Values of time for contrast‐enhanced ultrasonography were as follows: wash‐in = 8.78 s, peak enhancement = 21.62 s and wash‐out = 75.36 for left testicles; and wash‐in = 10.76 s, peak enhancement = 21.50 s and wash‐out = 81.81 for right testicles. Doppler and contrast‐enhanced ultrasonography of the testicles in healthy adult cats was easily implemented and may provide baseline data for this organ to allow the use of these techniques as a diagnostic tool for evaluating testicular abnormalities in sick cats. 相似文献
78.
79.
Pachystigma pygmaeum is a rubiaceous plant which causes heart failure after ingestion by ruminants. Isolation or characterization of a toxic entity has hitherto been unsuccessful. Extraction of the plant material with water or organic solvents gave poor yields of toxicity in guinea-pigs because of some unusual properties of the toxic entity. We present a method whereby liberation of a toxic entity from the plant material was achieved by fermentation with baker's yeast to give a crude extract with sufficient yield of toxicity for use in further isolation work. 相似文献
80.
T E Mason F T Potgieter L van Rensburg 《The Onderstepoort journal of veterinary research》1986,53(3):143-145
A strain of Babesia bovis that had been attenuated by rapid syringe passage through a series of 23 splenectomized calves was unable to infect its vector Boophilus microplus. An attempt to transmit the attenuated Australian Babesia bigemina G strain with a South African strain of B. microplus was likewise unsuccessful. The epidemiological implication of these observations in terms of babesiosis control is discussed. 相似文献