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1.
The development and morphology of Babesia bigemina in the gut of Boophilus microplus ticks were studied during laboratory maintenance of the babesia by four methods: tick transmission in unsplenectomised (intact) calves; tick transmission in splenectomised calves; syringe passage at intervals of five days or less in splenectomised calves; and syringe passage at intervals of six weeks or more in intact calves. The first method had no apparent effect on the development of B bigemina in ticks compared to that of the original isolate. The other three methods had obvious effects, the most pronounced being increased numbers of babesial forms with processes, particularly during early stages of development. The findings emphasise the importance of maintaining laboratory strains of parasites by natural means in life cycle studies. 相似文献
2.
R. J. Dalgliesh L. L. Callow L. T. Mellors W. McGregor 《Australian veterinary journal》1981,57(1):8-11
The virulence of a strain of Babesia bigemina was reduced by syringe passaging at 3 to 16-week intervals in a series of 7 calves. The calves were splenectomised 1 to 14 weeks after inoculation to induce the relapse parasitaemias used for passaging. Parasites taken at relapse from the last 3 calves in the series were inoculated into splenectomised calves from which highly parasitised blood for vaccine was obtained.
The vaccine produced mild infections in 32 recipient cattle. When challenged either 5 weeks or 7 months after vaccination, the cattle had substantial immunity to a heterologous strain of B. bigemina . 相似文献
The vaccine produced mild infections in 32 recipient cattle. When challenged either 5 weeks or 7 months after vaccination, the cattle had substantial immunity to a heterologous strain of B. bigemina . 相似文献
3.
Shkap V Rasulov I Abdurasulov S Fish L Leibovitz B Krigel Y Molad T Mazuz ML Savitsky I 《Veterinary parasitology》2007,146(3-4):221-226
The virulence of an Uzbek isolate of Babesia bigemina, obtained from infected Boophilus annulatus ticks from an endemic area in Uzbekistan, was attenuated for immunization of cattle with autochthonous calf- or culture-derived parasites in Uzbekistan. After four "slow passages" in vivo the virulence was reduced, as evidenced by the response of calves inoculated with an experimental live frozen vaccine produced from the following passage. The vaccine was safe and protective against homologous virulent challenge under laboratory conditions. The culture-derived experimental vaccine was produced from cultures initiated after 3 passages in vivo followed by 22 passages in vitro. The cultured parasites did not elicit any clinical sign, but inoculated calves seroconverted following vaccination and were protected against the virulent homologous challenge. Both calf- and culture-derived vaccines were safe for cattle grazing in an endemic area in Uzbekistan. Despite the high polymorphism of B. bigemina, as reported from various geographical regions, the Central Asian strain was attenuated similarly to those that form the basis of the existing live B. bigemina vaccines in other parts of the world. 相似文献
4.
Shkap V Pipano E Rasulov I Azimov D Savitsky I Fish L Krigel Y Leibovitch B 《Veterinary parasitology》2003,115(3):247-255
A field isolate of Theileria annulata (Uzbek strain) was obtained from calves infected by Hyalomma anatolicum ticks collected from an endemic region in Uzbekistan. Schizont-infected bovine cells that had been established and propagated in cell culture were examined for attenuation both in vivo, by inoculating cells from various passages into calves, and in vitro for metalloproteinase activity. During serial subcultivation a gradual reduction in virulence and in enzyme activity in cells infected with the Uzbek strain were observed. Complete attenuation of the Uzbek isolate was obtained at about passage 80, and only traces of proteolysis were detected in gelatin substrate gels. In contrast, there was no direct correlation between virulence and enzyme levels in an Israeli strain. While schizonts of the Israeli strain were completely attenuated at passage 80, proteolysis in the substrate gels was detected up to passage 197. Solid immunity was observed in calves immunized with attenuated T. annulata schizonts of the Uzbek strain upon challenge with the homologous H. excavatum sporozoites. For a strain to be used for vaccine production, it appears that animal inoculation still remains the most reliable method to assess the degree of attenuation and protection. 相似文献
5.
Boophilus microplus infected with Babesia bovis were transferred artificially from one splenectomised calf to another during each moult in the parasitic life cycle of the tick. Eggs from the engorged female ticks recovered at the end of the cycle were incubated and the resulting larvae used to infest more splenectomised calves. Babesia bovis was transmitted only by the original larvae used at the commencement of the experiment and it was concluded that the protozoan parasite did not persist in an infective form in the ticks beyond the larval stage. 相似文献
6.
K M Kocan D Holbert W Edwards S A Ewing S J Barron J A Hair 《American journal of veterinary research》1986,47(8):1657-1661
Colonies of Anaplasma marginale in midgut epithelial cells of experimentally infected Dermacentor andersoni were studied in adult ticks 1, 3, and 6 months old. Longevity of the parasite in ticks was assessed by evaluating its infectivity for splenectomized calves; calves were exposed by feeding ticks and by inoculation of tick gut homogenates. Longevity was also evaluated by determining size, type, and density of colonies in male and female ticks. The effect of incubation (2.5 days at 37 C) on colony density was also examined for ticks at each age period. All methods used to assess longevity of A marginale in ticks (tick transmission, calf inoculation, and histologic studies) indicated a decrease of the numbers of organisms in 6-month-old ticks. Furthermore, when tick gut homogenates from 6-month-old nonincubated ticks were not infectious for susceptible calves, incubation of ticks before dissection restored infectivity of homogenates. Colonies of A marginale were detected in gut tissues of 6-month-old ticks that were not infective; therefore, infectivity of ticks could not be confirmed merely by presence of A marginale colonies. 相似文献
7.
Gayo V Romito M Nel LH Solari MA Viljoen GJ 《The Onderstepoort journal of veterinary research》2003,70(3):197-204
Bovine babesiosis is responsible for serious economic losses in Uruguay. Haemovaccines play an important role in disease prevention, but concern has been raised about their use. It is feared that the attenuated Babesia bovis and Babesia bigemina vaccine strains may be transmitted by the local tick vector Boophilus microplus, and that reversion to virulence could occur. We therefore investigated the possibility that these strains could be transmitted via the transovarial route in ticks using a Babesia species-specific polymerase chain reaction (PCR) assay. DNA was extracted from the developmental stages of the tick vector that had fed on calves immunized with the haemovaccine. It was possible to detect Babesia DNA not only in adult ticks, but also in their eggs and larvae. In addition, it was shown that calves infested with larvae derived from eggs laid by ticks fed on acutely infected calves, were positive for Babesia using PCR. Caution should therefore be shown with the distribution of the haemovaccine in marginal areas. It is still advisable that suitable tick control measures be used to prevent transovarial transmission and the potential risk of attenuated Babesia reverting to virulence. 相似文献
8.
FAILURE OF VACCINE STRAINS OF BABESIA BOVIS TO REGAIN INFECTIVITY FOR TICKS DURING LONG-STANDING INFECTIONS IN CATTLE 总被引：1，自引：0，他引：1
SUMMARY Two strains of Babesia bovis that were known to have lost infectivity for the normal tick vector, Boophilus microplus, due to repeated blood passaging in cattle, were studied to determine whether the strains would regain infectivity for ticks during longstanding infections. Parasitaemlas were monitored in 4 chronically infected calves that were regularly infested with ticks. Two strains of ticks known to be susceptible to infection with unmodified strains of B. bovis were used. Adult female ticks that dropped from the calves on days that a parasitaemia was evident were tested for B. bovis infection. Sixty-six batches of ticks collected up to 279 days after infection of the calves produced 14 pools of larvae, none of which transmitted infection. Primary infections established from the chronic infections by subinoculation at 200, 259 and 333 days after infection of the calves were also not transmitted by ticks. 相似文献
9.
Adult Haemaphysalis punctata (Canestrini and Fanzago 1877) collected from an area of rough grazing at Mynydd Mawr, Aberdaron, North Wales, transmitted Theileria recondita (Wales); field-collected nymphs failed to transmit this parasite. Following adult tick infestation, piroplasms were first observed in the blood of splenectomised infested sheep 8 days after tick attachment; the parasitaemia lasted 9 days. The parasite can also be transferred by syringe passage of blood from splenectomised to normal sheep and vice versa. Parasitaemias were higher and of longer duration in splenectomised animals. A rise in parasitaemia was detected in a splenectomised ewe after parturition, 19 months following blood-transmitted infection from which it had recovered clinically. The morphometrics of the piroplasms of T. recondita (Wales) were investigated; the rod and the ring forms were the most common. The mean length of the rod form was 2.09 microns and the mean diameter of the ring form was 1.22 micron. 相似文献
10.
Sixty calves, 3 to 6 months old, were vaccinated once against Babesia bovis in groups of 10, by the following methods: (a) tick infestation; (b) inoculation of virulent parasites obtained from the tick-infested animals immediately after infection; (c) inoculation of the parasites used in (b) attenuated by passage through splenectomised calves; (d) inoculation of commercially-available, living, attenuated vaccine; (e) inoculation of virulent parasites obtained from the tick-infested animals in (a) one year after infection; (f) inoculation of the parasites used in (e) attenuated by passage. All vaccinated animals were maintained tick-free and were strongly immune to challenge with a heterologous strain of B. bovis approximately 4 years after vaccination. There was no difference in immunogenicity between any of the B. bovis populations. 相似文献
11.
The infectivity of unfed nymphs, adults and ground tissue suspensions of the cattle tick, Hyalomma anatolicum, infected with Theileria annulata was investigated using susceptible calves. Sporozoites of T. annulata introduced into the host by the above mentioned tick stages were able to induced clinical theileriasis in calves. The nature of the disease was the same, whether it was induced by sporozoites injected via 200 infected nymphs or 20 adults (both sexes in equal numbers). This suggests a direct correlation between the infectivity of the ticks and the volume of T. annulata-infected blood sucked by them during their preceding instars. 相似文献
12.
K B Wickwire K M Kocan S J Barron S A Ewing R D Smith J A Hair 《American journal of veterinary research》1987,48(1):96-99
Three isolates of Anaplasma marginale--Virginia (VAM), Illinois (IAM), and Florida (FAM)--were compared for infectivity for Dermacentor andersoni. The isolates were selected, in part, because of a tail-like appendage that has been demonstrated in the VAM and IAM, but not in the FAM. Ticks were exposed to the isolates as nymphs either naturally by feeding on a calf with anaplasmosis or artificially by percutaneous inoculation with infected bovine erythrocytes. They were examined for infectivity after molting to the adult stage by determining their capability to transmit the disease to susceptible calves and by demonstrating colonies in tick gut sections. Only those ticks exposed to the VAM proved to be infected with A marginale; ticks naturally exposed and those artificially infected with this isolate transmitted the disease to susceptible calves. Colonies of A marginale were observed only in gut tissues of ticks naturally infected with VAM. The IAM (appendage present) and FAM (appendage absent) could not be found in ticks exposed by either method, indicating that factors other than the presence of inclusion appendages may be involved in infection of ticks by A marginale. 相似文献
13.
D. P. Gray N. G. Willis A. Girard G. M. Ruckerbauer P. Boulanger G. L. Bannister 《Canadian journal of veterinary research》1967,31(7):182-188
The Cyprus strain of bluetongue virus was successfully transmitted through six passages and the Station strain through one passage in calves. Although the animals developed no visible evidence of infection, viremia as shown by both passage and fluorescent antibody examination of infected foetal bovine kidney culture, and by serological conversion was nevertheless demonstrated. No enhancement of virulence for calves or sheep was shown following bovine passage. A ewe inoculated in late pregnancy with blood drawn from a calf 59 days after its infection, gave birth to a lamb from whose blood the virus was isolated. Significant complement-fixation titres persisted for at least 200 days. 相似文献
14.
SUMMARY: Boophilus microplus ticks collected from calves with patent Anaplasma marginale infections were incubated at either 4 to 5°C, 14°C, 22°C, 27°C or 37°C for up to 14 days. Extracts prepared either from larvae, nymphs, immature females, adult males or mixtures of both sexes were infective for 14 of the 16 splenectomised calves inoculated. Extracts either from nymphs or from adult ticks deriving from nymphs moulted in vitro were infective for 11 of 12 nonsplenectomised calves. Possible application of the findings to producing a vaccine strain of A. marginale is discussed. 相似文献
15.
Standfast NF Bock RE Wiecek MM deVos AJ Jorgensen WK Kingston TG 《Veterinary parasitology》2003,115(3):213-222
Demand for live trivalent tick fever vaccine containing Babesia bovis, Babesia bigemina and Anaplasma centrale produced by the Department of Primary Industries, Queensland, has increased from less than 10,000 doses in 1988 to 500,000 doses in 2001. This paper describes a series of trials aimed at overcoming certain constraints to obtain B. bigemina parasitised erythrocytes (PEs) on a large enough scale from infected splenectomised calves to meet the demand. Passage through a series of splenectomised calves failed to increase the yield per calf but we showed that the dose rate of infected cells could be reduced from the long-time standard of 1x10(7) to 2.5x10(6) without affecting immunogenicity and still leaving a safety margin of at least 50-fold for infectivity. This change quadrupled the potential yield of doses per calf and allowed the DPI to meet the increased demand for B bigemina in vaccine. Due to the high cost and limited availability of suitable, health tested donors, calves previously infected with B. bovis or A. centrale were used to provide B. bigemina organisms but the practice resulted in red cell agglutination in some batches of prepared vaccine. A trial is described where B. bigemina-infected red cells were washed by centrifugation to remove agglutinating antibodies. Washing had no effect on parasite viability and this method is now in routine use in the production of trivalent vaccine. 相似文献
16.
Sheep babesiosis, caused by Babesia ovis (Babes, 1892) is one of the most important sheep diseases in the Mediterranean zone, as well as in other infected areas infested by the vector tick Rhipicephalus bursa (Yeruham et al., 1992, 1995). Attenuated strains of Babesia bovis following rapid blood passages in splenectomized calves have been used as a vaccine (Callow and Mellors, 1966; Stewart, 1978). In the work reported here, rapid passages of B. ovis parasites in splenectomized lambs, using blood collected at the acute stage of the disease, were carried out and their effect on the virulence of the parasite was examined. 相似文献
17.
A A Latif T Hove G K Kanhai S Masaka 《The Onderstepoort journal of veterinary research》2001,68(3):203-208
The Theileria parva carrier-state in cattle on commercial farms on Zimbabwe was investigated using parasitological and serological methods. The proportion of cattle showing Theileria piroplasms on two farms, which had recent histories of disease outbreaks, were 64% (n = 106, total of heifers and weaned calves examined) and 71.5% (n = 60) while the proportion of T. parva antibodies for the same animals were 59% and 98.5%, respectively. On four farms where no cases of the disease occurred for over 10 years, the average proportion of animals showing piroplasms and antibodies were 55.4% (range 32-82, n = 223) and 73% (range 47-91, n = 223), respectively. However, on another three farms which had no history of theileriosis outbreaks these proportions were very low, being 11.4% (0-24, n = 157) for piroplasms and 12.2% (5-23, n = 157) for antibodies. The mean infection rate in unfed Rhipicephalus appendiculatus adults collected from farms with a high prevalence of cattle which were carriers of Theileria piroplasms during the tick activity season was 29% (range 12-60%) with 9.3 (range 2-18.7) mean infected acini per infected tick. The infectivity of different tick batches to susceptible cattle produced a wide spectrum of theileriosis reactions. Laboratory controlled experiments were carried out to study the persistence of T. parva (Boleni) piroplasms in cattle immunized with this strain as well as its infectivity for ticks and its subsequent transmissibility to cattle. Examination of the salivary glands of 15 batches of ticks collected from six immunized cattle on three different occasions over 18 months showed that none were infected with Theileria parasites. However, the infectivity of other ticks in the same batches to susceptible animals was demonstrated 6, 10 and 18 months after cattle had been immunized with Boleni stabilate. 相似文献
18.
Quantal response bioassays were conducted with cattle ticks and sheep blowflies with three different isolates of Metarhizium anisopliae and different methods of inoculation. Ticks were either topically dosed with 2 μl or immersed in the conidial preparations. Blowflies were either topically dosed with 2 μl of the conidial preparation or fed on conidia mixed with sugar. Probit analyses were carried out on the mortality data to compare the virulence of these isolates to ticks and blowflies and look for indications of different virulence mechanisms employed by M. anisopliae isolates when invading these hosts. One isolate (ARIM16) showed high virulence to both hosts killing 95% of ticks after 2 days and 88 (± 2)% of blowflies after 4 days. Strikingly different mortality patterns indicated that virulence is dependent on different mechanisms in ticks and blowflies. The pattern of mortality seen with ticks suggested that the number of conidia adhering per unit area of the cuticle was more important for rapid tick death than the total number of conidia contacting the entire tick surface. Blowflies fed conidia mixed with food died rapidly after an initial lag phase regardless of dose. 相似文献
19.
Groups of Theileria annulata infected Hyalomma anatolicum anatolicum adults prefed on a calf for 1 to 6 days were separately ground in tissue culture medium-199, supplemented with bovine albumin powder, Fraction-V. Supernatant fluid was collected, made up with additional medium, so that each millilitre represented material from 25 ticks, and was injected subcutaneously into groups of cross-bred male calves. The results indicated that ground-up tick supernate (GUTS) prepared from unfed ticks was not infective, whereas that prepared from 1 to 6 days prefed ticks was infective. GUTS prepared from 3 days prefed ticks appeared to contain highest infectivity and 1 ml of it induced fatal theileriosis. 相似文献
20.
甘肃省部分牛羊血液原虫传播媒介的实验研究 总被引：4，自引：0，他引：4
利用蜱传播试验,确定了甘肃省一些牛羊血液原虫的媒介和传播方式。甘肃省牛的双芽巴贝斯虫媒介为微小牛蜱。大巴贝斯虫媒介为长角血蜱。瑟氏泰 勒虫媒介为长角血蜱;绵羊无浆体的媒介为草原革蜱。微小牛蜱、长角血蜱可分别传播双芽巴贝斯虫和大巴贝斯虫,传播方式为经卵传递。将采集于甘肃文县牛体上的微小牛蜱和两当县的长角血蜱饱血雌虫孵育而来的次代幼虫分别叮咬除脾牛体后,２头牛各自感染双芽巴贝斯虫或大巴贝斯虫。将采自崇 相似文献