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1.
West African Dwarf sheep were challenged with a low mouse brain-passaged Rift Valley fever virus (Ib-AR 55172) isolated from Nigeria. Viraemia, mild febrile reaction and neutralising antibodies were demonstrated in inoculated animals.  相似文献   

2.
Three strains of Rift Valley fever virus, namely Nigerian (NIG), Smithburn's neurotropic (SNT), and Lunyo variant (LUN) were compared by complement fixation (CF), neutralisation (N), haemagglutination/haemagglutination-inhibition (HA/HI) and agar gel diffusion (AGD) tests. They showed reciprocal cross-reactivity in CF tests. In N tests, using immune sheep sera, there was reciprocal cross-neutralisation between the NIG and SNT strains, but not with the LUN strain, the antiserum of which neutralised both NIG and SNT antigens whereas the reverse was not the case. When hyperimmune mouse ascitic fluid was employed in N tests, there was cross-reactivity between the three strains. Both the NIG and SNT strains yielded haemagglutinins, but not the LUN strain. Furthermore, by the antibody absorption and AGD techniques, the NIG and SNT strains were found to be identical and distinct from the LUN variant strain. The techniques found most useful in distinguishing between the three strains were HA and AGD. Laboratory neuro-adaptation of the classical pantropic virus did not appear to affect its haemagglutination activity.  相似文献   

3.
West African dwarf sheep were inoculated by the subcutaneous route with epizootic haemorrhagic disease of deer (EHD) virus or bluetongue (BT) virus. No clinical disease was observed following primary EHD or BT infection, or subsequent challenge with either homologous or heterologous virus. However, viraemia was detected in non-immune sheep exposed to BT virus, but not in BT- or EHD-immune sheep challenged with either virus, or in non-immune sheep exposed to primary EHD virus infection. Complement fixing antibodies developed against both EHD and BT viruses following the primary infection with either virus, or subsequent challenge with homologous or heterologous virus. Following a primary infection, virus-neutralising (VN) antibodies developed only against the inoculated virus, while the detection of VN antibodied to both viruses followed the challenge of an EHD- or BT-immuned sheep with either the homologous or heterologous virus. These findings further support previous reports of a relationship between EHD and BT viruses. between EHD and BT viruses.  相似文献   

4.
Three newborn calves were inoculated intracerebrally with bovine ephemeral fever virus strain 525. The 2 that lacked detectable neutralising antibody to bovine ephemeral fever vaccine developed fatal encephalitis after 4 and 7 days respectively. The third calf which had a low level of maternal antibody remained healthy and developed antibody that became undetectable after 6 months. Bovine ephemeral fever virus strain 525 was reisolated from the brains of both dead calves by intracerebral inoculation of suckling mice. Homogenates that were prepared from the brains of the calves failed to produce disease or to induce antibody formation in susceptible calves when inoculated intravenously. Strain 525 of BEF virus has been shown to possess a degree of neurovirulence for laboratory animals that has not been reported for other strains (Tzipori and Spradbrow 1974). Although this strain is unable to produce viraemia in calves after I/V inoculation, the present study shows that strain 525 can multiply in the brain tissues of calves and cause death after I/C inoculation.  相似文献   

5.
A South African isolate of bluetongue virus type 3 was inoculated intradermally into three different breeds of British sheep under conditions designed to test its virulence in animals under stress. All animals inoculated developed a pyrexia and viraemia followed by clinical evidence of bluetongue disease. Marked alterations in serum enzyme levels, in particular of creatine phosphokinase, lactate dehydrogenase and aldolase occurred in the more severely affected animals. Nine out of the 12 inoculated animals subsequently died. No major differences in response could be detected in the different breeds of sheep nor in the stressed compared with the unstressed groups. The virulence of this bluetongue virus isolate was thereby confirmed and its potential risk to the British sheep industry. Consequently, stringent import regulations must be maintained to prevent its entry into Britain.  相似文献   

6.
Groups of cattle, sheep and poultry were inoculated with a recombinant vaccinia virus expressing the haemagglutinin of the swine influenza virus A/NJ/11/76. No adverse clinical responses were recorded and none of the animals developed a viraemia when inoculated with the recombinant or wild-type vaccinia virus. Recombinant virus reisolated from lesions in cattle was stable, maintaining its thymidine kinase negative phenotype and ability to express the swine influenza haemagglutinin. Antibodies to the influenza haemagglutinin were detected in cattle, sheep and poultry inoculated with the recombinant virus. While no animals inoculated with wild-type virus developed these antibodies, there was no detectable spread of either recombinant or wild-type virus from the inoculation sites or to in-contact uninoculated animals. The results indicate that recombinant vaccinia viruses can induce immune responses in cattle, sheep and poultry demonstrating their potential as vaccine vectors in a variety of important veterinary species.  相似文献   

7.
The clinical course, post mortem lesions as well as virological and serological results after simultaneous intranasal inoculation of pigs with bovine viral diarrhoea virus (BVDV) and hog cholera virus (HCV) are described. Five groups of four weaners received constant doses of BVDV strain OSLOSS/2482 and tenfold decreasing doses of HCV strain ALFORT/187. Doses of 1,000 and 100 TCID50 of HCV in groups A and B of pigs led to fever and severe clinical signs in all animals of two groups, whereas at higher dilution of inoculum two, three or four animals survived without any clinical signs in the respective groups (C-E). Leucocyte samples taken from febrile animals and from normal pigs on five consecutive days were inoculated into both fetal calf kidney (FCK) and PK (15) cell cultures. Virus isolates were differentiated with BVDV and HCV specific monoclonal antibodies. HCV viraemia was detected in febrile animals exclusively, and BVDV viraemia occurred in not affected animals on days 3 to 7 post inoculation. Neutralizing antibodies (nab) against BVDV appeared before HCV nab in surviving animals of groups C and D after receiving low doses of HCV (10 or 1 TCID50). No BVDV nab were detected in group E that had received such a high dilution of HCV in addition to BVDV that theoretically no HCV was applied.  相似文献   

8.
Different isolates of peste-des-petits-ruminants virus (PPRV) from outbreaks in Africa and India were investigated for virulence in West African dwarf goats in the Ivory Coast. Six groups of five animals received a virulent suspension of various strains of virus at a concentration of 103 TCID50/mL and the goats were observed for 15 days after infection. The Côte-d’Ivoire 89 (CI89), Guinea Conakry and Bissau Guinea PPRV strains caused a peracute disease; the India-Calcutta strain caused acute disease; the Sudan-Sennar strain produced an acute to mild disease, while the Nigeria 75/1 wild-type strain caused a mild disease and the animals recovered. The viruses studied contained examples of PPRV from specific lineage groups based on their nucleoprotein PPRV gene. This experiment indicated that virulence characteristics might be a useful marker to help classify PPRV isolates.  相似文献   

9.
West African Dwarf Sheep inoculated sequentially with two flaviviruses: yellow fever and Dakar bat or West Nile and yellow fever viruses, developed neutralizing (N) and haemagglutination inhibiting (HI) antibodies to several flaviviruses; dengue type 1, dengue type 2, yellow fever, West Nile and Wesselsbron viruses. Experimental infection of these animals with the indigenous strain of Wesselsbron virus resulted in the modification of the clinical disease. The disease was reduced in severity and there was complete absence of, or marked reduction in the level and duration of circulating virus and fever. Seronegative animals infected with the same strain of Wesselsbron virus developed the classical disease characterized by a high fever, anorexia, leucopenia and a high level of viraemia. The absence of clinical reports of Wesselsbron disease and lack of other isolations of the virus from Nigeria could possibly be explained by the presence of the flavivirus group antibodies in domestic animal sera.  相似文献   

10.
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11.
The pathogenicity of a field strain, 417, of bovine ephemeral fever (BEF) virus for newborn and young calves was investigated. Three colostrum-deprived newborn calves inoculated intravenously developed severe clinical disease and viraemia, and produced long-lasting neutralising antibody. The incubation period in these animals was 10 and 11 days, compared with 5 to 7 days for older calves. Two newborn calves which received colostrum from immune dams and 2 which received colostrum from non-immune dams failed to respond clinically to intravenous inoculation with strain 417. The neutralising antibody response of these calves was of short duration. Four calves, 7 to 8 weeks old and lacking detectable neutralising antibody to BEF virus, or having low levels of antibody, did not develop clinical disease when inoculated intravenously. Four calves 12 to 14 weeks of age and free of detectable neutralising antibody to BEF virus developed clinical disease when inoculated with strain 417.  相似文献   

12.
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13.
Sheep pox: experimental studies with a west african isolate   总被引：2，自引：0，他引：2       下载免费PDF全文
Under conditions of a maximum security laboratory, four cross-bred sheep were inoculated intradermally only or intradermally and intratracheally with a West African isolate of sheep pox virus. All sheep had increased temperature and depression by the fourth or fifth day after infection. Nasal and lacrimal discharge and coughing occurred in all sheep but were more severe in sheep receiving the virus via the tracheal route. From the fifth day after infection, numerous papular erythematous skin lesions developed at the inoculation sites. These were 3-7 mm in diameter and gradually became nodular. Some of these lesions healed and others coalesced to form tumorlike masses. In one sheep, euthanized 14 days after intradermal and intratracheal inoculation, nodular lesions were found in the skin around the eyes, nostrils, oral and perianal regions, the mucosa of the rumen and throughout the lungs. Histologically, skin nodules were characterized by ischemic necrosis, vasculitis, microvesicualtion, eosinophilic cytoplasmic inclusions in the dermal epithelial cells and vacuolar nuclear degeneration. The pulmonary lesion was that of proliferative alveolitis with occasional cytoplasmic inclusions in the alveolar cells and macrophages. Ultrastructurally, large cuboidal virus particles were found both in the skin lesion and inoculated tissue cultures. The sheep pox virus structure was easily distinguished from contagious ecthyma virus, a parapoxvirus which causes sporadic disease in Canada. Serum neutralizing antibodies developed in all the sheep by 14 days postinfection.

The clinical and pathological characteristics of experimental sheep pox produced with this West African isolate were similar to those caused by Neethling virus of lumpy skin disease in cattle.

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14.
The caprinised strain of rinderpest virus was inoculated into goats to produce a challenge stock. These goats were kept with control animals (goats, sheep, calves). In this trial the caprinised strain was shown to have a mild pathogenicity for goats and it spread to one of two contact goats but not from goats to other species. The caprinised strain was then tested on cattle where a febrile reaction was observed. The caprinised strain also did not spread between cattle. The cattle vaccinated with a freeze-dried vaccine produced from the attenuated Kabete RBKO strain on bovine kidney cells were then challenged with the caprinised strain with good results.  相似文献   

15.
A mutagenized clone of Rift Valley fever virus (RVFV; MV P12) used in inoculation of 3 pregnant ewes was immunogenic, nonpathogenic, and nonabortogenic. In contrast, inoculation of a matched group of 3 pregnant ewes with parent RVFV induced clinical disease and abortions. Ewes given MV P12 delivered healthy lambs that had RVFV antibody titers of less than 1:10 at birth, increasing to greater than or equal to 1:80 after ingestion of colostrum. Ewes inoculated with parent RVFV developed marked viremia, followed by RVFV antibody titers greater than or equal to 1:1,280; ewes inoculated with MV P12 developed low viremia titers and RVFV antibody titers of 1:80 to 1:320. Postpartum challenge exposure of the previously MV P12-inoculated ewes with virulent Zagazig human 501 strain RVFV indicated that the ewes were protected from clinical disease. The RVFV-susceptible female Culex pipiens that fed on the MV P12-inoculated ewes failed to transmit RVFV to hamsters; mosquitoes that fed on the parent RVFV-inoculated ewes became infected and transmitted RVFV to hamsters.  相似文献   

16.
Twenty horses that were seronegative for equine arteritis virus antibodies were inoculated IM with live equine arteritis virus vaccine. The inoculation did not cause clinical signs of disease. A mild, transient febrile reaction developed in 6 horses, 3 of which were in poor condition before inoculation. Six horses, 2 of which were in poor condition before inoculation, experienced mild lymphopenia. Necropsy revealed mild lesions in the lymph nodes of 6 horses (3 of which were in poor condition before inoculation). Maximum concentrations of virus were detected in the lymph nodes and were consistently present from postvaccination day 3 through 8. Lesser concentrations of virus were detected in the spleen of 5 horses, liver and kidney of 4, abdominal fluid of 3, pleural fluid of 2, and lungs and urine of 1, between postvaccination days 3 and 7. Virus was not detected in the brain, nasal tract, or serum of any of the horses.  相似文献   

17.
Four Merino sheep inoculated intravenously with bovine blood containing ephemeral fever virus showed no clinical signs of ephemeral fever. Two sheep showed a mild haematological response and developed a neutralising antibody which closely paralled that of a steer inoculated at the same time. Leucocytes harvested from these 2 sheep on days 3 and 4 after inoculation with virus reproduced ephemeral fever when inoculated into susceptible steers whilst those harvested on days 1, 2 and 5 did not. Even though this indicates that EFV can multiply in some sheep when they are inoculated intravenously, it cannot be inferred that natural infection occurs.  相似文献   

18.
Eight sheep were inoculated with Icelandic maedi strain M 88; 2 sheep served as control sheep and were in close contact with the inoculated ones. Four of the sheep were inoculated via the respiratory tract with 7×106 TGID50 of strain M88 and the other 4 intracerebrally with 5×105 TGID50 of the same strain.Maedi M88 strain was isolated from peripheral blood leukocytes of all inoculated sheep. There was a striking difference between the 2 groups in the appearance of demonstrable viremia after inoculation. Viremia could be demonstrated in the intrapulmonarily inoculated sheep within 2–6 months but not until 8–11 months after inoculation in the intracerebrally inoculated ones. This finding is thought most probably to reflect a weak neurotropism of the strain used. After the first demonstration of viremia, maedi virus has been recovered quite reqularly in peripheral leukocytes of all intrapulmonarily inoculated sheep, but less regularly in the intracerebrally inoculated ones. Maedi virus was isolated from 1 of the uninoculated control sheep 15 months after inoculation.The first clinical case with a clinical appearance suggesting combined involvement of maedi and visna was found among the intrapulmonarily inoculated sheep, 8% months after inoculation. Histopathological examination and virus isolation confirmed maedi. The cause of paraplegia could not be confirmed. No histopathological changes were found and no virus isolation was made from the central nervous system of this animal.One of the intracerebrally inoculated sheep died suddenly without any observed clinical signs 11 months after inoculation. Histopathological examination revealed pulmonary lesions of maedi, but no visna lesions in the central nervous system, although maedi virus was isolated from various parts of brain.None of the other experimental sheep displayed clinical signs of maedi or visna during the observation period of 18 months.  相似文献   

19.
An enzyme-linked immunosorbent assay (ELISA) was developed for the rapid detection of antibodies to Rift Valley fever virus (RVFV) in ovine and bovine sera. Conditions to reduce nonspecific reactions were optimized. The ELISA results correlated with those of a plaque-reduction neutralization test, revealing 100% specificity and 90.7% sensitivity. In sera from sheep and cattle inoculated against RVFV, the hemagglutination-inhibition test in combination with the ELISA provided a better indication of response to killed RVFV vaccine than did either test alone.  相似文献   

20.
A CELL CULTURE VACCINE AGAINST BOVINE EPHEMERAL FEVER   总被引：1，自引：0，他引：1  
SUMMARY A vaccine was prepared from cell culture fluids harvested from the twelfth passage of the 919 strain of bovine ephemeral fever (BEF) virus in Vero cell cultures. Cattle were vaccinated subcutaneously with various combinations of strain 919 virus and adjuvants. Neutralising antibodies were assayed at various times after vaccination and some cattle were challenged by intravenous inoculation with the virulent 417WBC strain of BEF virus. Strain 919 virus of the third and twelfth passage levels in Vero cells produced neither fever, clinical illness nor detectable viraemia in 5 calves inoculated intravenously. Nor could viraemia be detected in 5 heifers receiving vaccine subcutaneously. When the vaccine was administered mixed with aluminium hydroxide adjuvant, the production of neutralising antibodies increased with an increase in the volume of vaccine from 2.5 ml to 10 ml and the response to 2 injections was significantly better than the response to a single injection. The neutralising antibody response was decreased when vaccine was diluted in phosphate buffered saline. The neutralising antibody response following 2 subcutaneous vaccinations with strain 919 virus mixed with aluminium hydroxide adjuvant was higher than that following intravenous inoculation with virulent virus. The vaccine-induced antibodies persisted for at least 12 months, and revaccination at this time led to an increase in the titre of neutralising antibody. Antibodies induced by a single subcutaneous administration of strain 919 virus mixed with Freund's complete adjuvant persisted for at least 40 weeks; those induced by vaccine containing Freund's incomplete adjuvant had virtually disappeared within 16 weeks. All these calves responded to vaccination with aluminium hydroxide-containing vaccine with increases in levels of neutralising antibodies. Of 26 vaccinated calves challenged with virulent BEF virus, 24 remained clinically normal. Two developed brief periods of pyrexia on the seventh day after challenge, but no other clinical signs. One of these calves had a viraemia that was demonstrated only by intravenous inoculation of a susceptible calf. The remaining calf had no detectable viraemia. All of 7 unvaccinated calves developed severe clinical BEF within 5 days of challenge. No disease attributable to the 919 virus occurred in 24 vaccinated pregnant heifers or their newborn calves.  相似文献   

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