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1.
OBJECTIVE: To evaluate vaccine safety, antibody response, and nonspecific lymphocyte blastogenesis following inoculation of a commercial monovalent live attenuated bluetongue virus (BTV) serotype 2 vaccine in goats. ANIMALS: 12 nonpregnant and nonlactating Saanen goats. PROCEDURE: 6 goats were inoculated with the monovalent live attenuated BTV serotype 2 vaccine, which has been widely used in Italy during the proceding 2 years. The other 6 goats were unvaccinated and represented negative controls. Nonspecific lymphocyte blastogenesis was evaluated 14 and 7 days before and 7, 21, and 49 days after vaccination by measuring DNA synthesis in peripheral blood mononuclear cells (PBMCs) stimulated with phytohemagglutinin, concanavalin-A, and pokeweed mitogen. On the same days as lymphocyte blastogenesis, blood samples were taken to determine serum concentrations of anti-BTV antibodies. RESULTS: During the 7 weeks following vaccination, PBMCs obtained from vaccinated goats had a significantly decreased response to mitogens in terms of DNA synthesis, compared with PBMCs from the same goats before vaccination. Conversely during the experiment, no significant change was found in the response of the PBMCs obtained from unvaccinated goats. Starting from 21 days after vaccination, serum from vaccinated goats had anti-BTV antibodies. No anti-BTV antibodies were detected in the serum from unvaccinated goats. CONCLUSIONS AND CLINICAL RELEVANCE: Inoculation of goats with the monovalent live attenuated BTV serotype 2 vaccine described herein resulted in a profound depression of nonspecific lymphocyte blastogenesis, which might compromise the resistance of vaccinated goats to pathogens.  相似文献   

2.
Clinical and immunologic responses of sheep to vaccination and subsequent bluetongue virus (BTV) challenge exposure were studied and compared with those of non-vaccinated sheep. Sheep were vaccinated with inactivated BTV administered with aluminum hydroxide and cimetidine or levamisole. After sheep were vaccinated, precipitating group-specific antibodies to BTV were detected, but serotype-specific neutralizing antibodies were not detected. Cellular immune responses (lymphocyte blastogenesis) to BTV were not detected. After virulent BTV challenge exposure, vaccinated and nonvaccinated sheep developed acute clinical disease of similar severity. Clinical signs included hyperemia and petechiae of oral mucosa and coronary bands of the feet, excess salivation, nasal discharge with crusting, ulceration of the muzzle, and edema of lips and intermandibular space. Marked increases in serum creatine kinase activity were associated with stiff gait, reluctance to move, and vomiting. Fever and leukopenia were detected in most of the challenge-exposed sheep. Viremia and neutralizing antibodies were detected in vaccinated and nonvaccinated sheep after challenge exposure. Bluetongue virus-specific reaginic antibodies were not detected in sera from any of the sheep when the passive cutaneous anaphylaxis test was used.  相似文献   

3.
The clinical, virological and serological responses of sheep infected with an Australian bluetongue virus (BTV) isolate (serotype 20) were compared to responses in sheep inoculated with an American bluetongue isolate (serotype 17) with which it had shown cross-reactions in serum neutralization tests. In sheep inoculated with BTV 20, clinical signs were very mild and viremia was first detected by day 5; virus was isolated intermittently for a further 2 to 3 days. Neutralizing and precipitating antibodies were first detected in the serum of the sheep between 2 to 3 weeks following inoculation. In contrast, sheep inoculated with BTV 17 showed pyrexia and severe hyperemia of the nasolabial area and oral mucosa from day 7 to 17. Viremia was first detected on day 3 and extended to day 20, while the appearance and titers of serum antibodies was similar in both groups.After challenge with BTV 17 the sheep in both groups remained clinically normal, and virus was not detected in the blood; however, serum neutralizing antibody titers to both viruses increased 2 weeks after challenge and the mean titer of the two groups ranged from 1:250 to 1:640.  相似文献   

4.
Bluetongue virus (BTV) is a non-enveloped dsRNA virus that causes a haemorrhagic disease mainly in sheep. It is an economically important Orbivirus of the Reoviridae family. In order to estimate the importance of T cell responses during BTV infection, it is essential to identify the epitopes targeted by the immune system. In the present work, we selected potential T cell epitopes (3 MHC-class II-binding and 8 MHC-class I binding peptides) for the C57BL/6 mouse strain from the BTV-8 non-structural protein NS1, using H2b-binding predictive algorithms. Peptide binding assays confirmed all MHC-class I predicted peptides bound MHC-class I molecules. The immunogenicity of these 11 predicted peptides was then determined using splenocytes from BTV-8-inoculated C57BL/6 mice. Four MHC-class I binding peptides elicited specific IFN-γ production and generated cytotoxic T lymphocytes (CTL) in BTV-8 infected mice. CTL specific for 2 of these peptides were also able to recognise target cells infected with different BTV serotypes. Similarly, using a combination of IFN-γ ELISPOT, intracellular cytokine staining and proliferation assays, two MHC-class II peptides were identified as CD4+ T cell epitopes in BTV-8 infected mice. Importantly, two peptides were also consistently immunogenic in sheep infected with BTV-8 using IFN-γ ELISPOT assays. Both of these peptides stimulated CD4+ T cells that cross-reacted with other BTV serotypes. The characterisation of these T cell epitopes can help develop vaccines protecting against a broad spectrum of BTV serotypes and differentiate infected from vaccinated animals.  相似文献   

5.
Bluetongue (BT), a serious disease of sheep and some wild ruminants, is caused by bluetongue virus (BTV), a member of the family, Reoviridae. The current research thrust for controlling BT is on development of efficient vaccines, necessitating clear understanding of ovine immunology. At present, comparative studies on cytokine gene expression profiles of naïve and BTV-sensitized peripheral blood mononuclear cells (PBMC) in sheep have not been clearly understood. In the present study, PBMC from naïve and BEI-inactivated-saponin-adjuvanted BTV-1 vaccinated sheep were stimulated in vitro with heterologous BTV-23. At various intervals, RT-qPCR was carried out to estimate cytokine (interferon-gamma, interleukin-12 and interleukin-2) mRNA expressions that are linked to cell-mediated immunity. The results showed that PBMC cytokine profiles were relatively increased both temporally and quantitatively in immunized sheep PBMC compared to naïve ones, suggesting that BTV-1 vaccination may prime immune system that can cross-react with BTV-23 antigens.  相似文献   

6.
After the incursion of bluetongue virus (BTV) into European Mediterranean countries in 1998, vaccination was used in an effort to minimize direct economic losses to animal production, reduce virus circulation and allow safe movements of animals from endemic areas. Vaccination strategies in different countries were developed according to their individual policies, the geographic distribution of the incurring serotypes of BTV and the availability of appropriate vaccines. Four monovalent modified live virus (MLV) vaccines were imported from South Africa and subsequently used extensively in both cattle and sheep. MLVs were found to be immunogenic and capable of generating strong protective immunity in vaccinated ruminants. Adverse side effects were principally evident in sheep. Specifically, some vaccinated sheep developed signs of clinical bluetongue with fever, facial oedema and lameness. Lactating sheep that developed fever also had reduced milk production. More severe clinical signs occurred in large numbers of sheep that were vaccinated with vaccine combinations containing the BTV-16 MLV, and the use of the monovalent BTV-16 MLV was discontinued as a consequence. Abortion occurred in <0.5% of vaccinated animals. The length of viraemia in sheep and cattle that received MLVs did not exceed 35 days, with the single notable exception of a cow vaccinated with a multivalent BTV-2, -4, -9 and -16 vaccine in which viraemia persisted at least 78 days. Viraemia of sufficient titre to infect Culicoides insects was observed transiently in MLV-vaccinated ruminants, and natural transmission of MLV strains has been confirmed. An inactivated vaccine was first developed against BTV-2 and used in the field. An inactivated vaccine against BTV-4 as well as a bivalent vaccine against serotypes 2 and 4 were subsequently developed and used in Corsica, Spain, Portugal and Italy. These inactivated vaccines were generally safe although on few occasions reactions occurred at the site of inoculation. Two doses of these BTV inactivated vaccines provided complete, long-lasting immunity against both clinical signs and viraemia, whereas a single immunization with the BTV-4 inactivated vaccine gave only partial reduction of viraemia in vaccinated cattle when challenged with the homologous BTV serotype. Additional BTV inactivated vaccines are currently under development, as well as new generation vaccines including recombinant vaccines.  相似文献   

7.
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8.
Red deer (Cervus elaphus) is a widespread and abundant species susceptible to bluetongue virus (BTV) infection. Inclusion of red deer vaccination among BTV control measures should be considered. Four out of twelve BTV antibody negative deer were vaccinated against serotype 1 (BTV-1), and four against serotype 8 (BTV-8). The remaining four deer acted as unvaccinated controls. Forty-two days after vaccination (dpv), all deer were inoculated with a low cell passage of the corresponding BTV strains. Serological and virological responses were analyzed from vaccination until 28 days after inoculation (dpi). The vaccinated deer reached statistically significant (P<0.05) higher specific antibody levels than the non vaccinated deer from 34 (BTV-8) and 42 (BTV-1) dpv, maintaining stable neutralizing antibodies until 28 dpi. The non vaccinated deer remained seronegative until challenge, showing neutralizing antibodies from 7 dpi. BTV RNA was detected in the blood of the non vaccinated deer from 2 to 28 dpi, whereas no BTV RNA was found in the vaccinated deer. BTV was isolated from the blood of non vaccinated deer from 7 to 28 dpi (BTV-1) and from 9 to 11 dpi (BTV-8). BTV RNA could be identified by RT-PCR at 28 dpi in spleen and lymph nodes, but BTV could not be isolated from these samples. BT-compatible clinical signs were inapparent and no gross lesions were found at necropsy. The results obtained in the present study confirm that monovalent BTV-1 and BTV-8 vaccines are safe and effective to prevent BTV infection in red deer. This finding indicates that vaccination programs on farmed or translocated red deer could be a useful tool to control BTV.  相似文献   

9.
In a field trial, 9174 lambs from seven commercial sheep flocks with a history of subclinical pneumonia were either vaccinated with Ovipast Plus (Intervet) or given a placebo by systematic random allocation; they were vaccinated twice at an interval of four to six weeks and grazed on pasture in the same paddocks. They were weighed at the first vaccination, 11 and 23 weeks later, and one to three days before they were slaughtered. The extent of the pneumonic lesions in their lungs was scored visually postmortem. A subset of pneumonic lung samples was examined bacteriologically and histopathologically. There were no statistically significant differences between the pneumonic lesions at slaughter or the mean average daily weight gains of the vaccinated and placebo-treated lambs between 11 and 23 weeks or between first vaccination and slaughter. The vaccinated lambs had a lower mean daily gain between first vaccination and 11 weeks. The extent of pneumonic lesions at slaughter was negatively correlated with the mean daily gain between first vaccination and slaughter. There were no significant differences between the frequency of isolation of Mannheimia (Pasteurella) haemolytica and Pasteurella trehalosi or the histopathological classification of disease between pneumonic lung samples from the placebo-treated and vaccinated lambs.  相似文献   

10.
Bluetongue (BT) virus, an orbivirus of the Reoviridae family encompassing 24 known serotypes, is transmitted to ruminants via certain species of biting midges (Culicoides spp.) and causes thrombo-hemorrhagic fevers mainly in sheep. During the 20th century, BTV was endemic in sub-tropical regions but in the last ten years, new strains of BTV (serotypes 1, 2, 4, 8, 9, 16) have appeared in Europe leading to a devastating disease in naive sheep and bovine herds (serotype 8). BTV enters into insect cells via the viral inner core VP7 protein and in mammalian cells via the external capsid VP2 haemagglutinin, which is the major determinant of BTV serotype and neutralization. BTV replicates in mononuclear phagocytes and endothelial cells where it induces expression of inflammatory cytokines as well as apoptosis. BTV can remain as nonreplicating entities concealed in erythrocytes for up to five months. Homologous protection against one BTV serotype involves neutralizing antibodies and T cell responses directed to the external VP2 and VP5 proteins, whereas heterologous protection is supported by T cells directed to the NS1 non structural protein and inner core proteins. Classical inactivated vaccines directed to a specific serotype generate protective immunity and may help control current epidemic situations. New recombinant vaccine strategies that allow differentiating infected from vaccinated animals and that generate cross protective immunity are urgently needed to efficiently combat this worldwide threatening disease.  相似文献   

11.
Bluetongue (BT), a serious disease of sheep and some wild ruminants, is caused by bluetongue virus (BTV), a member of the family, Reoviridae. The current research thrust for controlling BT is on development of efficient vaccines, necessitating clear understanding of ovine immunology. At present, comparative studies on cytokine gene expression profiles of na?ve and BTV-sensitized peripheral blood mononuclear cells (PBMC) in sheep have not been clearly understood. In the present study, PBMC from na?ve and BEI-inactivated-saponin-adjuvanted BTV-1 vaccinated sheep were stimulated in vitro with heterologous BTV-23. At various intervals, RT-qPCR was carried out to estimate cytokine (interferon-gamma, interleukin-12 and interleukin-2) mRNA expressions that are linked to cell-mediated immunity. The results showed that PBMC cytokine profiles were relatively increased both temporally and quantitatively in immunized sheep PBMC compared to na?ve ones, suggesting that BTV-1 vaccination may prime immune system that can cross-react with BTV-23 antigens.  相似文献   

12.
Bluetongue (BT) is an economically important disease of ruminants caused by bluetongue virus (BTV) and transmitted by Culicoides biting midges. The most practical and effective way to protect susceptible animals against BTV is by vaccination. Data from challenge studies in calves and sheep conducted by Intervet International b.v., in particular, presence of viral RNA in the blood of challenged animals, were used to estimate vaccine efficacy. The results of the challenge studies for calves indicated that vaccination is likely to reduce the basic reproduction number (R(0)) for BTV in cattle to below one (i.e. prevent major outbreaks within a holding) and that this reduction is robust to uncertainty in the model parameters. Sensitivity analysis showed that the whether or not vaccination is predicted to reduce R(0) to below one depended on the following assumptions: (i) whether "doubtful" results from the challenge studies are treated as negative or positive; (ii) whether or not the probability of transmission from host to vector is reduced by vaccination; and (iii) whether the extrinsic incubation period follows a realistic gamma distribution or the more commonly used exponential distribution. For sheep, all but one of the vaccinated animals were protected and, consequently, vaccination will consistently reduce R(0) in sheep to below one. Using a stochastic spatial model for the spread of BTV in Great Britain (GB), vaccination was predicted to reduce both the incidence of disease and spatial spread in simulated BTV outbreaks in GB, in both reactive vaccination strategies and when an incursion occurred into a previously vaccinated population.  相似文献   

13.
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14.
Immunologic response of sheep to inactivated and virulent bluetongue virus   总被引：2，自引：0，他引：2  
Humoral and cellular immune responses of sheep to inactivated and virulent bluetongue virus (BTV) were studied. All sheep inoculated with inactivated BTV developed BTV group-specific nonneutralizing antibodies, as determined by agar-gel immunodiffusion. The development of group-specific, nonneutralizing, complement-fixing antibodies was variable and appeared to be dependent on immunizing BTV serotype, sheep breed, and individual variation. Virus-neutralizing antibodies were never detected after inoculation with the inactivated BTV. In vitro lymphocyte stimulation to BTV soluble antigen was observed with cells from all inoculated Warhill sheep and with cells from 1 of 3 inoculated Suffolk cross sheep. Complement-fixation titers did not appear to correlate with the degree of protection observed, ie, duration of postchallenge-exposure viremia. The development of postchallenge-exposure neutralizing antibody titer was inversely correlated to protective immunity. The development of a response to BTV antigen in the lymphocyte-stimulation test associated most closely with protection. Warhill sheep were afforded better protection, by inoculation with inactivated BTV, to live virus challenge exposure than were the Suffolk cross sheep. Approximately 30% of the inoculated Suffolk cross sheep responded to challenge exposure with intensified clinical signs of blue-tongue, compared with the challenge-exposed control sheep of the same breed.  相似文献   

15.
The IgM and IgG response of mice to sheep erythrocytes (SRBC) and bluetongue virus (BTV) was determined by means of haemolytic plaque assays. Maximum primary IgM response to SRBC occurred after 4 days but declined rapidly to 4% of the maximum by Day 9. A lag period of about 2 days was observed in the appearance of IgG haemolytic plaque-forming cells (PFC) but they reached a maximum after 6-9 days. Secondary immunization resulted in the stimulation particularly of IgG PFC and from Day 6 onwards IgG predominated in the immunological response. The IgM response to BTV was remarkably similar to that observed when SRBC were used as antigen. IgG PFC, however, appeared within a day of the IgM, reaching a peak on Days 4-5. From then onwards, IgG PFC predominated in the response. At BTV concentrations of up to 10 mug per mouse, the virulent strain of BTV type 3 produced the weakest response. At higher antigen concentrations there was very little difference in the response to the serotypes tested, although the virulent strain of BTV type 4 tended to produce the strongest response.  相似文献   

16.
本试验旨在探明绵羊感染16型蓝舌病病毒(Bluetongue virus type 16,BTV16)后细胞因子IFN-γ、IL-2、IL-4和IL-10的消长特点。用实时荧光定量PCR检测方法对感染BTV16后3只绵羊上述4种因子mRNA进行检测,同时设立阴性对照绵羊,并以0 d mRNA为基准,计算mRNA的相对表达量,同时检测病毒抗体效价、测量绵羊体温。结果显示,接种BTV16的3只绵羊均不同程度产生抗体和体温症状,4种细胞因子的mRNA在接种病毒2~4 d内均出现显著上升,其中IFN-γ峰值在2.58~27.84倍之间,IL-2峰值在5.24~17.19倍之间,IL-4峰值在2.16~3.43倍之间,IL-10峰值在15.78~48.77倍之间,个体上升幅度存在显著差异,4种细胞因子均在高水平持续6 d左右后逐渐下降。对照绵羊上述参数在正常范围内波动。本研究阐明了接种BTV16后绵羊细胞因子IFN-γ、IL-2、IL-4、IL-10在转录水平上的消长特点,为进一步深入开展BTV感染特征、宿主机体免疫机制研究提供参考。  相似文献   

17.
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18.
Sheep had viremias that were first detected on day 3 (+/- 1) after infection with several strains of bluetongue virus (BTV) representing United States serotypes 10, 11, 13, and 17. Diphasic peaks of infectivity were attained on days 6 and 10 (+/- 2). Interferon (IFN) was first detected in serum samples on day 5 (+/- 1), and reached greatest concentrations on day 6 (+/- 2), which coincided with the first viremic peak; IFN concentrations then decreased toward zero by day 10 (+/- 2). Interferon peak concentrations induced approximately a 90% decrease in virus titer. The decrease in IFN concentrations by day 9 (+/- 2) corresponded with the second viremic peak on day 10 (+/- 2). Onset of the decrease in detectable concentrations of virus after the second peak of viremia corresponded to the initial detection of serum antibody to BTV by day 10 (+/- 2). Virus titer decreased and antibody production increased until approximately days 21 to 28, when the titers plateaued and virus was not detected. Febrile responses peaked on day 7 (+/- 1) during the peak viremic period. The WBC count was depressed at the time the virus titer increased, but returned to normal values while the sheep were still viremic. Diphasic viremias in BTV-infected sheep were attributed to induction of high concentrations of IFN concurrent with the first virus titer peak, followed by production of antibody to specific BTV strains and a subsequent reduction in viremia at the second virus titer peak.  相似文献   

19.
SUMMARY A cell culture attenuated Australian bluetongue virus serotype 23 (BLU23) prototype vaccine was assessed for its effects on pregnant Merino sheep. Seventy-six ewes were vaccinated at 5 different stages of gestation, and the failure to lamb at term was as follows: 35 to 43 days of gestation, 20/36 (56%); 57 to 64 days of gestation, 3/10 (30%); 81 to 88 days of gestation, 3/10 (30%); 109 to 116 days of gestation, 0/10 (0%); 130 to 137 days of gestation, 0/10 (0%). Of 30 ewes vaccinated with a cell culture supernatant fluid control between 35 and 43 days of gestation, 6.7% (2/30) failed to lamb at term. Two ewes vaccinated with BLU23 vaccine between 35 and 43 days of gestation had lambs with hydranencephaly. All other lambs born were clinically normal. Three ewes vaccinated with BLU23 aborted. Two of these were vaccinated between 35 and 43 days of gestation, the 3rd between 81 and 88 days of gestation. Five lambs were born with BLU group antibody. Four of these were from ewes vaccinated between 35 and 43 days of gestation, and 2 of these had hydranencephaly. The fifth was from a ewe vaccinated between 57 and 64 days of gestation. The vaccine did not produce disease in adult sheep, but was a potent cause of early foetal death and to a much lesser extent foetal malformation.  相似文献   

20.
本试验旨在探明绵羊感染16型蓝舌病病毒（Bluetongue virus type 16,BTV16）后细胞因子IFN-γ、IL-2、IL-4和IL-10的消长特点。用实时荧光定量PCR检测方法对感染BTV16后3只绵羊上述4种因子mRNA进行检测,同时设立阴性对照绵羊,并以0 d mRNA为基准,计算mRNA的相对表达量,同时检测病毒抗体效价、测量绵羊体温。结果显示,接种BTV16的3只绵羊均不同程度产生抗体和体温症状,4种细胞因子的mRNA在接种病毒2~4 d内均出现显著上升,其中IFN-γ峰值在2.58~27.84倍之间,IL-2峰值在5.24~17.19倍之间,IL-4峰值在2.16~3.43倍之间,IL-10峰值在15.78~48.77倍之间,个体上升幅度存在显著差异,4种细胞因子均在高水平持续6 d左右后逐渐下降。对照绵羊上述参数在正常范围内波动。本研究阐明了接种BTV16后绵羊细胞因子IFN-γ、IL-2、IL-4、IL-10在转录水平上的消长特点,为进一步深入开展BTV感染特征、宿主机体免疫机制研究提供参考。  相似文献   

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