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1.
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
2.
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
3.
Gubbins S Hartemink NA Wilson AJ Moulin V Vonk Noordegraaf CA van der Sluijs MT de Smit AJ Sumner T Klinkenberg D 《Preventive veterinary medicine》2012,105(4):297-308
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
4.
Malik Amir Iftikhar Ijaz Muhammad Yaqub Tahir Shabir Muhammad Zubair Avais Muhammad Ghaffar Awais Ali Ahmad Farooqi Shahid Hussain Mehmood Khalid 《Tropical animal health and production》2019,51(4):977-982
Bluetongue virus (BTV), a member of Orbivirus genus (family Reoviridae), is a non-contagious infection of domestic and wild ruminants. The current study was designed to detect various serotypes of BTV in small ruminants of Khyber Pakhtunkhwa (KPK) province of Pakistan, along with their effects on hemato-biochemical parameters. A total of 408 serum samples in four districts (Mansehra, Abbottabad, Swabi, and Kohat) of KPK from small ruminants were screened based on competitive ELISA (cELISA). A total of 204 (50%) samples were found positive for BTV group–specific antibodies. The seropositive samples were processed for the detection of BTV serotypes through real-time polymerase chain reaction (qPCR). Out of 204 cELISA-positive samples, 60 (29.41%) were found positive through qPCR. Three serotypes [6, 8, 9] were detected from Mansehra District and two from Kohat [2, 8] and Abbottabad [6, 8], while only one from Swabi [8]. The serotype “8” was found consistently in all the four study districts. A significant (p?<?0.05) increase in the level of blood urea nitrogen (BUN) and alkaline phosphatase (ALP) was recorded in goats, whereas aspartate aminotransferase (AST) in sheep infected with BTV, compared to healthy animals. The hematological parameters showed significantly (p?<?0.05) raised total leucocyte count (TLC) in both sheep and goats, whereas only hematocrit (HCT) value was increased significantly (p?<?0.05) in infected sheep. This is the first report on serotyping of BTV among small ruminants in Pakistan.
相似文献5.
Bluetongue virus infection in sheep: haematological changes and detection by polymerase chain reaction 总被引：2，自引：0，他引：2
SUMMARY Eight sheep vaccinated with 106 pfu of attenuated Australian bluetongue virus serotype 23 (BTV-free sheep were challenged with virulent BTV 23. There was little subsequent variation in the mean clinical score, or in the mean lymphocyte and platelet concentrations in the peripheral blood of the eight vaccinated sheep. There was a marked thrombocytopenia and lymphopenia in the naive sheep as the mean lymphocyte and platelet concentrations fell to a minimum at days 8 and 11 after inoculation, respectively. Similar changes were observed in three other naive sheep inoculated with field isolates of BTV 1, 9 or 23. BTV was detected by nested polymerase chain reaction in whole blood of these sheep between days 6 and 28, in mononuclear leukocytes between days 3 and 14, and in platelets between days 6 and 21. 相似文献
6.
Clinical and serological response of sheep to serial challenge with different bluetongue virus types
A group of British sheep was infected with bluetongue virus 5 (BTV5) and subsequently challenged with the same virus type. Protection from this challenge and a homotypic BTV neutralising antibody response were observed. A second group of sheep was infected serially with three different BTV types. Animals previously exposed to BTV4 and BTV3 were found to be resistant to challenge by BTV6. Animals infected with BTV4 and challenged with BTV3 were shown to produce a transient heterotypic neutralising antibody response to a number of types. Although the level of this heterotypic response diminished with time, after challenge with BTV6 these animals developed a similar broad heterotypic response. The nature of this response and its implications in terms of observed protection merit consideration in future vaccine design and evaluation of field survey work. 相似文献
7.
Lorca-Oró C López-Olvera JR Fernández-Sirera L Solanes D Navarro N García-Bocanegra I Lavín S Domingo M Pujols J 《Veterinary microbiology》2012,154(3-4):240-246
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
8.
Randall S. Singer Walter M. Boyce Ian A. Gardner Wesley O. Johnson Amy S. Fisher 《Preventive veterinary medicine》1998,35(4):6857-282
Five bluetongue virus (BTV) diagnostic tests were evaluated for use in free-ranging bighorn sheep. We sampled one bighorn sheep population four times between 1989 and 1995. The tests evaluated included virus isolation (VI), polymerase-chain reaction (PCR), serum neutralization (SN), agar-gel immunodiffusion (AGID), and competitive enzyme-linked immunosorbent assay (c-ELISA). The c-ELISA, AGID and SN tests had high levels of agreement in determining serogroup exposure in bighorn sheep. We used maximum-likelihood algorithms to estimate the parameters of each diagnostic test used. Although the c-ELISA and AGID had high sensitivity and specificity, the SN had perfect specificity but lower apparent sensitivity. Due to the potential of cross-reactions among multiple serotypes, results of the SN must be interpreted with caution when assessing serotype exposure in an area where multiple serotypes are endemic. The PCR assay delineated convalescent antibody titers from more-recent infections, and consequently, was pivotal in distinguishing a different exposure pattern between the bighorn sheep and cattle in an adjacent herd. Based on an increasing seroprevalence (50% to 100%), BTV circulated through this bighorn sheep population between 1989 and 1993. This increase in seroprevalence coincided with a bighorn die-off due to BTV infection in June, 1991. An adjacent cattle herd was sampled in 1995 for comparison. The bighorn sheep and adjacent cattle had different patterns of exposure to BTV between 1994 and 1995. There was no evidence that BTV circulated through the bighorn sheep population from 1994 to 1995. In 1995, seroprevalence to BTV decreased to 72%, none of yearling bighorn was seropositive, and all of the 39 bighorn sheep were PCR-negative. In contrast, all adult cattle were seropositive to BTV by c-ELISA and SN, and 4 of the calves were seropositive; 11 of the 24 cattle were PCR-positive, including all five calves. Overall, the pattern of temporal herd immunity in the bighorn sheep appeared to follow a classic epidemic curve, with the appearance and subsequent disappearance of herd immunity coinciding with the 1991 die-off in this population. As low levels of herd immunity and high proportions of susceptible animals are key factors in the development of epidemics, this population of bighorn sheep may be at increased risk for a BTV epidemic in the future. 相似文献
9.
Based upon epidemiological evidence, Culicoides insignis Lutz is a probable biological vector of bluetongue viruses (BTV) in South Florida, the Caribbean Region and Central America. The vector potential of this species for BTV was evaluated in the laboratory in a series of experiments using insects caught in the field. Although there was great variation in the percentage of flies that fed from any one catch, it was demonstrated that C. insignis became infected after membrane feeding on a mixture of blood and virus. The infection rates ranged from 20 to 62.5%. Following intrathoracic inoculation, BTV replicated to high titres in C. insignis. Such flies were also shown to be capable of transmitting BTV to susceptible sheep and embryonated chicken eggs. This series of experiments provides the first conclusive evidence that C. insignis is a biological vector of bluetongue virus. This is the first proven vector of BTV in the neotropics. 相似文献
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11.
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
12.
Savini G MacLachlan NJ Sanchez-Vizcaino JM Zientara S 《Comparative immunology, microbiology and infectious diseases》2008,31(2-3):101-120
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
13.
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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15.
Ten sheep were inoculated with bluetongue virus (BTV) serotype 17. Six of the sheep had been vaccinated before challenge exposure, 4 sheep served as nonvaccinated challenge-exposed controls, and 2 additional sheep served as nonvaccinated, nonchallenge-exposed, contact controls. Biopsy specimens (oral labial mucosa and skin) were obtained periodically after challenge exposure. Sheep were killed 8 to 13 days after challenge exposure, and necropsy was done. Vaccination did not seem to affect the nature or severity of the lesions observed. The changes in the mucosa of the cranial portion of the digestive tract included hyperemia, edema, inflammation, petechiae, erosions, ulcers, and surface encrustations. Lesions of skeletal, cardiac, and smooth muscles included hemorrhage, edema, myofiber degeneration, and necrosis. Lesions in cardiac muscles were sometimes widespread, indicating that cardiac failure may have been the major contributor to pulmonary congestion, edema, and eventual death during acute BTV infection. Damage to esophageal musculature resulted in vomiting. Hemorrhage was observed within the base of the pulmonary artery of all challenge-exposed sheep. Using immunofluorescence, bluetongue viral antigens were detected in small blood vessels of the skin, oral labial mucosa, tongue, esophagus, rumen, reticulum, urinary bladder, and pulmonary artery and in skeletal and cardiac muscles. Viral antigens were present in tissues obtained 3 to 11 days after inoculation. Ultrastructurally, changes in small-caliber blood vessels included congestion, hemorrhage, swollen degenerated endothelial cells, and occasional fibrin-platelet thrombi. Tubular structures and virus-like particles were observed within some of these endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
16.
实验采用6只绵羊分成3组,一组作为对照接种BHK21细胞上清液,另二组分别接种BIV10和中国分离株Z1株,攻毒定期采血提取抗原并提取病毒RNA,同时进行琼脂扩散试验、普通PCR、Nested-PCR试验。结果在整个攻毒期间,琼脂扩散方法检测不到抗原,普通PCR方法只能在攻毒后12d-15d测得抗原,而Nested-PCR在攻毒后6d即可测得病毒RNA,并且可一直持续到30d。试验证明,Nested-PCR方法是高度敏感的检测抗原的方法。在临床上能够较早地检出抗原,这对于及时采取有效措施,控制疾病流行具有积极的意义。 相似文献
17.
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
18.
Preliminary studies demonstrated that the argasid tick, Ornithodoros coriaceus Koch, could become infected with bluetongue virus (BTV). Ticks became infected after feeding through artificial membranes on BTV-infected suspensions of cell cultures, chicken embryos, and sheep blood. Ticks also became infected after natural feeding on viremic sheep (BTV serotype 17) and cattle (BTV serotype 11). Virus was recovered from the hemolymph and salivary glands of ticks which had ingested BTV either through an artificial membrane or by natural feeding on a host animal. Ticks infected with BTV serotype 13 were capable of transmitting the virus to a susceptible cow at 42 days after ingestion of virus-infected cultures, thus demonstrating the potential of the tick to serve as a biological vector of BTV. 相似文献
19.
A E Castro S R Montague J F Dotson D A Jessup J R DeForge 《Journal of veterinary diagnostic investigation》1989,1(3):247-253
A cell line (BHFTE) was derived from a tongue explant of a bighorn sheep fetus (Ovis canadensis nelsoni). The cells have been maintained through 23 serial passages, and the modal number of chromosomes was calculated to be 55. Monolayer cultures were shown to be susceptible to various viruses, including bluetongue virus (BTV). Of 5 BTV serotypes (2, 10, 11, 13, and 17) tested, each produced a cytopathic effect (CPE) on initial passage at 33 C. A field isolate (serotype 10) of BTV from a black-tailed deer (Odocoileus hemionus columbianus) in its second passage in Vero-M cells also produced CPE when inoculated into BHFTE cells. Antigens of BTV were demonstrated by direct immunofluorescence in the cytoplasm of BHFTE cells inoculated with homogenates of chicken embryos injected with clinical specimens from a domestic sheep and an Arabian oryx (Oryx gazella leucoryx). A suspension of BTV-infected gnats (Culicoides spp.) produced CPE and BTV-specific fluorescence on the first passage in cells inoculated with a suspension of blood from sheep experimentally infected with BTV. Additionally, selected bovine viruses induced CPE in the cells. The cell line, which is free of mycoplasma and bovine viral diarrhea virus contamination, may be useful in diagnostic medicine and research involving the ruminant species. 相似文献