蓝舌病研究综述

蓝舌病是由蓝舌病病毒引起的一种传染病,主要通过库蠓叮咬在反刍动物和骆驼中间传播流行。本文对该病的流行历史,传播,病原学,临床症状,诊断方法以及防控措施进行了综述。     

牛蓝舌病的诊治方法

正牛蓝舌病是由蓝舌病病毒引起的一种非接触性传染病,患病动物症状为水肿、充血、食欲不振。本文阐述了牛蓝舌病的病原、发病机制、临床症状、诊断方法和防治手段,意在为牛蓝舌病的综合防治提供理论依据。1病因牛蓝舌病的病原是蓝舌病病毒,该病毒属于呼肠孤病毒     

青海省柴达木绒山羊蓝舌病血清学调查

蓝舌病是蓝舌病病毒引起的,经媒介昆虫传播的一种非接触性疾病,主要侵害绵羊,其他反刍动物不表现临床症状.其症状以高热、口腔黏膜水肿、糜烂、溃疡、舌体肿胀、发病初期一过性白细胞减少为特征,蓝舌病可直接致死动物,引起孕畜流产和胎儿畸形,由其引起的间接损失更为严重.     

琼脂凝胶扩散试验在我省蓝舌病诊断中的应用

蓝舌病是由库蠓传播、蓝舌病病毒引起的侵害反刍动物的严重传染病。蓝舌病病毒系呼肠孤病毒科环状病毒属的成员,该病毒主要引起山羊、绵羊发病和死亡,牛及其他反刍动物常为隐性感染．但可通过媒介昆虫传播,成为本病的重要传染源。张念祖等（1979）在我省首次发现该病,近年来,英国、法国等欧洲国家先后报道在本国发生该疫情。     

国内首次报道山羊蓝舌病病理学

国内首次报道山羊蓝舌病病理学动物蓝舌病是经库蠓传播的一种主要侵害绵羊并可感染其他动物的非接触性传染病。蓝舌病病毒（ＢＴＶ）对绵羊的致病性研究较多，对山羊的致病性研究得很少，而且结果也不一样。在新疆动物蓝舌病血清学调查时，作者发现，山羊蓝舌病阳性群中，...     

规模化养殖场蓝舌病的临床诊断与治疗分析

蓝舌病(BT)是由呼肠孤病毒科环状病毒属的蓝舌病病毒(BTV)引起的一种烈性传染病,可以通过库朦在反刍动物间传播。反刍类动物感染蓝舌病后的平均病死率约为30%,其中绵羊的病死率则可高达80%。蓝舌病是OIE规定的上报疫病,我国农业部将其列为一类动物疫病。蓝舌病严重危害我国畜牧业及产品进出口贸易的发展。     

牛羊蓝舌病的综合防制

<正>牛羊蓝舌病是由蓝舌病病毒引起的反刍动物的一种急性热性传染病。临床上主要以高热、腹泻、黏膜水肿、溃疡和糜烂为主要症状,蓝舌病主要通过库蠓吸血传播,主要侵害绵羊。OIE将其列为A类疫病。本病可通过临床症状进行初步诊断,用免疫荧光试验、酶联免疫吸附试验最终确诊,一旦发生本病,应积极采取隔离、消毒、免疫、扑杀和无害化处理等综合防制措施。1病原蓝舌病病毒(Blue tongue virus,BTV)属于呼肠孤病毒科     

蓝舌病的研究进展

蓝舌病是由蓝舌病病毒以库蠓作为传播媒介引起的一种主要侵害家饲和野生反刍兽的传染病。目前,蓝舌病病毒有26个血清型分布世界各地,且型与型之间不发生交叉免疫,主要感染绵羊、山羊、牛、鹿等反刍兽,可引起不同程度的临床症状,甚至导致反刍兽死亡。检测蓝舌病病毒的方法有很多种,主要以血清学及分子生物学为主。文章综述了蓝舌病的流行分布情况、病原特性、传播媒介、发病机理与临床症状、诊断技术与疫苗等方面的研究进展。     

血清8型蓝舌病病毒侵入北欧

蓝舌病是由蓝舌病病毒感染引起的、库蠓传播的一种严重威胁绵羊和山羊的传染病，在世界许多地方都有流行。牛是贮存宿主，但通常不发病。已知的蓝舌病病毒分为24个血清型。以前，蓝舌病病毒几乎没有在欧洲出现过，但在1998年以后．陆续有几个血清型从土耳其和中东入侵希腊、意大利、西班牙、葡萄牙以及巴尔干半岛的国家。     

动物蓝舌病监控系统的建立及其流行病学研究

观测绵羊蓝舌病自然发病区蓝舌病的传播规律及病毒血清型的分布，为本病的防治提供科学依据。于1995年7月起，在师宗县建立了动物蓝舌病监控动物群，经3年的观测，对19头牛监控，共采血667份，分离获得蓝舌病病毒10株，经血清学鉴定为3、4、5、15型血清型，该3个血清型均为首次分离到的国内新毒株。     

Bluetongue disease in Swiss sheep breeds: clinical signs after experimental infection with bluetongue virus serotype 8

Clinical disease of bluetongue (BT) in sheep may differ depending on breed, age and immunity of infected sheep and may also vary between serotype and strain of BT virus (BTV). Since there are no data available on the susceptibility of Swiss sheep breeds for BT, we performed experimental infection of the 4 most common Swiss sheep breeds and the highly susceptible Poll Dorset sheep with the BTV serotype 8 (BTV-8) circulating in Northern Europe since 2006. Clinical signs were assessed regarding severity, localisation, progression and time point of their appearance. The results clearly show that the Swiss sheep breeds investigated were susceptible to BTV-8 infection. They developed moderate, BT-characteristic symptoms, which were similar to those observed in Poll Dorset sheep. Regardless of breed, the majority of infected animals showed fever, swelling of the head as well as erosions of the mouth and subcutaneous haemorrhages.     

Temporal development of bluetongue virus protein-specific antibody in sheep following natural infection

Humoral immune responses of sheep to natural bluetongue virus (BTV) infection were studied on a temporal basis. The temporal development of viral protein-specific IgG was determined by western immunoblotting; virus neutralization and agar gel immunodiffusion (AGID) were conducted for comparative purposes. Prior to the emergence of the arthropod vector and the associated transmission of BTV, virus-neutralizing antibody was absent from all sentinel sheep; 3 sheep had pre-existing AGID antibody and all sheep had IgG, specific for 4 viral proteins, as determined by immunoblotting. Following emergence of the BTV vector, 9 of 11 sheep became infected, as determined by virus isolation, with BTV. All sheep developed virus-neutralizing and AGID antibody. However, only those sheep with a demonstrable viremia experienced an increase in viral protein-specific antibody. Development of viral protein-specific IgG varied with the individual animal and no obvious correlation between a specific response and protective immunity or viral clearance was noted. From a diagnostic viewpoint, the immunoblotting procedure was superior in identifying past exposure to BTV, as compared with neutralization and AGID. In addition, the application of immunoblotting to paired serum samples appeared to be a sensitive indicator of viremia.     

Recovery of dual serotypes of bluetongue virus from infected sheep and cattle

Dual serotypes of bluetongue virus (BTV) were recovered from field-collected samples of sheep and cattle blood. Two sheep, each infected with both BTV serotypes 10 and 17, were found in a flock with bluetongue disease associated with these two serotypes. One sheep infected with BTV serotypes 11 and 17 was found in a second flock; it was the only viremic sheep detected and was clinically ill. Dual serotype infections of one beef and two dairy cattle were found in three geographically separate herds; mixtures recovered were of BTV serotypes 10 and 17 and serotypes 11 and 17. Clinical signs of illness were absent in the cattle in two herds, but severe conjuctivitis was seen in several cows in a third herd, including the cow with a dual serotype infection (BTV 11 and 17). Two of the cattle with dual infections had no serological evidence of BTV as determined by the agar gel precipitin test; serum was not available from the other cow with a dual serotype infection. The significance of dual infections and immune tolerance are discussed.     

Immunologic response of sheep to inactivated and virulent bluetongue virus

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.     

T lymphocyte subset alterations following bluetongue virus infection in sheep and cattle

To determine potential mechanisms of differential disease expression in ruminants infected with bluetongue virus (BTV), clinically normal, BTV-seronegative, yearling sheep and cattle were infected subcutaneously with a standardized insect-source inoculum of BTV serotype 17 (BTV-17) (three infected and one contact control each) or animal adapted BTV serotype 10 (BTV-10) (three sheep only). BTV was isolated from peripheral blood cell components of infected sheep and cattle and all infected animals showed evidence of seroconversion by 14 days post infection (PI). Sheep infected with both serotypes of BTV developed pyrexia, oral lesions, and leukopenia which were most severe on days 7-8 PI. Analysis of peripheral blood mononuclear leukocytes with specific monoclonal antibodies and flow cytometry revealed panlymphocytopenia on day 7 PI. This response was further characterized by an increase in the CD4/CD8 ratio (greater than 3) resultant from a greater decrease in absolute numbers of circulating SBU-T8(CD8+) ("cytotoxic/suppressor") lymphocytes compared to SBU-T4 (CD4)+ ("helper") lymphocytes. SBU-T19+ lymphocytes were also decreased below baseline values on days 5-14 post infection. On day 14 PI there were increased CD8+ lymphocytes and decreased CD4/CD8 ratios (approximately 0.6) in these sheep. Clinical and hematologic changes in cattle infected with BTV-17 were minimal and consisted of mild pyrexia (rectal temperature 103 degrees F) on day 9 PI in two of three infected animals and mild leukopenia on several days PI in one animal. This leukopenia was the result of a pan T lymphocytopenia with CD4/CD8 ratios in the expected range (1-2). Similar to infected sheep, infected cattle did have a shift (decrease, approximately 0.8) in the peripheral CD4/CD8 ratio associated with an increase in circulating BoT8 (CD8)+ lymphocytes on day 14 post infection. Lymphocytes in the peripheral blood of all sheep and cattle infected with BTV-17 proliferated in vitro in response to purified BTV-17. These results confirm and extend those of previous studies that indicate species differences in the hematologic response to an equivalent BTV infection in domestic ruminants.     

Epizootic hemorrhagic disease virus serotype 7 in European cattle and sheep: Diagnostic considerations and effect of previous BTV exposure

Epizootic hemorrhagic disease virus (EHDV), an arthropod-borne orbivirus (family Reoviridae), is an emerging pathogen of wild and domestic ruminants that is closely related to bluetongue virus (BTV). The present study examines the outcome of an experimental EHDV-7 infection of Holstein cattle and East Frisian sheep. Apart from na?ve animals that had not been exposed to BTV, it included animals that had been experimentally infected with either BTV-6 or BTV-8 two months earlier. In addition, EHDV-infected cattle were subsequently challenged with BTV-8. Samples were tested with commercially available ELISA and real-time RT-PCR kits and a custom NS3-specific real-time RT-PCR assay. Virus isolation was attempted in Vero, C6/36 and KC cells (from Culicoides variipennis), embryonated chicken eggs and type I interferon receptor-deficient IFNAR(-/-) mice. EHDV-7 productively infected Holstein cattle, but caused no clinical signs. The inoculation of East Frisian sheep, on the other hand, apparently did not lead to a productive infection. The commercial diagnostic kits performed adequately. KC cells proved to be the most sensitive means of virus isolation, but viremia was shorter than 2 weeks in most animals. No interference between EHDV and BTV infection was observed; therefore the pre-existing immunity to some BTV serotypes in Europe is not expected to protect against a possible introduction of EHDV, in spite of the close relation between the viruses.     

The epidemiology of bluetongue

The perception that bluetongue virus (BTV), once introduced to a country, would decimate its sheep industry, grew from the acceptance in the late 1950s that it was an emerging virus with Africa as its source. Epidemiological studies in the 1960s and early 1970s confirmed that the geographic distribution of BTV infections included regions of the world, outside the traditionally defined areas where BT was observed. This was interpreted at the time as representing serious and rapid spread of the virus.

This review provides evidence to rebut this earlier view. What has emerged through the 1980s is: (a) the recognition that BTV is a common infection of ruminant livestock throughout the tropics and sub-tropics apparently within several separate ecosystems; (b) in most areas of the world, infection is sub-clinical; (c) incursions of virus (with accompanying disease) into temperate climates do occur at certain key locations, but “die out” usually within the same year; (d) recognition of the vector competence of Culicoides spp in the different ecosystems of the world is critical for understanding the epidemiology of disease; (e) persistent infection in ruminants is no longer considered important in the long term perpetuation of the virus.     

Bluetongue virus serotype 26: infection kinetics and pathogenesis in Dorset Poll sheep

Bluetongue virus serotype 26 (BTV-26) has recently been isolated from sheep in Kuwait. The aim of this study was to assess the pathogenicity and infection kinetics of BTV-26 in Dorset Poll sheep. Six sheep were experimentally infected with BTV-26 and samples taken throughout the study were used to determine the kinetics of infection using a pan specific BTV real time RT-PCR assay and two group specific ELISAs. Five of the six sheep showed mild clinical signs characteristic of bluetongue including conjunctivitis, reddening of the mouth mucosal membranes, slight oedema of the face and nasal discharge. Viral RNA was detected in 5 of the 6 sheep by real time RT-PCR, however the levels of viral RNA detected in the samples were lower and of shorter duration than seen with other field strains of BTV. Virus was isolated from the blood of infected animals at the peak of viraemia at around 9 dpi. Antibodies against BTV were first detected by 7 dpi using the early detection BTV ELISA and a little later (7-14 dpi) using a BTV specific competitive ELISA. Four of the five remaining sheep developed neutralising antibodies to BTV-26, measured by a serum neutralisation test (SNT), with titres (log(10)) ranging from 1.40 to 2.08.