新疆绵羊梅迪(Maedi)病毒的分离和初步鉴定

梅迪(Maedi)病是由慢病毒引起的绵羊进行性肺炎(简称OPP),其病原体为梅迪——维斯纳(Maedi-Visna)病毒。病毒分类属于反录病毒科的慢病毒亚科,可以致癌。1930年,冰岛首先分离出病毒,以后欧、     

梅迪-维斯纳病的研究进展

梅迪-维斯纳羊的进行性肺炎被认为是一种独立的羊病。这种病在1954年由冰岛科学家Sigardsson首次发现,并将其划为慢性感染。1939—1962年,从冰岛地方流行性进行性肺炎（maedi）伴发进行性瘫痪（visna）绵羊病例中首次分离出梅迪一维斯纳病病毒（MVV）。梅迪-维斯纳为冰岛语,原来是用来描述绵羊的两种不同临床征状的慢性增生性传染病。     

新疆美利奴羊对绵羊慢病毒的品种敏感性实验

绵羊慢病毒 ( Ovine lentivirus,Ov LV) ,属逆转录病毒科 ( Retroviridae)、慢病毒亚科 ( Lentivirinae) ,它的原型病毒为冰岛的梅迪 -维思纳病毒 ( maedi- visnavirus,MVV) ,属强毒株 ,引起的疾病称梅迪 ( mae-di,意为呼吸困难 )。绵羊进行性肺炎病毒 ( Ovineprogressive pneumonia virus,OPPV)为 Ov LV的美国株 ,属弱毒株 ,引起的疾病称为绵羊进行性肺炎( OPP)。MVV和 OPPV属 Ov LV的 1型或溶解型 ,此型 Ov LV(包括 MVV、OPPV与其他国家或地区的病毒株 )可引起淋巴组织样间质性肺炎 ( LIP)与肺淋巴滤泡增生、淋巴细胞性…     

羊梅迪-维斯纳病的诊断与防制

正羊梅迪-维斯纳病是由梅迪-维斯纳病毒引起的成年绵羊和山羊的一种不表现发热症状的接触性传染病。进行缓慢,造成所器官损伤,以潜伏期长,间质性肺炎或脑膜炎,全身衰弱,消瘦,最终死亡为临床特征。梅迪是呼吸困难的意思,病羊以呼吸苦难或消瘦等为特征的慢性进行性肺炎;维斯纳是损耗的意思,病羊以神经症状为主要特征的脑脊髓炎。南非、荷兰、美国、冰岛、     

从绵羊进行性肺炎病例中分离提纯梅迪(Maedi)病毒及其形态观察

梅迪(Maedi)病是三十年代后期流行冰岛的一种慢性进行性肺炎,由梅迪病毒所引起。后来在欧洲、非洲、亚洲、美洲等许多国家均发现本病。本病主要发生于两岁以上的成年绵羊,以潜伏期长、病程缓慢、进行性呼吸困难为临床特征,以慢     

梅迪—维斯纳病毒

梅迪-维斯纳病毒能引起绵羊的慢病毒感染,目前国内针对该病毒的研究较少,本文就梅迪-维斯纳病毒的基本特征进行简要介绍,重点对梅迪-维斯纳病毒的基因组结构、基因编码产物以及表达调控作一综述。     

羊梅迪-维斯纳病的诊断与防治

梅迪-维斯纳病是一种慢性传染病,主要感染绵羊,本病为消耗性疾病,死亡率很高,造成的损失大,要特别留意,一旦发现应立刻扑杀。本文总结了梅迪-维斯纳病的病原、流行病学、致病机理等,阐述了两种主要发病症状和诊断要点,希望能够引起业内人员的重视。     

家畜慢病毒病

慢病毒(lentivirus)是指那些外源性的非肿瘤性反转录病毒,它可持续感染人和多种动物,并通过多种机理导致慢病毒病(lentivirus diseases)。慢病毒病是一类慢病(slow discases),是以较长的亚临床感染期和持续性感染及较窄的感染谱等为特征的疫病。现已发现的家畜慢病毒病包括马传染性贫血(EIA)、梅迪-维斯纳(MV)或绵羊进行性肺炎(OPP)、山羊关节炎-脑炎     

梅迪-维斯纳病概述

1简介 梅迪-维斯纳病是成年绵羊的一种不表现发热症状的接触性传染病。临床特征是经过漫长的潜伏期之后,表现为间质性肺炎或脑膜炎,病羊衰弱、消瘦,最后终归死亡。梅迪-维斯纳为冰岛语,原是用来描述绵羊的两种临床症状表现不同的慢性增生性传染病。梅迪的意思是“呼吸困难”，描述了一种增进性间质性肺炎；维斯纳的意思是“抽搐”或“消耗”，病状为麻痹性脑膜炎。     

浅谈绵羊肺炎支原体研究现状

绵羊肺炎支原体是引起引起绵羊、山羊,特别是羔羊增生性、间质性、高度接触传染性胸膜肺炎（非进行性肺炎）的病原体。本文主要从病原特征、致病机理等方面对绵羊肺炎支原体进行介绍;对绵羊肺炎支原体的研究概况进行总结。     

Immunomorphologic and morphometric changes in pulmonary lymph nodes of sheep with progressive pneumonia

Morphologic, immunohistochemical, and morphometric studies were conducted on the posterior mediastinal lymph nodes of eleven sheep with naturally occurring ovine progressive pneumonia and four apparently healthy sheep with no pulmonary lesions (three seropositive, one seronegative for antibody to ovine progressive pneumonia virus). Compared with lesion-free sheep, sheep with ovine progressive pneumonia had a seven-fold increase in B lymphocyte areas and a 21/2-fold increase in T lymphocyte areas of these lymph nodes. Immunochemistry revealed cytoplasmic immunoglobulin G in scattered cells of germinal centers, medullary cords and interfollicular areas and membrane-associated immunoglobulin G in dendritic cells of germinal centers. Immunoglobulin M staining cells were widely scattered in germinal centers and medullary cords. Although B cell hyperplasia seemed to be the predominant process in lymph nodes of sheep with ovine progressive pneumonia, this was not accompanied by the expected degree of plasmacytosis, morphologically and immunohistochemically. These findings may represent an aberrancy of immunoregulation in ovine progressive pneumonia.     

Detection of antibodies to ovine lentivirus using recombinant capsid and transmembrane proteins

The coding sequences of the capsid protein p25 and transmembrane protein of Maedi-Visna virus were amplified using polymerase chain reaction and cloned into the plasmid expression vector pRSET-B. Both DNA constructs expressed proteins tagged with polyhistidine. The recombinant proteins were purified using Ni-NTA agarose and used in immunoblot to detect antibodies against Maedi-Visna virus. A total of 260 ovine serum specimens was analysed. The total number of p25-positive sera was 111 (42.7%). Higher sensitivity was achieved with rTM antigen, which detected antibodies in 118 (45.4%) sera. The combination of both recombinant proteins as antigens resulted in higher sensitivity of serological detection compared to whole virus antigen.     

Ultrastructure and frequency of mastitis caused by ovine progressive pneumonia virus infection in sheep

Twenty-five sheep, experimentally (n = 15) or naturally (n = 6) infected with ovine progressive pneumonia virus and noninfected controls (n = 4), were evaluated for histological and ultrastructural lesions of mastitis. Histologically, nine of 15 experimentally infected sheep and all six naturally infected sheep had lympho-plasmacytic mastitis. Severity of the lesion increased with length of time after infection. Periductal lymphatic nodules were seen in five sheep experimentally infected for 2.8 years or longer and in five naturally infected sheep that were 3.7 years old or older. Ultrastructurally, responses to ovine progressive pneumonia virus were diffuse lympho-plasmacytic infiltrates in glandular interstitium, lymphocytic and occasional plasmacytic infiltrates in ductal walls and lumens, lymphoblasts surrounded by small lymphocytes in glandular interstitium, and degeneration of epithelium releasing cells and cellular debris into the lumen. Based on the prevalence of lesions, the mammary tissue was more susceptible to ovine progressive pneumonia virus than other target organs: lung, brain, and synovium. Lesions did not differ between breeds of sheep. Ovine progressive pneumonia virus was not seen in the mammary tissue but was isolated from 15 of 17 mammary glands.     

Eradication of ovine progressive pneumonia from sheep flocks

Two management methods for controlling ovine progressive pneumonia in sheep were evaluated. By a test and cull method, wherein seropositive sheep were culled from the flock, the causative virus was eradicated from a closed flock and controlled in an open flock. By an isolate-and-test method, wherein lambs were removed from infected ewes before nursing and reared in isolation, the virus was eradicated in 1 of 2 attempts to establish virus-free flocks. It was concluded that either method should be effective in controlling ovine progressive pneumonia. Results indicated that annual serologic monitoring of a virus-free flock would be necessary to ensure that the virus-free status is maintained.     

Evidence of decreased concanavalin A induced suppressor cell activity in the peripheral blood and pulmonary lymph nodes of sheep with ovine progressive pneumonia

Concanavalin A (Con A) induced suppressor cell activity was evaluated in a group of ovine progressive pneumonia virus-antibody positive sheep (OPPV+). Decreased levels of suppressor activity were observed in the peripheral blood and regional pulmonary lymph nodes of animals with clinical and pathological evidence of ovine progressive pneumonia (OPP) when compared to animals with no lesions and animals with caseous lymphadenitis involving the lungs and pulmonary lymph nodes. Decreased levels of Con A stimulated lymphocyte proliferation was also observed in the peripheral blood and iliac lymph nodes of sheep with OPP. Sheep with OPP were found to be hypogammaglobulinemic. Sera from OPPV+ sheep had no effect on T and B cell mitogen stimulated responses of lymphocytes from sheep seronegative for antibodies to ovine progressive pneumonia virus (OPPV-) when compared to normal sheep serum.     

Ovine progressive pneumonia: pathologic and virologic studies on the naturally occurring disease

Pathologic and virologic studies were conducted on 13 mature ewes with serum precipitin antibodies to progressive pneumonia virus (PPV). Pulmonary lesions of ovine progressive pneumonia were found in 4 sheep, a meningoencephalitis resembling visna in 1 sheep, chronic proliferative carpal arthritis in 2, and massive lymphoid proliferation in the mammary gland in 3. Virus producing cytopathic effect typical of PPV was isolated from the lungs, mediastinal lymph node, spleen, and choroid plexus of 4 sheep and from the carpal synovium of 2 sheep with chronic carpal arthritis. Three viral isolates selected for further study were antigenically related to visna virus by immunofluorescence and immunodiffusion, but these 3 isolates were not neutralized by antisera to reference strains of visna virus. Seemingly, infection of sheep by ovine retroviruses is common in the United States, and these viruses are capable of causing disease in more than 1 organ system.     

Evaluation of the agar-gel immunodiffusion test for the detection of precipitating antibodies against progressive pneumonia virus of sheep.

Various cell cultures were evaluated for their ability to support progressive pneumonia virus infection in vitro. Ovine trachea cells supported progressive pneumonia virus infection for an extended time,were extremely durable and could be passaged up until 30 passages. Progressive pneumonia virus infected ovine trachea cells were then used for the production of antigen for agar-gel immunodiffusion. A method for concentrating antigen, diafiltration, was compared to dialysis against polyethylene glycol. Using diafiltration, the concentrated virus was easily quantitated, less viscous (and therefore easier to apply) and only produced one precipitation line. Agar-gel immunodiffusion was used to survey 401 animals from two sheep flocks. One flock (96 sheep) was free of progressive pneumonia while the other flock had 111 of 305 total animals positive for precipitating antibodies. The incidence of precipitating antibodies in sheep ranged from 23% for yearling ewes to 80% in ewes seven years old.     

Prevalence of antibodies to seven viruses in a flock of ewes in Minnesota

Blood samples were collected from a flock of healthy ewes at a University of Minnesota research station. Sera from these blood samples were tested for antibodies against 7 viruses, using 3 tests (eg, virus-neutralization test for bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, bovine adenovirus type 3, and bovine respiratory syncytial virus; hemagglutination inhibition test for parainfluenza virus type 3; and agar-gel immunodiffusion test for lentivirus of ovine progressive interstitial pneumonia and bluetongue virus). The number of seropositive ewes for each antibody type were 1 of 377 (0.3%) for bovine viral diarrhea virus, 2 of 377 (0.5%) for infectious bovine rhinotracheitis virus, 29 of 378 (7.6%) for bovine adenovirus type 3, 200 of 378 (52.5%) for bovine respiratory syncytial virus, 273 of 373 (71.7%) for parainfluenza virus type 3, and 210 of 379 (55%) for ovine progressive pneumonia virus. All ewes were seronegative for bluetongue virus antibodies.     

Isolation and characterization of a virus associated with progressive pneumonia (maedi) of sheep.

A virus with growth and morphologic characteristics of progressive pneumonia (maedi-visna) virus was isolated from the lungs of sheep with typical clinical and postmortem changes of chronic progressive pneumonia. The virus grew slowly in cultures of embryonic ovine lung cells, causing syncytial formation and degeneration. Syncytia developed much slower and involved fewer cells than reported for other similar viruses isolated from sheep. As seen with the electron microscope, the virus reproduced by budding from cell surfaces. Two types of virions were seen-a large particle (120 to 140 nm) with an electron-lucent center and dense laminated outer rim, and a small particle (80 to 110 nm) with an electron-dense core surrounded by a single membrane. Viral structures and fragments similar to the large extracellular particles were seen in the cytoplasm of a few cells. These characteristics are reported for other viruses isolated from sheep with progressive pneumonia.     

绵羊进行性肺炎病毒与山羊关节炎一脑炎病毒的血清学交叉反应的研究

本实验用琼脂凝胶免疫扩散试验（ＡＧＩＤＴ）和免疫印迹试验（ＩＢＡ）对实验感染绵羊进行性肺炎病毒（ＯＰＰＶ）的山羊血清与山羊关节炎—脑炎病毒（ＣＡＥＶ）抗原以及实验感染ＣＡＥＶ的绵羊血清与ＯＰＰＶ抗原的交叉反应进行了研究。４只接种ＯＰＰＶ的山羊中有一只山羊的血清可与ＣＡＥＶ琼扩抗原发生交叉反应,并在免疫印迹试验中可识别ＣＡＥＶ的ｇｐ４４、ｐ３５和ｐ２８。２只接种ＣＡＥＶ的绵羊中有一只绵羊的血清可与ＯＰＰＶ琼扩抗原发生交叉反应,并在免疫印迹试验中可识别ＯＰＰＶ的ｇｐ４４和ｐ２８。以上的交叉反应结果表明ＯＰＰＶ与ＣＡＥＶ的抗原之间具有密切的相关性,这对于ＯＰＰＶ通过山羊和ＣＡＥＶ通过绵羊的传代研究是非常重要的,并对将来的免疫预防策略具有重要的指导意义。