Ovine interleukin-2: partial purification and assay in normal sheep and sheep with ovine progressive pneumonia

Interleukin-2 (IL-2), a T cell derived lymphokine, acts in nonspecific hormone-like fashion to maintain proliferation of activated lymphocytes in vitro and is believed to play a key role in cell-mediated immune function in vivo. The parameters of induction and assay of factors with IL-2 activity were examined in a group of clinically normal sheep seronegative for antibodies to ovine progressive pneumonia virus (OPPV-). Supernatants from cultures of Concanavalin A (Con A) stimulated mononuclear leukocytes (ML) derived from peripheral blood and lymph nodes contained factors with the capacity to maintain continued proliferation in Con A stimulated lymphoblasts. This activity was localized by gel chromatography to fractions containing proteins of 17,000-20,000 daltons. In a group of sheep seropositive for antibodies to OPPV (OPPV+), decreased levels of IL-2 activity were found in ML culture supernatants derived from the posterior mediastinal lymph nodes of sheep with clinical and pathological evidence of OPP, when compared to OPPV+ sheep with no lesions and sheep with visceral caseous lymphadenitis. This decrease in IL-2 activity appeared not to be associated directly with levels of prostaglandin E2 in these supernatants. These findings may correlate with virus induced alterations in cell mediated immune function in lymphoproliferative lesions of OPP.     

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。     

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.     

自然感染绵羊肺腺瘤病和绵羊进行性肺炎病例肺脏的病理组织学观察

绵羊肺腺瘤病(ovine pulmonary adenomatosis,OPA)和绵羊进行性肺炎(ovine progressive pneumonia,OPP)是改良绵羊很容易发生的两种呼吸系统疾病,两者都可引起明显的肺脏病变。为了从病理组织学变化上对这两种疾病加以鉴别,分别描述了OPA和OPP自然病例肺脏的眼观病变,采集OPA和OPP病死羊的肺脏,制成石蜡切片,经HE染色后,在光学显微镜下观察、拍照,并记录病理形态学变化。     

用绵羊进行性肺炎病毒实验感染山羊的研究

用绵羊进行肺炎病毒接种４只山羊３－４个月后，可观察到接毒山羊都出现了发育迟缓和消瘦现象，并有１只山羊山现了明显的临床病症。而未接毒的对照山羊则发育正常。接毒２８ｄ后，可以从接毒山羊的外周血单核细胞中分离到病毒。病理剖检发现４只接毒山羊中有１只山羊的多种器官出现了较为严重的病变，组织学检查则可看到典型的间质性肺炎、中度的脑炎和较为严重的脾炎的症变。以上的结果表明ＯＰＰＶ可以感染山羊，并对山羊有较强的     

绵羊慢病毒自然感染绵羊的硬化性淋巴细胞性乳腺炎

７头来自新疆南部某绵羊慢病毒（ＯｖＬＶ）感染的羊场的绵羊用于本研究。用琼脂凝胶免疫扩散检查绵羊血清中对绵羊进行性肺炎（ＯＰＰ）病毒（ＯＰＰＶ）的抗体，结果表明有６例呈阳性，１例阴性，抗体效价在３年中呈下降趋势。４例血清学阳性边菜羊和１例阴性和田羊有不同程度的硬化性（纤维性）淋巴细胞性乳腺炎，小叶内有不等的淋巴细胞浸润，导管周围无淋巴滤泡形成，小叶间大量纤维组织增生。７例的肺、脑、关节、血管均无ＯｖＬＶ性特异性病变。从血清学阳性羊的外周血白细胞中未分离到ＯｖＬＶ。     

Seroreactivity of Peruvian sheep and goats to small ruminant lentivirus-ovine progressive pneumonia virus

Sera from 3,369 sheep and 1,394 goats in Peru were examined by agar-gel immunodiffusion for antibodies to ovine progressive pneumonia virus (OPPV). The point prevalence rates for antibodies to OPPV in sheep were 1.7% to 40.6% (mean, 19.02%) in the 7 flocks studied, whereas for goats, the point prevalence rates for antibodies that cross-reacted with OPPV in 12 herds were 0.0% to 45.1%. For sheep, a direct association between increasing age and increasing seroreactivity to OPPV was established, and there was evidence to indicate that lambs born to primiparous ewes and raised separated from all other sheep after they were weaned may have been less likely to become infected with OPPV than those lambs born to multiparous ewes and not separated from other sheep after they were weaned. For goats, antibodies to OPPV were detected in 7 of 12 herds studied, the highest infection rate being present within a herd in the Lima department (district).     

Vasculitis associated with ovine progressive pneumonia virus infection in sheep

Vasculitis, involving small muscular arteries and arterioles, was found in 5 of 18 sheep naturally infected with ovine progressive pneumonia (OPP) virus and in 5 of 11 sheep experimentally infected with OPP virus. In order of frequency, arterial lesions were seen in carpal joint capsules, kidneys, meninges, brains, lungs, and tracheas. The lesions were intramural edema and hemorrhage, mononuclear cell infiltration, fibrinoid necrosis of media, and thrombosis. The vascular lesions were frequently associated with interstitial pneumonitis, arthritis, and encephalitis also induced by OPP virus.     

Failure of experimental vaccines to protect against infection with ovine progressive pneumonia (maedi-visna) virus

Cell culture medium was harvested from cells infected with ovine progressive pneumonia (OPP) virus and used to prepare killed virus vaccines. Virus was inactivated by either heat, formalin, or ethyleneimine and used either without adjuvant, with Freund incomplete adjuvant, or with aluminum hydroxide adjuvant to vaccinate sheep. The sheep produced precipitating antibody against the virus but were not protected against infection when challenged with live OPP virus.     

Minimum intravenous infectious dose of ovine progressive pneumonia virus (OPPV)

The minimum intravenous infectious dose for ovine progressive pneumonia virus (OPPV) WLC1 was determined using twenty-four 6 month-old lambs. Twelve groups of two 6 month-old lambs were inoculated intravenously (i.v.) with tissue culture fluid containing ovine progressive pneumonia virus (OPPV) WLC1 titers ranging from 10^7.6 TCID₅₀/lamb down to 10^−3.4 TCID₅₀/lamb and were monitored for seroconversion using the OPPV agar gel immunodiffusion assay (AGID). Fifteen of the 16 lambs given equal or greater than 10^0.6 TCID₅₀ seroconverted, and virus could be isolated from peripheral blood leukocytes in 13 out of the 15 of these lambs. None of the eight lambs receiving less than 10^0.6 TCID₅₀ seroconverted during the 12 months. The results of this study indicated that 10^0.6 or 4 TCID₅₀/lamb given i.v. was capable of establishing infection.     

Breed susceptibility to ovine progressive pneumonia (maedi/visna) virus

In this retrospective study of breed differences in susceptibility to disease caused by ovine progressive pneumonia (OPP) virus, 29 Border Leicester sheep were compared with 46 Columbia sheep. As judged by frequency and severity of clinical signs and lesions attributable to the infection, Border Leicester sheep were markedly more susceptible than Columbia sheep and experimentally infected sheep were slightly more susceptible than naturally infected sheep. Differences in susceptibility to infection by the virus were not determined.     

Arthritis associated with ovine progressive pneumonia

Chronic nonsuppurative arthritis developed in carpal and tarsal joints of border Leicester sheep that were naturally or experimentally infected with ovine progressive pneumonia (OPP) virus. Clinical signs of arthritis began at 1 to 6.2 years of age (1 to 5.7 years after inoculation of OPP virus) and slowly progressed in severity until the sheep died or were killed. The joint lesions were characterized by edema, hyperemia, hyperplasia, and necrosis of the synovial membrane; by necrosis and erosion of articular bone; by necrosis and fibrosis of subchondral bone; and by extensive periarticular fibrosis. The OPP virus alone was isolated from arthritic joints. In 7 of 14 sheep, the arthritis was associated with interstitial pneumonitis induced by the virus. Therefore, it was concluded that OPP virus was the cause of arthritis in this group of sheep.     

Lesions and retroviruses associated with naturally occurring ovine pulmonary carcinoma (sheep pulmonary adenomatosis)

Five sheep with ovine pulmonary carcinoma were markedly dyspneic and had sporadic coughing; two had copious watery nasal exudate. In four, lesions consisted of multifocal nodules of neoplastic cuboidal epithelial cells in acinar or papillary patterns. Electron microscopically, cells had microvilli, tight junctions, and cytoplasmic lamellar bodies typical of alveolar type II cells. One sheep had a single lung tumor of nonciliated bronchiolar epithelial cells. Vacuolated alveolar macrophages surrounded adenomatous foci. One sheep had a metastatic lesion in the caudal mediastinal lymph node. All sheep had histologic lesions of lymphoid interstitial pneumonia (LIP, ovine progressive pneumonia) consisting of peribronchiolar and interstitial lymphoid hyperplasia, and fibromuscular proliferation; all had serum precipitating antibodies to ovine lentivirus. Lung fluids or tumor homogenates contained a 26-kd peptide that crossreacted with a primate-derived type D retrovirus as detected by immunoblotting or interspecies competition radioimmunoassay. Ovine lentivirus was isolated from concentrated lung fluids or tumor tissues of four sheep tested and from tumor cell DNA of one animal transfected into ovine muscle cells. These studies document the presence of type D-related retrovirus antigen in ovine pulmonary carcinoma (OPC) in the United States and indicate that lentivirus-induced LIP is a lesion frequently associated with this disease.     

山羊实验感染绵羊进行性肺炎病毒的抗体应答反应

用琼脂凝胶免疫扩散试验（ＡＧＩＤＴ）和免疫印迹试验（ＩＢＡ）对山羊实验感染绵羊进行性肺炎病毒（ＯＰＰＶ）的抗体应答反应进行了研究。结果,用ＡＧＩＤＴ和ＩＢＡ都可在接毒山羊的血清中检测到ＯＰＰＶ的抗体。ＡＧＩＤＴ最早于接毒后１５ｄ检测到抗体;ＩＢＡ最早于接毒后４ｄ检测到抗ＯＰＰＶ的ｇｐ４４和ｐ２８的抗体,以后又陆续检测到抗ｐ９４、ｐ１４和ｇｐ１２５的抗体。由此看出,ＩＢＡ比ＡＧＩＤＴ更为敏感。本研究结果表明,ＯＰ－ＰＶ可在山羊体内诱生较强的体液免疫应答反应,因此用ＯＰＰＶ通过山羊体传代的方法可能会得到具有良好抗原性的ＯＰＰＶ毒株。     

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.     

Immunodiffusion test for ovine progressive pneumonia.

An agar gel immunodiffusion test was developed to detect precipitating antibody against ovine progressive pneumonia (OPP) virus. The test was conducted in plastic petri dishes containing 6 ml of 1% purified agar in tris buffer and 8% sodium chloride. Wells for serum and antigen were 8 mm in diameter and were cut in a hexagonal pattern 3 cm from a central well. Tests were read at 24 and 48 hours. Soluble antigen for the test consisted of concentrated nutrient medium removed every 2 weeks from a cell culture persistently infected with isolate WLC 1 of OPP virus. Specificity of results was verified by testing serums from experimentally exposed sheep and appropriate controls. Two lines of precipitate formed with some serums from experimentally inoculated sheep. Serums taken soon after exposure of sheep to the virus and those taken 3 to 4 years after exposure frequently formed only 1 line of precipitate. Of 37 lambs inoculated with OPP virus, 25% of those tested were positive by postinoculation (PI) month 1, 79% of those tested were positive by PI month 3, and all of those tested were positive by PI month 6. The test appears adequate to detect exposure of sheep to OPP virus.     

New types of virus infections of domestic animals in the German Democratic Republic. 3. Seroepizootiologic and experimental studies of herpesvirus infections in sheep--the etiology of pulmonary adenomatosis

Neutralisation tests for antibodies against ovine herpesvirus were applied to 848 sera which had been sampled from different sheep herds across the GDR. Between six and 20 percent of sheep in the herds tested exhibited neutralising antibodies, notwithstanding their pulmonary adenomatosis status. Incidence and titre distribution of antibodies against ovine herpesviruses in pulmonary adenomatosis herds were identical with those recorded from unsuspected herds. From among 21 sheep with pathomorphologically secured pulmonary adenomatosis, six animals exhibited antibody titres just as high as those recorded from responders of all herds examined. Lambs were obtained by hysterectomy and raised without mothers and were experimentally infected with Herpesvirus ovis. All of these animals responded to infection by clearly rising titres (between 1:2 and 1:32). Adenomatous pulmonary lesions were not recordable from any of them. One lamb, following experimental ovine herpesvirus infection, exhibition, exhibited subclinical interstitial pneumonia. Herpesvirus ovis has been widespread in sheep herds across the GDR. The authors' serological and experimental investigations do not support the assumption of an aetiological relationship between ovine herpesvirus infection and incidence of pulmonary adenomatosis.     

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.     

Effect of infections with swine fever virus on immune functions II. Lymphocyte response to mitogens and enumeration of lymphocyte subpopulations

Peripheral blood and spleen lymphocytes from pigs infected with a low-virulent strain of swine fever virus (SFV) were transiently hyporesponsive to the mitogenic action of PHA, PWM and Con A. The mitogenic reactivity of lymphocytes from lymph nodes from such pigs appeared to be enhanced rather than depressed at that time. In addition, hyperresponsiveness of peripheral blood lymphocytes (PBL) to these mitogens occurred in some pigs.PBL from pigs lethally infected with virulent SFV showed a persistent depression of the response to these mitogens, whereas lymphocytes from lymph nodes had a high responding capacity.A lymphocyte response to SFV antigens could not be demonstrated in infected pigs.These SFV infections did not markedly affect the percentage of lymphocytes in the blood and most lymphoid organs rosetting with sheep red blood cells. On the other hand, surface immunoglobulin-bearing lymphocytes were markedly increased in lymph nodes from pigs exposed to virulent SFV. The sum of both lymphocyte subpopulations in the lymph nodes from these pigs often considerably exceeded the 100% value, which strongly suggests the presence of cells bearing both surface immunoglobulin and receptors for dextran-treated sheep red blood cells.Possible correlations between these findings are discussed. The results suggest that infections with SFV induce systemic alterations in the process of lymphocyte recirculation in the pig.     

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.