[Indurative mastitis in a herd of Dorper sheep caused by an infection with Maedi Visna virus]. / Indurative Mastitis in einer Herde Dorperschafe als Folge einer Infektion mit dem Maedi-Visna-Virus.

This case report describes indurative mastitis in a herd of sheep caused by Maedi Visna virus (MVV) infection. Reduced udder formation after delivery, small, indurated udders and increased losses of lambs were observed in a herd of Dorper sheep. Examination of the mammary gland and milk did not reveal findings characteristic of chronic bacterial mastitis. The protein supply was insufficient which may have contributed to reduced milk yield, but was considered unlikely as cause for the induration of the mammary gland. Nineteen of the 21 mothers were positive for MVV by serology. Mammary gland and supramammary lymph nodes were collected in a sheep with indurated udder at the time of slaughter. Meat inspection did not reveal lesions in any other organs. One part of the mammary gland showed a mild to moderate multifocal lymphohistiocytic mastitis, the other exhibited a severe diffuse lymphohistiocytic mastitis with atrophy of the glandular acini, vasculopathy, fibrosis and calcification. MVV antigen was visualized by immunohistochemistry in macrophages, dendritic cells, epithelial cells and endothelial cells in the mammary gland, and macrophages and dendritic cells in the supramammary lymph nodes. A large amount of MVV provirus was detected in the supramammary lymph nodes and the severely indurated part of the mammary gland by PCR. In conclusion, indurative mastitis as a result of a systemic infection may occur independently of the commonly known manifestations of Maedi Visna in the lung and central nervous system. MVV should be considered as differential diagnosis in mastitis of sheep. The MVV status of the herd can be tested by serological detection of specific antibodies. Additionally, characteristic histological lesions are present in the mammary gland. MVV antigen can also be detected by immunohistochemistry and MVV provirus by PCR in the altered mammary gland and regional lymph nodes.

Detection of PrPSc in lung and mammary gland is favored by the presence of Visna/maedi virus lesions in naturally coinfected sheep.

There are few reports on the pathogenesis of scrapie (Sc) and Visna/maedi virus (VMV) coinfections. The aim of this work was to study in vivo as well as post mortem both diseases in 91 sheep. Diagnosis of Sc and VMV infections allowed the distribution of animals into five groups according to the presence (+) or absence (-) of infection by Sc and VMV: Sc-/VMV-, Sc-/VMV+, Sc+/VMV- and Sc+/VMV+. The latter was divided into two subgroups, with and without VMV-induced lymphoid follicle hyperplasia (LFH), respectively. In both the lung and mammary gland, PrPSc deposits were found in the germinal center of hyperplasic lymphoid follicles in the subgroup of Sc+/VMV+ having VMV-induced LFH. This detection was always associated with (and likely preceded by) PrPSc observation in the corresponding lymph nodes. No PrPSc was found in other VMV-associated lesions. Animals suffering from scrapie had a statistically significantly lower mean age than the scrapie free animals at the time of death, with no apparent VMV influence. ARQ/ARQ genotype was the most abundant among the 91 ewes and the most frequent in scrapie-affected sheep. VMV infection does not seem to influence the scrapie risk group distribution among animals from the five groups established in this work. Altogether, these data indicate that certain VMV-induced lesions can favor PrPSc deposits in Sc non-target organs such as the lung and the mammary gland, making this coinfection an interesting field that warrants further research for a better comprehension of the pathogenesis of both diseases.

Polimiositis y afectación pulmonar intersticial con buena respuesta a glucocorticoides y metotrexato / Polymyositis and interstitial lung disease with a favorable response to corticosteroids and methotrexate

La polimiositis es una colagenopatía rara, que puede afectar al pulmón. Entre un 5 y un 30% de los pacientes con polimiositis presenta una enfermedad pulmonar intersticial en el momento del diagnóstico o durante el curso de la enfermedad. El inicio suele ser insidioso en forma de disnea y tos seca. Son varias las entidades histopatológicas que se asocian a polimiositis, de las cuales la más frecuente es la neumonía intersticial no específica. El pronóstico de la enfermedad pulmonar intersticial difusa asociada a polimiositis es mejor que el de la fibrosis pulmonar idiopática, ya que la mayoría de los pacientes responde al tratamiento con glucocorticoides e inmunodepresores. Presentamos el caso clínico de una mujer de 60 años con síntomas de disnea y debilidad muscular, a quien se diagnosticó de polimiositis y enfermedad pulmonar intersticial difusa (posible neumonía intersticial no específica por hallazgos radiológicos), y que mostró buena respuesta al tratamiento con prednisona y metotrexato

Polymyositis is a rare collagen disease that can involve the lungs. Between 5% and 30% of patients with polymyositis present interstitial lung disease at diagnosis or during the course of disease. Onset is usually insidious and involves dyspnea and nonproductive cough. Several histopathological findings are associated with polymyositis and the most common is nonspecific interstitial pneumonia. The prognosis of interstitial lung disease associated with polymyositis is better than that of idiopathic pulmonary fibrosis, since most patients respond to treatment with corticosteroids and immunosuppressants. We report the case of a 60-year-old woman with dyspnea and muscle weakness who was diagnosed with polymyositis and interstitial lung disease (radiography indicated possible nonspecific interstitial pneumonia). The patient responded well to prednisone and methotrexate

Demonstration of coinfection with and recombination by caprine arthritis-encephalitis virus and maedi-visna virus in naturally infected goats.

Recombination of different strains and subtypes is a hallmark of lentivirus infections, particularly for human immunodeficiency virus, and contributes significantly to viral diversity and evolution both within individual hosts and within populations. Recombinant viruses are generated in individuals coinfected or superinfected with more than one lentiviral strain or subtype. This, however, has never been described in vivo for the prototype lentivirus maedi-visna virus of sheep and its closely related caprine counterpart, the caprine arthritis-encephalitis virus. Cross-species infections occur in animals living under natural conditions, which suggests that dual infections with small-ruminant lentiviruses (SRLVs) are possible. In this paper we describe the first documented case of coinfection and viral recombination in two naturally infected goats. DNA fragments encompassing a variable region of the envelope glycoprotein were obtained from these two animals by end-limiting dilution PCR of peripheral blood mononuclear cells or infected cocultures. Genetic analyses, including nucleotide sequencing and heteroduplex mobility assays, showed that these goats harbored two distinct populations of SRLVs. Phylogenetic analysis permitted us to assign these sequences to the maedi-visna virus group (SRLV group A) or the caprine arthritis-encephalitis virus group (SRLV group B). SimPlot analysis showed clear evidence of A/B recombination within the env gene segment of a virus detected in one of the two goats. This case provides conclusive evidence that coinfection by different strains of SRLVs of groups A and B can indeed occur and that these viruses actually recombine in vivo.

Association of Maedi Visna virus with Brucella ovis infection in rams.

Maedi Visna Virus (MVV) is the etiological agent of a systemic disease of sheep, which causes lesions in lungs, the central nervous system, joints, and mammary glands. It has been speculated that the association with Brucella ovis may lead to the venereal shedding of the virus. In this work, samples of epididymis from ten rams positive for MVV and infected experimentally with Brucella ovis, were subjected to liquid-phase PCR, immunohistochemistry (IHC) and in situ PCR tests, aimed at identifying the pathogens in a tissue context. IHC was carried out using a monoclonal antibody raised against p28 MVV protein and a polyclonal antibody to B. ovis. Liquid phase- and in situ PCR were designed to amplify a portion of MVV proviral DNA Pol sequence. In the animals showing B. ovis-related histopathological changes, IHC clearly demonstrated a positivity for B. ovis and MVV in interstitial and epithelial ductal cells. In situ PCR assessed the presence of MVV proviral DNA in macrophages and elements inside the epithelium. The unaffected and reagent control samples constantly gave negative results. Taken together, these data demonstrate that MVV may affect ovine epididymis, apparently taking advantage of the concurrent infection by B. ovis. The tropism of MVV for the epididymal epithelial cells, may be responsible for its excretion with the semen.

Experimental Maedi Visna Virus Infection in sheep: a morphological, immunohistochemical and PCR study after three years of infection.

A morphological, immunohistochemical and polymerase chain reaction (PCR) study was performed on eight ewes experimentally infected with an Italian strain of Maedi-Visna Virus (MVV) in order to evaluate the lesions and the viral distribution after three years of infection. At the moment of euthanasia, seven sheep were seropositive for MVV, while one sheep in poor body conditions was seronegative since one year. Lungs, pulmonary lymph nodes, udder, supramammary lymph nodes, carpal joints, the CNS, spleen and bone marrow of the eight infected sheep were collected for histology, for immunohistochemical detection of the MVV core protein p28 and for PCR amplification of a 218 bp viral DNA sequence of the pol region. The most common histological findings consisted of interstitial lymphoproliferative pneumonia and lymphoproliferative mastitis of different severity, while no lesions were observed in the CNS. MVV p28 antigen was immunohistochemically labelled in lungs, udder, pulmonary lymph nodes, spleen and bone marrow but not in the CNS of all the eight infected sheep. A 218 bp sequence of MVV pol region was detected in lung of a seropositive and of the seroconverted negative sheep. The results suggest that (i) MVV causes heterogeneous lesions in homogeneously reared ewes, (ii) MVV p28 antigen is detectable not only in inflammed target organs, but also in pulmonary lymph nodes, spleen and bone marrow, and (iii) immunohistochemistry and PCR are useful methods for Maedi-Visna diagnosis in suspected cases, also when serological tests are negative.

Respiratory infections of sheep.

Sheep respiratory infections appear as differing clinical syndromes. Mild, acute infections are usually due to parainfluenza 3 (PI3) virus. A mild but chronic respiratory problem in lambs under 1 year old is thought to be caused by Mycoplasma ovipneumoniae probably in association with Pasteurella and PI3. Acute bacterial pneumonia usually results from infection with Pasteurella of biotype A. Infection with PI3 can initiate invasion by Pasteurella. Bordetella parapertussis infection has also been implicated. Serotypes of biotype T P. haemolytica cause an acute septicaemia. Stressful management practices may be a predisposing factor. Chronic proliferative pneumonia results from infection by retroviruses of pulmonary adenomatosis or maedi-visna. Both infections have incubation periods extending into years. The former produces fatal tumorous masses in the lungs. Diagnostic tests are being actively sought. Maedi-visna can present as several clinical problems, frequently as an insidious but fatal proliferative pneumonia.

Ovine lentivirus induced indurative lymphocytic mastitis and its effect on the growth of lambs.

The effect of the indurative lymphocytic mastitis caused by infection with maedi-visna virus was quantified by comparing the pre-weaning growth of lambs from infected and uninfected ewes under the same conditions. A total of 73 infected, but clinically healthy, ewes and 75 ewes from a maedi-visna virus-free source were purchased to form a new flock; they were all three years old. The ewes were mated and the flock was managed as a normal field flock. Serum samples were taken at regular intervals and tested for antibodies to maedi-visna virus. The lambs were weighed at birth and at 14, 30, 50 and, finally, 80 days old, when they were weaned. The ewes were slaughtered, their udders were examined histologically, and the lesions were assessed by counting the typical lymphocytic follicles. Sixty-six per cent of the ewes that were seropositive at slaughter appeared to have follicles. A statistically significant association was found between the number of follicles in the udder and the reduction in the growth rate of the lambs. Lambs from ewes with the mean number of follicles weighed 1.7 kg less at weaning.

Pathological and epidemiological aspects of the coexistence of maedi-visna and sheep pulmonary adenomatosis.

Between 1982 and 1991, 159 sheep suffering from chronic respiratory disease were subjected to clinical, pathological, histopathological and serological examination. Maedi was diagnosed in 82 sheep and sheep pulmonary adenomatosis (SPA) in another 59. Forty-one of the latter (69.5 per cent) were seropositive for maedi-visna (MV) virus infection, but only six (10.2 per cent) showed concurrent lung lesions of maedi. Even disregarding the MV seronegative sheep and those younger than two years old, the rate of concurrent maedi lesions did not exceed 18 per cent. During a similar period, 5060 sheep from 161 flocks (86 of which also provided the 159 affected animals) were tested for antibodies to MV virus. The average seroprevalence of MV virus infection among flocks in which SPA was detected was 66.4 per cent, whereas in those in which SPA could not be demonstrated, and in those in which necropsies were not performed, the levels of MV virus infection were 55.1 per cent and 43.6 per cent, respectively. The effect of SPA on the seroprevalence of MV virus infection was independent of other factors, such as breed of sheep or the size of the flocks. These results provide evidence that SPA plays a role in the spread of MV virus infection, although a synergistic effect of the simultaneous infection on the expression of concurrent lesions does not seem to occur.

[Double infection with maedi virus and adenomatosis virus in Merino sheep]. / Doppelinfektion mit Maedi-Virus und Adenomatose-Virus bei Merinolandschafen.

This is the first report of the simultaneous occurrence of sheep pulmonary adenomatosis and lymphoid interstitial pneumonia (Maedi) in the same animal in the Federal Republic of Germany. Seven adult sheep of the Merino Landrace were tested by immunodiffusion-assay for antibodies against Maedi/Visna-virus. Five of them originating from three different flocks had a positive reaction. In all pulmonary foci, which were examined by light microscopy, we found proliferations of the alveolar epithelium and therefore made a diagnosis of pulmonary adenomatosis. The animals with antibodies against Maedi-virus were additionally affected by a non-purulent peribronchitis and interstitial pneumonia. The diagnostic difficulties in double infections like those reported here are discussed. Eradication is complicated by the unknown epidemiologic situation.

Human and ovine lentiviral infections compared.

Maedi-visna virus (MVV) of sheep was the first lentivirus to be isolated. The genomic organization of MVV is very similar to that of human immunodeficiency virus (HIV) with several genes regulating the expression of the viral genome. Viral replication is severely restricted in the host and some cells apparently contain the genetic information in a DNA provirus form with little or no expression of viral antigens. This seems to be a major factor in causing the "slowness" of lentiviral infections and the persistence of the virus in the host since the immune system may not recognize the provirus-containing cells. The target cells for HIV and MVV are similar although T4 lymphocytes are not specifically destroyed in maedi-visna. There are also certain similarities in the pathological changes in both diseases, both in the central nervous system, the lungs and the lymphatic system. Although the severe final immunodeficiency state characteristic of AIDS has not been observed in maedi-visna, the basic biological features of the MVV and its interaction with host cells are so similar to HIV infection, that we consider ovine maedi-visna useful animal model for the human lentivirus infections.

Maedi-visna and sheep pulmonary adenomatosis: a study of concurrent infection.

The transmission of maedi-visna (MV) virus was studied within two groups of sheep, one of which was also affected with sheep pulmonary adenomatosis (SPA). Serological monitoring of sheep kept in contact with both groups indicated that MV virus replication occurred to a greater extent in the group with both diseases, three of five in-contact sheep being seropositive after 1 year's exposure compared with none of six held with MV-virus-only infected lambs.

Concurrent maedi-visna virus infection and pulmonary adenomatosis in a commercial breeding flock in East Anglia.

The seroprevalence of maedi-visna virus infection in thin potential cull ewes aged over two years in a flock in East Anglia increased from 3.7 per cent in August 1985 to 39.0 per cent in September 1987 and 93.3 per cent in May 1989. This increase coincided with the first appearance of sheep pulmonary adenomatosis in the flock. Four emaciated ewes which were dyspnoeic were necropsied between 1987 and 1989. Maedi and pulmonary adenomatosis were confirmed histologically in one of these ewes and pulmonary adenomatosis was confirmed in the other three.

Retrovirus-associated ovine pulmonary carcinoma (sheep pulmonary adenomatosis) and lymphoid interstitial pneumonia. I. Lesion development and age susceptibility.

To determine the lesion development of retrovirus-induced ovine pulmonary carcinoma (OPC), ten neonatal lambs were inoculated intratracheally with either 1) lung fluid preparations derived from a sheep with Type D retrovirus-associated OPC and concurrent ovine lentivirus (OvLV)-associated lymphoid interstitial pneumonia (LIP) (n = 8); or 2) lung fluid from a sheep with only OvLV-LIP (n = 2). Seven of eight neonates that received Type D retrovirus-associated OPC/OvLV-LIP lung fluid developed both OPC and LIP lesions between 9 and 32 weeks after inoculation. Mild OPC lesions consisted of foci of type II alveolar epithelial cells lining alveoli surrounded by minimal alveolar macrophage infiltrates. More severe OPC lesions consisted of multifocal aggregates of cuboidal to columnar neoplastic cells forming acini or masses associated with abundant alveolar macrophage infiltrates. Lesions of LIP consisted of peribronchiolar and perivascular lymphoid hyperplasia and heterogeneous interstitial leukocytic infiltrates. The two neonates that received OvLV-LIP lung fluid developed rapid and severe LIP, but not OPC lesions. Two lambs (inoculated as neonates with virus-free lung fluid) and three lambs (uninoculated contacts) served as controls and did not develop OPC. To investigate age susceptibility for development of OPC, 20 additional lambs within defined age groups (neonates, 2 weeks old, 5 weeks old, and 10 weeks old) received ultracentrifuged tumor homogenate. Neonatal to 5-week-old lambs inoculated with Type D retrovirus-associated OPC/OvLV-LIP tumor homogenate were equally likely to develop OPC, but lambs inoculated at 10 weeks of age were more refractory to tumor development.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of indurative lymphocytic mastitis in a flock of sheep infected with maedi-visna virus.

Sheep in a flock in which 88 per cent of the ewes had antibodies to maedi-visna virus were clinically examined for udder induration during lactation and after drying off. On both occasions about half of the ewes had indurated udders. Histological examination revealed lymphocytic mastitis associated with maedi-visna virus infection, in the udders of six of 25 hoggs (24 per cent), 21 of 39 shearlings (53.8 per cent) and 42 of 67 ewes (62.7 per cent). Distinct lung lesions were found in 8 per cent of the hoggs, 12.5 per cent of the shearlings and 10 per cent of the ewes. The results of a clinical examination of dry udders were correlated with the histological findings.

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.

Indurative lymphocytic mastitis in sheep after experimental infection with maedivisna virus.

In order to provide further evidence for the association of an indurative lymphocytic mastitis in sheep with MVV (maedi-visna virus) infection, an experimental study was performed. Fourteen MVV-free pregnant ewes, 2 years of age, were divided into two groups. Eight were intravenously inoculated with MVV (strain ZZV-1050); six ewes served as sham-inoculated controls. Post-mortem examinations were carried out at 8, 16 and 28 months. After 8 months, the 3 infected ewes had indurated udders with extensive lymphoid proliferation around lactiferous ducts and in the acinar tissue. The ducts were often partially obliterated. After 16 months, one of the two infected ewes suffered from indurative lymphocytic mastitis. The other was free of specific udder lesions. After 28 months only one of three infected ewes had mild lymphocytic infiltration in the udder. None of the controls, two in each post-mortem session, had lesions typical of this form of mastitis. The lesions were most severe 8 months after infection. At 16 and 28 months lesions were of a lesser degree or were absent. The lung lesions in the infected ewes 8 months after inoculation were similar to the changes in the udder regarding the lymphoid accumulation, although the proliferation around bronchial tree and blood vessels was less pronounced. After 16 and 28 months all infected ewes had peribronchial and perivascular lymphocytic infiltration though of a lesser degree than after 8 months. From these results it is concluded that in addition to the lung and brain lesions MVV infections may cause a specific indurative lymphocytic mastitis.