M. De las Heras

Epithelial tumour cells in the lungs of sheep with pulmonary adenomatosis are major sites of replication for Jaagsiekte retrovirus

Sheep pulmonary adenomatosis (SPA) is a naturally occurring contagious lung tumour of sheep which has been associated aetiologically with a type D- and B-related retrovirus (Jaagsiekte retrovirus; JSRV). To improve understanding of the aetio-pathogenesis of SPA, the distribution and the sites of JSRV replication in sheep with naturally or experimentally induced SPA or in unaffected controls were identified. New immunological reagents were produced and a blocking enzyme-linked immunosorbent assay (B-ELISA) and an immunohistochemical technique for the detection of JSRV major capsid protein at the tissue and cellular levels were developed. JSRV was detected only in the respiratory tract of sheep affected by pulmonary adenomatosis and specifically in the transformed epithelial cells of the alveoli of SPA-affected sheep.

Pathology of Ovine Pulmonary Adenocarcinoma

Clinical, gross pathology, histopathology and electron microscopy of the ovine pulmonary adenocarcinoma (OPA, jaagsiekte) either natural or experimentally induced in sheep, goat and moufflon are described. OPA is caused by an oncogenic betaretrovirus,jaagsiekte sheep retrovirus (JSRV). Most natural cases of OPA appear in animals 1-4 years old. There is no evidence of sex or breed susceptibility. Sheep affected by OPA show an afebrile respiratory illness associated with loss of weight. A very characteristic clinical sign is moist rales caused by the accumulation of fluid in the respiratory airways which is discharged from the nostrils when the head is lowered. Gross lesions are confined to the lungs but occasionally thoracic or extrathoracic structures are also affected. Two pathologic forms of OPA are currently recognized, classical and atypical. In classical forms the neoplastic lesions occurs particularly in the cranioventral parts of all lung lobes. They are diffuse or nodular, light grey or light purple in colour. On the cut surface the tumour is moist, and frothy fluid may pour from the airways on slight pressure. Atypical forms tend to be more nodular in both early and advanced tumours. They are pearly white in colour, very hard in consistency, very well demarcated from the surrounding parenchyma and their surface is dry. Histology of the lung sections reveals the presence of several foci of epithelial cell neoplastic proliferation in both alveolar or bronchiolar regions. The tumours, derived from type II pneumocytes and Clara cells, proliferate into mostly papillary but also acinar or occasionally solid growths. The tumour generally shows a benign histological pattern but intra- and extrathoracic metastases have been detected in some cases. Several considerations suggest that the tumour should be classified as an adenocarcinoma of the lung. The histology of atypical OPA is similar to that of the classical disease, with an increase in the stromal reaction accompanying the epithelial proliferations. Pathological features of OPA induced experimentally in sheep, or of OPA in goats and moufflon are similar to those described in sheep. Detailed electron microscopy of tumour material confirms that type II pneumocytes and Clara bronchiolar epithelial cells are the origin of the neoplasia. Also included in this chapter is a description of the morphology of the viral particles associated with OPA.

Pathology of Human Bronchioloalveolar Carcinoma and Its Relationship to the Ovine Disease

Lung cancer is a leading cause of cancer with a poor prognosis. Bronchioloalveolar carcinoma (BAC) is a rare tumor that has always intrigued physicians. Since the last World Health Organization classification the pathology has been clarified; BAC per se is an adenocarcinoma with a pure bronchioloalveolar growth pattern and appears as an in situ alveolar adenocarcinoma. More usually BAC is a clinically recognizable entity presenting as multi-focal nodules evolving towards pneumonia associated with pulmonary shunting. Pathology is that of a multifocal mixed adenocarcinoma: bronchioloalveolar and papillar. Whatever the stage, survival is better than in other forms of non-small cell lung cancer (NSCLC). The true frequency of BAC is unknown, although it is a rare form of lung cancer; smoking cannot be excluded as a risk factor. It appears that p53 and ras genes are less often mutated than in other lung adenocarcinomas, suggesting that the cellular mechanisms involved are different. Ovine pulmonary adenocarcinoma (OPA) presents with the same symptoms as BAC in humans and is caused by a betaretrovirus Jaagsiekte sheep retrovirus. Very early on, clinical and histological similarities with human BAC were stressed. A recent series of OPA described, according to the third edition of the WHO classification for human lung cancer, mixed adenocarcinoma, BAC and papillary and/or acinar carcinoma. An immunohistochemical study suggested that some human pulmonary tumors (including BAC) may be associated with a Jaagsiekte sheep retrovirus-related retrovirus,but so far no molecular study has confirmed this observation. Thus, OPA is an exquisite model of carcinogenesis for human lung adenocarcinomas.

Enzootic Nasal Adenocarcinoma of Sheep and Goats

Enzootic nasal adenocarcinoma is a contagious tumour of the mucosal nasal glands affecting young adult sheep or goats. The disease occurs naturally in all continents except Australia and New Zealand. Clinical signs include continuous nasal discharge, respiratory distress, exophthalmos and skull deformations. The tumour is classified histologically as a low-grade adenocarcinoma. Nasal glands of both respiratory and olfactory muosal glands seem to be the origin of the neoplasia. It has been experimentally transmitted in sheep and goats using either tumour extracts or concentrated nasal fluids. Two distinct retroviruses are implicated in the aetiology of the neoplasia one in sheep (ONAV) and one in goats (CNAV). We suggest that jaagsiekte sheep retrovirus (JSRV), ONAV, CNAV, and their endogenous counterparts represent a unique family of retroviruses. The similarities between these viruses suggests that any control strategies, including vaccination, may be appropriate to both diseases. The differences, however, represent a unique resource for delineating the function of individual regions of the virus. It is intriguing that whilst ONAV and CNAV appear to be as different to each other as they are to JSRV, that they have very similar disease pathologies, distinct from that of OPA. Additionally, all three exogenous viruses manage to avoid instigating any apparent immune response. Whether this is indeed a result of tolerance induced by the endogenous counterparts or whether the viruses themselves have unique immunosuppressive properties will be an important finding.

Enzootic nasal tumour of goats: demonstration of a type D-related retrovirus in nasal fluids and tumours.

Nasal exudate and tumour tissue from goats with enzootic nasal tumours were shown to contain a reverse transcriptase activity associated with a particle of buoyant density typical of retroviruses. The same particle contained a 25,000 Mr protein that cross-reacted with the p27 of Mason-Pfizer monkey virus (MPMV) and with p25 of sheep pulmonary adenomatosis retrovirus. It also contained a low Mr protein related to p10-12 of MPMV.

Pathology of Enzootic Intranasal Tumor in Thirty-eight Goats

Intranasal tumors were studied in 38 goats ranging from 7 months to 8 years of age of both Murciana-Granadina and crossed breeds. Tumors were diagnosed in eight herds. Clinically, the affected goats showed a copious seromucous nasal discharge, ocular protusion, and skull deformations. The tumors originated from the ethmoid region. They involved one or both nasal cavities, although most were bilateral (26/38). The tumors were generally accompanied by inflammatory polyps. The histologic patterns were very similar in all cases, and the tumors were classified as low grade adenocarcinomas of the nasal glands. Histochemical, immunohistochemical, and ultrastructural studies suggested that the serous glands of nasal mucosa were the probable origin of the neoplastic cells. Budding and extracellular retrovirus-like particles were observed ultra-structurally in 6/8 tumors. The similarities between these caprine tumors and nasal tumors in sheep and the etiologic role of the retrovirus are discussed.

Experimental Transmission of Enzootic Intranasal Tumors of Goats

The successful experimental transmission of enzootic intranasal tumor (EIT) from goat to goat is described. Ten kids, less than 48 hours old, from a flock free of the disease and seronegative for ruminant lentiviruses were inoculated intranasally or intrasinusally with either nasal fluid from goats with naturally occurring EIT or EIT retrovirus concentrated from such fluids. EIT was induced in three kids after 12-24 months. The EIT retrovirus was demonstrated in tumor material from each of the three kids by western blotting and electron microscopy. All kids were seronegative for ruminant lentiviruses.

Possible adverse reactions in sheep after vaccination with inactivated BTV vaccines.

PREVENTION programmes against bluetongue virus (BTV) infection have been conducted in numerous countries throughout Europe. In spite of some variations, depending on the expected serotypes of BTV and country-specific conditions, generally, inactivated vaccines have been selected. In the period from

Pathological and Aetiological Studies in Sheep Exhibiting Extrathoracic Metastasis of Ovine Pulmonary Adenocarcinoma (Jaagsiekte)

Seven sheep with a histopathological diagnosis of pulmonary adenocarcinoma with extrathoracic metastases were included in this retrospective study aiming to describe the pathological findings and to establish their relationship with Jaagsiekte sheep retrovirus (JSRV). In order of frequency, extrathoracic metastases were found in the liver, kidneys, skeletal muscle, digestive tract, spleen, skin and adrenal glands. Intrathoracic metastases involved the chest wall, regional lymph nodes, diaphragm and heart. Immunohistochemistry and polymerase chain reaction allowed detection of JSRV-related protein and nucleic acid, respectively, in the extrathoracic tumours of all cases. It is concluded that extrathoracic metastases constitute a pathological event of ovine pulmonary adenocarcinoma and confirm the malignant character of this virus-induced neoplasia.

Natural border disease virus infection in feedlot lambs

Border disease is caused by border disease virus (BDV, a pestivirus from the family Flaviviridae ) infection in sheep and goats (Vantsis and others 1976). BDV infection causes sizeable economic losses in sheep production around the world. In Spain, serological surveys have found 100 per cent flocks and 8–93 per cent sheep seropositive, respectively (Valdazo-Gonzalez and others 2006). BD is considered a congenital disease, but infections in healthy animals at all age groups may also occur. These are named acute infections and are characterised by transitory leucopaenia and fever associated with viraemia (Nettleton and others 1998). The aim of this study was to evaluate the impact of these acute infections in lambs in a commercial feedlot. A longitudinal observational study in a feedlot located in Aragon (Spain) was carried out. Lambs were supplied to the feedlot at minimum 10 kg bodyweight (BW) (45 days old), housed in groups of 250–300 per pen and slaughtered at 25–35 kg BW (about 45 days later). Thirty-six male lambs were randomly selected, ear-tagged, weighed, clinically evaluated and sampled on days: 0 (day lambs entered the feedlot), 14, 27 and 41. From each lamb, whole blood in anticoagulant solution and serum samples for haematological, virological and serological studies were taken. Haematological analysis with an electronic counter …