The distribution of immune cells in the lungs of classical and atypical ovine pulmonary adenocarcinoma

Ovine pulmonary adenocarcinoma (OPA) is a contagious tumour caused by infection of sheep with Jaagsiekte sheep retrovirus. Two forms of OPA have been identified, classical and atypical, which can be distinguished clinically and pathologically. Most notably classical OPA is progressive until death, while atypical OPA remains subclinical. In the present study the local immune responses in the lungs of cases of atypical OPA were compared with those from classical cases by immunohistochemistry using a panel of mouse anti-sheep mAbs. Distinct differences in the distribution of immune cell subsets in the two forms of OPA were observed. In particular there was an intratumoural influx of T cell subsets and MHC Class II expression on the tumour cells in atypical OPA, neither of which was seen in classical OPA. It is possible that these differences may contribute, at least in part, to determining the progressive course of classical OPA compared with the subclinical nature of atypical OPA.

Expression of glial fibrillary acidic protein and glutamine synthetase genes in the natural scrapie of sheep

Gene expression of two astroglial markers, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS), was investigated in cerebellum and brainstem from scrapie-affected sheep. The GFAP and GFAP-mRNA concentrations were increased in the two cerebral regions studied in the scrapie-affected animals as compared to the controls. The good correlation between the increase in GFAP and GFAP-mRNA concentrations found in scrapie-affected sheep indicates a significant de novo synthesis of GFAP in this pathology. In contrast to these results, in scrapie no significant differences in GS-mRNA content appeared in either brain area from scrapie-affected sheep as compared to the controls. This fact could suggest some specificity of GFAP expression changes in this pathology. The overexpression of GFAP gene could be related to a possible interaction between GFAP and scrapie infectious agent in astrocytes. The relative increase in the GFAP and its encoding message in affected animals was higher in the cerebellum than in the brainstem, which would suggest regional comparative differences in the effect here described.

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 protrusion, 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 ultrastructurally in 6/8 tumors. The similarities between these caprine tumors and nasal tumors in sheep and the etiologic role of the retrovirus are discussed.

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.