Exogenous Jaagsiekte Sheep Retrovirus type 2 related to ovine pulmonary adenocarcinoma in Romania: prevalence, anatomical forms, pathological description, immunophenotyping and virus identification
Abstract Ovine pulmonary adenocarcinoma (OPA) is a neoplastic disease caused by exogenous Jaagsiekte Sheep Retrovirus (exJSRV). The prevalence of JSRV-related OPA in Eastern European countries, including Romania is unknown. We aimed to investigate: the prevalence and morphological features of OPA (classical and atypical forms) in Romania, the immunophenotype of the pulmonary tumors and their relationships with exJSRV infection. Lung tumors from 28 slaughtered adult sheep and 6 necropsied individuals were grossly evaluated. Cytology, histology, immunocytochemistry, immunohistochemistry, electron microscopy and DNA testing were subsequently performed. Out of 2693 examined sheep, 34 had OPA (1.26% prevalence). The diaphragmatic lobe was the most affected. Grossly, the classical OPA was identified in 88.24% of investigated cases and the atypical OPA in 11.76% that included solitary myxomatous nodules. Histopathology results confirmed the presence of OPA in all suspected cases, which were classified into acinar and papillary types. Myxoid growths (MGs) were diagnosed in 6 classical OPA cases and in 2 cases of atypical form. JSRV-MA was identified by IHC (94.11%) in both epithelial and mesenchymal cells of OPA. Immunocytochemistry and electron microscopy also confirmed the JSRV within the neoplastic cells. Adenocarcinoma was positive for MCK and TTF-1, and MGs showed immunoreaction for Vimentin, Desmin and SMA; Ki67 expression of classical OPA was higher than atypical OPA and MGs. Phylogenetic analysis revealed the presence of the exJSRV type 2 in Romanian sheep affected by lung cancer and showed a high similarity with the UK strain (AF105220.1), confirming exJSRV2 for the first time in Romania. Additionally, we described the first report of atypical OPA in Romania, and to the best of our knowledge, in Eastern Europe. Finally, we showed that MGs have a myofibroblastic origin.