Sheep pulmonary adenomatosis: Characterization of two pathological forms associated with jaagsiekte retrovirus

Pathological and immunohistochemical studies were performed on the lungs of 10 sheep with lesions of "classical" sheep pulmonary adenomatosis (SPA) an d sis sheep with "atypical" lung tumours. Lung tumour samples:and other tis sues from the same 16 animals were tested for the presence of jaagsiekte re trovirus (JSRV) by a polymerase chain reaction (PCR) that amplified a porti on of the U3 long terminal repeat. The differences in the gross appearance of the classical and atypical Forms paralleled the histopathological differ ences. The latter mainly concerned the stroma of the tumours which in the a typical cases was more heavily infiltrated by inflammatory cells and connec t-ive:tissue fibres. JSRV major capsid protein was detected immunohistochem ically in the epithelial transformed cells of both classical and atypical t umours, but the immune reactivity was slightly milder in atypical SPA, Prov iral U3 sequences of JSRV were detected by specific PCR in all the tumour s amples. Furthermore. the sequences of amplimers obtained from the two diffe rent pathological forms of the tumour were very similar. However, the disse mination of JSRV to other organs was greater in sheep with classical SPA th an in those with atypical SPA. The pathological and virological features of these two forms of tumour are compared in an attempt to clarify whether cl assical and atypical SPA are two separate diseases or different expressions of a single disease spectrum. (C) 2000 Harcourt Publishers Ltd.