Comparison effect of fresh frozen and paraffin embedded samples in diagnosis of ovine pulmonary adenomatosis by PCR and immunohistochemistry

Abstract

Ovine pulmonary adenomatosis (OPA) is a contagious bronchio-alveolar carcinoma that is caused by Jaagsiekte sheep retrovirus. The virus induces transformation in Clara cells and pneumocyte type II. In the present study, 42 grossly suspected lungs of slaughtered sheep to OPA were collected. Lungs were enlarged, failed to collapse with distribution of firm greyish-white nodules on the cranioventral or diaphragmatic lobes and some of them contained foamy fluid in their airways. The lung samples were taken for histopathologic, PCR and immunohistochemistry investigations. Histopathologically, 16 lungs (n= 16/42) showed neoplastic foci that were composed of proliferated pneumocytes type II and Clara cells arranged in the acinar or papillary growth pattern. Immunohistochemical analysis detected JSRV capsid protein (JSRV-CA) in the cytoplasm of pneumocytes type II and Clara cells. PCR technique was done on 16 paraffin embedded and fresh frozen tissues. Based on PCR technique targeting U3 region, amplicons of expected size (176 bp) were observed in all 15 paraffin embedded and 16 fresh frozen sections. No positive results were detected in the apparently normal lungs. It seems PCR can be used on paraffin-embedded tissues to reveal Jaagsiekte sheep retrovirus infection, but complementary studies on a large number of samples are required to determine sensitivity.