Detection of bovine viral diarrhea virus in formalin fixed paraffin embedded tissue sections by real time RT-PCR...

Real time quantitative RT-PCR (Taqman) identified specifically BVD virus in freshly processed formalin-fixed paraffin-embedded tissue sections and archival samples up to 7 years old. Samples included tissue from both acutely and persistently infected animals. To assess RNA degradation due to tissue handling and processing, freshly collected tissues from a calf persistently infected with BVD virus were stored at 4 degrees C or room temperature for up to 1 week prior to 24 h formalin fixation and routine histologic processing. Samples stored at 4 degrees C for up to a week prior to fixation were positive while samples stored at room temperature were positive at 74 h but became negative after 96 h. Fixation of fresh tissue in formalin for 1 week prior to processing resulted in a mild decrease in signal strength compared with tissue fixed for 24-48 h. Real time RT-PCR improves diagnosis of BVD infection by allowing prospective and retrospective identification of BVD virus in tissues processed routinely and stored for histologic evaluation.