Detection of bovine viral diarrhea virus RNA in formalin-fixed, paraffin-embedded brain tissue by nested polymerase chain reaction.

Isolation and amplification of RNA from formalin-fixed, paraffin-embedded tissues is delicate due to its fragility and ubiquitous ribonucleases. For retrospective studies, however, a convenient procedure for the detection of RNA in archived material is of great value. Bovine viral diarrhea (BVD) virus is a member of the pestivirus genus in the family Flaviviridae. Different protocols for the isolation of BVD virus RNA from fresh and autolytic as well as from routinely formalin-fixed and paraffin-embedded brain tissue of BVDV-infected calves were compared. The polymerase chain reaction (PCR) after reverse transcription (RT-PCR) was carried out subsequently for the detection of viral RNA. Using proteinase K digestion of deparaffinized tissue sections without additional ribonuclease inhibitors and subsequent nested PCR, a 803 bp fragment of the gene coding for the nonstructural protein p125 of BVD virus could be consistently detected. In addition, BVD virus RNA was detected by RT-PCR from non-fixed brain tissue after 10 days of autolysis.