Detection of viral RNA from paraffin-embedded tissues after prolonged formalin fixation.

Background: Isolating amplifiable RNA from formalin-fixed, paraffin-embedded (FFPE) tissues is more difficult than isolating DNA because of RNases, chemical modification of the RNA, and cross-linking of nucleic acids and proteins. Tissues containing infectious disease agents that require biosafety level (BSL)-3 and -4 necessitate fixation times of 21 and 30 days, respectively.

Objective: To improve procedures for extracting RNA from these FFPE tissues and detect the RNA with the more sensitive TaqManbased reverse transcriptase (RT)-PCR.