Development of nested RT-PCR for the detection of swine hepatitis E virus in formalin-fixed, paraffin-embedded tissues and comparison with in situ hybridization

Swine hepatitis E virus (HEV) was detected in formalin-fixed, paraffin-embedded tissues from naturally infected pigs by nested reverse transcription-polymerase chain reaction (RT-PCR). The results for seminested RT-PCR were compared with those determined by in situ hybridization. The results obtained show that use of xylene deparaffinization, digestion with proteinase K followed by nested RT-PCR is a reliable detection method. Swine HEV nucleic acid was detected in formalin-fixed, paraffin-embedded hepatic tissues from 40 pigs. Distinct positive signals for swine HEV were obtained in the same hepatic tissues by in situ hybridization. Swine HEV nucleic acid was localized to the cytoplasm of hepatocytes and had a granular staining pattern. The rate of agreement between nested RT-PCR and in situ hybridization for the detection of swine HEV in formalin-fixed, paraffin-embedded hepatic tissues was 100%.