A new real-time RT-PCR for the detection of piscine orthoreoviruses PRV-1 and PRV-3.

Piscine orthoreoviruses (PRV) are often associated with pathologies affecting various salmonid species, especially farmed species. Both surveillance and research purposes require diagnostic molecular-based tools able to detect the most frequent genotypes, namely PRV-1 and PRV-3. A new one-step reverse-transcription real-time PCR (RT-qPCR) was set up targeting a conserved region of the L1 segment. Based on the French standard NF U47-600, this PCR method proved to be specific to PRV, excluding other salmonid viruses. The assay can detect 1000 copies of a synthetic transcript of PRV-3, pure or mixed with nucleic acids from healthy fish. This assay produced signals similar to those observed using a previously published generic assay targeting a different viral segment. The new assay is reliable and can be used for the detection of PRV-1 and PRV-3 in rainbow trout and Atlantic salmon.