Validation of a real-time reverse transcriptase-PCR assay for the detection of H7 avian influenza virus

This report describes the validation of an avian influenza virus (AIV) H7 subtype-specific real-time reverse transcriptase-PCR (rRT-PCR) assay developed at the Southeast Poultry Research Laboratory (SEPRL) for the detection of H7 AI in North and South American wild aquatic birds and poultry. The validation was a collaborative effort by the SEPRL and the National Veterinary Services Laboratories. The 2008 H7 rRT-PCR assay detects 10(1) 50% embryo infectious doses per reaction, or 10(3)-10(4) copies of transcribed H7 RNA. Diagnostic sensitivity and specificity were estimated to be 97.5% and 82.4%, respectively; the assay was shown to be specific for H7 AI when tested with > 270 wild birds and poultry viruses. Following validation, the 2008 H7 rRT-PCR procedure was adopted as an official U.S. Department of Agriculture procedure for the detection of H7 AIV. The 2008 H7 assay replaced the previously used (2002) assay, which does not detect H7 viruses currently circulating in wild birds in North and South America.