Development of real time RT-PCR assays for detection of type A influenza virus and for subtyping of avian H5 and H7 hemagglutinin subtypes.

Rapid detection and subtyping of H5 and H7 subtypes influenza A viruses are important for disease control in poultry and potential transmission to humans. Currently, virus isolation and subsequent HA and NA subtyping constitute the standard for avian influenza viruses detection and subtype identification. These methods are highly accurate and sensitive but are also laborious and time-consuming. Reverse transcription PCR and real time reverse transcription PCR assays, suitable tests for rapid detection, have previously been used for the specific diagnosis of H5 and H7 viruses, however, at present, no primer and probe sets are available for the identification of all H5 and H7 strains. Herein, we have developed specific and sensitive real time reverse transcription PCR assays for the detection of type A influenza virus and for subtyping of avian H5 and H7 hemagglutinin subtypes and we have also compared these molecular assays with viral isolation in terms of sensitivity. Our results demonstrate that the real time reverse transcription PCR assays are more sensitive, specific, less expensive compared to viral isolation. In conclusion, molecular assays could represent an useful tool for rapid detection and screening of H5 and H7 isolates during influenza A virus outbreaks alternatively to viral isolation.