Multiplex one-step Real-time PCR by Taqman-MGB method for rapid detection of pan and H5 subtype avian influenza viruses.

Avian influenza virus (AIV) can infect a variety of avian species and mammals, leading to severe economic losses in poultry industry and posing a substantial threat to public health. Currently, traditional virus isolation and identification is inadequate for the early diagnosis because of its labor-intensive and time-consuming features. Real-time RT-PCR (RRT-PCR) is an ideal method for the detection of AIV since it is highly specific, sensitive and rapid. In addition, as the new quencher MGB is used in RRT-PCR, it only needs shorter probe and helps the binding of target gene and probe. In this study, a pan-AIV RRT-PCR for the detection of all AIVs and H5-AIV RRT-PCR for detection of H5 AIV based on NP gene of AIV and HA gene of H5 AIV were successfully established using Taqman-MGB method. We tested 14 AIV strains in total and the results showed that the pan-AIV RRT-PCR can detect AIV of various HA subtypes and the H5-AIV RRT-PCR can detect H5 AIV circulating in poultry in China in recent three years, including H5 viruses of clade 7.2, clade 2.3.4.4 and clade 2.3.2.1. Furthermore, the multiplex detection limit for pan-AIV and H5-AIV RRT-PCR was 5 copies per reaction. When this multiplex method was applied in the detection of experimental and live poultry market samples, the detection rates of pan-AIV and H5 AIV in RRT-PCR were both higher than the routine virus isolation method with embryonated chicken eggs. The multiplex RRT-PCR method established in our study showed high sensitivity, reproducibility and specificity, suggesting the promising application of our method for surveillance of both pan AIV and prevalent H5 AIV in live poultry markets and clinical samples.