Efficacy of the H7N9 vaccine as a candidate for the Korean avian influenza antigen bank

The avian influenza A virus (H7N9), first detected in China in 2013, is a zoonotic virus that remains persistent in bird populations despite a decline in human cases owing to control measures. Therefore, this study aimed to develop a vaccine as one preventive strategy in anticipation of the potential entry of H7N9 into Korea. Using the hemagglutinin and neuraminidase consensus sequences of H7N9 from 2018-2019, a recombinant H7N9 vaccine, rgAPQAH7N9, was developed, and its protective efficacy in specific pathogen-free chickens was evaluated. The rgAPQAH7N9 vaccine exhibited proliferation in eggs and demonstrated high immunogenicity, with a hemagglutination inhibition titer of 9.3 log2. Furthermore, the vaccine provided complete protection, as vaccinated chickens did not exhibit clinical signs or viral shedding. Moreover, when the rgAPQAH7N9 vaccine was boosted, the resulting immunity was long-lasting, with hemagglutination inhibition titers > 7 log2 persisting after 6 months. Therefore, the rgAPQAH7N9 vaccine virus may be considered a potential candidate for inclusion in the avian influenza antigen bank to ensure preparedness for emergency vaccination in poultry.