Live-attenuated influenza virus vaccine strain with an engineered temperature-sensitive and genetically stable viral polymerase variant

Influenza virus elicits respiratory tract disease and is a threat to global human health. Vaccination is considered an effective tool for reducing the morbidity and mortality caused by influenza disease. The only licensed live-attenuated influenza vaccine that has been proven safe and effective is FluMist. In this study, we isolated an attenuated influenza mutant virus with a Lys471 single amino acid substitution in PB1, which displayed a temperature-sensitive and a low-pathogenicity phenotype. By applying the PB1-Lys471 substitution to the vaccine mother strain or the circulating influenza virus using reverse genetic technology, a high-performance and safe live-attenuated vaccine carrying the viral antigens of the vaccine-targeted strain can be developed.