Abstract: Inactivated influenza virus vaccines usually require adjuvants to enhance their immune protection. Aluminium hydroxide (Al ) adjuvant is commonly used as an adjuvant in human vaccines, mainly inducing Th2 immune response. In this study, Al adjuvant and TLR7/8 agonist R848 were combined to form a complex adjuvant, and its adjuvancity was evaluated in immunization of mice with inactivated influenza virus H7N9 vaccine. Three weeks after a single immunization, mice were attacked with a lethal dose (20 LD50) of homologous virus. The results showed that, compared with vaccine adjuvanted with R848 or Al alone, R848+ Al adjuvanted vaccine enhanced mice higher titers of serum IgG and IgG2a subtype antibodies and induced both Th1 and Th2 cytokines, with a Th1-biased response, and provided potent protection in mice against lethal virus infection. Therefore, the adjuvancity of R848+ Al is superior to that of R848 or Al alone. The study may help to improve Al adjuvancity and immune effects of inactivated influenza vaccines.
Key words: R848; aluminium hydroxide; inactivated vaccine; influenza virus
（Acta Laser Biology Sinica, 2023, 32(2): 170-176）