OX40-Ligand Enhances H7N9 Whole Inactivated Virus Vaccine-induced Antibody Responses by Promoting Proliferation of Follicular Helper T Cells and Germinal Centre B Cells

Abstract

Abstract The H7N9 avian influenza virus first emerged in eastern China in the spring of 2013 and became epidemic nationwide, causing wide concern worldwide due to its rapid outbreak and spread. Currently, vaccination remains the best way to prevent and control the spread of H7N9 influenza, and adjuvants are indispensable for the development of inactivated vaccines. Therefore, it is of great significance to develop efficient and inexpensive novel H7N9 influenza vaccine adjuvants. In this study, we constructed OX40L/Fc and H7N9 whole inactivated virus (WIV) co-immunized mice model and evaluated the efficacy of OX40L as an immune adjuvant in co-immunized mice. Mice co-immunized with H7N9 WIV + OX40L/Fc produced more T follicular helper cells (Tfh), germinal center (GC) B cells, and plasma cells (PCs) than mice immunized with the vaccine alone. This suggested that OX40L could improve protective antibody responses after co-immunization with H7N9 WIV by affecting T cell-dependent humoral immune responses. Overall, our results reveal that OX40L has a good adjuvant effect on H7N9 WIV vaccine.