Precisemodification of the surface charge of antigen enhances vaccine immunogenicity

Aluminum(alum)adjuvant is the most extensively used protein subunit vaccine adjuvant,and its effectiveness and safety have been widely recognized.The surface charge of the antigen determines its electrostatic adsorption to alum adjuvant,which directly affects the immune efficacy of the protein vaccine.In our study,we precisely modified its surface charge by inserting charged amino acids into the flexible region of the SARS-CoV-2 receptorbinding domain(RBD),achieving electrostatic adsorption and a site-specific anchor between the immunogen and alum adjuvant.