B cell targeting by molecular adjuvants for enhanced immunogenicity

Introduction: Adjuvants are critical components of vaccines to improve the quality and durability of immune responses. Molecular adjuvants are a specific subclass of adjuvants where ligands of known immune-modulatory receptors are directly fused to an antigen. Co-stimulation of the B cell receptor (BCR) and immune-modulatory receptors through this strategy can augment downstream signaling to improve antibody titers and/or potency, and survival in challenge models.

Areas covered: C3d has been the most extensively studied molecular adjuvant and shown to improve immune responses to a number of antigens. Similarly, tumor necrosis superfamily ligands, such as BAFF and APRIL, as well as CD40, CD180, and immune complex ligands can also improve humoral immunity as molecular adjuvants.

Expert opinion: However, no single strategy has emerged that improves immune outcomes in all contexts. Thus, systematic exploration of molecular adjuvants that target B cell receptors will be required to realize their full potential as next-generation vaccine technologies.