Exploiting 4-1BB costimulation for enhancing antiviral vaccination

4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is emerging as an important costimulatory molecule, particularly in the regulation of CD8⁺ T cell responses. Costimulation through 4-1BB, such as by utilizing agonistic anti-4-1BB monoclonal antibodies, has been well studied in various tumor models. However, 4-1BB is also an important regulator of antiviral CD8⁺ T cell responses. This review summarizes these findings and describes how 4-1BB is beginning to be exploited in terms of boosting antiviral vaccine responses.