Provided is a pharmaceutical composition, including an antigen fusion protein which includes an antigen and an antagonist of an Fc gamma receptor. Also provided is a method of enhancing immunogenicity of an antigen, including conjugating the antigen with an antagonist of an Fc gamma receptor to form an antigen fusion protein. Also provided is a method of enhancing an immune response to an antigen in a subject, including administering to the subject an effective amount of an antigen fusion protein which includes an antigen and an antagonist of an Fc gamma receptor. The present invention may be applied in the development of potent vaccines based on targeting vaccine antigens to antigen-presenting cells via binding to Fc gamma receptors.