Abstract: The present invention provides a composition comprising a chimeric polypeptide comprising a recall antigen that reactivates memory T cells in a subject and a new antigen that activates naïve B cells in a subject and a composition comprising a nucleic acid encoding a chimeric polypeptide comprising a recall antigen that reactivates memory T cells in a subject and a new antigen that activates naïve B cells in a subject. Further provided are methods of modulating an immune response, as well as treating and/or preventing disease in subjects in whom the ability to mount an immune response to a new antigen is impaired, by administering the compositions of this invention.