5-MethylCytosine/BSA is a conjugate of 5-MethylCytosine and Bovine Serum Albumin (BSA). By conjugating the antigen with the protein adjuvant , the production of antigen-specific antibodies in vaccine models can be enhanced. The conjugate does not affect protein folding or destroy key epitopes, and it can enhance cross-presentation and the generation of antigen-specific T cells.