The present invention is directed to methods of suppressing the virulence of one or more virulence antigenic factors of methicillin resistant Staphylococcus aureus (MRSA). Aspects of the invention include administering of an expression vector alone or in conjunction with a fusion protein. The expression vector has a transcription unit encoding a fusion protein composed of a virulence antigenic factor of MRSA attached through a linker to the aminoterminal end of the ecd CD40 ligand. The fusion protein is composed of a virulence antigenic factor of MRSA and CD40 ligand and has the ability to generate antibodies which prevents host cell infection by suppressing virulence functions of MRSA.
