CDC researchers have developed methods and adjuvants for enhancing a subject's immune response to respiratory syncytial virus (RSV) by inclusion of a CD40 binding protein. RSV has long been recognized as a major respiratory tract pathogen of infants, as well as older children and the elderly. Established, successful methods for preventing RSV are currently unavailable. CD40 ligand (CD40L, also known as CD154) is an important costimulatory molecule found on the T-cell and is critical for the development of immunity. CD40L may provide a novel adjuvant to enhance cytokine and antibody response to RSV, directing a subject's immune response further towards Th1-mediated outcomes rather than a less effective Th2-type response. This Th2-type response has been previously suggested as the cause of previous live-RSV vaccine failures. This technology, appropriately developed and integrated into an RSV vaccination agenda, may be useful in improving the efficacy of current or future RSV vaccines.