The magnitude and specificity of cell-mediated and humoral immunity are critically determined by
peptide sequences;
peptides corresponding to the B- or
T-cell receptor epitopes are sufficient to induce an effective immune response if delivered properly. Therefore, studies on the screening and application of
peptide-based
epitopes have been done extensively for the development of therapeutic
antibodies and prophylactic
vaccines. However, the efficacy of immune response and antibody production by
peptide-based immunization is too limited for human application at the present. To improve the efficacy of
vaccines, researchers formulated adjuvants such as
alum, water-in-oil
emulsion, and
Toll-like receptor agonists. They also employed
liposomes as delivering vehicles to stimulate immune responses. Here, we review our recent studies providing a potent method of
epitope screening and antibody production without conventional carriers. We adopted Lipoplex(O), comprising a natural phosphodiester bond CpG-
DNA and a specific
liposome complex, as an adjuvant. Lipoplex(O) induces potent stimulatory activity in humans as well as in mice, and immunization of mice with several
peptides along with Lipoplex(O) without general carriers induces significant production of each
peptide-specific
IgG2a. Immunization of
peptide vaccines against virus-associated
antigens in mice has protective effects against the
viral infection. A
peptide vaccine against
carcinoma-associated antigen and the
peptide-specific
monoclonal antibody has functional effects against
cancer cells in mouse models. In conclusion, we improved the efficacy of
peptide vaccines in mice. Our strategy can be applied in development of therapeutic
antibodies or in defense against pandemic
infectious diseases through rapid screening of potent
B-cell epitopes.