ABSTRACT
Successful subunit vaccines are comprised of two essential components. The first component is the antigen to which protective immune responses are to be generated. Such antigens may be proteins, polysaccharides, or lipopolysaccharides (LPS) purified from target organisms, or recombinant somatic proteins, genetically or chemically detoxified toxins, or synthetic peptides. Using defined products has the advantage of including only those moieties required for protective immune responses while excluding extraneous or toxic cellular or nuclear components commonly present in whole microorganisms or crude extracts. The second component is comprised of the adjuvant and/or vaccine delivery vehicle, which provides structure and/or immunostimulation. This component promotes antigen recognition, presentation, and processing in a manner that generates optimal immune responses of the types and at the sites required to provide protective immunity.
