Humoral, mucosal, and cellular immune response to topical immunization with a subunit respiratory syncytial virus vaccine.

The efficacy of topical immunization with the respiratory syncytial virus (RSV) fusion (F) protein was tested in mice using cholera toxin B chain (CTB) as an adjuvant. The dose of CTB required for the adjuvant effect (as measured by local and systemic antibody stimulation) and protection from viral challenge was > or = 5 micrograms. With this dose, mice immunized intranasally with CTB plus F protein were highly protected from viral replication in the upper and lower respiratory tract. This protection was associated with the induction of mucosal IgA and serum IgG and neutralizing antibody. Addition of parenteral immunization with F protein to the topical vaccination provided protection from viral challenge nearly equivalent to immunization with live RSV intranasally. Topical and parenteral immunization with F protein was not associated with induction of splenic cytotoxic T cells, in contrast to live virus given intranasally.