Mucosal vaccination with a recombinant OprF-I vaccine of Pseudomonas aeruginosa in healthy volunteers: comparison of a systemic vs. a mucosal booster schedule.

We compared the immunogenicity of two vaccination schedules with either a systemic or a mucosal booster, both following a mucosal primary vaccination with a recombinant outer membrane fusion protein of Pseudomonas aeruginosa (OprF-I) in 12 healthy volunteers. The systemic booster induced higher levels of OprF-I-specific serum antibodies of IgG isotype, with a mean+/-S.E.M. of 32.6+/-7.8x10(7) enzyme-linked immunosorbent assay (ELISA) units (EU) as compared to the nasal booster with 14.6+/-2.1x10(7) EU (P=0.05). Specific serum IgA antibodies and antibodies in saliva did not differ between the two vaccination groups. We conclude that a combined mucosal/systemic vaccination with the OprF-I vaccine may offer an enhanced systemic immunogenicity. Further studies on the long-term immunogenicity and induction of antibodies on the respiratory airway surface are warranted.