SPECIFIC MUCOSAL IMMUNITY AND ENHANCED NASOPHARYNGEAL CLEARANCE OF NONTYPABLE HAEMOPHILUS-INFLUENZAE AFTER INTRANASAL IMMUNIZATION WITH OUTER-MEMBRANE PROTEIN P6 AND CHOLERA-TOXIN

Nontypeable Haemophilus influenzae (NTHi) is one of the leading pathog ens in otitis media. Studies of vaccines against NTHi have focused on outer membrane proteins (OMPs). One outer membrane protein P6 is highl y conserved among strains and is an attractive candidate for a subunit bacterial vaccine. In this study, mucosal immunity induced by intrana sal immunization with P6 and cholera toxin (CT) was investigated in a mouse model. Intranasal immunization with P6 and CT evoked a good muco sal IgA as well as a systemic IgG response against P6. On the other ha nd, intranasal immunization with P6 alone induced a weak mucosal IgA r esponse. Enzyme linked immunospot assay detected anti-P6 specific anti body producing cells in the nasopharyngeal mucosal of immunized mice. The protective response of intranasal immunization was demonstrated by enhancement of nasopharyngeal clearance of NTHi and inhibition of adh erence of NTHi to cultured human epithelial cells. Based on these resu lts, intranasal immunization with P6 and CT may be an effective approa ch to protect human from H. influenzae infections in the upper respira tory tract. (C) 1998 Elsevier Science Ltd. All rights reserved.