Intranasal immunization with recombinant outer membrane protein P6 induces specific immune responses against nontypeable Haemophilus influenzae.
OBJECTIVE
Nontypeable Haemophilus influenzae (NTHi) is one of the leading causative pathogens for otitis media. The outer membrane protein P6 of NTHi is highly conserved among the strains and is an attractive candidate for a preventive vaccine. However, for the production of a relatively small amount P6 containing lipopolysaccharides, the development of a recombinant version of this protein is required. This study was designed to investigate the specific mucosal immunity induced by intranasal immunization of recombinant P6 (rP6) with cholera toxin (CT).


METHODS
BALB/c mice were immunized with of rP6 (30 microg) and CT (2 microg) intranasally every 2 days for 2 weeks. Anti-rP6 specific IgG, IgA and IgM antibodies and the subclass of anti-rP6 specific IgG antibody were determined by enzyme linked immunosorbent assay (ELISA). Anti-rP6 specific IgA in nasopharyngeal washings were also determined by ELISA. Nasopharyngeal clearance of inoculated NTHi after the intranasal immunization were assessed. All statistical differences between the two groups were assessed by ANOVA parametric test.


RESULTS
Intranasal immunization with rP6 and CT evoked rP6-specific mucosal IgA immune response as well as the systemic IgG immune response against rP6 and enhanced nasopharyngeal clearance of inoculated live NTHi.


CONCLUSIONS
These results indicate the good immunogenicities of rP6 to induce specific immune responses against NTHi. Intranasal immunization with rP6 will be an effective approach to protect infections of NTHi.
Hotomi
Muneki
M
Department of Otolaryngology - Head and Neck Surgery, Wakayama Medical University, Kimiidera 811-1, Wakayama-shi, Wkayama 641-0032, Japan. mhotomi@wakayama-med.ac.jp
Yamanaka
Noboru
N
Shimada
Jun
J
Suzumoto
Masaki
M
Ikeda
Yorihiko
Y
Sakai
Akihiro
A
Arai
Jun
J
Green
Bruce
B
D000704:Analysis of Variance; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000096:biosynthesis; D001422:Bacterial Adhesion / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology* / Q000494:pharmacology*; D002772:Cholera Toxin / Q000276:immunology / Q000494:pharmacology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000276:immunology* / Q000494:pharmacology*; D006193:Haemophilus influenzae / Q000276:immunology*; D018928:Immunity, Mucosal / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D017817:Nasal Lavage Fluid / Q000276:immunology; D010033:Otitis Media / Q000382:microbiology / Q000517:prevention & control; D011897:Random Allocation; D012016:Reference Values; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D018073:Haemophilus Vaccines; C069990:P6 outer membrane protein, Haemophilus; D002772:Cholera Toxin