The C-terminal fragment of the internal 110-kilodalton passenger domain of the Hap protein of nontypeable Haemophilus influenzae is a potential vaccine candidate.
Nontypeable Haemophilus influenzae is a major causative agent of bacterial otitis media in children. H. influenzae Hap autotransporter protein is an adhesin composed of an outer membrane Hapbeta region and a moiety of an extracellular internal 110-kDa passenger domain called Hap(S). The Hap(S) moiety promotes adherence to human epithelial cells and extracellular matrix proteins, and it also mediates bacterial aggregation and microcolony formation. A recent work (D. L. Fink, A. Z. Buscher, B. A. Green, P. Fernsten, and J. W. St. Geme, Cell. Microbiol. 5:175-186, 2003) demonstrated that Hap(S) adhesive activity resides within the C-terminal 311 amino acids (the cell binding domain) of the protein. In this study, we immunized mice subcutaneously with recombinant proteins corresponding to the C-terminal region of Hap(S) from H. influenzae strains N187, P860295, and TN106 and examined the resulting immune response. Antisera against the recombinant proteins from all three strains not only recognized native Hap(S) purified from strain P860295 but also inhibited H. influenzae Hap-mediated adherence to Chang epithelial cells. Furthermore, when mice immunized intranasally with recombinant protein plus mutant cholera toxin CT-E29H were challenged with strain TN106, they were protected against nasopharyngeal colonization. These observations demonstrate that the C-terminal region of Hap(S) is capable of eliciting cross-reacting antibodies that reduce nasopharyngeal colonization, suggesting utility as a vaccine antigen for the prevention of nontypeable H. influenzae diseases.
Liu
Dai-Fang
DF
Wyeth Vaccines Research, 401 N. Middletown Road, Pearl River, NY 10965, USA. liudf@wyeth.com
Mason
Kathryn W
KW
Mastri
Maria
M
Pazirandeh
Mehran
M
Cutter
David
D
Fink
Doran L
DL
St Geme
Joseph W
JW
Zhu
Duzhang
D
Green
Bruce A
BA
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001665:Binding Sites; D005260:Female; D018073:Haemophilus Vaccines / Q000276:immunology*; D006193:Haemophilus influenzae / Q000276:immunology*; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D009305:Nasopharynx / Q000382:microbiology; D010446:Peptide Fragments / Q000276:immunology*; D012697:Serine Endopeptidases / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000276:immunology*
D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D018073:Haemophilus Vaccines; C091552:Hap protein, Hemophilus influenzae; D010446:Peptide Fragments; D014614:Vaccines, Synthetic; D012697:Serine Endopeptidases