title: Immunologic and structural relationships of the minor pilus subunits among Haemophilus influenzae isolates.
abstract: Two proteins, HifD and HifE, have been identified as structural components of Haemophilus influenzae pili. Both are localized at the pilus tip, and HifE appears to mediate pilus adherence to host cells. In this study we examined the immunologic and structural diversity of these pilus subunits among type b H. influenzae (Hib) and nontypeable H. influenzae (NTHI) strains. Western immunoblot analysis revealed that antibodies directed against the C terminus of HifD and HifE from Hib strain Eagan bound to HifD and HifE proteins, respectively, of all piliated Hib and NTHI strains tested. Whole-cell enzyme-linked immunosorbent assays showed that antibodies specific for native HifD or HifE of strain Eagan also bound to all piliated Hib strains but did not bind to the piliated NTHI strains. Antibodies against HifE of strain Eagan inhibited the binding of Hib to human erythrocytes but did not inhibit the binding of NTHI strains. Restriction fragment length polymorphism (RFLP) analysis was used to determine strain-to-strain structural differences within hifD and hifE genes, either by PCR or by nucleotide sequence analysis. DNA and derived amino acid sequence analyses of HifD and HifE confirmed the uniqueness of the RFLP types. The hifD and hifE genes of all type b strains showed identical restriction patterns. Analysis of hifD and hifE genes from the NTHI strains, however, revealed seven unique RFLP patterns, suggesting that these genes encode proteins with diverse primary structures. These results indicate that HifD and HifE are immunologically and structurally similar among the Hib strains but vary among the NTHI strains.
authors.affiliation: Departments of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan 48109-0244, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: McCrea
authors.forename: J L
authors.initials: JL
authors.lastname: Sauver
authors.forename: C F
authors.initials: CF
authors.lastname: Marrs
authors.forename: D
authors.initials: D
authors.lastname: Clemans
authors.forename: J R
authors.initials: JR
authors.lastname: Gilsdorf
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000940:Antigenic Variation; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D015373:Bacterial Typing Techniques; D017124:Conserved Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006193:Haemophilus influenzae / Q000145:classification / Q000235:genetics / Q000276:immunology*; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011485:Protein Binding; D011489:Protein Denaturation; D017386:Sequence Homology, Amino Acid
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D000939:Epitopes; C090011:HifD protein, Haemophilus influenzae; C090010:HifE protein, Haemophilus influenzae; D036781:Fimbriae Proteins