Outer membrane proteins and lipopolysaccharides of nontypeable Haemophilus influenzae

Several outer membrane proteins of nontypeable Haemophilus influenzae are potential vaccine candidates: P2 and P6 elicit antibodies that are bactericidal and protective in experimental models of infection. Other proteins are being investigated. A group of surface-exposed high-molecular-weight proteins that are major targets of antibody in human convalescent sera were identified. Monoclonal antibodies to the high-molecular-weight proteins of a prototype strain recognized two distinct but related proteins and were bactericidal for the prototype strain and other strains that shared the epitope recognized by the monoclonals. Genes encoding the two proteins in the prototype strain recognized by the monoclonals were cloned and sequenced. The sequences were distinct but related, and the derived amino acid sequences had sequence similarity to that of filamentous hemagglutinin of Bordetella pertussis, an important adherence factor and protective antigen.