The invention described herein relates to a Haemophilus influenzae (H. influenzae) regulon encoding type IV pili. In particular, the invention relates to type pili from nontypeable H. influenzae (NTHi) and from H. influenzae strains a, b, c, e and f. The invention provides isolated H. influenzae pilus polynucleotides and polypeptides encoded by the polynucleotides as well as polynucleotides and polypeptides encoded by the polynucleotides involved in the assembly/disassembly of the structure. The invention also relates to uses of these polynucleotides and/or polypeptides including methods for eliciting an immune response to H. influenzae and methods of treating and preventing H. influenzae related pathological conditions.