The invention described herein relates to a Haemophilus influenzae (H. influenzae) regulon encoding type IV pili. In particular, the invention relates to type IV 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.