the invention described herein relates to a haemophilus influenzae regulon encoding type iv pili . in particular , the invention relates to type iv pili from nontypeable h . influenzae 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 .