Purified and isolated nucleic acid molecules are provided which encode a FlaC flagellin protein of a strain of Campylobacter, particularly C. jejuni, or a fragment or an analog of the FlaC flagellin protein. The nucleic acid molecules may be used to produce proteins free of contaminants derived from bacteria normally containing the FlaA or FlaB proteins for purposes of diagnostics and medical treatment. Furthermore, the nucleic acid molecules, proteins encoded thereby and antibodies raised against the proteins, may be used in the diagnosis of infection.