The invention relates to an isolated
nucleic acid fragment whichencodes a polypeptide fragment which exhibits a substantial immunological reactivity with a rabbit polyclonal
antibody raised against a polypeptide having an apparent molecular weight of 13 kDa as determined by SDS-PAGE followed by
visualization, said polypeptide being derived from
Borrelia burgdorferi B313 and being encoded by the
nucleotide sequence of SEQ ID NO: 18, said rabbit polyclonal
antibody exhibiting substantially no immunological reactivity with proteins from at least 95% of spirochaetes randomly selected from the group consisting of Borrelia hermsii, Borrelia crocidurae, Borrelia anserina, and Borrelia hispanica, and / orhybridises readily under highly stringent hybridization conditions with
a DNA fragment having a
nucleotide sequence selected from the group consisting of SEQ ID NO: 18, SEQ ID NO: 20, and SEQ ID NO: 22, or with
a DNA fragment complementary thereto, but exhibits no substantial hybridization when the hybridization conditions are highly stringent with
genomic DNA from at least 95% of spirochaetes randomly selected from the group consisting of Borrelia hermsii, Borrelia crocidurae, Borrelia anserina, and Borrelia hispanica.Furthermore, the invention relates to polypeptide fragments, vectors, transformed cells and
cell lines, a method of preparing a polypeptide fragment and, vaccines as well as diagnostic compositions and kits.