Multivalent OspA polypeptides and methods and uses relating thereto

A nucleic acid molecule encoding an immunogenic polypeptide comprising a C-terminal domain of an outer surface protein A (OspA) of Borrelia, characterized in that said C-terminal OspA domain comprises at least three specific OspA epitopes each from distinct Borrelia strains causing Lyme Borreliosis;

• wherein said C-terminal OspA domain is able to induce a protective immune response to all of said distinct Borrelia strains, wherein the C-terminal OspA domain is selected from the group consisting of SEQ ID NO:
• 9, SEQ ID NO:
• 10, SEQ ID NO:
• 12, SEQ ID NO:
• 13, and immunogenic variants thereof that have at least 95% sequence identity with any one of SEQ ID NO:9, SEQ ID NO:
• 10, SEQ ID NO:
• 12, or SEQ ID NO:
• 13, and wherein a three-dimensional structure of the C-terminal OspA domain is stabilized by introduction of at least two cysteine residues that form a disulfide bond.