The invention provides compositions (e.g., peptide compositions) useful for the detection of antibodies that bind to Borrelia antigens. The peptide compositions comprise polypeptide sequences comprising variants in the IR6 domain of the Borrelia VlsE protein. The invention also provides devices, methods, and kits comprising such peptide compositions and useful for the detection of antibodies that bind to Borrelia antigens and the diagnosis of Lyme disease.