The C6 Lyme Enzyme Immunoassay (EIA) is a single-tier FDA-approved serologic test that measures IgG antibodies to a specific protein of Borrelia burgdorferi, the C6 peptide of the variable major protein-like sequence-expressed (VlsE). The VlsE lipoprotein creates a strong immune response throughout all stages of  Lyme disease. Since it’s unique to B. burgdorferi, the presence of antibodies to C6 indicates infection. The debate remains as to whether the C6 ELISA is superior to the standard ELISA. One study did indicate using the C6 Elisa resulted in 82 fewer false positives out of 2208 control sera, which produced a 77% reduction in immunoblot testing, a possible cost-saving benefit.[1] [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4052829/