A novel single-tier serologic test to diagnose all stages of Lyme disease

Lyme disease, a bacterial zoonosis, is the most commonly reported vector-borne disease in the United States. Laboratory diagnosis has relied on a two-tier serologic approach, originally comprising an ELISA, or another first-tier assay, followed by separate IgG and IgM immunoblots to confirm a positive first-tier result. This standard two-tier testing (STTT) approach provides high specificity, but at the cost of low sensitivity in early Lyme disease. Recent studies have shown that a modified two-tier (MTTT) testing approach, in which a second ELISA replaces the immunoblot, can provide an increase in test sensitivity without a loss of specificity. Nevertheless, neither STTT nor MTTT is considered sensitive enough for diagnosing patients with erythema migrans, the most common clinical manifestation of early Lyme disease. We have developed a novel ELISA methodology termed "Hybrid Lyme ELISA" for single-tier Lyme antibody detection, which relies on the simultaneous binding of individual antibody molecules to the <i>Borrelia burgdorferi</i> surface protein VlsE and to the C6 peptide derived from it. This dual binding requirement builds exceptionally high specificity into the assay, eliminating the majority of non-specific antibody interactions. In this study, the single-tier Hybrid Lyme ELISA was shown to provide greater sensitivity, but with equivalent specificity, to both STTT and MTTT. In addition, given the >90% sensitivity of the Hybrid Lyme ELISA in patients with erythema migrans, this assay may not only transform serologic testing from two-step to single-step testing, but may also provide a means for the first time to diagnose patients with erythema migrans.IMPORTANCEThe diagnosis of Lyme disease, a tick-borne spirochetal infection caused by <i>Borrelia burgdorferi</i> sensu lato, is subject to two major limitations: the need for a two-tier serologic testing algorithm to provide adequate specificity, and the low sensitivity of this algorithm in practice for detection of early Lyme disease manifesting with the erythema migrans skin lesion, the most common clinical manifestation. This study presents the first description of a new assay, the Hybrid Lyme ELISA, which demonstrates sensitivity high enough to potentially diagnose over 90% of patients with erythema migrans, and specificity high enough to preclude the need for a second-tier test. These test characteristics suggest the potential for the Hybrid Lyme ELISA to be the first single-tier serologic test suitable for laboratory diagnosis of all stages of Lyme disease.