A new study published in Microbiology Spectrum suggests that FDA-cleared single-step immunoblot (IB) tests developed by IGeneX may improve the early diagnosis of Lyme disease, addressing a longstanding challenge in identifying infections during the initial stages when treatment is most effective.
Researchers reported that the single-step immunoblot tests detected antibodies in 58.3% of early-stage Lyme disease cases, compared with 30.0% using standard two-tier testing (STTT), nearly doubling detection during the earliest phase of infection. The findings are based on an analysis of more than 1,100 serum samples, including well-characterized specimens from the Centers for Disease Control and Prevention (CDC) and the Bay Area Lyme Foundation's Lyme Disease Biobank.1
STTT vs Immunoblot Assays
Unlike conventional STTT, which relies primarily on a single Borrelia burgdorferi strain and requires sequential testing, the new IgG and IgM immunoblot assays incorporate recombinant protein antigens from multiple Borrelia species and strains found in the United States and Europe. According to the investigators, this broader antigen coverage enhances antibody detection while simplifying laboratory workflows by eliminating the need for multiple testing steps.2
“These findings represent a meaningful advancement in Lyme disease diagnostics, particularly given that commonly used FDA-cleared MTTT and STTT testing methods have been shown to miss 64–78% of early Lyme disease cases,” Jyotsna S Shah, PhD, lead author of the study and president of IGeneX ,said in a statement. 2
The study also evaluated performance in 290 acute-phase samples from the Lyme Disease Biobank, where the IgG immunoblot significantly outperformed standard two-tier testing. When the IgG and IgM assays were used together, antibodies were detected in 30.2% of patients with confirmed erythema migrans lesions, compared with 20.6% using STTT. Investigators reported that discrepancy analysis confirmed 21 of 22 samples that were positive by the immunoblot but negative by STTT were true positives.1
What You Need to Know
Among CDC stage 1 (early) Lyme disease samples, the IgG IB test identified antibodies in 58.3% of cases versus 30.0% with STTT, nearly doubling accurate detection during the critical early treatment window.
The IB tests use recombinant protein antigens from multiple Borrelia species and strains found in both the US and Europe, unlike conventional STTT, which typically relies on a single Borrelia burgdorferi strain, while also simplifying lab workflow by eliminating sequential testing steps.
Across 387 sera from patients with potentially cross-reactive conditions (other tick-borne diseases, autoimmune disorders, viral infections, pregnancy), only one IgM false positive occurred, yielding specificity of about 99.7% for IgM and 99.4–100% for IgG, with no cross-reactivity observed in the IgG IB test.
In addition to improved sensitivity, the assays demonstrated high specificity across 387 control samples representing conditions that can produce cross-reactive antibodies, including other tick-borne diseases, autoimmune disorders, viral infections, and pregnancy. Researchers observed only one IgM false-positive result, corresponding to approximately 99.7% specificity for IgM and 99.4% to 100% specificity for IgG. No cross-reactivity was observed with the IgG assay.1
The improved diagnostic performance is attributed to several design features, including a proprietary Lyme Screen Antigen derived from immunodominant regions of the VlsE protein across multiple Borrelia species, along with additional antigens such as OspA and OspB that broaden immune response detection.2
“There is an urgent need for more accurate diagnostic tests for Lyme patients, particularly in early-stage disease when standard testing falls short,” Liz Horn, PhD, MBI, principal investigator of the Lyme Disease Biobank and study co-author, said in a statement. “This study demonstrates how a more sensitive, streamlined approach can improve detection and highlights the potential of this technology to support earlier and more accurate diagnosis for Lyme patients.”2
The immunoblot assays evaluated in the study serve as the basis for the FDA 510(k)-cleared iDart IgG and IgM Immunoblot Tests, which are intended for the laboratory diagnosis of Lyme disease. Researchers noted that all samples in the study were tested in a blinded manner, with independent statistical validation and discrepancy analyses performed using clinical and serological criteria.2
References
1.Shah JS, Liu S, Calalo-Ramos C, Myint M, Lee O, Cruz I, Horn EJ, Ramasamy R. 0. Single-step immunoblot tests with recombinant protein antigens for detecting IgG and IgM antibodies in Lyme disease. Microbiol Spectr 0:e00199-26.https://doi.org/10.1128/spectrum.00199-26
