April 14, 2021Miriam Bergeret, MSc
Current tests for Lyme disease (LD) lack sensitivity during the early stages of disease and often cannot distinguish between different tick-borne diseases, but a new highly sensitive test promises to improve LD detection. The test was recently described in Frontiers in Microbiology.
The most common disease transmitted by tick bite, LD is usually diagnosed based on clinical symptoms and a history of tick exposure. However, the symptoms don’t occur in every LD patient and are also largely indistinguishable from other tick-borne illnesses that require different treatments. The similarity between symptoms and lack of a diagnostic test that can accurately distinguish between infections often hinders correct diagnosis and treatment.
LD is difficult to detect in the early stages of disease when it is easier to treat as current PCR tests directly target LD-causing bacteria using DNA regions with a single copy in each bacterium. To overcome these challenges, researchers developed a new highly sensitive test that uses an internally controlled quantitative PCR to target a multicopy gene called terminase large subunit (terL) only present in prophages found in LD-causing bacteria.
The researchers evaluated the new test, known as Ter-qPCR, and found that it was able to detect the presence of a single bacterium in a 0.3 mL sample of blood, a sensitivity appropriate for clinical settings. Moreover, in a set of blood samples from healthy controls and LD patients, they found significant quantitative differences in the amount of terL in LD patients with early- versus late-stage disease, demonstrating the potential of using terL as an early marker of LD.
“Together, the data suggests that the prophage-targeting PCR has significant power to improve success detection for LD,” wrote the authors, who believe this technique could be applied to other diseases caused by bacteria that carry unique prophages.