Development of Molecular Diagnostic Test for Early Onset of Lyme disease

项目总结/文摘

Project Summary/Abstract There is no validated assay to reliably detect the early onset of the Lyme disease infection at the time when antibiotic therapy has the best chance of a cure without sequelae. Diagnosis is often difficult because most symptoms are often nebulous, with the telltale “bulls-eye” rash only appearing and clearly recognizable in approximately half of cases. The standard types of infectious diagnostic tests – both culture and serology – require >3 weeks for a positive result after the onset of infection with Lyme disease and serology only indicates exposure but not active infection. This introduces a significant delay in treatment. While PCR for B. burgdorferi DNA in the blood has potential for a rapid, accurate result, past tests have not had sufficient sensitivity because of too few bacteria and low copy numbers of DNA in the blood. We have developed an approach that “enlarges the targetability”, by 160,000 fold, thereby increasing the sensitivity of PCR test for B. burgdorferi. Our data show we are successfully accomplishing this by: using a larger amount of blood to start (10 fold); then selectively multiplying the target by using Borrelia-directed primers prior to PCR (2000 fold); and then probing the product for the B. burgdorferi on a multi-loci PCR platform (8 fold). To assure reliability and acceptance of a new test based on this approach, we formally consulted with the FDA from the beginning. We obtained a Qsub (pre-IDE) approval with guidance as to what we need for a cleared test. During this proposal we will continue to test blood samples (from eventually confirmed Lyme cases and control subjects) with our PCR-based assay at the time the patient presents to the doctor in order to prove the assay can detect the B. burgdorferi infection, earlier and with greater sensitivity, than the FDA benchmark of two-tiered serology taken at the same time. If successful, at the number agreed on with the FDA, this Phase II should result in a test that has FDA clearance. Our goal is deliver a functional and affordable diagnostic assay for Early Onset Lyme Disease that has superior sensitivity and specificity compared to two-tiered serology. The test will permit immediate diagnosis well before seroconversion or cultures become positive so treatment can be started right away.