Dr. Jinyu Shan
University of Leicester
Title: Use of bacterial viruses for diagnosis of bacterial infections: a case study of Lyme disease
Biography
Biography: Dr. Jinyu Shan
Abstract
Lyme disease (LD) is caused by the bacterium Borrelia, and is transmitted to humans when ticks (vehicle of Borrelia) drink our blood. We all know LD is difficult to diagnose. We also know that at some point the PCR detecting Borrelia is considered to be a promising alternative because theoretically PCR should be able to detect Borrelia DNA from any stages of LD patients as long as the Borrelia happens to be present in the samples collected for testing. Although PCR can have very high specificity, it suffers from low sensitivity because the number of Borrelia in patient’s samples is normally very low, bearing in mind that evidence from published studies indicates that Borrelia presence in LD patients can range from 1-100 cells/ml. To avoid devastating consequences of prolonged suffering, better ways to diagnose LD are urgently needed.
To stand up to these diagnostic challenges, we have been investigating bacterial viruses (phages) for detecting LD. We demonstrated that Borrelia phage genes are present in multiple copies and tightly correlate with their Borrelia hosts (Fig. 1). Intuitively, targeting multi-copy genes offers an elegant and reliable way of increasing the amount of PCR template. Moreover, targeting phage-encoded genes would provide additional sensitivity to detect Borrelia infections because phages can be released into bloodstream, even though Borrelia cells may be hiding and not circulating in the blood. This situation of detecting free phage DNA from human blood bears some resemblance to identifying cell-free circulating DNA (cfDNA) as with cancer diagnosis. The phage-based technology could potentially complement the current LD diagnostics.
In a nutshell, the phage-based technology detects phages to diagnose bacterial infections. This method showed high sensitivity (90%) when tested against Lyme patient samples. A fully validated phage-based test would transform the current clinical practice of Lyme disease.