Bacteriophages (phages) are viruses that infect bacteria. They are natural bacteria killers, and have enjoyed a renaissance due to the emergence of antimicrobial resistance. Lyme disease (LD) is caused by a group of spirochaetes, Borrelia burgdorferi sensu lato (s.l.). Among LD spirochaetes, B. burgdorferi sensu stricto (s.s.) is the predominant species in North America, but also present in Europe; B. afzelii; and B. garinii are both predominant in Europe. The LD bacteria are spread to humans through the bite of infected ticks. It is the most commonly reported tick-born disease in the United States, and the number of LD cases in Europe has increased steadily over the last two decades with an estimation of 85 000 cases every year. In England and Wales, it is estimated that around 3,000 new cases of LD are diagnosed each year. In order to exploit the therapeutic use of phages to combat Borrelia infection, the fundamental biology of Borrelia phages needs to be investigated. So far, only sporadic Borrelia phages have been reported and no systematic effort has been made to study phages that infect the Lyme Borrelia bacterial species.

In this project, we aim to identify/characterise phages that infect Lyme Borrelia strains. Three strategies will be adopted. Tick and environmental samples will be screened for lytic phages. Meanwhile, temperate phages will be induced from Borrelia strains using low dose of antibiotics. In parallel, metagenomic sequencing will be used to analyse tick enrichment samples to identify novel Borrelia phage genomes. So far, we have established a pipeline of methodology including enrichment, prophage induction, lytic phage screening, and Borrelia phage molecular markers. We are currently working on phage propagation and purification. Borrelia phage metagenomic data will be studied to explore the phage-encode holins and endolysins, and their ‘antibacterial’ activity will be tested on Borrelia strains.