Mapping the Borrelia Bavariensis Genome: A New Lyme Player in Korea

When a tick bites, it does not simply inject a generic poison; it delivers a living, evolving organism that varies depending on where you are in the world. If you hike in Europe, the bacteria in local ticks differ from those in East Asia. To understand these regional risks, scientists have finally produced the first complete map of the Borrelia bavariensis genome from a sample found in South Korea.

The researchers isolated a specific strain, named KW3, from an Ixodes granulatus tick in the Kangwon region. By mixing two different sequencing technologies, they assembled the bacteria's full genetic instruction manual. They found one main linear chromosome and 12 smaller DNA rings, known as plasmids.

What the Borrelia bavariensis genome reveals

The study measured the genetic distance between KW3 and other known strains. The analysis placed the Korean bacteria firmly in a family group with Japanese strains (NT24 and JAASAAF1029). They are cousins. However, the Korean strain formed a distinct sub-branch. This suggests that while they share an ancestor, the bacteria in Korea are drifting apart and evolving on their own.

The team also looked at the plasmids. These small DNA rings often carry the tools bacteria use to infect humans. If the main chromosome is the operating system, plasmids are the downloadable apps. The study found that some plasmids in the Korean strain seem to be fused versions of plasmids found in European strains. Most infection-related genes remained intact. However, one gene usually used to evade the immune system, vlsE, was completely missing. The authors propose this likely happened artificially while the bacteria were being grown in the lab, as these bugs often discard unused DNA in a test tube.