Date: 02.12.2025
Borrelia Are Cunning, Slipping into Blood Vessels Stealthily: Scientists Describe in Detail the First Moments of Lyme Disease Infection
A team of researchers from the Biology Centre of the Czech Academy of Sciences has brought forward important new insights into the very first phase of Lyme disease infection, occurring immediately after transmission from a tick. Using advanced electron microscopy, they obtained the most detailed view to date of how Borrelia bacteria move from the tick bite site into blood vessels. The scientists discovered previously unknown mechanisms of how borrelia interact with host cells, opening new possibilities for medical applications. The study was published in the prestigious journal Nature Communications, which ranked it among the 50 most significant microbiology and infectious disease papers of the year.
Lyme disease is a serious infectious illness caused by Borrelia bacteria, transmitted to humans by ticks. After an infected tick attaches, borrelia penetrate the skin and spread to other parts of the body; in advanced stages, they may affect the heart, joints, or nervous system. A key step in the spread of infection is crossing the endothelial barrier—the wall of blood and lymphatic vessels. Until now, it was unclear how exactly borrelia achieve this and by what mechanisms they move from the skin into circulation.
To precisely track the bacteria’s movements, the researchers used high-resolution 3D electron microscopy. “Borrelia have a shape similar to a corkscrew, so it was assumed it forcefully drills through these barriers, much like drilling into a wall. But we found that borrelia does not drill perpendicular to the surface. Instead, it first attaches lengthwise to the vessels and then gradually passes through. In the bloodstream, it even actively searches for suitable spots where pericytes are located—cells that surround blood capillaries and ensure their stability. It seems that before entering the bloodstream, borrelia needs to destabilize the vessel wall to some degree,” explains Martin Strnad of the Biology Centre of the Czech Academy of Sciences. In the lymphatic system, where pericytes are naturally absent and the walls are more permeable, borrelia uses a different strategy—it passes through the endothelial layer by gradually inserting itself into cells or slipping through loose junctions between cells.
“These observations show that borrelia is truly cunning. Its strategy adapts to the type of vessel: in blood capillaries it uses pericytes as orientation points, whereas in lymphatic vessels it carefully inserts itself into cells to cross the barrier without disrupting it,” says Martin Strnad.
These new findings pave the way toward a better understanding of the early phase of Lyme disease and highlight potential targets for prevention and treatment. Thanks to the detailed view of how borreliae interact with vascular cells, scientists may now search for ways to slow the bacteria’s spread or prevent their entry into critical parts of the body.
Visualization of a Borrelia bacterium (yellow) in contact with a pericyte (blue) situated on an endothelial cell (green). It appears that the Borrelia is attempting to slip between the pericyte and the endothelial cell and disrupt their contact.
