University of Basel Scientists Decipher Atomic Switch That Activates Pathogenic Virulence in Leptospira Bacteria

University of Basel researchers uncover the atomic structure of the LvrB protein, revealing how pathogens switch on virulence genes to infect humans.

By: AXL Media

Published: Apr 27, 2026, 6:41 AM EDT

Source: Information for this report was sourced from EurekAlert

The Molecular Trigger of Zoonotic Infection

A research breakthrough at the University of Basel has identified the specific biological mechanism that allows the Leptospira pathogen to transition from a dormant state to a virulent threat. Leptospirosis, a zoonotic disease transmitted from animals to humans, currently causes approximately one million severe cases and 60,000 deaths annually. As climate change increases the frequency of these infections through contaminated water and soil, understanding the bacteria's survival strategy has become a global health priority. Professor Sebastian Hiller’s team has now pinpointed the protein LvrB as the primary regulator that enables the pathogen to survive and spread within a human host.

Unlocking the Atomic Structure of LvrB

In a detailed study published in Nature Communications, the Basel research team used atomic-level imaging to elucidate the three-dimensional structure of the LvrB protein. This protein belongs to a critical class of signaling systems that dictate how bacteria respond to their environment. By understanding the "on" and "off" states of this molecular switch, scientists can now visualize how the bacteria prepare for infection. Professor Hiller notes that these findings provide a mechanical blueprint that was previously missing, allowing researchers to see exactly how the protein’s configuration changes when it encounters a host.

The Locked State of Inactive Pathogens

Under normal conditions, such as when the bacteria reside in water or soil outside a host, LvrB remains in a "locked" position. In this state, the protein maintains a symmetric and inactive conformation, which prevents the bacterium from expending energy on virulence factors that are not yet needed. First author Elia Agustoni explains that this symmetry is essential for keeping the pathogen harmless while it is outside the body. This structural inhibition ensures that the bacteria do not produce toxins prematurely, preserving their resources until they successfully enter a target organism.