University of Basel Researchers Decode Atomic Switch Controlling Leptospirosis Virulence to Combat Rising Zoonotic Threat

University of Basel scientists map the LvrB protein switch that turns Leptospira bacteria harmful, opening new doors for anti-virulence antibiotic treatments.

By: AXL Media

Published: Apr 28, 2026, 6:01 AM EDT

Source: Information for this report was sourced from University of Basel

Decoding the Molecular Machinery of a Climate Sensitive Pathogen

Leptospirosis has emerged as a significant global health challenge, causing approximately one million severe infections and 60,000 deaths annually. As climate change increases the frequency of flooding and environmental contamination, the prevalence of this waterborne zoonotic disease is rising even in traditionally temperate regions like Switzerland. Researchers at the University of Basel have now reached a breakthrough by identifying the atomic mechanism that allows the Leptospira bacterium to adapt to the human body. By uncovering the structural secrets of the protein LvrB, the team has provided the first clear look at the machinery that transforms a dormant environmental bacterium into a lethal pathogen.

The Structural Architecture of the LvrB Protein Switch

At the center of this discovery is the LvrB protein, which serves as a master regulator for hundreds of genes associated with bacterial virulence. Lead researcher Professor Sebastian Hiller and his team utilized high resolution imaging to determine that LvrB exists in a "locked" and symmetric conformation when the bacterium is outside a host. This inactive state is a survival strategy, preventing the organism from wasting energy by producing virulence factors in soil or water where they are unnecessary. Elia Agustoni, the study’s first author, noted that this symmetry effectively keeps the pathogen's harmful capabilities in an "off" position until specific environmental cues are detected.

Activation Cascades and Host Signaling Mechanisms

The transition from harmless to harmful is triggered by a signaling cascade once the bacterium enters a human or animal host. These external signals induce chemical modifications that disrupt the protein’s internal symmetry, causing a structural rearrangement into an "on" state. Once activated, LvrB transfers these signals to a specific partner protein, which then initiates the transcription of virulence genes. This molecular handshake allows the bacteria to navigate the host's immune system, spread through the bloodstream, and eventually cause organ failure if the infection is not intercepted with early medical treatment.