1.The Invisible War: Cholera vs. Phages
When we think of cholera, contaminated water and deadly outbreaks come to mind. However, behind the scenes, Vibrio cholerae faces a microscopic battle against viruses called bacteriophages (phages). These phages don’t just infect bacteria—they can sway entire epidemics by limiting outbreaks.
2.The 7th Pandemic’s Global Surge
Since the 1960s, the seventh cholera pandemic has spread worldwide through resilient “7PET” strains. Remarkably, these bacteria evolved defenses against phages, using mobile genetic elements as anti-viral tools. But why do some strains evade phages so effectively?
3.The 1990s Latin American Outbreak: A Mystery
In the early 1990s, a massive cholera epidemic struck Peru and Latin America, infecting over 1 million people. The culprit? The West African South American (WASA) lineage of V. cholerae. Yet, its explosive success remained unexplained—until now.
4.EPFL’s Breakthrough: Unlocking Cholera’s Defense Secrets
Researchers at EPFL’s Global Health Institute, led by Melanie Blokesch, discovered the WASA lineage’s secret: multiple immune systems protecting it from phages. Published in Nature Microbiology, their study reveals how these defenses likely fueled the Latin American outbreak.
5.Bacterial Immune Systems: A Multi-Layered Shield
Testing Peruvian strains against phages like ICP1—a key virus in curbing outbreaks—the team found WASA strains uniquely resistant. By editing bacterial DNA, they identified two defense hubs: the WASA-1 prophage and the VSP-II genomic island. These regions encode specialized anti-phage systems.
6.Sacrificing the Few to Save the Many
One system, WonAB, triggers “abortive infection”: infected cells die before phages replicate. “This sacrifices a few bacteria to save the population,” explains lead author David Adams. Unlike traditional defenses, WonAB acts after phages hijack cellular machinery, preventing viral spread.
7.Broad-Spectrum Protection Against Phages
Two additional systems add layers of defense. GrwAB targets phages with chemically disguised DNA, while VcSduA fights diverse viruses. Together, they create a resistance spectrum, shielding WASA strains from multiple threats, including the dominant ICP1 phage.
8.Implications for Cholera Control and Treatment
Understanding phage resistance is critical as phage therapy gains traction against antibiotic resistance. If cholera strains boost transmission via phage defenses, outbreak strategies must adapt. This research underscores the need to monitor phage-bacteria dynamics in managing epidemics.
9.Why It Matters:
By decoding cholera’s viral defenses, scientists can better predict outbreaks and refine treatments—highlighting the invisible warfare shaping global health.
Source:Ecole Polytechnique Fédérale de Lausanne
Date:May 22 2025
