Sequential gene loss promotes expansion of monophasic Salmonella Typhimurium ST34.

Sequential gene loss in Salmonella Typhimurium ST34 drives its clonal expansion, with 44,597 genomes revealing a stepwise pathoadaptation process.

• Why it matters: Understanding how pathogenic bacterial variants expand is vital for predicting and preventing future infectious disease outbreaks, yet the genetic mechanisms remain poorly understood.
• What they did: The study analyzed a large genomic dataset and conducted functional and in vivo experiments, identifying a frameshift mutation in dinB that affects flagellin expression and gut infection requirements.
• The result: Findings demonstrate that ordered gene loss facilitates the global spread of mSTM ST34, offering mechanistic insights for forecasting and potentially controlling future pandemics.