Experimental evolution of a pathogen confronted with innate immune memory increases variation in virulence

PMCID: PMC12176410

PMID: 40532126

DOI: 10.1371/journal.ppat.1012839

Journal: PLoS pathogens

Publication Date: 2025-6-18

Authors: Korša A, Baur M, Schulz NK, Anaya-Rojas JM, Mellmann A, et al.

Key Points

• Immune priming creates selective pressure that increases pathogen virulence variability without compromising host defense mechanisms
• 96.6% probability of higher virulence variability in primed-evolved bacteria when infecting control hosts
• Innate immune memory represents a robust protective strategy that constrains pathogen evolutionary potential

Summary

This experimental evolution study investigated how innate immune memory (immune priming) influences pathogen virulence using red flour beetles (Tribolium castaneum) and the bacterial pathogen Bacillus thuringiensis tenebrionis (Btt). Through eight selection cycles, researchers examined how pathogens evolve when confronted with primed versus non-primed host immune responses, revealing complex dynamics of virulence adaptation.

The key findings demonstrated that while average pathogen virulence did not significantly change, immune priming induced increased variability in virulence among bacterial lines. Notably, primed-evolved pathogens failed to develop resistance to host immune priming, and the host's primed immune response remained consistently effective. Genomic analysis revealed increased activity in the bacterial mobilome, with changes in prophage and plasmid dynamics potentially driving evolutionary adaptations.