Dynamics of bacterial phenotype selection in a colonized host

Area of Science:

• Microbial population dynamics
• Evolutionary biology
• Host-pathogen interactions

Background:

• Helicobacter pylori exhibits phenotype variability, particularly in Lewis antigen expression.
• This variability is driven by high mutation frequencies, providing a substrate for host-driven selection.
• Understanding these dynamics is crucial for modeling microbial evolution in vivo.

Purpose of the Study:

• To establish a quantifiable experimental model for in vivo microbial phenotype evolution using H. pylori colonization.
• To track H. pylori phenotype variability from initial inoculation to quasispecies establishment in animal hosts.
• To develop and apply a mathematical model to interpret colonization data and understand evolutionary processes.

Main Methods:

• Experimental colonization of mice and gerbils with H. pylori.
• Tracking of phenotype variability (Lewis antigen expression) over time (>10^3 generations).
• Development of a mathematical model to analyze population dynamics, distinguishing selection and mutation.

Main Results:

• Successful colonization and quasispecies establishment were observed in animal models.
• Data allowed for tracking of H. pylori phenotype evolution in a large population (>10^4 individuals).
• The mathematical model successfully quantified the roles of initial diversity, mutation, and selection.

Conclusions:

• H. pylori colonization in animal hosts provides a robust model for studying in vivo microbial evolution.
• The study quantifies the interplay between mutation, selection, and initial diversity in shaping microbial populations.
• The developed mathematical model offers a general framework for analyzing phenotype evolution in biological systems.