# Host and Aquatic Environment Dependent Cost and Benefits of the Shigella Flexneri Virulence Plasmid and Shiga Toxin Production

> **NIH NIH P20** · KANSAS STATE UNIVERSITY · 2020 · $239,039

## Abstract

Project Summary/Abstract:
Many emerging infectious diseases maintain significant populations outside of host environments. The
consequences of dynamics occurring in these environmental reservoirs on the pathogenesis of these
pathogens is seldom investigated and poorly characterized. This project examines how the molecular systems
that facultative pathogens use to exploit hosts are shaped by the consequences of dynamics occurring within
both host and environmental reservoir environments. Specifically, the researchers aim to test the hypothesis
that context dependent costs and benefits result in selective dynamics within aquatic environments that lead to
loss of Shigella flexneri virulence plasmid encoded virulence factors while promoting the maintenance of
chromosomally encoded Shiga toxin production. The researchers will use a combination of competition
experiments to measure the costs and benefits of pINV virulence plasmid carriage and virulence regulon
expression in both host and aquatic environments. Further the researchers will determine how Shiga toxin
expression in host and aquatic environments influences the fitness of pathogenic Shigella. Finally, the
researchers will test predictions with respect to the evolutionary dynamics of both pINV encoded and Shiga
toxin virulence factors using an experimental evolution approach. The researchers predict that increased
duration of bouts of selection within aquatic reservoirs will result in the spread of non-invasive Shigella while
the presence of Tetrahymena thermophila predation in these reservoirs will result in increased Shiga toxin
production. The proposed work will determine the context dependent fitness consequences of Shigella
virulence factors and determine whether selection in environmental reservoirs may contribute to the recent
emergence of novel Shiga toxin producing Shigella pathogens.

## Key facts

- **NIH application ID:** 9852902
- **Project number:** 1P20GM130448-01A1
- **Recipient organization:** KANSAS STATE UNIVERSITY
- **Principal Investigator:** Thomas Gene Platt
- **Activity code:** P20 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $239,039
- **Award type:** 1
- **Project period:** — → —

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9852902

## Citation

> US National Institutes of Health, RePORTER application 9852902, Host and Aquatic Environment Dependent Cost and Benefits of the Shigella Flexneri Virulence Plasmid and Shiga Toxin Production (1P20GM130448-01A1). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9852902. Licensed CC0.

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