# "Reverse Evolution" Approach to Identify Coxiella burnetii Strategies of Intracellular Survival

> **NIH NIH R03** · OKLAHOMA STATE UNIVERSITY STILLWATER · 2020 · $72,336

## Abstract

Project Summary
 Coxiella burnetii (Cb) is an obligate intracellular bacterium in nature and the causative agent of human
acute Q fever as well as chronic disease. Upon infection, Cb is trafficked along a bacterially modified endocytic
pathway and establishes a parasitophorous vacuole (PV) that retains many of the features of mature
phagolysosomes. Throughout the infectious cycle within a host cell, Cb face an array of physiological needs
and stresses unique to life within an acidified intracellular vesicle. The pathogen manipulates a plethora of host
cell pathways and processes from within the PV via a bacterial Type 4 Secretion System (T4BSS) in order to
survive and replicate. However, axenic media supports Cb replication in an environment where the bacterial
genes required for many of its adaptations to intracellular growth are no longer needed. Deletion and insertion
mutants have demonstrated some of Cb host cell specific gene requirements, however, an understanding of
the breadth of the bacteria’s genes, and/or their expression, that will change when cellular stresses are removed
is still lacking. This is a fundamental gap in our understanding of how Cb subverts host cell processes during
infection and will lead to a broader understanding of Cb biology and pathogenesis. The long-term goal of our
research is to elucidate molecular mechanisms employed by Cb to orchestrate parasitism of the host cell during
infection. Our hypotheses are 1- Cb changes its gene expression within the first few passages upon
transition from intracellular to axenic media growth, and 2- Cb will progressively acquire and
accumulate DNA mutations upon transition from intracellular to axenic media growth after repetitive
passages since certain bacterial genes/proteins are no longer required for successful growth. We will
test our hypotheses by 1- Identifying Cb gene expression changes that occur during early and long term
passages after inoculating axenic growth media with host cell propagated Cb, and 2- Identifying Cb
genetic mutations/changes that occur/accumulate over multiple passages after inoculating axenic
growth media with host cell propagated Cb. Understanding the virulence mechanisms employed by this
unique pathogen to survive within the harsh environment of the host cell phagosome and cause disease will
enable us to develop countermeasures to this poorly understood bacteria.

## Key facts

- **NIH application ID:** 9874891
- **Project number:** 1R03AI149144-01
- **Recipient organization:** OKLAHOMA STATE UNIVERSITY STILLWATER
- **Principal Investigator:** Edward I. Shaw
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $72,336
- **Award type:** 1
- **Project period:** 2020-05-18 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9874891

## Citation

> US National Institutes of Health, RePORTER application 9874891, "Reverse Evolution" Approach to Identify Coxiella burnetii Strategies of Intracellular Survival (1R03AI149144-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9874891. Licensed CC0.

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