# SURFACE CHANGE AND VIRULENCE IN COXIELLA BURNETII

> **NIH NIH R01** · WASHINGTON STATE UNIVERSITY · 1990 · $156,415

## Abstract

The rickettsial agent of Q fever, Coxiella burnetii is an obligate
intracellular parasite which replicates within the cellular phagolysosome.
Classical genetic methods to define functional characteristics are not
available and as a result, the physiology and genetic capabilities of C.
burnetii are poorly understood.  Although the mechanisms of virulence of C.
burnetii is not known, a distinct antigenic phase variation has been
associated with a reduction in virulence.  The antigenic shift occurs when
organisms isolated from infected animals (phase I) are repeatedly passed in
eggs (phase II).  As the organisms undergo an antigenic change to phase II,
there is a concomitant decrease in virulence.  In order to develop an
understanding of the nature of the genes involved in virulence, we will
examine a recently isolated plasmid and chromosomal DNA for genes relating
to phase variation and virulence.  We will first use the plasmid isolated
from the Nine Mile, phase I strain (labeled by nick translation) to
determine how widely plasmid sequences are distributed in other strains of
C. burnetii (Southern blotting, hybridization).  We will also attempt to
cure C. burnetii of its plasmid.  These studies will allow us to see if a
correlation exists between virulence and the plasmid.  Next recombinant DNA
techniques will be used to place plasmid and chromosomal genes in E. coli.
Those genes coding for phase specific and other surface antigens will be
identified by specific antisera.  Other bacteria which share properties
with C. burnetii will be examined for the presence of DNA sequences related
to those of the plasmid.  In addition, possible metabolic functions will be
examined using recombinant DNA techniques to place plasmid sequences into
defined E. coli auxotrophs and look for growth due to complementation.
These studies will provide the first analysis of the genetic capabilities
of a rickettsial agent, and are part of the long range objectives of our
laboratory in understanding the biochemical basis of the hostparasite
relationship.

## Key facts

- **NIH application ID:** 3129692
- **Project number:** 5R01AI020190-08
- **Recipient organization:** WASHINGTON STATE UNIVERSITY
- **SAM.gov UEI:** XRJSGX384TD6
- **Principal Investigator:** LOUIS P MALLAVIA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $156,415
- **Award type:** 5
- **Project period:** 1983-07-01 → 1991-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3129692

## Citation

> US National Institutes of Health, RePORTER application 3129692, SURFACE CHANGE AND VIRULENCE IN COXIELLA BURNETII (5R01AI020190-08). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3129692. Licensed CC0.

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