A proteomics approach to understanding the pathogenesis mechanisms of the obligate intracellular pathogen Coxiella burnetii

Abstract number: 1733_1232

Samoilis G., Psaroulaki A., Vougas K., Gikas A., Tselentis Y., Tsiotis G.

Objectives:Coxiella burnetii is an obligate intracellular pathogen with nearly worldwide distribution. It is the pathogenic agent of Q-fever in man [1], and it has been classified as a Class-B possible agent for bioterrorism [2]. Coxiella burnetii enters target cells by phagocytosis and forms within the infected cell phagosomes that fuse with lysosomal compartments to form the phagolysosome. Within the harsh environment of the phagolysosome Coxiella burnetii manages to survive and replicate. In this work we have attempted to construct a 2-dimensional map of the proteome of intracellular Coxiella burnetii Phase II strain Nine Mile. Identifying proteins being expressed by the intracellular form of the bacterium can provide us with vital information concerning its pathogenesis.

Methods: Intracellular Coxiella burnetii Phase II strain Nine Mile was cultivated in Vero cell lines, isolated and separated from host cell components in a renographin density gradient [4]. Total protein extracts were analysed by conventional 2-dimensional PAGE. Trypsinised protein spots were analysed in a MALDI-TOF MS instrument. Peptide analysis and protein identification were performed as previously described [5]. Peptide matching and protein searches were performed automatically using the Mascot Software.

Results: We have detected 600 protein spots in 2-DE gels, and MS allowed us the identification of 168 Coxiella burnetii proteins. Identified species seem to be involved in a wide range of bacterial processes, whereas 12% of them were hypothetical.

Conclusion: The present study allowed the identification of 168 different proteins and, as far as we know, represents the first proteome analysis of Coxiella burnetii Phase II strain Nine Mile. Genome analysis has predicted that Coxiella burnetii possesses components of the Secretion IV System [3], and in our work we have confirmed the expression of DotB. This pathogen expresses an extensive network of chaperones, which also seems to be coupled to the secretory pathway. We have also found several other proteins that may be essential virulence or survival factors for Coxiella burnetii. This work opens the way to characterise the proteome of Coxiella burnetii, and to compare protein profiles of different isolates.


[1] M. Maurin and D. Raoult, 1999, Clin Micro Re, 12, 518.

[2] M. Maurin et al., 1992, Inf and Immu, 60, 5013.

[3] R. Seshadri et al., 2003, PNAS USA, 100, 5455.

[4] I. Spyridaki et al., 2002, J Anti Chem, 49, 379.

[5] L. Jiang et al., 2003, Amino Acids, 25, 49.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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