This Article Full Text (PDF) Other Versions of this Article: IAI.01174-07v1 76/2/788    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by MacKichan, J. K. Articles by Koehler, J. E. Search for Related Content PubMed PubMed Citation Articles by MacKichan, J. K. Articles by Koehler, J. E.

 Previous Article  |  Next Article 

Infect. Immun. doi:10.1128/IAI.01174-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

A SacB Mutagenesis Strategy Reveals that the Bartonella quintana Variably-Expressed Outer Membrane Proteins (Vomp) are Required for Bloodstream Infection of the Host

Microbial Pathogenesis and Host Defense Program, and Division of Infectious Diseases, Department of Medicine, University of California at San Francisco, San Francisco, California 94143-0654

^* To whom correspondence should be addressed. Email: jkoehler{at}medicine.ucsf.edu.

	Abstract

Bartonella bacteria adhere to erythrocytes and persistently infect the mammalian bloodstream. We previously identified four highly conserved B. quintana adhesin genes that undergo phase variation during prolonged bloodstream infection. These v ariably-expressed outer membrane proteins (Vomp) are members of the trimeric autotransporter adhesin family. Each B. quintana Vomp appears to contribute a different adhesion phenotype, likely mediated by the major variable region at the adhesive tip of each Vomp. Although studies document that the Vomp confer virulence phenotypes in vitro, little is known about in vivo virulence strategies of Bartonella. We sought to determine whether the B. quintana Vomp are necessary for infection in vivo, using a vomp null mutant.

It first was necessary to develop a system to generate in-frame deletion of defined genes by allelic exchange in a wild type Bartonella background, which had not been achieved previously. We utilized sacB negative selection to generate a targeted, in-frame, markerless deletion of the entire vomp locus in B. quintana. We also recently developed the first animal model for B. quintana, and using this model, we demonstrate here that deletion of the entire vomp locus, but not deletion of two vomp genes, results in a null mutant strain that is incapable of establishing bloodstream infection in vivo. The Vomp therefore represent critical virulence factors in vivo, warranting further study. Finally, our allelic exchange strategy provides an important advance in the genetic manipulation of all Bartonella species, and combined with the animal model that recapitulates human disease, will facilitate pathogenesis studies of B. quintana.