In:
Infection and Immunity, American Society for Microbiology, Vol. 80, No. 2 ( 2012-02), p. 539-549
Abstract:
Enterococcus faecalis is a member of the mammalian gastrointestinal microflora that has become a leading cause of nosocomial infections over the past several decades. E. faecalis must be able to adapt its physiology based on its surroundings in order to thrive in a mammalian host as both a commensal and a pathogen. We employed recombinase-based in vivo expression technology (RIVET) to identify promoters on the E. faecalis OG1RF chromosome that were specifically activated during the course of infection in a rabbit subdermal abscess model. The RIVET screen identified 249 putative in vivo -activated loci, over one-third of which are predicted to generate antisense transcripts. Three predicted antisense transcripts were detected in in vitro - and in vivo -grown cells, providing the first evidence of in vivo -expressed antisense RNAs in E. faecalis . Deletions in the in vivo -activated genes that encode glutamate 5-kinase ( proB [EF0038]), the transcriptional regulator EbrA ( ebrA [EF1809]), and the membrane metalloprotease Eep ( eep [EF2380]) did not hinder biofilm formation in in vitro assays. In a rabbit model of endocarditis, the Δ ebrA strain was fully virulent, the Δ proB strain was slightly attenuated, and the Δ eep strain was severely attenuated. The Δ eep virulence defect could be complemented by the expression of the wild-type gene in trans . Microscopic analysis of early Δ eep biofilms revealed an abundance of small cellular aggregates that were not observed in wild-type biofilms. This work illustrates the use of a RIVET screen to provide information about the temporal activation of genes during infection, resulting in the identification and confirmation of a new virulence determinant in an important pathogen.
Type of Medium:
Online Resource
ISSN:
0019-9567
,
1098-5522
DOI:
10.1128/IAI.05964-11
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2012
detail.hit.zdb_id:
1483247-1
