agr Expression Precedes Escape of Internalized Staphylococcus aureus from the Host Endosome.

Qazi, Saara N. A. and Counil, Emilie and Morrissey, Julie and Rees, Catherine E. D. and Cockayne, Alan and Winzer, Klaus and Chan, Weng C. and Williams, Paul and Hill, Philip J. (2001) agr Expression Precedes Escape of Internalized Staphylococcus aureus from the Host Endosome. Infection and Immunity, 69 (11). pp. 7074-7082. ISSN 0019-9567

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Staphylococcus aureus is a versatile pathogen capable of causing life-threatening infections. Many of its cell wall and exoproduct virulence determinants are controlled via the accessory gene regulator (agr). Although considered primarily as an extracellular pathogen, it is now recognized that S. aureus can be internalized by epithelial and endothelial cells. Traditional experimental approaches to investigate bacterial internalization are extremely time-consuming and notoriously irreproducible. We present here a new reporter gene method to assess intracellular growth of S. aureus in MAC-T cells that utilizes a gfp-luxABCDE reporter operon under the control of the Bacillus megaterium xylA promoter, which in S. aureus is expressed in a growth-dependent manner. This facilitates assessment of the growth of internalized bacteria in a nondestructive assay. The dual gfp-lux reporter cassette was also evaluated as a reporter of agr expression and used to monitor the temporal induction of agr during the MAC-T internalization process. The data obtained suggest that agr induction occurs prior to endosomal lysis and that agr-regulated exoproteins appear to be required prior to the release and replication of S. aureus within the infected MAC-T cells.

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Journal Article
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Infection and Immunity
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16 Jun 2008 10:12
Last Modified:
22 Sep 2023 00:10