agr expression precedes escape of internalized Staphylococcus aureus from the host endosome

• Published in: Infection and immunity Vol. 69; no. 11; pp. 7074 - 7082
• Main Authors: QAZI, Saara N. A, COUNIL, Emilie, MORRISSEY, Julie, REES, Catherine E. D, COCKAYNE, Alan, WINZER, Klaus, CHAN, Weng C, WILLIAMS, Paul, HILL, Philip J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01-11-2001
• Subjects: Acyltransferases; agr gene; Animals; Bacterial diseases; Bacterial Proteins - genetics; Bacteriology; Biological and medical sciences; Cattle; Cell Line; Cellular Microbiology: Pathogen-Host Cell Molecular Interactions; Endocytosis - immunology; endosomes; Endosomes - immunology; Endosomes - microbiology; Epithelial Cells - cytology; Experimental bacterial diseases and models; Fundamental and applied biological sciences. Psychology; Gene Expression; Genes, Reporter; Genetic Engineering; Genetics; gfp gene; Green Fluorescent Proteins; Humanities and Social Sciences; Infectious diseases; Life Sciences; Luminescent Proteins - genetics; luxABCDE gene; Medical sciences; Microbiology; Molecular Structure; Operon; Oxidoreductases; Santé publique et épidémiologie; Staphylococcus aureus; Staphylococcus aureus - genetics; Staphylococcus aureus - immunology; Staphylococcus aureus - pathogenicity; Trans-Activators; Transcription Factors - genetics; xylA gene; Endothelial cell; Determinant; Virulence; Regulator gene; Host; Extracellular; Cell wall; Infection; Reporter gene; Pathogenic; Bacteriosis; Bacteria; Micrococcales; Epithelial cell; Micrococcaceae; Staphylococcal infection; Endosome; Staphylococcus aureus; epidemiology; reporter gene method; accessory gene regulator
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.69.11.7074-7082.2001

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.