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Infection and Immunity, April 2000, p. 1765-1772, Vol. 68, No. 4
Departments of Medical Microbiology1
and Endocrinology and Metabolism5 and
Institute for Ophthalmology,4
Academic Medical Center, University of
Amsterdam, Amsterdam, Department of Bacteriology, ID-DLO,
Lelystad,3 and Department of
Infectious Diseases, Leiden University Medical Center,
Leiden,2 The Netherlands
Received 30 August 1999/Returned for modification 21 October
1999/Accepted 3 January 2000
Staphylococcus aureus is isolated from a substantial
number of patients with infective endocarditis who are not known to
have predisposing heart abnormalities. It has been suggested that the infection is initiated by the direct binding of S. aureus
to human vascular endothelium. To determine the mutual response of the endothelial cells and the bacteria, we studied the interaction between
S. aureus and human vascular endothelium. Scanning electron microscopic analyses showed that binding of S. aureus to
human umbilical vein endothelial cells (HUVEC) mainly occurred via
thread-like protrusions extending from the cell surface. Bound bacteria
appeared to be internalized via retraction of the protrusions into
newly formed invaginations of the endothelial cell surface. The growth phase of S. aureus had a major impact on the interaction
with HUVEC. Logarithmically growing bacteria showed increased binding to, and were more readily internalized by, HUVEC compared to
stationary-phase bacteria. To assess the bacterial response to the
cellular environment, an expression library of S. aureus
was used to identify genes whose expression was induced after 4 h
of exposure to HUVEC. The identified genes could be divided into
different categories based on the functions of the encoded proteins
(transport, catabolism, biosynthesis, and DNA repair). Further analyses
of five of the S. aureus transposon clones showed that
HUVEC as well as human serum are stimuli for triggering gene expression
in S. aureus.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Altered Gene Expression in Staphylococcus aureus upon
Interaction with Human Endothelial Cells
*
Corresponding author. Present address: Department of
Biotechnology, Numico Research B.V., P.O. Box 7005, 6700 CA Wageningen, The Netherlands. Phone: 31 317 467 800. Fax: 31 317 466 500. E-mail: Aldwin.Vriesema{at}numico-research.nl.
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