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Infection and Immunity, July 2008, p. 2950-2957, Vol. 76, No. 7
0019-9567/08/$08.00+0     doi:10.1128/IAI.00055-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Expression of Staphylococcus epidermidis SdrG Increases following Exposure to an In Vivo Environment

Bret R. Sellman, Yekaterina Timofeyeva,^* Jasdeep Nanra, Adrienne Scott, James P. Fulginiti, Yury V. Matsuka, and Steve M. Baker

Wyeth Vaccine Research, Pearl River, New York

Received 15 January 2008/ Returned for modification 15 February 2008/ Accepted 31 March 2008

SdrG is a surface-associated fibrinogen binding protein present in most strains of Staphylococcus epidermidis. Surface expression of SdrG was not detected by flow cytometry or immunofluorescence microscopy on S. epidermidis 0-47 grown in nutrient broth or in the presence of human serum. sdrG transcript levels increased 1 hour following a shift from growth in nutrient broth to growth in the bloodstream of a mouse and resulted in a concomitant increase in protein levels as detected by immunofluorescence microscopy. The environmental signal(s) resulting in the increase in expression is elusive, as growth under conditions known to mimic in vivo conditions (elevated CO₂, iron limitation, human serum, and citrated human blood) did not affect expression of SdrG. Immunizing mice with either the N1N2N3 (amino acids 50 to 597) or N2N3 (amino acids 273 to 597) subdomain of the N-terminal A domain of recombinant SdrG (rSdrG) elicited a robust antibody response; however, only mice vaccinated with rSdrG_N23 exhibited a significant reduction in 0-47 recovered after experimental infection. Since SdrG is expressed early during infection in response to specific host environmental cues present in the bloodstream and since antibodies to it are effective in reducing bacteremia, SdrG possesses attributes of a vaccine component effective against the pathogenic form of the ubiquitous human commensal S. epidermidis.

Published ahead of print on 21 April 2008.

Editor: R. P. Morrison

Present address: Medimmune, Inc., Dept. of Infectious Diseases, 1 Medimmune Way, Gaithersburg, MD 20878.