Identification of Immunogenic and Serum Binding Proteins of Staphylococcus epidermidis

• Published in: Infection and Immunity 2005-10, Vol.73 (10), p.6591-6600
• Main Authors: Sellman, Bret R, Howell, Alan P, Kelly-Boyd, Cari, Baker, Steve M
• Format: Article
• Language: English
• Subjects: Animals; Antigens, Bacterial - blood; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; Bacterial Proteins - blood; Bacterial Proteins - genetics; Bacterial Proteins - immunology; Bacteriology; Biological and medical sciences; Blood Proteins - metabolism; Carrier Proteins - blood; Carrier Proteins - genetics; Carrier Proteins - immunology; Cell Wall - immunology; Electrophoresis, Gel, Two-Dimensional; Escherichia coli; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Mass Spectrometry; Mice; Microbial Immunity and Vaccines; Microbiology; Miscellaneous; Rabbits; Recombinant Proteins - genetics; Recombinant Proteins - immunology; Serum - immunology; Spleen - microbiology; Staphylococcus epidermidis; Staphylococcus epidermidis - growth & development; Staphylococcus epidermidis - immunology; Vaccination
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.73.10.6591-6600.2005

Staphylococcus epidermidis is a commensal of human skin and a leading cause of nosocomial bloodstream infections. Limited information is available about S. epidermidis proteins that are expressed upon transition to the bloodstream or those involved in host-pathogen interactions. A cell surface fraction from S. epidermidis 0-47 grown in rabbit serum to mimic environmental signals encountered during a bloodstream infection was separated by two-dimensional (2D) gel electrophoresis. Following 2D separation, the proteins were transferred to nitrocellulose and detected with either pooled sera generated in rabbits immunized with live S. epidermidis 0-47 or with biotin-labeled serum proteins eluted from the surface of bacteria grown in rabbit serum. Twenty-nine immunoreactive or serum binding proteins of S. epidermidis were identified by mass spectrometry. Twenty-seven of the corresponding genes were expressed in Escherichia coli, and the purified recombinant proteins were used to immunize mice. In a preliminary screen, 12 of the 27 recombinant proteins induced a response that reduced the number of bacteria recovered from the spleen or bloodstream of infected mice. In subsequent vaccination studies, 5 of the 12 proteins resulted in a statistically significant reduction in the number of bacteria. The identification of five candidate vaccine antigens from the initial screen of only 29 proteins demonstrates the utility of this approach.