EFFECT OF GROWTH-CONDITIONS ON EXPRESSION AND ANTIGENICITY OF STAPHYLOCOCCUS-EPIDERMIDIS RP62A CELL-ENVELOPE PROTEINS

Staphylococcus epidermidis RP62A (ATCC 35984) was grown in tryptic soy broth (TSB), iron-depleted TSB (TSB-Fe), iron-reconstituted TSB-Fe (T SB+Fe), a chemically defined medium, and fetal calf serum (FCS) and on silastic disks in chambers that were sutured to the pig peritoneal wa ll. Bacterial cell wall proteins were extracted by digestion with reco mbinant lysostaphin, separated by sodium dodecyl sulfate-polyacrylamid e gel electrophoresis, and detected by silver staining. Cell wall prot eins from TSB-, chemically defined medium-, or FCS-grown cells had a c omplex profile of greater than 25 protein bands spanning the full mole cular mass range. By contrast, a digest obtained from in vivo-grown ce lls had only five major proteins of 40 kDa or greater. Proteins of 130 and 106 kDa were present in the cell envelopes of TSB-Fe- and in vivo -grown cells but not in those grown in TSB or TSB+Fe. A 43-kDa protein expressed by in vitro-grown cells and 52- and 96-kDa proteins express ed by in vivo-grown cells reacted with antisera from pigs with the cha mber implants and from catheterized, paracatheter-inoculated pigs but not with hyperimmune sera from pigs immunized with TSB-grown cells. Th e data indicate that S. epidermidis, growing under in vivo conditions, expresses antigens distinct from those that are grown in vitro.