title: Temporal expression of extracellular products of Staphylococcus aureus in vivo mouse cage model.
abstract: OBJECTIVE
  To test the hypothesis that Staphylococcus aureus genome has regulatory genes which coordinate the expression of extracellular products, and particular genes not expressed in vitro conditions may be turned on in a vivo environment.
  
  
  METHODS
  The study was conducted at the Immunology and Infectious Disease Research Laboratory (IIDRL), Microbiology Department, Husein Ebrahim Jamal Research Institute (HEJ), Animal House, Karachi University, from July to December 2009. Micro pore Teflon cages using a mouse cage model were fixed into the subcutaneous tissue in Albino mice (BALB/c) on their dorsal surface. After 15 days, the holes closed down with healthy tissue. Three staphylococcal isolates from clinical samples confirmed by DNA sequencing of 16s ribosomal RNA were tested for expression of extracellular protein in vitro and were later injected into the cages. After the institution of infection, the fluid aspirated from the cages was analysed by Sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE). This was done to test for possible induction of additional extracellular proteins in vivo.
  
  
  RESULTS
  The appearance of enhanced extracellular products was observed in the fluid recovered from the cages of two mice on days 5 and 7 subsequent to the institution of infection, suggesting a turn-on of particular genes which were not expressed in vitro conditions.
  
  
  CONCLUSIONS
  In-vivo host and environmental signals contribute to the induction of genes for the production of extracellular proteins.
authors: Department of Pathology, Dow University of Health Sciences, University of Karachi. y.taj@hotmail.com
authors: Yasmeen
authors: Y
authors: Taj
authors: Farhan Essa
authors: FE
authors: Abdullah
authors: Faisal
authors: F
authors: Aziz
authors: Shahana Urooj
authors: SU
authors: Kazmi
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D008807:Mice, Inbred BALB C; D011138:Polytetrafluoroethylene; D019736:Prostheses and Implants; D012329:RNA, Bacterial / Q000032:analysis; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D011138:Polytetrafluoroethylene