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Human serum induces streptococcal c5a peptidase expression

Ute Gleich-Theurer1, Simone Aymanns, Gregor Haas

  • 1Insitute of Medical Microbiology and Hygiene, University of Ulm, D-89081 Ulm, Germany.

Infection and Immunity
|June 10, 2009
PubMed

Insights

Human serum specifically induces Streptococcus agalactiae's C5a peptidase (scpB) gene, highlighting its role in human infections. This contrasts with bovine strains lacking scpB induction, suggesting host adaptation.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogen Adaptation

Background:

  • Streptococcus agalactiae is a significant human and animal pathogen.
  • Virulence factors, like C5a peptidase (scpB) and Lmb, are often linked to mobile genetic elements and host-modulated expression.
  • The scpB and Lmb genes are located on a composite transposon absent in many bovine isolates.

Purpose of the Study:

  • To investigate the role of scpB and Lmb genes in Streptococcus agalactiae's adaptation to human hosts.
  • To determine the influence of human and bovine serum on the promoter activity of scpB and lmb.

Main Methods:

  • Fluorescence-activated cell sorter analysis to measure reporter gene activity for scpB and lmb promoter.
  • Culturing S. agalactiae in varying concentrations of human and fetal calf serum.
  • Reverse transcription-PCR to confirm differential gene induction.

Main Results:

  • Human serum dose-dependently induced reporter gene activity for scpB, but not lmb.
  • Fetal calf serum did not alter reporter gene activity.
  • A bovine S. agalactiae strain showed no induction of scpB by either human or bovine serum.

Conclusions:

  • The C5a peptidase (scpB) gene in S. agalactiae is specifically induced by human serum.
  • This human-specific induction suggests scpB is a crucial virulence factor for human infections.
  • The absence of scpB induction in bovine strains supports its role in host adaptation.

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