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Insights into Streptococcus agalactiae PI-2b pilus biosynthesis and role in adherence to host cells

Bruno Périchon1, Julie Guignot2, Noémi Szili1

  • 1Institut Pasteur, Biology of Gram-positive Pathogens Unit, 75015, Paris, France; Centre National de la Recherche Scientifique (CNRS) ERL6002, France.

Microbes and Infection
|November 13, 2018
PubMed

Insights

The PI-2b pilus in hypervirulent Streptococcus agalactiae enhances bacterial adherence to brain cells and increases phagocytosis by macrophages. Understanding this pilus is key to combating infections.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Infectious Diseases

Background:

  • Hypervirulent ST-17 Streptococcus agalactiae strains possess the PI-2b pilus.
  • The PI-2b pilus is composed of Spb1, Ap1, and Ap2 pilins, assembled by SrtC1 and anchored by Srt2.
  • Ap1 is a potential adhesin, and the operon includes orf and lep genes.

Purpose of the Study:

  • To investigate the roles of Lep and Ap1 in PI-2b pilus biogenesis.
  • To determine the contribution of PI-2b expression to bacterial virulence.

Main Methods:

  • Investigated the contribution of Lep and Ap1 to pilus assembly.
  • Assessed the impact of PI-2b expression levels on bacterial interactions with host cells.

Main Results:

  • Higher PI-2b pilus expression correlated with increased adherence to human brain endothelial cells.
  • Elevated PI-2b expression also led to enhanced phagocytosis by human THP1 macrophages.

Conclusions:

  • The PI-2b pilus plays a significant role in the virulence of hypervirulent Streptococcus agalactiae.
  • PI-2b expression influences bacterial interaction with host immune cells and barriers, suggesting a role in pathogenesis.
Keywords:
GBSGroup B StreptococcusPI-2b pilusS. agalactiaeTHP-1 phagocytosis

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