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Published on: April 2, 2013

Identification of a novel adhesion molecule involved in the virulence of Legionella pneumophila

Bin Chang1, Fumiaki Kura, Junko Amemura-Maekawa

  • 1Department of Bacteriology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan.

Infection and Immunity
|June 24, 2005
PubMed

Insights

Legionella pneumophila uses the LaiA protein for adhesion and invasion, crucial for disease transmission. This virulence factor is essential for L. pneumophila infection in mice but not for intracellular replication.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Bacterial Pathogenesis

Background:

  • Legionella pneumophila is an intracellular bacterium responsible for Legionnaires' disease.
  • Bacterial virulence relies on factors enabling host cell transmission and replication.

Purpose of the Study:

  • To identify novel virulence genes in L. pneumophila.
  • To characterize the role of identified genes in host-pathogen interactions.

Main Methods:

  • Screening of an L. pneumophila genomic DNA library using convalescent-phase sera.
  • Isolation and characterization of antigen-encoding genes.
  • In vitro adhesion, invasion, and intracellular replication assays.
  • In vivo intranasal infection model in mice.

Main Results:

  • Three antigens reacting with patient sera were isolated; one, LaiA, showed homology to yeast integrin.
  • LaiA facilitated L. pneumophila adhesion to and invasion of human lung epithelial cells (A549).
  • LaiA did not impact intracellular replication in macrophages (U937) or bacterial multiplication in mouse lungs.
  • A laiA mutant exhibited reduced virulence and mortality in a mouse infection model.

Conclusions:

  • The laiA gene encodes a virulence factor essential for L. pneumophila transmission and host cell invasion.
  • LaiA plays a significant role in the pathogenesis of Legionnaires' disease.
  • LaiA is critical for initial host colonization rather than intracellular replication.

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