The Drosophila immune system detects bacteria through specific peptidoglycan recognition

Nat Immunol. 2003 May;4(5):478-84. doi: 10.1038/ni922.


The Drosophila immune system discriminates between different classes of infectious microbes and responds with pathogen-specific defense reactions through selective activation of the Toll and the immune deficiency (Imd) signaling pathways. The Toll pathway mediates most defenses against Gram-positive bacteria and fungi, whereas the Imd pathway is required to resist infection by Gram-negative bacteria. The bacterial components recognized by these pathways remain to be defined. Here we report that Gram-negative diaminopimelic acid-type peptidoglycan is the most potent inducer of the Imd pathway and that the Toll pathway is predominantly activated by Gram-positive lysine-type peptidoglycan. Thus, the ability of Drosophila to discriminate between Gram-positive and Gram-negative bacteria relies on the recognition of specific forms of peptidoglycan.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Bacillus thuringiensis / immunology
  • Base Sequence
  • DNA / genetics
  • Drosophila / genetics
  • Drosophila / immunology*
  • Drosophila / microbiology
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Escherichia coli / immunology
  • Gene Expression
  • Genes, Insect
  • Gram-Negative Bacteria / immunology*
  • Gram-Positive Bacteria / immunology*
  • Insect Proteins / genetics
  • Lac Operon
  • Muramidase
  • Peptidoglycan / immunology*
  • Pseudomonas aeruginosa / immunology
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism
  • Signal Transduction
  • Toll-Like Receptors


  • DptA protein, Drosophila
  • Drosophila Proteins
  • Insect Proteins
  • Peptidoglycan
  • Receptors, Cell Surface
  • Tl protein, Drosophila
  • Toll-Like Receptors
  • imd protein, Drosophila
  • DNA
  • Muramidase