Drosophila eiger mutants are sensitive to extracellular pathogens

PLoS Pathog. 2007 Mar;3(3):e41. doi: 10.1371/journal.ppat.0030041.


We showed previously that eiger, the Drosophila tumor necrosis factor homolog, contributes to the pathology induced by infection with Salmonella typhimurium. We were curious whether eiger is always detrimental in the context of infection or if it plays a role in fighting some types of microbes. We challenged wild-type and eiger mutant flies with a collection of facultative intracellular and extracellular pathogens, including a fungus and Gram-positive and Gram-negative bacteria. The response of eiger mutants divided these microbes into two groups: eiger mutants are immunocompromised with respect to extracellular pathogens but show no change or reduced sensitivity to facultative intracellular pathogens. Hence, eiger helps fight infections but also can cause pathology. We propose that eiger activates the cellular immune response of the fly to aid clearance of extracellular pathogens. Intracellular pathogens, which can already defeat professional phagocytes, are unaffected by eiger.

MeSH terms

  • Animals
  • Beauveria / immunology
  • Beauveria / pathogenicity*
  • Burkholderia cepacia / immunology
  • Burkholderia cepacia / pathogenicity*
  • Drosophila / immunology
  • Drosophila / microbiology*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / physiology*
  • Gene Expression Regulation
  • Gram-Positive Bacteria / immunology
  • Gram-Positive Bacteria / pathogenicity*
  • Immunity, Innate / physiology
  • Immunocompromised Host / immunology
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Mutation


  • Drosophila Proteins
  • Membrane Proteins
  • egr protein, Drosophila