title: Effects of co-occurring Wolbachia and Spiroplasma endosymbionts on the Drosophila immune response against insect pathogenic and non-pathogenic bacteria.
abstract: BACKGROUND
  Symbiotic interactions between microbes and animals are common in nature. Symbiotic organisms are particularly common in insects and, in some cases, they may protect their hosts from pathogenic infections. Wolbachia and Spiroplasma endosymbionts naturally inhabit various insects including Drosophila melanogaster fruit flies. Therefore, this symbiotic association is considered an excellent model to investigate whether endosymbiotic bacteria participate in host immune processes against certain pathogens. Here we have investigated whether the presence of Wolbachia alone or together with Spiroplasma endosymbionts in D. melanogaster adult flies affects the immune response against the virulent insect pathogen Photorhabdus luminescens and against non-pathogenic Escherichia coli bacteria.
  
  
  RESULTS
  We found that D. melanogaster flies carrying no endosymbionts, those carrying both Wolbachia and Spiroplasma, and those containing Wolbachia only had similar survival rates after infection with P. luminescens or Escherichia coli bacteria. However, flies carrying both endosymbionts or Wolbachia only contained higher numbers of E. coli cells at early time-points post infection than flies without endosymbiotic bacteria. Interestingly, flies containing Wolbachia only had lower titers of this endosymbiont upon infection with the pathogen P. luminescens than uninfected flies of the same strain. We further found that the presence of Wolbachia and Spiroplasma in D. melanogaster up-regulated certain immune-related genes upon infection with P. luminescens or E. coli bacteria, but it failed to alter the phagocytic ability of the flies toward E. coli inactive bioparticles.
  
  
  CONCLUSIONS
  Our results suggest that the presence of Wolbachia and Spiroplasma in D. melanogaster can modulate immune signaling against infection by certain insect pathogenic and non-pathogenic bacteria. Results from such studies are important for understanding the molecular basis of the interactions between endosymbiotic bacteria of insects and exogenous microbes.
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. upasana@gwu.edu.
authors: Upasana
authors: U
authors: Shokal
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. shrutiyadav@gwmail.gwu.edu.
authors: Shruti
authors: S
authors: Yadav
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. jaishri@gwmail.gwu.edu.
authors: Jaishri
authors: J
authors: Atri
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. jlaccetta@gmail.com.
authors: Julia
authors: J
authors: Accetta
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. etkenney2@email.gwu.edu.
authors: Eric
authors: E
authors: Kenney
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. katiebanks@gwmail.gwu.edu.
authors: Katherine
authors: K
authors: Banks
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. akatakam@gwmail.gwu.edu.
authors: Akash
authors: A
authors: Katakam
authors: Department of Biology, University of Rochester, Rochester, NY, 14627, USA. john.jaenike@rochester.edu.
authors: John
authors: J
authors: Jaenike
authors: Insect Infection and Immunity Lab, Department of Biological Sciences, Institute for Biomedical Sciences, The George Washington University, 5675 Science and Engineering Hall, 800 22nd Street NW, Washington, D.C. 20052, USA. ioannise@gwu.edu.
authors: Ioannis
authors: I
authors: Eleftherianos
mesh_terms: D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics / Q000276:immunology; D004331:Drosophila melanogaster / Q000276:immunology* / Q000382:microbiology* / Q000502:physiology; D005260:Female; D008297:Male; D013149:Spiroplasma / Q000502:physiology*; D013559:Symbiosis; D020577:Wolbachia / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins