title: Shigella flexneri infection in Caenorhabditis elegans: cytopathological examination and identification of host responses.
abstract: The Gram-negative bacterium Shigella flexneri is the causative agent of shigellosis, a diarrhoeal disease also known as bacillary dysentery. S. flexneri infects the colonic and rectal epithelia of its primate host and induces a cascade of inflammatory responses that culminates in the destruction of the host intestinal lining. Molecular characterization of host-pathogen interactions in this infection has been challenging due to the host specificity of S. flexneri strains, as it strictly infects humans and non-human primates. Recent studies have shown that S. flexneri infects the soil dwelling nematode Caenorhabditis elegans, however, the interactions between S. flexneri and C. elegans at the cellular level and the cause of nematode death are unknown. Here we attempt to gain insight into the complex host-pathogen interactions between S. flexneri and C. elegans. Using transmission electron microscopy, we show that live S. flexneri cells accumulate in the nematode intestinal lumen, produce outer membrane vesicles and invade nematode intestinal cells. Using two-dimensional differential in-gel electrophoresis we identified host proteins that are differentially expressed in response to S. flexneri infection. Four of the identified genes, aco-1, cct-2, daf-19 and hsp-60, were knocked down using RNAi and ACO-1, CCT-2 and DAF-19, which were identified as up-regulated in response to S. flexneri infection, were found to be involved in the infection process. aco-1 RNAi worms were more resistant to S. flexneri infection, suggesting S. flexneri-mediated disruption of host iron homeostasis. cct-2 and daf-19 RNAi worms were more susceptible to infection, suggesting that these genes are induced as a protective mechanism by C. elegans. These observations further our understanding of the processes involved in S. flexneri infection of C. elegans, which is immensely beneficial to the routine use of this new in vivo model to study S. flexneri pathogenesis.
authors.affiliation: Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australia.
authors.forename: Divya T
authors.initials: DT
authors.lastname: George
authors.affiliation: Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australia.
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Behm
authors.affiliation: Center for C. elegans Anatomy, Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America.
authors.forename: David H
authors.initials: DH
authors.lastname: Hall
authors.affiliation: Division of Plant Science, Research School of Biology, The Australian National University, Canberra, Australia.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mathesius
authors.affiliation: Centre for Advanced Microscopy, The Australian National University, Canberra, Australia.
authors.forename: Melanie
authors.initials: M
authors.lastname: Rug
authors.affiliation: Center for C. elegans Anatomy, Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America.
authors.forename: Ken C Q
authors.initials: KC
authors.lastname: Nguyen
authors.affiliation: Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australia.
authors.forename: Naresh K
authors.initials: NK
authors.lastname: Verma
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000382:microbiology* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D018834:Chaperonin 60 / Q000037:antagonists & inhibitors / Q000235:genetics; D004195:Disease Models, Animal; D004405:Dysentery, Bacillary / Q000235:genetics / Q000382:microbiology / Q000473:pathology; D055785:Gene Knockdown Techniques; D005798:Genes, Bacterial; D017238:Genes, Helminth; D058507:Host Specificity; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology / Q000502:physiology; D006801:Humans; D007113:Immunity, Innate; D007413:Intestinal Mucosa / Q000382:microbiology / Q000473:pathology; D007501:Iron / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D034622:RNA Interference; D012763:Shigella flexneri / Q000235:genetics / Q000472:pathogenicity*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D029742:Caenorhabditis elegans Proteins; D018834:Chaperonin 60; C410596:DAF-19 protein, C elegans; D014157:Transcription Factors; D007501:Iron