title: The Galleria mellonella larvae as an in vivo model for evaluation of Shigella virulence.
abstract: Shigella spp. causing bacterial diarrhea and dysentery are human enteroinvasive bacterial pathogens that are orally transmitted through contaminated food and water and cause bacillary dysentery. Although natural Shigella infections are restricted to humans and primates, several smaller animal models are used to analyze individual steps in pathogenesis. No animal model fully duplicates the human response and sustaining the models requires expensive animals, costly maintenance of animal facilities, veterinary services and approved animal protocols. This study proposes the development of the caterpillar larvae of Galleria mellonella as a simple, inexpensive, informative, and rapid in-vivo model for evaluating virulence and the interaction of Shigella with cells of the insect innate immunity. Virulent Shigella injected through the forelegs causes larvae death. The mortality rates were dependent on the Shigella strain, the infectious dose, and the presence of the virulence plasmid. Wild-type S. flexneri 2a, persisted and replicated within the larvae, resulting in haemocyte cell death, whereas plasmid-cured mutants were rapidly cleared. Histology of the infected larvae in conjunction with fluorescence, immunofluorescence, and transmission electron microscopy indicate that S. flexneri reside within a vacuole of the insect haemocytes that ultrastructurally resembles vacuoles described in studies with mouse and human macrophage cell lines. Some of these bacteria-laden vacuoles had double-membranes characteristic of autophagosomes. These results suggest that G. mellonella larvae can be used as an easy-to-use animal model to understand Shigella pathogenesis that requires none of the time and labor-consuming procedures typical of other systems.
authors.affiliation: a Department of Enteric Infections , Bacterial Diseases Branch (BDB), Walter Reed Army Institute of Research , Silver Spring , Maryland , USA.
authors.forename: Shoshana
authors.initials: S
authors.lastname: Barnoy
authors.affiliation: b Wound Infections Department , BDB, Walter Reed Army Institute of Research , Silver Spring Maryland , USA.
authors.forename: Hanan
authors.initials: H
authors.lastname: Gancz
authors.affiliation: a Department of Enteric Infections , Bacterial Diseases Branch (BDB), Walter Reed Army Institute of Research , Silver Spring , Maryland , USA.
authors.forename: Yuewei
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: c Department of Pathology , Walter Reed Army Institute of Research , Silver Spring , Maryland , USA.
authors.forename: Cary L
authors.initials: CL
authors.lastname: Honnold
authors.affiliation: b Wound Infections Department , BDB, Walter Reed Army Institute of Research , Silver Spring Maryland , USA.
authors.forename: Daniel V
authors.identifier: 0000-0002-7920-5601
authors.initials: DV
authors.lastname: Zurawski
authors.affiliation: a Department of Enteric Infections , Bacterial Diseases Branch (BDB), Walter Reed Army Institute of Research , Silver Spring , Maryland , USA.
authors.forename: Malabi M
authors.initials: MM
authors.lastname: Venkatesan
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004405:Dysentery, Bacillary / Q000382:microbiology*; D006801:Humans; D007814:Larva / Q000382:microbiology; D009036:Moths / Q000382:microbiology*; D012760:Shigella / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence
chemical_list: D001426:Bacterial Proteins
keywords: Galleria mellonella; IpaB mutant; Shigella; haemocytes; virulence