title: Molecular pathogenesis of Listeria monocytogenes in the alternative model host Galleria mellonella.
abstract: Larvae of Galleria mellonella, the greater wax moth, provide an alternative infection model for many human pathogens as they are amenable to use at elevated incubation temperatures (37&emsp14;°C). This study and a parallel study by Mukherjee et al. [Mukherjee, K., Altincicek, B., Hain, T., Domann, E., Vilcinskas, A. & Chakraborty, T. (2010). Appl Environ Microbiol 76, 310-317] establish this insect host as an appropriate model to investigate the pathogenesis of Listeria species. In this study we show that inoculation with Listeria monocytogenes initiates a dynamic infection in G. mellonella and that production of the cytolysin listeriolysin O (LLO) is necessary for toxicity and bacterial growth. Production of LLO by the non-pathogenic species Lactococcus lactis is sufficient to induce mortality in the insect model. We employed real-time bioluminescence imaging to examine the dynamics of listerial growth and virulence gene expression in the G. mellonella model. Analysis of lux promoter fusions demonstrated significant induction of virulence gene expression upon introduction of the pathogen into insects at both 30 and 37&emsp14;°C. The host response to listerial infection was examined which demonstrated that haemocyte destruction accompanies L. monocytogenes pathogenesis and is preceded by activation of the phenoloxidase system. Furthermore, we demonstrate that Listeria innocua is pathogenic to G. mellonella through a persistence mechanism that implicates an alternative mechanism for pathogenicity in this model.
authors.affiliation: Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.|Department of Microbiology, University College Cork, Cork, Ireland.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Joyce
authors.affiliation: School of Pharmacy, University College Cork, Cork, Ireland.|Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.|Department of Microbiology, University College Cork, Cork, Ireland.
authors.forename: Cormac G M
authors.initials: CGM
authors.lastname: Gahan
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D004195:Disease Models, Animal; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006434:Hemocytes / Q000382:microbiology; D006460:Hemolysin Proteins / Q000378:metabolism*; D007814:Larva / Q000201:enzymology / Q000382:microbiology; D008089:Listeria monocytogenes / Q000235:genetics / Q000472:pathogenicity*; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009036:Moths / Q000201:enzymology / Q000382:microbiology*; D013696:Temperature; D014774:Virulence
chemical_list: D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D014442:Monophenol Monooxygenase; C038705:hlyA protein, Listeria monocytogenes