title: Immuno-physiological adaptations confer wax moth Galleria mellonella resistance to Bacillus thuringiensis.
abstract: Microevolutionary mechanisms of resistance to a bacterial pathogen were explored in a population of the Greater wax moth, Galleria mellonella, selected for an 8.8-fold increased resistance against the entomopathogenic bacterium Bacillus thuringiensis (Bt) compared with a non-selected (suspectible) line. Defense strategies of the resistant and susceptible insect lines were compared to uncover mechanisms underpinning resistance, and the possible cost of those survival strategies. In the uninfected state, resistant insects exhibited enhanced basal expression of genes related to regeneration and amelioration of Bt toxin activity in the midgut. In addition, these insects also exhibited elevated activity of genes linked to inflammation/stress management and immune defense in the fat body. Following oral infection with Bt, the expression of these genes was further elevated in the fat body and midgut of both lines and to a greater extent some of them in resistant line than the susceptible line. This gene expression analysis reveals a pattern of resistance mechanisms targeted to sites damaged by Bt with the insect placing greater emphasis on tissue repair as revealed by elevated expression of these genes in both the fat body and midgut epithelium. Unlike the susceptible insects, Bt infection significantly reduced the diversity and richness (abundance) of the gut microbiota in the resistant insects. These observations suggest that the resistant line not only has a more intact midgut but is secreting antimicrobial factors into the gut lumen which not only mitigate Bt activity but also affects the viability of other gut bacteria. Remarkably the resistant line employs multifactorial adaptations for resistance to Bt without any detected negative trade off since the insects exhibited higher fecundity.
authors.affiliation: a Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Science , Novosibirsk , Russia.
authors.forename: Ivan M
authors.initials: IM
authors.lastname: Dubovskiy
authors.affiliation: a Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Science , Novosibirsk , Russia.
authors.forename: Ekaterina V
authors.initials: EV
authors.lastname: Grizanova
authors.affiliation: b Institute of Life Science, College of Medicine, Swansea University , Swansea , Wales , UK.
authors.forename: Miranda M A
authors.initials: MM
authors.lastname: Whitten
authors.affiliation: c Department of Bioresources , Fraunhofer Institute for Molecular Biology and Applied Ecology , Giessen , Germany.
authors.forename: Krishnendu
authors.initials: K
authors.lastname: Mukherjee
authors.affiliation: d Department of Biosciences , College of Science, Swansea University , Swansea , Wales , UK.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Greig
authors.affiliation: e Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Science , Novosibirsk , Russia.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Alikina
authors.affiliation: e Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Science , Novosibirsk , Russia.
authors.forename: Marsel
authors.initials: M
authors.lastname: Kabilov
authors.affiliation: f Institute for Insect Biotechnology, Justus-Liebig University , Giessen , Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
authors.affiliation: a Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Science , Novosibirsk , Russia.
authors.forename: Viktor V
authors.initials: VV
authors.lastname: Glupov
authors.affiliation: d Department of Biosciences , College of Science, Swansea University , Swansea , Wales , UK.
authors.forename: Tariq M
authors.initials: TM
authors.lastname: Butt
mesh_terms: D000222:Adaptation, Physiological; D000273:Adipose Tissue / Q000276:immunology; D000818:Animals; D001413:Bacillus thuringiensis / Q000472:pathogenicity*; D000069196:Gastrointestinal Microbiome / Q000502:physiology; D020869:Gene Expression Profiling; D007249:Inflammation / Q000235:genetics; D007814:Larva / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D009036:Moths / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*
keywords: Bt; experimental evolution; immune response; insect; microevolution; resistance