title: Symbiosis with Francisella tularensis provides resistance to pathogens in the silkworm.
abstract: Francisella tularensis, the causative agent of tularemia, is a highly virulent facultative intracellular pathogen found in a wide range of animals, including arthropods, and environments. This bacterium has been known for over 100 years, but the lifestyle of F. tularensis in natural reservoirs remains largely unknown. Thus, we established a novel natural host model for F. tularensis using the silkworm (Bombyx mori), which is an insect model for infection by pathogens. F. tularensis established a symbiosis with silkworms, and bacteria were observed in the hemolymph. After infection with F. tularensis, the induction of melanization and nodulation, which are immune responses to bacterial infection, were inhibited in silkworms. Pre-inoculation of silkworms with F. tularensis enhanced the expression of antimicrobial peptides and resistance to infection by pathogenic bacteria. These results suggest that silkworms acquire host resistance via their symbiosis with F. tularensis, which may have important fitness benefits in natural reservoirs.
authors: The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.
authors: Jin
authors: J
authors: Suzuki
authors: Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.
authors: Akihiko
authors: A
authors: Uda
authors: The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.|Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan.
authors: Kenta
authors: K
authors: Watanabe
authors: The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.|Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan.
authors: Takashi
authors: T
authors: Shimizu
authors: The United Graduate School of Veterinary Science, Yamaguchi University, Yamaguchi, Japan.|Joint Faculty of Veterinary Medicine, Laboratory of Veterinary Public Health, Yamaguchi University, Yamaguchi, Japan.
authors: Masahisa
authors: M
authors: Watarai
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D012831:Bombyx / Q000378:metabolism / Q000382:microbiology*; D004195:Disease Models, Animal; D060467:Disease Resistance; D005604:Francisella tularensis / Q000502:physiology*; D006458:Hemolymph / Q000382:microbiology; D007109:Immunity; D019476:Insect Proteins / Q000378:metabolism; D013559:Symbiosis
chemical_list: D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins