title: Invasin of Edwardsiella tarda is essential for its haemolytic activity, biofilm formation and virulence towards fish.
abstract: OBJECTIVE
  The aim of this study was to investigate the role of invasin in a bacterial fish pathogen Edwardsiella tarda.
  
  
  RESULTS
  In this study, an in-frame deletion mutant of invasin (Δinv) in Edw. tarda H1 was constructed through double crossover allelic exchange to explore the function of invasin in virulence to fish. Meanwhile, an invasin overexpression strain (inv(+)) was obtained by electrotransformation of a low-copy plasmid pACYC184 carrying the intact invasin into the Δinv mutant. Several virulence-associated characters of the mutants and wild-type strain were tested. Compared with the wild-type H1, haemolytic activity and biofilm formation were decreased in Δinv, while increased significantly in inv(+). In addition, the invasin overexpressing strain inv(+) exhibited increased internalization into Epithelioma Papulosum Cyprini (EPC) cells. Moreover, in zebrafish model, Δinv showed decreased virulence compared with H1, while inv(+) restored the virulence of wild type completely.
  
  
  CONCLUSIONS
  The results demonstrated that invasin of Edw. tarda plays essential roles in haemolytic activity, biofilm formation, adherence, internalization and pathogenicity of this bacterium.
  
  
  CONCLUSIONS
  This study revealed the role of invasin in Edw. tarda infection and provided useful information for further unveiling the pathogenesis of Edw. tarda.
authors.affiliation: College of Marine Life Sciences, Ocean University of China, Qingdao, China.
authors.forename: X
authors.initials: X
authors.lastname: Dong
authors.forename: X
authors.initials: X
authors.lastname: Fan
authors.forename: B
authors.initials: B
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Shi
authors.forename: X-H
authors.initials: XH
authors.lastname: Zhang
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000502:physiology*; D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D020609:Edwardsiella tarda / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D004756:Enterobacteriaceae Infections / Q000382:microbiology / Q000662:veterinary*; D005393:Fish Diseases / Q000382:microbiology*; D005399:Fishes / Q000382:microbiology; D006461:Hemolysis; D017384:Sequence Deletion; D014774:Virulence / Q000235:genetics; D015027:Zebrafish
chemical_list: D018829:Adhesins, Bacterial