title: Interaction of Francisella noatunensis subsp. orientalis with Oreochromis mossambicus bulbus arteriosus cell line.
abstract: Francisella noatunensis subsp. orientalis (Fno) (syn. F. asiatica) is an emergent warmwater fish pathogen and the causative agent of piscine francisellosis. Although Fno causes septicemia and can live extracellularly in infected tilapia (Oreochromis spp.), the early interaction of Fno with vasculature endothelium is unknown. In the present study, we examined the interaction of wild-type Fno (WT) and two Fno knockout [intracellular growth loci C (ΔiglC) and pathogenicity determinant protein A (ΔpdpA)] strains with the endothelial O. mossambicus bulbus arteriosus cell line (TmB) at 25 °C and 30 °C. Similar amounts of WT, ΔiglC, and ΔpdpA attached and were detected intracellularly after 5 h of incubation at both temperatures; however temperature affected attachment and uptake. While significantly greater amounts of Fno (WT, ΔiglC, and ΔpdpA) were detected intracellularly when TmB cells were incubated at 30 °C, bacteria attached to TmBs at greater levels at 25 °C. Only WT Fno was able to replicate intracellularly at 25 °C, which resulted in Fno mediated cytotoxicity and apoptosis at 24 and 72 h post-infection. WT Fno incubated at 30 °C as well as ΔiglC, and ΔpdpA incubated at 25 °C and 30 °C were all defective for survival, replication, and the ability to cause cytotoxicity in TmB. Taken together, these results demonstrate that temperature plays a vital role for Fno intracellular survival, persistence and cytotoxicity.
authors.affiliation: University of California-Davis, Department of Medicine and Epidemiology, School of Veterinary Medicine, Davis, CA 95616, USA. Electronic address: sotomartinez@ucdavis.edu.
authors.forename: Esteban
authors.initials: E
authors.lastname: Soto
authors.affiliation: University of California-Davis, Department of Medicine and Epidemiology, School of Veterinary Medicine, Davis, CA 95616, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Yun
authors.affiliation: University of California-Davis, Department of Medicine and Epidemiology, School of Veterinary Medicine, Davis, CA 95616, USA.
authors.forename: Jainee
authors.initials: J
authors.lastname: Lewis
authors.affiliation: Louisiana State University, Department of Pathobiological Sciences, School of Veterinary Medicine, Baton Rouge, LA 70803, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Kearney
authors.affiliation: U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA.
authors.forename: John
authors.initials: J
authors.lastname: Hansen
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D002460:Cell Line; D004727:Endothelium / Q000382:microbiology; D005393:Fish Diseases / Q000382:microbiology* / Q000473:pathology; D005603:Francisella / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D055786:Gene Knockout Techniques; D016680:Genome, Bacterial; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D054884:Host-Pathogen Interactions; D009154:Mutation; D017210:Tilapia / Q000382:microbiology*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins
keywords: Endothelium; Francisella; Mutant; Temperature; Tilapia