title: O antigen modulates insect vector acquisition of the bacterial plant pathogen Xylella fastidiosa.
abstract: Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen.
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California, USA.
authors.forename: Jeannette N
authors.initials: JN
authors.lastname: Rapicavoli
authors.affiliation: Department of Chemical and Environmental Engineering, University of California, Riverside, California, USA.
authors.forename: Nichola
authors.initials: N
authors.lastname: Kinsinger
authors.affiliation: Department of Entomology, University of California, Riverside, California, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Perring
authors.affiliation: USDA, Agricultural Research Service, USDA-ARS San Joaquin Valley Agricultural Sciences Center, Parlier, California, USA.
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Backus
authors.affiliation: Department of Entomology, Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA.
authors.forename: Holly J
authors.initials: HJ
authors.lastname: Shugart
authors.affiliation: Department of Chemical and Environmental Engineering, University of California, Riverside, California, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Walker
authors.affiliation: Department of Plant Pathology and Microbiology, University of California, Riverside, California, USA mcroper@ucr.edu.
authors.forename: M Caroline
authors.initials: MC
authors.lastname: Roper
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D041981:Gastrointestinal Tract / Q000382:microbiology; D006430:Hemiptera / Q000382:microbiology*; D008070:Lipopolysaccharides / Q000378:metabolism*; D019081:O Antigens / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D044167:Xylella / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D019081:O Antigens