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Category: Bacterial Pathogenesis
The Role of Flagella in Campylobacter Virulence, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815851/9781555814694_Chap13-1.gif /docserver/preview/fulltext/10.1128/9781555815851/9781555814694_Chap13-2.gifAbstract:
This chapter summarizes our present state of understanding of the role of flagella in campylobacter pathogenesis. The flagellar filament of Campylobacter species is composed of two flagellin subunits. Prokaryotic protein glycosylation was at one time thought to be uncommon, but flagellins from all polarly flagellated bacteria that have been examined thus far are glycosylated. Flagellin glycosylation is required for filament assembly in both of these pathogens. Flagella isolated from this mutant showed increased solubility in detergent, suggesting that changes in the glycan composition affected subunit interactions within the filament. Spontaneous autoagglutination (AAG) of campylobacters has long been recognized as a problem in serotyping schemes. The differences can be visualized using green fluorescent protein (GFP)-labeled bacteria. A proteomic comparison of biofilm-grown and planktonic cells indicated the up-regulation of a number of flagellar proteins in biofilm cells, and mutational studies also suggested that flagella (and FlaC expression) are critical to biofilm development. At least one (and likely more) virulence factor appears to be regulated along with the flagellar regulon. Additionally, the flagellin structure appears to have evolved in ways that allow the pathogen to avoid the innate immune response and form aggregates that are critical to virulence.
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A) Autoagglutination of C. jejuni. C. jejuni cells were suspended to an OD600 of 1.0 and allowed to incubate at room temperature overnight. Left, wild-type 81-176; right, a nonflagellated mutant. (B) Scanning electron micrograph of aggregated 81–176 cells.
Microcolony of C. jejuni 81–176 labeled with GFP on a monolayer of INT407 cells. A monolayer of INT407 cells was inoculated with 81-176 expressing GFP and incubated at 37°C for 24 h ( 22 ). The fluorescent image is shown enhanced in black and white. A dense microcolony is visible with chains of fluorescent bacteria extending from the colony.