Abstract
An enzyme-linked [rabbit] antibody centrifuge assay for the detection of E. coil pilus K99 was a specific and quantitative assay for the detection of cell-bound K99. The assay is useful as a diagnostic tool. Using the assay, several factors that affect expression of K99 were investigated. Expression of K99 was dependent upon the degree of aeration provided: non-aerated bacteria produced little or no K99, whereas aerated bacteria produced large amounts of K99. K99 appeared to be produced only by logarithmically growing cells, whereas there was a demonstrable decline in the amount of K99/cell during stationary phase. Glucose repressed K99 expression. At 0.5% glucose, K99 expression was highly repressed. Glucose-mediated repression could be overcome by the addition of cyclic AMP. Several other C sources inhibited K99 expression, including pyruvate, arabinose and lactose; glycerol was stimulatory. [K99 mediates adhesion of enterotoxigenic E. coli to the small intestinal mucosa of neonatal calves, lambs and pigs].

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