Abstract
Abstract
Global gene expression in a pathogenic avian O78:K80 strain of Escherichia coli, harvested from infected avian macrophage-like HD11 cells, was compared by microarray with bacteria cultured in tissue culture medium. The changes observed included the use of different electron acceptors and carbon sources such as ethanolamine, β -glucosides, galactonate, dicarboxylic acids and amino acids, up-regulation of genes associated with Fe and Mn uptake and up-regulation of type-1 and curli fimbriae, other adhesion genes and down-regulation of sialic acid synthesis genes. This information, coupled with evidence of intracellular stress, was used to produce a synthetic liquid culture medium which aimed at reproducing the conditions in the macrophage phagosome. The E. coli strain was cultured using this medium to produce an inactivated vaccine (bacterin). This was statistically more protective than a bacterin prepared from bacteria cultured in nutrient broth when tested in vaccinated chickens challenged with a different virulent E. coli O78:K80 strain.

Key words: Key words APEC, microarray, vaccine, chicken, gene expression, synthetic medium