[Construction of aerobactin and sit operon mutant of avian pathogenic Escherichia coli E058 and evaluation of its pathogenicity].

Objective: To elucidate the pathogenesis role of the vir region of APEC 02 strain E058.

Methods: The gene aerobactin/sitABC operon knockout mutants E058deltavir of APEC E058 strain was generated using Red recombination system. A series of pathogenicity tests including chick embryo inoculation, the competition experiment and the colonization and persistence in vivo were used to evaluate the pathogenicity of APEC E058deltavir and the wild-type strain E058.

Role of the lpxM lipid A biosynthesis pathway gene in pathogenicity of avian pathogenic Escherichia coli strain E058 in a chicken infection model.

Lipopolysaccharide (LPS) is a major surface component of avian pathogenic Escherichia coli (APEC), and is a possible virulence factor in avian infections caused by this organism. The contribution of the lpxM gene, which encodes a myristoyl transferase that catalyzes the final step in lipid A biosynthesis, to the pathogenicity of APEC has not previously been assessed. In this study, an isogenic lpxM mutant, E058ΔlpxM, was constructed in APEC O2 strain E058 and then characterized.

Aerobactin synthesis genes iucA and iucC contribute to the pathogenicity of avian pathogenic Escherichia coli O2 strain E058.

Aerobactin genes are known to be present in virulent strains and absent from avirulent strains, but contributions of iucC and iucA, which are involved in aerobactin synthesis, to the pathogenicity of avian pathogenic Escherichia coli (APEC) have not been clarified. In this study, effects of double mutants (iucA/iutA or iucC/iutA) compared to those of single mutants (iucA, iucC or iutA) of aerobactin genes on the virulence of APEC strain E058 were examined both in vitro (aerobactin production, ingestion into HD-11 cells, survival in chicken serum) and in vivo (competitive growth against parental strain, colonization and persistence). In competitive co-infection assays, compared to the E058 parental strain, the E058ΔiucA mutant was significantly reduced in the liver, kidney, spleen (all P<0.

Roles of iron acquisition systems in virulence of extraintestinal pathogenic Escherichia coli: salmochelin and aerobactin contribute more to virulence than heme in a chicken infection model.

Background: Avian pathogenic Escherichia coli (APEC) and uropathogenic E. coli (UPEC) are the two main subsets of extraintestinal pathogenic E. coli (ExPEC).

Construction of iucB and iucBiutA mutants of avian pathogenic Escherichia coli and evaluation of their pathogenicity.

Aerobactin counts for much to the pathogenesis of avian pathogenic Escherichia coli (APEC), iutA is responsible for the expression of a specific outer membrane receptor protein for ferric aerobactin, and iucB is involved in the aerobactin synthesis. To our knowledge, the contribution of iucB to the pathogenicity of APEC has not been assessed till now. In this study, the mutants E058ΔiucB and E058ΔiucBΔiutA were constructed and characterized.