Characterization of icmF of the type VI secretion system in an avian pathogenic Escherichia coli (APEC) strain

Fernanda de Pace, Jacqueline Boldrin de Paiva, Gerson Nakazato, Marcelo Lancellotti, Marcelo Palma Sirsili, Eliana Guedes Stehling, Wanderley Dias da Silveira, Vanessa Sperandio

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


The intracellular multiplication factor (IcmF) protein is a component of the recently described type VI secretion system (T6SS). IcmF has been shown to be required for intra-macrophage replication and inhibition of phagosome-lysosome fusion in Legionella pneumophila. In Vibrio cholerae it is involved in motility, adherence and conjugation. Given that we previously reported that two T6SS genes (hcp and clpV) contribute to the pathogenesis of a septicaemic strain (SEPT362) of avian pathogenic Escherichia coli (APEC), we investigated the function of IcmF in this strain. Further elucidation of the virulence mechanisms of APEC is important because this pathogen is responsible for financial losses in the poultry industry, and is closely related to human extraintestinal pathogenic E. coli (ExPEC) strains, representing a potential zoonotic risk, as well as serving as a reservoir of virulence genes. Here we show that an APEC icmF mutant has decreased adherence to and invasion of epithelial cells, as well as decreased intra-macrophage survival. The icmF mutant is also defective for biofilm formation on abiotic surfaces. Additionally, expression of the flagella operon is decreased in the icmF mutant, leading to decreased motility. The combination of these phenotypes culminates in this mutant being altered for infection in chicks. These results suggest that IcmF in APEC may play a role in disease, and potentially also in the epidemiological spread of this pathogen through enhancement of biofilm formation.

Original languageEnglish (US)
Pages (from-to)2954-2962
Number of pages9
Issue number10
StatePublished - Oct 2011

ASJC Scopus subject areas

  • Microbiology


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