title: Characterization of IcmF of the type VI secretion system in an avian pathogenic Escherichia coli (APEC) strain.
abstract: 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.
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas - Unicamp, Campinas, SP CP6109, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: de Pace
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas - Unicamp, Campinas, SP CP6109, Brazil.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Boldrin de Paiva
authors.affiliation: State University of Londrina - UEL, Londrina, PR, Brazil.
authors.forename: Gerson
authors.initials: G
authors.lastname: Nakazato
authors.affiliation: Department of Biochemistry, Institute of Biology, State University of Campinas - Unicamp, Campinas, SP CP6109, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Lancellotti
authors.affiliation: Laboratory of Bacteriology, Butantan Institute, São Paulo, CP 05503-900, Brazil.
authors.forename: Marcelo Palma
authors.initials: MP
authors.lastname: Sircili
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas - Unicamp, Campinas, SP CP6109, Brazil.
authors.forename: Eliana
authors.initials: E
authors.lastname: Guedes Stehling
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas - Unicamp, Campinas, SP CP6109, Brazil.
authors.forename: Wanderley
authors.initials: W
authors.lastname: Dias da Silveira
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, TX 75390-9048, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Sperandio
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D058947:Bacterial Secretion Systems; D018441:Biofilms; D002460:Cell Line; D002645:Chickens; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011201:Poultry Diseases / Q000382:microbiology*; D014774:Virulence
chemical_list: D058947:Bacterial Secretion Systems; D029968:Escherichia coli Proteins