title: Protozoa and human macrophages infection by Legionella pneumophila environmental strains belonging to different serogroups.
abstract: Three Legionella pneumophila strains isolated from municipal hot tap water during a multicentric Italian survey and belonging to serogroups 1, 6, 9 and the reference strain Philadelphia-1 were studied to determine the intracellular replication capability and the cytopathogenicity in human monocyte cell line U937 and in an Acanthamoeba polyphaga strain. Our results show that both serogroups 1 and Philadelphia-1 were able to multiply into macrophages inducing cytopathogenicity, while serogroup 6 and ever more serogroup 9 were less efficient in leading to death of the infected macrophages. Both serogroups 1 and 6 displayed a quite good capability of intracellular replication in A. polyphaga, although serogroup 1 was less cytopathogenic than serogroup 6. Serogroup 9, like Philadelphia-1 strain, showed a reduced efficiency of infection and replication and a low cytopathogenicity towards the protozoan. Our study suggests that bacterial pathogenesis is linked to the difference in the virulence expression of L. pneumophila serogroups in both hosts, as demonstrated by the fact that only L. pneumophila serogroup 1 shows the contextual expression of the two virulence traits. Serogroup 6 proves to be a good candidate as pathogen since it shows a good capacity for intracellular replication in protozoan.
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy. patrizia.messi@unimore.it
authors.forename: Patrizia
authors.initials: P
authors.lastname: Messi
authors.forename: Messi
authors.initials: M
authors.lastname: Patrizia
authors.forename: Annalisa
authors.initials: A
authors.lastname: Bargellini
authors.forename: Bargellini
authors.initials: B
authors.lastname: Annalisa
authors.forename: Immacolata
authors.initials: I
authors.lastname: Anacarso
authors.forename: Anacarso
authors.initials: A
authors.lastname: Immacolata
authors.forename: Isabella
authors.initials: I
authors.lastname: Marchesi
authors.forename: Marchesi
authors.initials: M
authors.lastname: Isabella
authors.forename: Simona
authors.initials: S
authors.lastname: de Niederhäusern
authors.forename: Moreno
authors.initials: M
authors.lastname: Bondi
authors.forename: Bondi
authors.initials: B
authors.lastname: Moreno
mesh_terms: D000048:Acanthamoeba / Q000382:microbiology*; D060766:Drinking Water / Q000382:microbiology; D058507:Host Specificity; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification* / Q000254:growth & development / Q000472:pathogenicity*; D008264:Macrophages / Q000382:microbiology*; D020298:U937 Cells; D014774:Virulence
chemical_list: D060766:Drinking Water