title: Genetic and phenotypic differences between Legionella pneumophila strains.
abstract: Legionnaires' disease is a potentially lethal pneumonia that is primarily due to infection by the species Legionella pneumophila, although more than 40 other species are known. Certain L. pneumophila subgroups, particularly serogroup 1, are associated with the majority of the epidemics. The genetic bases for these differences in virulence have not been determined. Three strains, AA100, JR32, and Lp01, have been used in many molecular pathogenesis studies of L. pneumophila. We found genetic differences between these strains by PCR and Southern analyses that may be related to their ability to cause disease. We also examined the distribution of these genetic loci in clinical and environmental isolates of Legionella and found a correlation between the presence of two of these loci, rtxA and lvh, and the ability to cause disease in humans. Examination of the interactions of these strains with host cells suggested that they differ in important phenotypic characteristics including adherence, entry, and intracellular replication. Furthermore, in the mouse model of infection they display differing levels of replication in lungs. These studies emphasize the importance of further investigation into the genetic makeup of these strains, which is likely to lead to the identification of additional factors involved in Legionella pathogenesis.
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, Lincoln, Nebraska 68583, USA.
authors.forename: Mustapha M
authors.initials: MM
authors.lastname: Samrakandi
authors.forename: Suat L G
authors.initials: SL
authors.lastname: Cirillo
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Ridenour
authors.forename: Luiz E
authors.initials: LE
authors.lastname: Bermudez
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Cirillo
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D004195:Disease Models, Animal; D005838:Genotype; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D007877:Legionnaires' Disease / Q000382:microbiology* / Q000503:physiopathology; D008168:Lung / Q000382:microbiology; D008264:Macrophages; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010641:Phenotype; D017422:Sequence Analysis, DNA; D014407:Tumor Cells, Cultured; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C459580:Lvh protein, Legionella pneumophila; C459581:Tra1 protein, Legionella pneumophila