title: Plaque assay for virulent Legionella pneumophila.
abstract: Methods of assessing virulence of Legionella pneumophila, the etiologic agent of Legionnaires disease, include the infection of guinea pigs, fertile chicken eggs, and mammalian and protozoan cell cultures. Guinea pig assays, in particular, are expensive, laborious, or unsuitable for routine screening of Legionella isolates. We have developed a virulence assay that requires the enumeration of viruslike plaques which are the result of virulent L. pneumophila infecting mouse L929 cells. Each plaque is the consequence of the initial infection of an L cell with a single bacterium. A nonvirulent mutant derived from the serial passage of virulent L. pneumophila on Mueller-Hinton agar fails to survive within L cells and consequently fails to produce plaques.
authors.affiliation: Department of Microbiology, Dalhousie University, Victoria General Hospital, Halifax, Nova Scotia, Canada.
authors.forename: R C
authors.initials: RC
authors.lastname: Fernandez
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: D
authors.initials: D
authors.lastname: Haldane
authors.forename: R
authors.initials: R
authors.lastname: Sumarah
authors.forename: K R
authors.initials: KR
authors.lastname: Rozee
mesh_terms: D000818:Animals; D002277:Carcinoma; D002460:Cell Line; D002642:Chick Embryo; D005455:Fluorescent Antibody Technique; D006168:Guinea Pigs; D006801:Humans; D007875:Legionella / Q000254:growth & development / Q000472:pathogenicity*; D007877:Legionnaires' Disease / Q000382:microbiology*; D008175:Lung Neoplasms; D008297:Male; D014407:Tumor Cells, Cultured; D010948:Viral Plaque Assay; D014774:Virulence