title: Intracellular viability of toxigenic Corynebacterium diphtheriae strains in HEp-2 cells.
abstract: Corynebacterium diphtheriae, generally considered an extracellular coloniser, was evaluated for its ability to enter and survive within HEp-2 monolayers by gentamicin protection assay. Intracellular viability of HC01 strain, isolated from endocarditis, was more expressive (2.59%) than observed in 241 (0.21%) and CDC-E8392 (1.93%) strains. Electron microscopy of C. diphtheriae-infected HEp-2 cells revealed intracellular bacteria inside membrane-bound vacuoles. Bacterial internalisation was totally inhibited by 5 microM cytochalasin E and significantly inhibited by 100 microM genistein (P<0.05). Therefore, C. diphtheriae presents the ability to survive within cultured epithelial cells and signalling cascade as well as actin polymerisation are required for entry of diphtheria bacilli into HEp-2 cells.
authors.affiliation: Disciplina de Microbiologia e Imunologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Av. 28 de Setembro 87, Fundos, 3 degrees andar., P.O. Box 20 551-030, Vila Isabel, Rio de Janeiro, RJ, Brazil.
authors.forename: Raphael
authors.initials: R
authors.lastname: Hirata
authors.forename: Fátima
authors.initials: F
authors.lastname: Napoleão
authors.forename: Luiz Henrique
authors.initials: LH
authors.lastname: Monteiro-Leal
authors.forename: Arnaldo F B
authors.initials: AF
authors.lastname: Andrade
authors.forename: Prescilla E
authors.initials: PE
authors.lastname: Nagao
authors.forename: Luiz Carlos D
authors.initials: LC
authors.lastname: Formiga
authors.forename: Leila S
authors.initials: LS
authors.lastname: Fonseca
authors.forename: Ana Luíza
authors.initials: AL
authors.lastname: Mattos-Guaraldi
mesh_terms: D000900:Anti-Bacterial Agents; D002294:Carcinoma, Squamous Cell; D003353:Corynebacterium diphtheriae / Q000254:growth & development* / Q000472:pathogenicity*; D004165:Diphtheria / Q000382:microbiology*; D004696:Endocarditis / Q000382:microbiology; D005839:Gentamicins; D006801:Humans; D007822:Laryngeal Neoplasms; D008854:Microscopy, Electron; D014407:Tumor Cells, Cultured; D014617:Vacuoles / Q000382:microbiology / Q000648:ultrastructure; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins