Naslov
Heterogeneity in intracellular replication and cytopathogenicity of Legionella pneuophila and Legionella micdadei in mammalian and protozoan cells

Autori
Gao, Lian-Yong ; Šuša, Milorad ; Tićac, Brigita ; Abu Kwaik, Yousef

Izvornik
Microbial pathogenesis (0882-4010) 27 (1999), 5; 273-287

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
intracellular; bacteria; toxin; apoptosis; protozoa; Legionnaires'

Sažetak
In contrast to Legionella pneumophila, little is known about the pathogenesis of other legionellae species that are capable of causing Legionnaires' disease. In this report, we contrast L.pneumophila and L.micdadei for their cytopathogenicity and intracellular replication within mammalian and protozoan cells. We show by transmission electron microscopy that L.micdadei replicates within an endoplasmic reticulum (RER)-free phagosome within human macrophages, alveolar epithelial cells, and within the protozoan Hartmannella vermiformis. In contrast, L.pneumophila replicates within a RER-sorrounded phagosome within the same host cells. In contrast to replication of L.pneumophila within Acanthamoebae polyphaga, L.micdadei does not replicate within this protozoan host. Despite the prolific intracellular replication, L.micdadei is less cytopathogenic to all host cells than L.pneumophilia. Since both species replicate intracellularly to a similar level, we have examined whether the reduced cytopathogenicity of L.micdadei is due to a reduced capacity to induce appoptosis or pore formation-mediated necrosis, both of which contribute to killing of the host cell by L.pneumophila. The data show that both species induced apoptosis-mediated killing of mammalian cells to a similar level. In contrast to L.pneumophila, expression of the pore-forming toxin by L.micdadei and its necrotic effect on macrophages and alveolar epithelial cells is undetectable. This has been further confirmed showing thal L.micdadei is completely defective in contract-dependent haemolysis of RBCs, an activity mediated by the pore-forming toxin. finally, in contrast to L.pneum ophila, there was no significant intrapulmonary replication of L.micdadei in the A/J mice animal model. Our data show dramatic differences between L.pneumophila and L.micdadei in intracellular replication, cytopathogenicity, and infectivity to mammalian and protozoan cells.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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