Growth of Legionella pneumophila in Acanthamoeba castellanii enhances invasion

  title={Growth of Legionella pneumophila in Acanthamoeba castellanii enhances invasion},
  author={Jeffrey D. Cirillo and Stanley Falkow and Lucy S. Tompkins},
  journal={Infection and Immunity},
  pages={3254 - 3261}
Legionella pneumophila is considered to be a facultative intracellular parasite. Therefore, the ability of these bacteria to enter, i.e., invade, eukaryotic cells is expected to be a key pathogenic determinant. We compared the invasive ability of bacteria grown under standard laboratory conditions with that of bacteria grown in Acanthamoeba castellanii, one of the protozoan species that serves as a natural host for L. pneumophila in the environment. Amoeba-grown L. pneumophila cells were found… 

Intracellular Growth in Acanthamoeba castellanii Affects Monocyte Entry Mechanisms and Enhances Virulence of Legionella pneumophila

Amoeba-grown L. pneumophila displays increased replication in monocytes and is more virulent in A/J, C57 BL/6 Beige, and C57BL/6 mice, demonstrating for the first time that the intra-amoebal growth environment affects the entry mechanisms and virulence of L. pneumonia.

Expression of Legionella pneumophilaVirulence Traits in Response to Growth Conditions

Together, these data indicate that while nutrients are plentiful, intracellular L. pneumophila organisms are dedicated to replication; when amino acids become limiting, the progeny express virulence factors to escape the spent host, to disperse and survive in the aquatic environment, and to reestablish a protected intrACEllular niche favorable for growth.

Differential expression of virulence genes in Legionella pneumophila growing in Acanthamoeba and human monocytes

The gene expression profiles observed in this study indicated the increased cytotoxicity of L. pneumophila in A. castellanii, suggesting an increased adaptation of Legionella to this host.

Permissiveness of freshly isolated environmental strains of amoebae for growth of Legionella pneumophila.

Assessment of the permissiveness of freshly isolated environmental strains of amoebae belonging to three common genera suggests that virulent strains of L. pneumophila could equally infect a large number of isolates of common freshwater amoEBa genera.

Localization of Legionella pneumophila Mip Protein Inside Phagosomes of Acanthamoeba castellanii

To get morphological evidence for the virulence association of the Mip protein, the immunogold technique was applied to localize this protein on legionellae before and after invasion of Acanthamoeba castellanii, one of the protozoan species that serve as a natural host in the environment.

Characterization of Legionella pneumophila pmiA, a Gene Essential for Infectivity of Protozoa and Macrophages

ABSTRACT The ability of Legionella pneumophila to cause pneumonia is dependent on intracellular replication within alveolar macrophages. The Icm/Dot secretion apparatus is essential for the ability

Impact of inter-amoebic phagocytosis on the L. pneumophila growth.

Free-living amoebae are known to act as replication niches for the pathogenic bacterium L. pneumophila in freshwater environments, and the occurrence of inter-amoebic phagocytosis with A. castellanii and W. magna being able to ingest V. vermiformis infected or not infected with L. pneumonia is demonstrated.

Role of the Legionella pneumophila rtxA gene in amoebae.

Data support a role for this gene both during disease in humans and in environmental reservoirs, as well as demonstrating involvement of rtxA in the interaction of L. pneumophila with host cells.

Invasion of eukaryotic cells by Legionella pneumophila: A common strategy for all hosts?

  • P. Hoffman
  • Biology
    The Canadian journal of infectious diseases = Journal canadien des maladies infectieuses
  • 1997
Virulence of L pneumophila is considered to be multifactorial, and there is growing evidence for both stage specific and sequential gene expression, which suggests it may be a good model system for dissecting events associated with the host-parasite interactions.

Intraphagocytic growth induces an antibiotic-resistant phenotype of Legionella pneumophila

The successful treatment of Legionnaires disease may be related as much to the resistance phenotype induced by intramacrophage growth as to the ability of the antibiotic to enter phagocytic cells.



Cocultivation of Legionella pneumophila and free-living amoebae

Studies of the interaction of Legionella pneumophila with free-living amoebae showed that Naegleria lovaniensis and Acanthamoeba royreba could use L. pneumophila as a sole food source. However,

Intracellular replication of Legionella pneumophila.

These studies indicate that L. pneumophila acts as an intracellular pathogen in tissue cultures, and this characteristic may offer a simple method for studying growth and pathogenicity of this unusual bacillus in humans.

Adhesion, penetration and intracellular replication of Legionella pneumophila: an in vitro model of pathogenesis.

Uptake and intracellular development was similar for each cell type, and was initiated by 'bacteriopexis', a process in which the organisms bound via receptors and were surrounded by cellular microvilli which eventually fused, leading to bacterial engulfment.

Legionnaires' disease bacterium (Legionella pneumophila) multiples intracellularly in human monocytes.

Findings indicate that L. pneumophila falls into a select category of bacterial pathogens that evade host defenses by parasitizing monocytes, and it remains to be determined whether cell-mediated immunity plays a dominant role in host defense against L.neumophila as it does against other intracellular pathogens.

Virulence conversion of Legionella pneumophila serogroup 1 by passage in guinea pigs and embryonated eggs

The suggestion that a suitable host is required for the selection of the virulent form of L. pneumophila is supported, as a nonflagellated form of the bacterium was recovered which had an increased virulence for guinea pigs and embryonated eggs.

Virulence conversion of Legionella pneumophila: a one-way phenomenon

The results suggest that the conversion process which occurs between virulent andAvirulent forms of L. pneumophila is a one-way phenomenon from virulence to avirulence and that stable avirulent derivatives can be isolated.

Association between Legionella pneumophila and amoebae in water.

Results confirmed that interaction between L. pneumophila and amoebae could occur in nature, and that the latter could act as hosts for legionellae and support their growth.

Interaction of L. pneumophila and a free living amoeba (Acanthamoeba palestinensis)

SUMMARY Co-cultivation of Legionella pneumophila serogroup I and Acanthamoeba palestinensis in Neff's medium at 35 °C resulted in the intracellular multiplication of the bacteria as demonstrated by

Localized adherence by enteropathogenic Escherichia coli is an inducible phenotype associated with the expression of new outer membrane proteins

The correspondence of the 18.5-kD polypeptide to an EPEC- specific pilus protein, and the temporal correlation of its expression with the development of the LA phenotype suggest that it may contribute to the EPEC colonial mode of growth.

Temperature-dependent expression of virulence genes in Shigella species

The Henle cell assay determined that the loss of ability to penetrate epithelial cells was completely reversed by shifting the growth temperature from 30 to 37 degrees C, and expression of virulence in Shigella spp.