Attachment and Entry of Legionella pneumophila in Hartmannella vermiformis

Legionella pneumophila is an intracellular parasite of Hartmannella vermiformis. Attachment to the amebae and entry of L. pneumophila were studied by two quantitative assays: One used plate counts to measure the number of bacteria attaching to amebae at 4°C; the other determined the number of intrac...

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Bibliographic Details
Published in:The Journal of infectious diseases 1993-05, Vol.167 (5), p.1146-1150
Main Authors: Fields, Barry S., Fields, Suzanne R. Utley, Loy, Janine N. Chin, White, Elizabeth H., Steffens, W. L., Shotts, Emmett B.
Format: Article
Language:English
Subjects:
Animals
Bacteria
Bacterial Adhesion
Bacteriology
Biological and medical sciences
Chemical suspensions
Endocytosis
Flasks
Fundamental and applied biological sciences. Psychology
Hartmannella - microbiology
Hartmannella - ultrastructure
Hartmannella vermiformis
Infections
Legionella
Legionella pneumophila
Legionella pneumophila - pathogenicity
Legionella pneumophila - physiology
Legionella pneumophila - ultrastructure
Legionnaires disease
Major Articles
Microbiology
Microscopy, Electron, Scanning
Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains
Phagocytosis
Protozoa
Virulence
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Summary:Legionella pneumophila is an intracellular parasite of Hartmannella vermiformis. Attachment to the amebae and entry of L. pneumophila were studied by two quantitative assays: One used plate counts to measure the number of bacteria attaching to amebae at 4°C; the other determined the number of intracellular bacteria by use of transmission electron microscopy (TEM). The attachment assay showed that L. pneumophila are inefficient in attachment to amebae. About 0.05% of the bacteria were bound after 1 h with a 10- to 40-fold increase over the next 11 h. Attachment of both virulent and avirulent strains of L. pneumophila occurred at a similar rate. Uptake of L. pneumophila was measured by counting intracellular bacteria using TEM. Limited numbers of virulent L. pneumophila were found intracellularly before 4 h, but the numbers increased logarithmically after this time. The number of amebae containing virulent L. pneumophila increased linearly during the 12-h co-incubation. Avirulent L. pneumophila were rarely detected within amebae throughout the 12-h incubation. Results indicate that entry, not attachment, of virulent L. pneumophila is the limiting step in infection of axenically grown H. vermiformis.
ISSN:0022-1899
1537-6613
DOI:10.1093/infdis/167.5.1146