This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bandyopadhyay, P.
Right arrow Articles by Steinman, H. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bandyopadhyay, P.
Right arrow Articles by Steinman, H. M.

 Previous Article  |  Next Article 

Infection and Immunity, February 2007, p. 723-735, Vol. 75, No. 2
0019-9567/07/$08.00+0     doi:10.1128/IAI.00956-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Environmental Mimics and the Lvh Type IVA Secretion System Contribute to Virulence-Related Phenotypes of Legionella pneumophila{triangledown}

Purnima Bandyopadhyay, Shuqing Liu,{dagger} Carolina B. Gabbai,{ddagger} Zeah Venitelli,§ and Howard M. Steinman*

Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York

Received 15 June 2006/ Returned for modification 26 July 2006/ Accepted 26 October 2006

Legionella pneumophila, the causative organism of Legionnaires' disease, is a fresh-water bacterium and intracellular parasite of amoebae. This study examined the effects of incubation in water and amoeba encystment on L. pneumophila strain JR32 and null mutants in dot/icm genes encoding a type IVB secretion system required for entry, delayed acidification of L. pneumophila-containing phagosomes, and intracellular multiplication when stationary-phase bacteria infect amoebae and macrophages. Following incubation of stationary-phase cultures in water, mutants in dotA and dotB, essential for function of the type IVB secretion system, exhibited entry and delay of phagosome acidification comparable to that of strain JR32. Following encystment in Acanthamoeba castellanii and reversion of cysts to amoeba trophozoites, dotA and dotB mutants exhibited intracellular multiplication in amoebae. The L. pneumophila Lvh locus, encoding a type IVA secretion system homologous to that in Agrobacterium tumefaciens, was required for restoration of entry and intracellular multiplication in dot/icm mutants following incubation in water and amoeba encystment and was required for delay of phagosome acidification in strain JR32. These data support a model in which the Dot/Icm type IVB secretion system is conditionally rather than absolutely required for L. pneumophila virulence-related phenotypes. The data suggest that the Lvh type IVA secretion system, previously thought to be dispensable, is involved in virulence-related phenotypes under conditions mimicking the spread of Legionnaires' disease from environmental niches. Since environmental amoebae are implicated as reservoirs for an increasing number of environmental pathogens and for drug-resistant bacteria, the environmental mimics developed here may be useful in virulence studies of other pathogens.

* Corresponding author. Mailing address: Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461. Phone: (718) 430-3010. Fax: (718) 430-8565. E-mail: steinman{at}aecom.yu.edu.

{triangledown} Published ahead of print on 13 November 2006.

Editor: D. L. Burns

{dagger} Present address: Center for Proteomics and Mass Spectrometry, School of Medicine, Case Western Reserve University, Cleveland, OH.

{ddagger} Present address: Program in Molecular Biology, Weill Graduate School of Medical Sciences, Cornell University, New York, NY.

§ Present address: Department of Surgery, Gastric and Mixed Tumor Service, Memorial Sloan-Kettering Cancer Center, New York, NY.

Infection and Immunity, February 2007, p. 723-735, Vol. 75, No. 2
0019-9567/07/$08.00+0     doi:10.1128/IAI.00956-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Stewart, C. R., Rossier, O., Cianciotto, N. P. (2009). Surface Translocation by Legionella pneumophila: a Form of Sliding Motility That Is Dependent upon Type II Protein Secretion. J. Bacteriol. 191: 1537-1546 [Abstract] [Full Text]  
  • Rossier, O., Dao, J., Cianciotto, N. P. (2008). The Type II Secretion System of Legionella pneumophila Elaborates Two Aminopeptidases, as Well as a Metalloprotease That Contributes to Differential Infection among Protozoan Hosts. Appl. Environ. Microbiol. 74: 753-761 [Abstract] [Full Text]  
  • De Buck, E., Anne, J., Lammertyn, E. (2007). The role of protein secretion systems in the virulence of the intracellular pathogen Legionella pneumophila. Microbiology 153: 3948-3953 [Abstract] [Full Text]  
  • Chatfield, C. H., Cianciotto, N. P. (2007). The Secreted Pyomelanin Pigment of Legionella pneumophila Confers Ferric Reductase Activity. Infect. Immun. 75: 4062-4070 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»