Histoplasmosis is a poorly understood disease, in part because of the wide spectrum of syndromes that are possible following infection by Histoplasma capsulatum. The organism may remain confined to the lungs or may disseminate to other tissues; the infection may resolve with little symptomatology, may cause life-threatening illness, or may reactivate many years after all signs and symptoms have vanished. Some of this variation in pathogenesis clearly relates to the immune status of the host, and these aspects are being studied by a number of other research groups. In contrast, the efforts of this laboratory are centered on understanding how variations and adaptations by the organism itself could influence the manifestation of disease. The overall objective of this grant renewal remains unchanged from the original application: to study characteristics that define H. capsulatum as a pathogen. An emphasis has been placed on employing a variety of in vitro models of histoplasmosis as primary tools in studying pathogen-host interactions. A consistent theme (unique to this laboratory) is the use of a wide variety of geographically diverse and genetically distinct H. capsulatum strains, allowing broad-based comparisons of characteristics potentially related to virulence. In general, the planned research program is designed to exchange observations about H. capsulatum between molecular biology systems and cell biology systems. This application for 4 years of renewed support focuses on the following three research goals: I. To continue development of molecular genetic systems for cloning and gene disruption in H. capsulatum. The proposed work will take advantage of this group's recently published DNA transformation methodology for H. capsulatum. URA5 will continue to serve as a selectable marker for reverse genetics strategies and in a telomere-based shuttle vector. II. To refine our macrophage and epithelial cell systems as in vitro models for H. capsulatum infection and persistence. Macrophage-like cell lines, primary macrophage cultures, and respiratory epithelial cells will be used for studying H. capsulatum-host cell interactions, especially the effects on intracellular pH and calcium levels. III. To continue studying (using the systems described above)the genetic basis and mechanisms of action of virulence-associated phenotypes. Molecular biology will play a key role in evaluating the function and importance of CBP, a calcium-binding protein produced by H. capsulatum. Additional studies are proposed to characterize the ability of H. capsulatum to modulate phagolysosomal pH in non-activated and activated macrophages.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI025584-05
Application #
2063016
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Project Start
1988-07-01
Project End
1997-02-28
Budget Start
1994-03-01
Budget End
1995-02-28
Support Year
5
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Washington University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
062761671
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
SepĂșlveda, Victoria E; Williams, Corinne L; Goldman, William E (2014) Comparison of phylogenetically distinct Histoplasma strains reveals evolutionarily divergent virulence strategies. MBio 5:e01376-14
Edwards, Jessica A; Alore, Elizabeth A; Rappleye, Chad A (2011) The yeast-phase virulence requirement for ?-glucan synthase differs among Histoplasma capsulatum chemotypes. Eukaryot Cell 10:87-97
Chamilos, Georgios; Ganguly, Dipyaman; Lande, Roberto et al. (2010) Generation of IL-23 producing dendritic cells (DCs) by airborne fungi regulates fungal pathogenicity via the induction of T(H)-17 responses. PLoS One 5:e12955
Beck, Moriah R; Dekoster, Gregory T; Cistola, David P et al. (2009) NMR structure of a fungal virulence factor reveals structural homology with mammalian saposin B. Mol Microbiol 72:344-53
Beck, Moriah R; DeKoster, Gregory T; Hambly, David M et al. (2008) Structural features responsible for the biological stability of Histoplasma's virulence factor CBP. Biochemistry 47:4427-38
Rappleye, Chad A; Eissenberg, Linda Groppe; Goldman, William E (2007) Histoplasma capsulatum alpha-(1,3)-glucan blocks innate immune recognition by the beta-glucan receptor. Proc Natl Acad Sci U S A 104:1366-70
Rappleye, Chad A; Goldman, William E (2006) Defining virulence genes in the dimorphic fungi. Annu Rev Microbiol 60:281-303
Marion, Christopher L; Rappleye, Chad A; Engle, Jacquelyn T et al. (2006) An alpha-(1,4)-amylase is essential for alpha-(1,3)-glucan production and virulence in Histoplasma capsulatum. Mol Microbiol 62:970-83
Rappleye, Chad A; Engle, Jacquelyn T; Goldman, William E (2004) RNA interference in Histoplasma capsulatum demonstrates a role for alpha-(1,3)-glucan in virulence. Mol Microbiol 53:153-65
Magrini, Vincent; Warren, Wesley C; Wallis, John et al. (2004) Fosmid-based physical mapping of the Histoplasma capsulatum genome. Genome Res 14:1603-9

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