Current understanding of the molecular mechanisms that underly Histoplasma pathogenesis remains limited. Unlike opportunistic pathogens, the fungal pathogen Histoplasma capsulatum can cause disease even in immunocompetent hosts by parasitizing phagocytes of the host. Only a few virulence factors have been identified and characterized to date. In this proposal, we will use a forward genetics approach to discover the virulence factors that enable Histoplasma to subvert the defenses of the macrophage, Histoplasma's primary host cell. Random mutants of Histoplasma yeasts will be created using insertional mutagenesis. Mutants will be screened for decreased virulence in macrophages using a transgenic macrophage line and a Histoplasma strain that has been engineered with fluorescence to provide high-throughput screening capability. Mutants will be classified according to the stage at which Histoplasma pathogenesis is blocked by analysis of intramacrophage growth kinetics. The virulence genes represented by each attenuated mutant will be identified by mapping of the mutation. The final collection of virulence-defective mutants will be ranked according to the severity of their impairment, the classification of their pathogenesis defects, and the identity of the virulence gene identities. These rankings will be used to prioritize further characterization of the discovered virulence factors in future studies t define their roles in facilitating Histoplasma survival and growth in host macrophages.

Public Health Relevance

Histoplasmosis, a respiratory and systemic disease caused by infections with the fungal pathogen Histoplasma capsulatum, afflicts thousands each year in the United States regardless of the host's immune status. The mechanisms that enable Histoplasma to subvert immune defenses are poorly understood. This proposal will identify new virulence factors through a genetics approach to improve our understanding of Histoplasma pathogenesis. Identification of these processes essential to virulence will aid in the development of improved therapeutic options to treat histoplasmosis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Small Research Grants (R03)
Project #
5R03AI111015-02
Application #
8822824
Study Section
Pathogenic Eukaryotes Study Section (PTHE)
Program Officer
Duncan, Rory A
Project Start
2014-04-01
Project End
2017-03-31
Budget Start
2015-04-01
Budget End
2017-03-31
Support Year
2
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Ohio State University
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
832127323
City
Columbus
State
OH
Country
United States
Zip Code
43210
Shen, Qian; Beucler, Matthew J; Ray, Stephanie C et al. (2018) Macrophage activation by IFN-? triggers restriction of phagosomal copper from intracellular pathogens. PLoS Pathog 14:e1007444