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K.J. Kwon-Chung, Ph.D.
Building 10, Room 11C104
10 Center Drive
Bethesda, MD 20892-1882
Phone: 301-496-1602
Fax: 301-480-3240

Laboratory of Clinical Infectious Diseases

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K.J. Kwon-Chung, Ph.D.

Photo of K.J. Kwon-Chung, Ph.D. 

Chief, Molecular Microbiology Section, LCID

Major Areas of Research

  • Virulence determinants of Cryptococcus neoformans and Aspergillus fumigatus
  • Mechanism by which Cryptococcus neoformans invades the brain
  • Mechanism by which cryptococci adapt to the brain environment and produce fulminating disease
  • The signaling mechanism involved in the cryptococcal invasion of human brain microvascular endothelial cells
  • The relationship between cryptococcal adaptation to azole drugs and azole therapy failure
  • Identification of genes differentially expressed in spores and hyphae upon exposure to human neutrophils
  • Construction of isogenic strains for genetic analysis
  • Pathogenic difference between A. fumigatus and A. nidulans in chronic granulomatous disease (CGD) patients

Program Description

The Molecular Microbiology Section is focused on the pathobiology of Cryptococcus neoformans andAspergillus fumigatus, two of the most common and serious fungal pathogens that primarily affect immunocompromised patients. Both C. neoformans and A. fumigatus are environmental pathogens that cause life-threatening systemic disease upon inhalation. The fatality rate of these diseases is high even if treated with the most effective antimycotic agents currently available.

Cryptococcus neoformans
Cryptococcus neoformans, an environmental yeast species most commonly found in pigeon droppings and soil contaminated with avian guano, is the etiologic agent of cryptococcosis. Cryptococcosis has been recognized as an AIDS-defining disease because the major risk group of the disease is people infected with HIV. Although C. neoformans can cause lesions in almost every organ after being inhaled by the host, the most common clinical manifestation and most common cause of death is meningoencephalitis, an infection of the brain.

Image of Cryptococus neoformans lifecycle
Cryptococus neoformans Lifecycle

Aspergillus fumigatus
Pathogenic Aspergillus species are ubiquitous in our environment, and humans regularly inhale numerous Aspergillus spores (conidia) during daily life. Of those species, Aspergillus fumigatus is known to be the major cause of life-threatening invasive pulmonary aspergillosis (IPA) in immunocompromised patients throughout the world. The major risk for IPA is profound neutropenia and chronic granulomatous diseae (CGD). The Molecular Microbiology Section is currently focused on the genes that are differentially expressed in conidia and hyphae of A. fumigatus upon exposure to neutrophils from normal individuals and those from CGD patients to understand the difference in host/parasite interaction between the two groups. We also constructed an isogenic set of compatible mating type strains by using a pair of super maters. The genomes of this isogenic set are being sequenced and will be used as a tool for genetic analysis.


Dr. Kwon-Chung received her B.S. and M.S. in biology from Ewha Womans University in Seoul, South Korea, prior to receiving a Fulbright Scholarship to pursue her doctoral work in the bacteriology department at the University of Wisconsin, Madison. After receiving her Ph.D., she joined the Medical Mycology Section of the NIAID Laboratory of Microbiology as a visiting fellow. She became a senior investigator in the NIAID Laboratory of Clinical Investigation in 1973 and has been the chief of the Molecular Microbiology Section since 1995.

Research Group

Yun C. Chang, Ph.D.; Ashok Varma, Ph.D; Janyce Sugui, Ph.D.; Edward Sionov, Ph.D.; Arpita Singh, Ph.D.; Ami Kahanal-Lamichhane, M.S.; Tomo Saijo, M.D.

Selected Publications

Sugui JA, Peterson SW, Clark LP, Nardone G, Folio L, Riedlinger G, Zerbe CS, Shea Y, Henderson CM, Zelazny AM, Holland SM, Kwon-Chung KJ. Aspergillus tanneri sp. nov., a new pathogen that causes invasive disease refractory to antifungal therapy. J Clin Microbiol. 2012 Aug 1. Epub ahead of print.

Ngamskulrungroj P, Chang Y, Hansen B, Bugge C, Fischer E, Kwon-Chung KJ. Cryptococcus neoformans Yop1 , an endoplasmic reticulum curvature-stabilizing protein, participates with Sey1 in influencing fluconazole-induced disomy formation. FEMS Yeast Res. 2012 Jun 26. Epub ahead of print.

Ngamskulrungroj P, Chang Y, Sionov E, Kwon-Chung KJ. The primary target organ of Cryptococcus gattii is different from that of Cryptococcus neoformans in a murine model. MBio. 2012 May 8;3(3). pii: e00103-12.

Lee H, Khanal Lamichhane A, Garraffo HM, Kwon-Chung KJ, Chang YC. Involvement of PDK1, PKC and TOR signalling pathways in basal fluconazole tolerance in Cryptococcus neoformans. Mol Microbiol. 2012 Apr;84(1):130-46.

Sionov E, Chang YC, Garraffo HM, Dolan MA, Ghannoum MA, Kwon-Chung KJ. Identification of a Cryptococcus neoformans cytochrome P450 lanosterol 14α-demethylase (Erg11) residue critical for differential susceptibility between fluconazole/voriconazole and itraconazole/posaconazole. Antimicrob Agents Chemother. 2012 Mar;56(3):1162-9.

Sionov E, Lee H, Chang YC, Kwon-Chung KJ. Cryptococcus neoformans overcomes stress of azole drugs by formation of disomy in specific multiple chromosomes. PLoS Pathog. 2010 Apr 1;6(4):e1000848.

View a complete publication listing in PubMed.

Last Updated October 03, 2012

Last Reviewed October 03, 2012