Opportunistic infections remain the most important complication of infection with the Human Immunodeficiency Virus (HIV) and the principal cause of death in patients with the Acquired Immune Deficiency Syndrome (AIDS). A large proportion of these patients develop severe oropharyngeal and esophageal candidiasis and treatment with the azole class of anti-fungal drugs such as fluconazole, has led to an increase in the prevalence of azole-resistant Candida strains. Many drug-resistant strains exhibit genetic alterations including changes in chromosome copy number (aneuploidy) and loss of heterozygosity at genes important for drug resistance. Our long-term goal is to understand whether Candida albicans genome instability facilitates its adaptation to stresses encountered in the human host and, if it does, to determine the molecular mechanisms by which it does so. We will use three powerful tools to analyze genetic changes across the entire C. albicans genome will be used: Single Nucleotide Polymorphism (SNP) arrays will monitor loss of heterozygosity events throughout the C. albicans genome; Comparative Genome Hybridization arrays will detect the toss or gain of whole chromosomes or chromosome fragments (aneuploidy); And the counter-selectable GAL1 gene will be used to isolate rare loss of heterozygosity events in vivo and in vitro. Preliminary results indicate that the SNP arrays readily distinguish homozygous and heterozygous genotypes, that the Comparative Genome Hybridization arrays accurately detect increases and decreases in chromosome copy number, that recombination frequency in C. albicans cells is elevated when cells are propagated in vivo and that loss of heterozygosity and/or aneuploidy occurs in strains that exhibit increased levels of drug resistance or increased ability to colonize the host. In this proposal, we will test the hypothesis that C. albicans responds to stresses it encounters in the host and/or when exposed to antifungal drugs with increased levels of aneuploidy and/or loss of heterozygosity. Further, we will ask if specific genome changes provide C. albicans a selective advantage under these stress conditions. We will detect aneuploidy and loss of heterozygosity in fluconazole resistant strains, measure the frequency, rates and types of loss of heterozygosity events that occur, and will identify specific genome segments and genes necessary for fluconazole resistance. Our proposed research has the potential to make two unique contributions. Specific pathogen genotypes that have a higher potential to become drug resistant may be identified, improved strategies for preserving the efficacy of existing antifungal agents through the use of companion drugs or therapies may be discovered.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI062427-03
Application #
7196419
Study Section
AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
Program Officer
Duncan, Rory A
Project Start
2005-06-01
Project End
2010-02-28
Budget Start
2007-03-01
Budget End
2008-02-29
Support Year
3
Fiscal Year
2007
Total Cost
$348,600
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Genetics
Type
Schools of Medicine
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
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Gerstein, Aleeza C; Berman, Judith (2015) Shift and adapt: the costs and benefits of karyotype variations. Curr Opin Microbiol 26:130-6
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Hickman, Meleah A; Zeng, Guisheng; Forche, Anja et al. (2013) The 'obligate diploid' Candida albicans forms mating-competent haploids. Nature 494:55-9
Berman, Judith; Hadany, Lilach (2012) Does stress induce (para)sex? Implications for Candida albicans evolution. Trends Genet 28:197-203
Berman, Judith (2012) Candida albicans. Curr Biol 22:R620-2
Gerami-Nejad, Maryam; Forche, Anja; McClellan, Mark et al. (2012) Analysis of protein function in clinical C. albicans isolates. Yeast 29:303-9
Abbey, Darren; Hickman, Meleah; Gresham, David et al. (2011) High-Resolution SNP/CGH Microarrays Reveal the Accumulation of Loss of Heterozygosity in Commonly Used Candida albicans Strains. G3 (Bethesda) 1:523-30
Forche, A; Abbey, D; Pisithkul, T et al. (2011) Stress alters rates and types of loss of heterozygosity in Candida albicans. MBio 2:

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