scholarly journals Tetraploidy accelerates adaption under drug-selection in a fungal pathogen

2021 ◽  
Author(s):  
Ognenka Avramovska ◽  
Emily Rego ◽  
Meleah A Hickman
Keyword(s):  
Drug Resistance ◽  
Genome Size ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Antifungal Drug ◽  
Drug Selection ◽  
Antifungal Drug Resistance ◽  
Evolutionary Trajectories ◽  
Work Supports ◽  
Initial Genome

AbstractBaseline ploidy significantly impacts evolutionary trajectories, and in particular, tetraploidy has been associated with higher rates of adaptation compared to haploidy and diploidy. While the majority of experimental evolution studies investigating ploidy use Saccharomyces cerivisiae, the fungal pathogen Candida albicans is a powerful system to investigate ploidy dynamics, particularly in the context of antifungal drug resistance. C. albicans laboratory and clinical strains are predominantly diploid, but have also been isolated as haploid and polyploid. Here, we evolved diploid and tetraploid C. albicans for ∼60 days in the antifungal drug caspofungin. Tetraploid-evolved lines adapted faster than diploid-evolved lines and reached higher levels of caspofungin resistance. While diploid-evolved lines generally maintained their initial genome size, tetraploid-evolved lines rapidly underwent genome-size reductions and did so prior to caspofungin adaption. Furthermore, fitness costs in the absence of drug selection were significantly less in tetraploid-evolved lines compared to the diploid-evolved lines. Taken together, this work supports a model of adaptation in which the tetraploid state is transient but its ability to rapidly transition ploidy states improves adaptative outcomes and may drive drug resistance in fungal pathogens.

scholarly journals Pathogenesis and Antifungal Drug Resistance of the Human Fungal Pathogen Candida glabrata

2011 ◽  
Vol 4 (1) ◽  
pp. 169-186 ◽  
Author(s):  
Michael Tscherner ◽  
Tobias Schwarzmüller ◽  
Karl Kuchler
Keyword(s):  
Drug Resistance ◽  
Fungal Pathogen ◽  
Candida Glabrata ◽  
Antifungal Drug ◽  
Antifungal Drug Resistance ◽  
Human Fungal Pathogen

scholarly journals Candida albicansgenetic background influences mean and heterogeneity of drug responses and genome stability during evolution to fluconazole

2018 ◽  
Author(s):  
Aleeza C. Gerstein ◽  
Judith Berman
Keyword(s):  
Drug Resistance ◽  
Candida Albicans ◽  
Genome Size ◽  
Fungal Pathogen ◽  
Genetic Background ◽  
Antifungal Drug ◽  
Human Fungal Pathogen ◽  
Evolutionary Level ◽  
Ancestral Strain ◽  
Strain Background

AbstractThe importance of within-species diversity in determining the evolutionary potential of a population to evolve drug resistance or tolerance is not well understood, including in eukaryotic pathogens. To examine the influence of genetic background, we evolved replicates of twenty different clinical isolates ofCandida albicans,a human fungal pathogen, in fluconazole, the commonly used antifungal drug. The isolates hailed from the majorC. albicansclades and had different initial levels of drug resistance and tolerance to the drug. The majority of replicates rapidly increased in fitness in the evolutionary environment, with the degree of improvement inversely correlated with ancestral strain fitness in the drug. Improvement was largely restricted to up to the evolutionary level of drug: only 4% of the evolved replicates increased resistance (MIC) above the evolutionary level of drug. Prevalent changes were altered levels of drug tolerance (slow growth of a subpopulation of cells at drug concentrations above the MIC) and increased diversity of genome size. The prevalence and predominant direction of these changes differed in a strain-specific manner but neither correlated directly with ancestral fitness or improvement in fitness. Rather, low ancestral strain fitness was correlated with high levels of heterogeneity in fitness, tolerance, and genome size among evolved replicates. Thus, ancestral strain background is an important determinant in mean improvement to the evolutionary environment as well as the diversity of evolved phenotypes, and the range of possible responses of a pathogen to an antimicrobial drug cannot be captured by in-depth study of a single strain background.ImportanceAntimicrobial resistance is an evolutionary phenomenon with clinical implications. We tested how replicates from diverse strains ofCandida albicans, a prevalent human fungal pathogen, evolve in the commonly-prescribed antifungal drug fluconazole. Replicates on average increased in fitness in the level of drug they were evolved to, with the least fit ancestral strains improving the most. Very few replicates increased resistance above the drug level they were evolved in. Notably, many replicates increased in genome size and changed in drug tolerance (a drug response where a subpopulation of cells grow slowly in high levels of drug) and variability among replicates in fitness, tolerance and genome size was higher in strains that initially were more sensitive to the drug. Genetic background influenced the average degree of adaptation and the evolved variability of many phenotypes, highlighting that different strains from the same species may respond and adapt very differently during adaptation.

scholarly journals Adenylyl Cyclase and Protein Kinase A Play Redundant and Distinct Roles in Growth, Differentiation, Antifungal Drug Resistance, and Pathogenicity of Candida auris

mBio ◽  
2021 ◽  
Author(s):  
Ji-Seok Kim ◽  
Kyung-Tae Lee ◽  
Myung Ha Lee ◽  
Eunji Cheong ◽  
Yong-Sun Bahn
Keyword(s):  
Drug Resistance ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Fungal Pathogen ◽  
Fungal Pathogens ◽  
Antifungal Drugs ◽  
Candida Auris ◽  
Content Type ◽  
Antifungal Drug Resistance ◽  
Kinase A

Despite the recently growing concern of pan-resistant Candida auris infection, the pathogenicity of this ascomycetous fungal pathogen and the signaling circuitries governing its resistance to antifungal drugs are largely unknown. Therefore, we analyzed the pathobiological functions of cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway in C. auris , which plays conserved roles in the growth and virulence of fungal pathogens.

scholarly journals Rampant transposition following RNAi loss causes hypermutation and antifungal drug resistance in clinical isolates of a human fungal pathogen

2021 ◽  
Author(s):  
Shelby Priest ◽  
Vikas Yadav ◽  
Cullen Roth ◽  
Tim Dahlmann ◽  
Ulrich Kueck ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Nonsense Mutation ◽  
Fungal Pathogen ◽  
Genetic Locus ◽  
Antifungal Drugs ◽  
Antifungal Drug ◽  
Gene Encoding ◽  
Antifungal Drug Resistance ◽  
Trait Locus ◽  
Almost All

Abstract Microorganisms survive and compete within their environmental niches and avoid evolutionary stagnation by stochastically acquiring mutations that enhance fitness. Although increased mutation rates are often deleterious in multicellular organisms, hypermutation can be beneficial for microbes in the context of strong selective pressures. To explore how hypermutation arises in nature and elucidate its consequences, we employed a collection of 387 sequenced clinical and environmental isolates of Cryptococcus neoformans. This fungal pathogen is responsible for ~ 15% of annual AIDS-related deaths and is associated with high mortality rates, attributable to a dearth of antifungal drugs and increasing drug resistance. Isolates were screened for the ability to rapidly acquire antifungal drug resistance, and two robust hypermutators were identified. Insertion of the non-LTR Cnl1 retrotransposon was found to be responsible for the majority of drug-resistant isolates. Long-read whole-genome sequencing revealed both hypermutator genomes have two unique features: 1) hundreds of Cnl1 copies organized in subtelomeric arrays on both ends of almost all chromosomes, and 2) a nonsense mutation in the first exon of ZNF3, a gene encoding an RNAi component involved in silencing transposons. Quantitative trait locus mapping identified a significant genetic locus associated with hypermutation that includes the mutant znf3 allele, and CRISPR-mediated genome editing of the znf3 single-base pair nonsense mutation abolished the hypermutation phenotype and restored siRNA production. In sum, hypermutation and drug resistance in these isolates results from loss of RNAi combined with subsequent accumulation of a large genomic burden of a novel transposable element in C. neoformans.

scholarly journals Rampant transposition following RNAi loss causes hypermutation and antifungal drug resistance in clinical isolates of a human fungal pathogen

2021 ◽  
Author(s):  
Shelby J Priest ◽  
Vikas Yadav ◽  
Cullen Roth ◽  
Tim Alexander Dahlmann ◽  
Ulrich Kuck ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Nonsense Mutation ◽  
Fungal Pathogen ◽  
Genetic Locus ◽  
Antifungal Drugs ◽  
Antifungal Drug ◽  
Gene Encoding ◽  
Antifungal Drug Resistance ◽  
Trait Locus ◽  
Almost All

Microorganisms survive and compete within their environmental niches and avoid evolutionary stagnation by stochastically acquiring mutations that enhance fitness. Although increased mutation rates are often deleterious in multicellular organisms, hypermutation can be beneficial for microbes in the context of strong selective pressures. To explore how hypermutation arises in nature and elucidate its consequences, we employed a collection of 387 sequenced clinical and environmental isolates of Cryptococcus neoformans. This fungal pathogen is responsible for ~15% of annual AIDS-related deaths and is associated with high mortality rates, attributable to a dearth of antifungal drugs and increasing drug resistance. Isolates were screened for the ability to rapidly acquire antifungal drug resistance, and two robust hypermutators were identified. Insertion of the non-LTR Cnl1 retrotransposon was found to be responsible for the majority of drug-resistant isolates. Long-read whole-genome sequencing revealed both hypermutator genomes have two unique features: 1) hundreds of Cnl1 copies organized in subtelomeric arrays on both ends of almost all chromosomes, and 2) a nonsense mutation in the first exon of ZNF3, a gene encoding an RNAi component involved in silencing transposons. Quantitative trait locus mapping identified a significant genetic locus associated with hypermutation that includes the mutant znf3 allele, and CRISPR-mediated genome editing of the znf3 single-base pair nonsense mutation abolished the hypermutation phenotype and restored siRNA production. In sum, hypermutation and drug resistance in these isolates results from loss of RNAi combined with subsequent accumulation of a large genomic burden of a novel transposable element in C. neoformans.

scholarly journals Antifungal Innate Immunity: A Perspective from the Last 10 Years

2018 ◽  
Vol 10 (5-6) ◽  
pp. 373-397 ◽  
Author(s):  
Fabián Salazar ◽  
Gordon D. Brown
Keyword(s):  
Drug Resistance ◽  
Innate Immunity ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Antifungal Drug ◽  
Cellular Basis ◽  
Antifungal Drug Resistance ◽  
Life Threatening ◽  
Antifungal Immunity ◽  
New Strategies

Fungal pathogens can rarely cause diseases in immunocompetent individuals. However, commensal and normally nonpathogenic environmental fungi can cause life-threatening infections in immunocompromised individuals. Over the last few decades, there has been a huge increase in the incidence of invasive opportunistic fungal infections along with a worrying increase in antifungal drug resistance. As a consequence, research focused on understanding the molecular and cellular basis of antifungal immunity has expanded tremendously in the last few years. This review will provide an overview of the most exciting recent advances in innate antifungal immunity, discoveries that are helping to pave the way for the development of new strategies that are desperately needed to combat these devastating diseases.

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