Suchergebnisse

Invasive candidiasis is the most commonly reported invasive fungal infection worldwide. Although Candida albicans remains the main cause, the incidence of emerging Candida species, such as C. parapsilosis is increasing. It has been postulated that C. parapsilosis clinical isolates result from a recent global expansion of a virulent clone. However, the availability of a single genome for this species has so far prevented testing this hypothesis at genomic scales. We present here the sequence of three additional strains from clinical and environmental samples. Our analyses reveal unexpected patterns of genomic variation, shared among distant strains, that argue against the clonal expansion hypothesis. All strains carry independent expansions involving an arsenite transporter homolog, pointing to the existence of directional selection in the environment, and independent origins of the two clinical isolates. Furthermore, we report the first evidence for the existence of recombination in this species. Altogether, our results shed new light onto the dynamics of genome evolution in C. parapsilosis. ; This work was supported by the La Caixa-CRG International Fellowship Program to L.P., the TAMOP 4.2.4. A/2-11-1-2012-001 "National Excellence Program" to T.N., and was supported in part by OTKA NF 84006, NN00374 (ERA-Net/nPathoGenomics Program), EMBO Installation Grant and by the Janos Bolyai Fellowship of the Hungarian Academy of Sciences to A.G. T.G. group research is funded in part by a grant from the Spanish Ministry of Economy and Competitiveness (BIO2012-37161), a grant from the Qatar National Research Fund grant (NPRP 5-298-3-086), and a grant from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC (grant agreement no. ERC-/n2012-StG-310325)

Invasive candidiasis is the most commonly reported invasive fungal infection worldwide. Although Candida albicans remains the main cause, the incidence of emerging Candida species, such as C. parapsilosis is increasing. It has been postulated that C. parapsilosis clinical isolates result from a recent global expansion of a virulent clone. However, the availability of a single genome for this species has so far prevented testing this hypothesis at genomic scales. We present here the sequence of three additional strains from clinical and environmental samples. Our analyses reveal unexpected patterns of genomic variation, shared among distant strains, that argue against the clonal expansion hypothesis. All strains carry independent expansions involving an arsenite transporter homolog, pointing to the existence of directional selection in the environment, and independent origins of the two clinical isolates. Furthermore, we report the first evidence for the existence of recombination in this species. Altogether, our results shed new light onto the dynamics of genome evolution in C. parapsilosis. ; This work was supported by the La Caixa-CRG International Fellowship Program to L.P., the TÁMOP 4.2.4. A/2-11-1-2012-001 "National Excellence Program" to T.N., and was supported in part by OTKA NF 84006, NN00374 (ERA-Net PathoGenomics Program), EMBO Installation Grant and by the Janos Bolyai Fellowship of the Hungarian Academy of Sciences to A.G. T.G. group research is funded in part by a grant from the Spanish Ministry of Economy and Competitiveness (BIO2012-37161), a grant from the Qatar National Research Fund grant (NPRP 5-298-3-086), and a grant from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC (grant agreement no. ERC-2012-StG-310325)

The Candida parapsilosis species complex comprises a group of emerging human pathogens of varying virulence. This complex was recently subdivided into three different species: C. parapsilosis sensu stricto, C. metapsilosis, and C. orthopsilosis. Within the latter, at least two clearly distinct subspecies seem to be present among clinical isolates (Type 1 and Type 2). To gain insight into the genomic differences between these subspecies, we undertook the sequencing of a clinical isolate classified as Type 1 and compared it with the available sequence of a Type 2 clinical strain. Unexpectedly, the analysis of the newly sequenced strain revealed a highly heterozygous genome, which we show to be the consequence of a hybridization event between both identified subspecies. This implicitly suggests that C. orthopsilosis is able to mate, a so-far unanswered question. The resulting hybrid shows a chimeric genome that maintains a similar gene dosage from both parental lineages and displays ongoing loss of heterozygosity. Several of the differences found between the gene content in both strains relate to virulent-related families, with the hybrid strain presenting a higher copy number of genes coding for efflux pumps or secreted lipases. Remarkably, two clinical strains isolated from distant geographical locations (Texas and Singapore) are descendants of the same hybrid line, raising the intriguing possibility of a relationship between the hybridization event and the global spread of a virulent clone. ; This work was supported in part by a grant from the Spanish ministry of Economy and Competitiveness (BIO2012-37161), a Grant from the Qatar National Research Fund grant (NPRP 5-/n298-3-086), and a grant from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC (Grant Agreement No. ERC-2012-StG-310325) to T.G.; by La Caixa-CRG International Fellowship Program to L.P.P.; by the TA´ MOP 4.2.4. A/2-11-1-2012-001/n"National Excellence Program" to T.N.; in part by OTKA NF 84006, NN00374 (ERA-Net PathoGenomics Program), EMBO Installation Grant, and the Janos Bolyai Fellowship of the/nHungarian Academy of Sciences to A.G.

Invasive candidiasis is among the most life-threatening infections in patients in intensive care units. Although Candida albicans is the leading cause of candidaemia, the incidence of Candida parapsilosis infections is also rising, particularly among the neonates. Due to differences in their biology, these species employ different antifungal resistance and virulence mechanisms and also induce dissimilar immune responses. Previously, it has been suggested that core virulence effecting transcription regulators could be attractive ligands for future antifungal drugs. Although the virulence regulatory mechanisms of C. albicans are well studied, less is known about similar mechanisms in C. parapsilosis. In order to search for potential targets for future antifungal drugs against this species, we analyzed the fungal transcriptome during host-pathogen interaction using an in vitro infection model. Selected genes with high expression levels were further examined through their respective null mutant strains, under conditions that mimic the host environment or influence pathogenicity. As a result, we identified several mutants with relevant pathogenicity affecting phenotypes. During the study we highlight three potentially tractable signaling regulators that influence C. parapsilosis pathogenicity in distinct mechanisms. During infection, CPAR2_100540 is responsible for nutrient acquisition, CPAR2_200390 for cell wall assembly and morphology switching and CPAR2_303700 for fungal viability. ; The project was subsidized by the European Union and co-financed by the European Social Fund. AG was funded by NKFIH NN 113153, by GINOP-2.3.2-15-2016-00035, by GINOP-2.3.3-15-2016-00006. AG and LN were also founded by CNPq (Program Science without borders - 407380/2013-2). TN was supported by the Postdoctoral Fellowship by the Hungarian Academy of Sciences. Research at TG lab was partially funded by grants from Spanish Ministry of Economy and Competitiveness BFU2015-67107 cofounded by European Regional Development Fund (ERDF); from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreements FP7-PEOPLE-2013-ITN-606786 "ImResFun" and from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No H2020-MSCA-ITN-2014-642095. JDN is partially supported by US NIH grants R21 AI124797-02 and AI52733-06A2. We would like to thank Prof. Geraldine Butler for the KO strategy and parental strains necessary for mutant strain generation. We would like to thank Chetna Tyagi for the help with the in silico data analyses, Mónika Homolya for contributing to the chitinase and chitin synthase expression experiments, Dr. Sándor Kocsubé for the summary table and Tamás Petkovits for the help with the SEM experiments.