Ilse Jacobsen - Academia.edu (original) (raw)
Papers by Ilse Jacobsen
PLoS genetics, 2014
Lichtheimia species are the second most important cause of mucormycosis in Europe. To provide bro... more Lichtheimia species are the second most important cause of mucormycosis in Europe. To provide broader insights into the molecular basis of the pathogenicity-associated traits of the basal Mucorales, we report the full genome sequence of L. corymbifera and compared it to the genome of Rhizopus oryzae, the most common cause of mucormycosis worldwide. The genome assembly encompasses 33.6 MB and 12,379 protein-coding genes. This study reveals four major differences of the L. corymbifera genome to R. oryzae: (i) the presence of an highly elevated number of gene duplications which are unlike R. oryzae not due to whole genome duplication (WGD), (ii) despite the relatively high incidence of introns, alternative splicing (AS) is not frequently observed for the generation of paralogs and in response to stress, (iii) the content of repetitive elements is strikingly low (<5%), (iv) L. corymbifera is typically haploid. Novel virulence factors were identified which may be involved in the regul...
Iron is essential for a wide range of cellular processes. Here we show that the bZIP-type regulat... more Iron is essential for a wide range of cellular processes. Here we show that the bZIP-type regulator HapX is indispensable for
the transcriptional remodeling required for adaption to iron starvation in the opportunistic fungal pathogen Aspergillus
fumigatus. HapX represses iron-dependent and mitochondrial-localized activities including respiration, TCA cycle, amino
acid metabolism, iron-sulfur-cluster and heme biosynthesis. In agreement with the impact on mitochondrial metabolism,
HapX-deficiency decreases resistance to tetracycline and increases mitochondrial DNA content. Pathways positively affected by HapX include production of the ribotoxin AspF1 and siderophores, which are known virulence determinants. Iron
starvation causes a massive remodeling of the amino acid pool and HapX is essential for the coordination of the production
of siderophores and their precursor ornithine. Consistent with HapX-function being limited to iron depleted conditions and
A. fumigatus facing iron starvation in the host, HapX-deficiency causes significant attenuation of virulence in a murine model
of aspergillosis. Taken together, this study demonstrates that HapX-dependent adaption to conditions of iron starvation is
crucial for virulence of A. fumigatus.
Cellular microbiology, Jan 7, 2015
Candida albicans and Candida glabrata account for the majority of candidiasis cases worldwide. Al... more Candida albicans and Candida glabrata account for the majority of candidiasis cases worldwide. Although both species are in the same genus, they differ in key virulence attributes. Within this work, live cell imaging was used to examine the dynamics of neutrophil activation after confrontation with either C. albicans or C. glabrata. Analyses revealed higher phagocytosis rates of C. albicans than C. glabrata that resulted in stronger PMN activation by C. albicans. Furthermore, we observed differences in the secretion of chemokines, indicating chemotactic differences in PMN signaling towards recruitment of further immune cells upon confrontation with Candida spp. Supernatants from co-incubations of neutrophils with C. glabrata primarily attracted monocytes and increased the phagocytosis of C. glabrata by monocytes. In contrast, PMN activation by C. albicans resulted in recruitment of more neutrophils. Two complex infection models confirmed distinct targeting of immune cell populations...
FEMS Yeast Research, 2009
PLoS genetics, 2014
Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo mi... more Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo microevolution, which leads to the emergence of drug resistance. However, the capacity for microevolutionary adaptation of fungi goes beyond the development of resistance against antifungals. Here we used an experimental microevolution approach to show that one of the central pathogenicity mechanisms of C. albicans, the yeast-to-hyphae transition, can be subject to experimental evolution. The C. albicans cph1Δ/efg1Δ mutant is nonfilamentous, as central signaling pathways linking environmental cues to hyphal formation are disrupted. We subjected this mutant to constant selection pressure in the hostile environment of the macrophage phagosome. In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation. In addition, the evolved mutant exhibited hyper-virulence in a murine infection model and an altered cell wall composition compared to the cph1Δ...
Zygomycetes of the order Mucorales can cause life-threatening infections in humans. These mucormy... more Zygomycetes of the order Mucorales can cause life-threatening infections in humans. These mucormycoses are emerging and associated with a rapid tissue destruction and high mortality. The resistance of Mucorales to antimycotic substances varies between and within clinically important genera such as Mucor, Rhizopus, and Lichtheimia. Thus, an accurate diagnosis before onset of antimycotic therapy is recommended. Matrix-assisted laser desorption ionization
Eukaryotic Cell, 2015
The supply and intracellular homeostasis of trace metals are essential for every living organism.... more The supply and intracellular homeostasis of trace metals are essential for every living organism. Therefore, the struggle for micronutrients between a pathogen and its host is an important determinant in the infection process. In this work, we focus on the acquisition of zinc by Candida dubliniensis, an emerging pathogen closely related to C. albicans. We show that the transcription factor Csr1 is essential for C. dubliniensis to regulate zinc uptake mechanisms under zinc limitation: It governs the expression of the zinc transporter genes ZRT1, ZRT2, ZRT3 and of the zincophore gene PRA1. Exclusively, artificial overexpression of ZRT2 partially rescued the growth defect of a csr1Δ/Δ mutant in a zinc-restricted environment. Importantly, we found that, in contrast to C. albicans, Csr1 (aka Zap1) is not a major regulator of dimorphism in C. dubliniensis. However, although a csr1Δ/Δ strain showed normal germ tube formation, we detected a clear attenuation in virulence using an embryonated chicken egg infection model. We conclude that, unlike in C. albicans, Csr1 seems to be a virulence factor of C. dubliniensis that is not coupled to filamentation, but is strongly linked to zinc acquisition during pathogenesis.
Disease models & mechanisms, Jan 18, 2015
Studying infectious diseases requires suitable hosts for experimental in vivo infections. Recent ... more Studying infectious diseases requires suitable hosts for experimental in vivo infections. Recent years have seen the advent of many alternatives to murine infection models. However, the use of non-mammalian models is still controversial, as it is often unclear how well findings from these systems predict virulence potential in humans or other mammals. Here we compare the commonly used models, fruit fly and mouse (representing invertebrate and mammalian hosts) for their similarities and degree of correlation upon infection with a library of mutants of an important fungal pathogen, the yeast Candida glabrata. Using two indices, for fly survival time and for mouse fungal burden in specific organs, we show a good agreement between the models. We provide a suitable predictive model for estimating the virulence potential of mutants in the mouse from fly survival data. As examples, we found cell wall integrity mutants attenuated in flies and mutants of a MAP kinase pathway defective in bot...
The Journal of antimicrobial chemotherapy, 2014
Candida albicans is an important fungal pathogen that can cause life-threatening disseminated inf... more Candida albicans is an important fungal pathogen that can cause life-threatening disseminated infections. To determine the efficacy of therapy in murine models, a determination of renal fungal burden as cfu is commonly used. However, this approach provides only a snapshot of the current situation in an individual animal and cryptic sites of infection may easily be missed. Thus, we aimed to develop real-time non-invasive imaging to monitor infection in vivo. Bioluminescent C. albicans reporter strains were developed based on a bioinformatical approach for codon optimization. The reporter strains were analysed in vitro and in vivo in the murine model of systemic candidiasis. Reporter strains allowed the in vivo monitoring of infection and a determination of fungal burden, with a high correlation between bioluminescence and cfu count. We confirmed the kidney as the main target organ but additionally observed the translocation of C. albicans to the urinary bladder. The treatment of infe...
Berliner und Münchener tierärztliche Wochenschrift
For vaccine licensing data about efficiency and duration of protection are essential. Within the ... more For vaccine licensing data about efficiency and duration of protection are essential. Within the scope of the developement of a new subunit vaccine against Actinobacillus pleuropneumoniae (A.pp.) the protective efficiency over the whole length of the fattening period must be proven. This required infection experiments in finishing pigs. Eight pigs in the age of six months were infected experimentally into the trachea with an A.pp. serotyp 2 strain. To our knowledge data about the susceptibility of pigs of this age do not exist, so that the infectious dose for pigs of this age and this route of infection had to be determined. Two pigs each were infected with different doses of 10(10), 6 x 10(5), 8 x 10(3) and 2 x 10(3) CFU (colony forming units). The aim of the study was to produce a typical pleuropneumonia with fever and severe respiratory symptoms as well as characteristic pathomorphological lung alterations without loss of animals during the acute stage of infection. The pathogen ...
Infection and immunity, 2005
Actinobacillus pleuropneumoniae, the etiological agent of porcine pleuropneumonia, is able to sur... more Actinobacillus pleuropneumoniae, the etiological agent of porcine pleuropneumonia, is able to survive on respiratory epithelia, in tonsils, and in the anaerobic environment of encapsulated sequesters. It was previously demonstrated that a deletion of the anaerobic dimethyl sulfoxide reductase gene (dmsA) results in attenuation in acute disease (N. Baltes, S. Kyaw, I. Hennig-Pauka, and G. F. Gerlach, Infect. Immun. 71:6784-6792, 2003). In the present study, using two-dimensional polyacrylamide gel electrophoresis and quadrupole time-of-flight mass spectrometry, we identified an aspartate ammonia-lyase (AspA) which is upregulated upon induction with bronchoalveolar lavage fluid (BALF). This enzyme is involved in the production of fumarate, an alternative electron acceptor under anaerobic conditions. The coding gene (aspA) was cloned and shown to be present in all A. pleuropneumoniae serotype reference strains. The transcriptional start point was identified downstream of a putative FNR...
Infection and immunity, 2003
Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is capable of pe... more Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is capable of persisting in oxygen-deprived surroundings, namely, tonsils and sequestered necrotic lung tissue. Utilization of alternative terminal electron acceptors in the absence of oxygen is a common strategy in bacteria under anaerobic growth conditions. In an experiment aimed at identification of genes expressed in vivo, the putative catalytic subunit DmsA of anaerobic dimethyl sulfoxide reductase was identified in an A. pleuropneumoniae serotype 7 strain. The 90-kDa protein exhibits 85% identity to the putative DmsA protein of Haemophilus influenzae, and its expression was found to be upregulated under anaerobic conditions. Analysis of the unfinished A. pleuropneumoniae genome sequence revealed putative open reading frames (ORFs) encoding DmsB and DmsC proteins situated downstream of the dmsA ORF. In order to investigate the role of the A. pleuropneumoniae DmsA protein in virulence, an isogenic d...
Expert Review of Anti-infective Therapy, 2014
PLoS genetics, 2014
Lichtheimia species are the second most important cause of mucormycosis in Europe. To provide bro... more Lichtheimia species are the second most important cause of mucormycosis in Europe. To provide broader insights into the molecular basis of the pathogenicity-associated traits of the basal Mucorales, we report the full genome sequence of L. corymbifera and compared it to the genome of Rhizopus oryzae, the most common cause of mucormycosis worldwide. The genome assembly encompasses 33.6 MB and 12,379 protein-coding genes. This study reveals four major differences of the L. corymbifera genome to R. oryzae: (i) the presence of an highly elevated number of gene duplications which are unlike R. oryzae not due to whole genome duplication (WGD), (ii) despite the relatively high incidence of introns, alternative splicing (AS) is not frequently observed for the generation of paralogs and in response to stress, (iii) the content of repetitive elements is strikingly low (<5%), (iv) L. corymbifera is typically haploid. Novel virulence factors were identified which may be involved in the regul...
Iron is essential for a wide range of cellular processes. Here we show that the bZIP-type regulat... more Iron is essential for a wide range of cellular processes. Here we show that the bZIP-type regulator HapX is indispensable for
the transcriptional remodeling required for adaption to iron starvation in the opportunistic fungal pathogen Aspergillus
fumigatus. HapX represses iron-dependent and mitochondrial-localized activities including respiration, TCA cycle, amino
acid metabolism, iron-sulfur-cluster and heme biosynthesis. In agreement with the impact on mitochondrial metabolism,
HapX-deficiency decreases resistance to tetracycline and increases mitochondrial DNA content. Pathways positively affected by HapX include production of the ribotoxin AspF1 and siderophores, which are known virulence determinants. Iron
starvation causes a massive remodeling of the amino acid pool and HapX is essential for the coordination of the production
of siderophores and their precursor ornithine. Consistent with HapX-function being limited to iron depleted conditions and
A. fumigatus facing iron starvation in the host, HapX-deficiency causes significant attenuation of virulence in a murine model
of aspergillosis. Taken together, this study demonstrates that HapX-dependent adaption to conditions of iron starvation is
crucial for virulence of A. fumigatus.
Cellular microbiology, Jan 7, 2015
Candida albicans and Candida glabrata account for the majority of candidiasis cases worldwide. Al... more Candida albicans and Candida glabrata account for the majority of candidiasis cases worldwide. Although both species are in the same genus, they differ in key virulence attributes. Within this work, live cell imaging was used to examine the dynamics of neutrophil activation after confrontation with either C. albicans or C. glabrata. Analyses revealed higher phagocytosis rates of C. albicans than C. glabrata that resulted in stronger PMN activation by C. albicans. Furthermore, we observed differences in the secretion of chemokines, indicating chemotactic differences in PMN signaling towards recruitment of further immune cells upon confrontation with Candida spp. Supernatants from co-incubations of neutrophils with C. glabrata primarily attracted monocytes and increased the phagocytosis of C. glabrata by monocytes. In contrast, PMN activation by C. albicans resulted in recruitment of more neutrophils. Two complex infection models confirmed distinct targeting of immune cell populations...
FEMS Yeast Research, 2009
PLoS genetics, 2014
Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo mi... more Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo microevolution, which leads to the emergence of drug resistance. However, the capacity for microevolutionary adaptation of fungi goes beyond the development of resistance against antifungals. Here we used an experimental microevolution approach to show that one of the central pathogenicity mechanisms of C. albicans, the yeast-to-hyphae transition, can be subject to experimental evolution. The C. albicans cph1Δ/efg1Δ mutant is nonfilamentous, as central signaling pathways linking environmental cues to hyphal formation are disrupted. We subjected this mutant to constant selection pressure in the hostile environment of the macrophage phagosome. In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation. In addition, the evolved mutant exhibited hyper-virulence in a murine infection model and an altered cell wall composition compared to the cph1Δ...
Zygomycetes of the order Mucorales can cause life-threatening infections in humans. These mucormy... more Zygomycetes of the order Mucorales can cause life-threatening infections in humans. These mucormycoses are emerging and associated with a rapid tissue destruction and high mortality. The resistance of Mucorales to antimycotic substances varies between and within clinically important genera such as Mucor, Rhizopus, and Lichtheimia. Thus, an accurate diagnosis before onset of antimycotic therapy is recommended. Matrix-assisted laser desorption ionization
Eukaryotic Cell, 2015
The supply and intracellular homeostasis of trace metals are essential for every living organism.... more The supply and intracellular homeostasis of trace metals are essential for every living organism. Therefore, the struggle for micronutrients between a pathogen and its host is an important determinant in the infection process. In this work, we focus on the acquisition of zinc by Candida dubliniensis, an emerging pathogen closely related to C. albicans. We show that the transcription factor Csr1 is essential for C. dubliniensis to regulate zinc uptake mechanisms under zinc limitation: It governs the expression of the zinc transporter genes ZRT1, ZRT2, ZRT3 and of the zincophore gene PRA1. Exclusively, artificial overexpression of ZRT2 partially rescued the growth defect of a csr1Δ/Δ mutant in a zinc-restricted environment. Importantly, we found that, in contrast to C. albicans, Csr1 (aka Zap1) is not a major regulator of dimorphism in C. dubliniensis. However, although a csr1Δ/Δ strain showed normal germ tube formation, we detected a clear attenuation in virulence using an embryonated chicken egg infection model. We conclude that, unlike in C. albicans, Csr1 seems to be a virulence factor of C. dubliniensis that is not coupled to filamentation, but is strongly linked to zinc acquisition during pathogenesis.
Disease models & mechanisms, Jan 18, 2015
Studying infectious diseases requires suitable hosts for experimental in vivo infections. Recent ... more Studying infectious diseases requires suitable hosts for experimental in vivo infections. Recent years have seen the advent of many alternatives to murine infection models. However, the use of non-mammalian models is still controversial, as it is often unclear how well findings from these systems predict virulence potential in humans or other mammals. Here we compare the commonly used models, fruit fly and mouse (representing invertebrate and mammalian hosts) for their similarities and degree of correlation upon infection with a library of mutants of an important fungal pathogen, the yeast Candida glabrata. Using two indices, for fly survival time and for mouse fungal burden in specific organs, we show a good agreement between the models. We provide a suitable predictive model for estimating the virulence potential of mutants in the mouse from fly survival data. As examples, we found cell wall integrity mutants attenuated in flies and mutants of a MAP kinase pathway defective in bot...
The Journal of antimicrobial chemotherapy, 2014
Candida albicans is an important fungal pathogen that can cause life-threatening disseminated inf... more Candida albicans is an important fungal pathogen that can cause life-threatening disseminated infections. To determine the efficacy of therapy in murine models, a determination of renal fungal burden as cfu is commonly used. However, this approach provides only a snapshot of the current situation in an individual animal and cryptic sites of infection may easily be missed. Thus, we aimed to develop real-time non-invasive imaging to monitor infection in vivo. Bioluminescent C. albicans reporter strains were developed based on a bioinformatical approach for codon optimization. The reporter strains were analysed in vitro and in vivo in the murine model of systemic candidiasis. Reporter strains allowed the in vivo monitoring of infection and a determination of fungal burden, with a high correlation between bioluminescence and cfu count. We confirmed the kidney as the main target organ but additionally observed the translocation of C. albicans to the urinary bladder. The treatment of infe...
Berliner und Münchener tierärztliche Wochenschrift
For vaccine licensing data about efficiency and duration of protection are essential. Within the ... more For vaccine licensing data about efficiency and duration of protection are essential. Within the scope of the developement of a new subunit vaccine against Actinobacillus pleuropneumoniae (A.pp.) the protective efficiency over the whole length of the fattening period must be proven. This required infection experiments in finishing pigs. Eight pigs in the age of six months were infected experimentally into the trachea with an A.pp. serotyp 2 strain. To our knowledge data about the susceptibility of pigs of this age do not exist, so that the infectious dose for pigs of this age and this route of infection had to be determined. Two pigs each were infected with different doses of 10(10), 6 x 10(5), 8 x 10(3) and 2 x 10(3) CFU (colony forming units). The aim of the study was to produce a typical pleuropneumonia with fever and severe respiratory symptoms as well as characteristic pathomorphological lung alterations without loss of animals during the acute stage of infection. The pathogen ...
Infection and immunity, 2005
Actinobacillus pleuropneumoniae, the etiological agent of porcine pleuropneumonia, is able to sur... more Actinobacillus pleuropneumoniae, the etiological agent of porcine pleuropneumonia, is able to survive on respiratory epithelia, in tonsils, and in the anaerobic environment of encapsulated sequesters. It was previously demonstrated that a deletion of the anaerobic dimethyl sulfoxide reductase gene (dmsA) results in attenuation in acute disease (N. Baltes, S. Kyaw, I. Hennig-Pauka, and G. F. Gerlach, Infect. Immun. 71:6784-6792, 2003). In the present study, using two-dimensional polyacrylamide gel electrophoresis and quadrupole time-of-flight mass spectrometry, we identified an aspartate ammonia-lyase (AspA) which is upregulated upon induction with bronchoalveolar lavage fluid (BALF). This enzyme is involved in the production of fumarate, an alternative electron acceptor under anaerobic conditions. The coding gene (aspA) was cloned and shown to be present in all A. pleuropneumoniae serotype reference strains. The transcriptional start point was identified downstream of a putative FNR...
Infection and immunity, 2003
Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is capable of pe... more Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is capable of persisting in oxygen-deprived surroundings, namely, tonsils and sequestered necrotic lung tissue. Utilization of alternative terminal electron acceptors in the absence of oxygen is a common strategy in bacteria under anaerobic growth conditions. In an experiment aimed at identification of genes expressed in vivo, the putative catalytic subunit DmsA of anaerobic dimethyl sulfoxide reductase was identified in an A. pleuropneumoniae serotype 7 strain. The 90-kDa protein exhibits 85% identity to the putative DmsA protein of Haemophilus influenzae, and its expression was found to be upregulated under anaerobic conditions. Analysis of the unfinished A. pleuropneumoniae genome sequence revealed putative open reading frames (ORFs) encoding DmsB and DmsC proteins situated downstream of the dmsA ORF. In order to investigate the role of the A. pleuropneumoniae DmsA protein in virulence, an isogenic d...
Expert Review of Anti-infective Therapy, 2014