Correction: Molecular detection of airborne Emergomyces africanus, a thermally dimorphic fungal pathogen, in Cape Town, South Africa.
Ontology highlight
ABSTRACT:
SUBMITTER: PLOS Neglected Tropical Diseases Staff
PROVIDER: S-EPMC5931619 | biostudies-literature | 2018 May
REPOSITORIES: biostudies-literature
Publications
Correction: Molecular detection of airborne Emergomyces africanus, a thermally dimorphic fungal pathogen, in Cape Town, South Africa.
PLoS neglected tropical diseases 20180502 5
[This corrects the article DOI: 10.1371/journal.pntd.0006174.]. ...[more]
Similar Datasets
Project description:Emergomyces africanus is a thermally dimorphic fungus that causes a systemic mycosis in immunocompromised persons in South Africa. Infection is presumed to follow inhalation of airborne propagules. We developed a quantitative PCR protocol able to detect as few as 5 Es. africanus propagules per day. Samples were collected in Cape Town, South Africa over 50 weeks by a Burkard spore trap with an alternate orifice. We detected Es. africanus in air samples from 34 days (10%) distributed over 11 weeks. These results suggest environmental exposure to airborne Es. africanus propagules occurs more commonly in endemic areas than previously appreciated.
| S-EPMC5800596 | biostudies-literature
Project description:We detected Emergomyces africanus, a thermally dimorphic fungus that causes an HIV-associated systemic mycosis, by PCR in 18 (30%) of 60 soil samples from a wide range of habitats in South Africa. Direct and indirect culture techniques were unsuccessful. Experimental intraperitoneal inoculation of conidia induced murine disease.
| S-EPMC5782882 | biostudies-other
Project description:Coccidioides spp. are mammalian fungal pathogens endemic to the Southwestern US and other desert regions of Mexico, Central and South America, with the bulk of US infections occurring in California and Arizona. In the soil, Coccidioides grows in a hyphal form that differentiates into 3-5 micron asexual spores (arthroconidia). When arthroconidia are inhaled by mammals they undergo a unique developmental transition from polar hyphal growth to isotropic expansion with multiple rounds of nuclear division, prior to segmentation, forming large spherules filled with endospores. Very little is understood about the molecular basis of spherule formation. Here we characterize the role of the conserved transcription factor Ryp1 in Coccidioides development. We show that Coccidioides Δryp1 mutants have altered colony morphology under hypha-promoting conditions and are unable to form mature spherules under spherule-promoting conditions. We analyze the transcriptional profile of wild-type and Δryp1 mutant cells under hypha- and spherule-promoting conditions, thereby defining a set of hypha- or spherule-enriched transcripts ("morphology-regulated" genes) that are dependent on Ryp1 for their expression. Forty percent of morphology-regulated expression is Ryp1-dependent, indicating that Ryp1 plays a dual role in both hyphal and spherule development. Ryp1-dependent transcripts include key virulence factors such as SOWgp, which encodes the spherule outer wall glycoprotein. Concordant with its role in spherule development, we find that the Δryp1 mutant is completely avirulent in the mouse model of coccidioidomycosis, indicating that Ryp1-dependent pathways are essential for the ability of Coccidioides to cause disease. Vaccination of C57BL/6 mice with live Δryp1 spores does not provide any protection from lethal C. posadasii intranasal infection, consistent with our findings that the Δryp1 mutant fails to make mature spherules and likely does not express key antigens required for effective vaccination. Taken together, this work identifies the first transcription factor that drives mature spherulation and virulence in Coccidioides.
| S-EPMC9015156 | biostudies-literature
Project description:Coccidioides spp. are fungal pathogens endemic to Southern California, Arizona, and other desert regions where they cause a spectrum of symptoms known as Valley Fever in otherwise healthy individuals. In the soil, Coccidioides grows in a hyphal form that produces vegetative spores (arthroconidia). When arthroconidia are inhaled by mammals they undergo an elaborate developmental transition consisting of germination, multiple rounds of nuclear division, and segmentation to form large spherules filled with vegetative endospores. Very little is understood about the molecular basis of spherule formation. Here we characterize the role of the conserved transcription factor Ryp1 in Coccidioides spherule formation. We show that Coccidioides ryp1 mutants are unable to form mature spherules, instead arresting at an early stage of spherulation. We analyze the transcriptional profile of wild-type and Δryp1 mutant cells under hyphal and spherule-promoting conditions, thereby defining a set of hyphal- or spherule-enriched transcripts that are dependent on Ryp1 for their expression. Ryp1-dependent transcripts include key virulence factors such as SOWgp, which encodes the spherule outer wall glycoprotein. In the mouse model of coccidioidomycosis, we find that the Δryp1 mutant is completely avirulent, indicating that Ryp1-dependent pathways are essential for the ability of Coccidioides to cause disease. Vaccination of C57BL/6 mice with live Δryp1 spores does not provide any protection from lethal C. posadasii intranasal infection, consistent with our findings that the Δryp1 mutant fails to make mature spherules. Taken together, this work identifies the first transcriptional regulator that drives mature spherulation and virulence in Coccidioides.
2022-03-03 | GSE178277 | GEO
Project description:In South Africa, young people's "multiple" or "concurrent" partnerships have been increasingly prominent in public health discourses - as drivers of HIV transmission. Multiple partnerships are typically framed in moralising, negative terms and depicted primarily as male-driven, within a broader framework of women's vulnerability and use of sex for survival and material gain. Based on ethnographic fieldwork with adolescents and young adults in Khayelitsha township near Cape Town, this article investigates young women's partnerships by exploring their complex interpersonal and social dynamics. We unpack women's multiple motivations for, and careful management strategies of, both sexual and social relationships in a broader context of socioeconomic exclusion, threats to health and wellbeing, social obligations and relationships of care. The meanings and practices associated with young people's relationships are more than the sum of individual sexual behaviours, rigid cultural scripts or simply a locus of "risk." The data presented here highlight some of the limitations of "prevention" approaches that do not take into account this nuanced and multilayered view of such relationships. The affective and empathetic dimensions of young peoples' relationships, as well as the socioeconomic contexts in which they occur should also be considered. Without accounting for this context, standard "prevention" approaches are less likely to succeed.
| S-EPMC5371405 | biostudies-other
Project description:During infection, pathogens must utilise the available nutrient sources in order to grow while simultaneously evading or tolerating the host's defence systems. Amino acids are an important nutritional source for pathogenic fungi and can be assimilated from host proteins to provide both carbon and nitrogen. The hpdA gene of the dimorphic fungus Penicillium marneffei, which encodes an enzyme which catalyses the second step of tyrosine catabolism, was identified as up-regulated in pathogenic yeast cells. As well as enabling the fungus to acquire carbon and nitrogen, tyrosine is also a precursor in the formation of two types of protective melanin; DOPA melanin and pyomelanin. Chemical inhibition of HpdA in P. marneffei inhibits ex vivo yeast cell production suggesting that tyrosine is a key nutrient source during infectious growth. The genes required for tyrosine catabolism, including hpdA, are located in a gene cluster and the expression of these genes is induced in the presence of tyrosine. A gene (hmgR) encoding a Zn(II)2-Cys6 binuclear cluster transcription factor is present within the cluster and is required for tyrosine induced expression and repression in the presence of a preferred nitrogen source. AreA, the GATA-type transcription factor which regulates the global response to limiting nitrogen conditions negatively regulates expression of cluster genes in the absence of tyrosine and is required for nitrogen metabolite repression. Deletion of the tyrosine catabolic genes in the cluster affects growth on tyrosine as either a nitrogen or carbon source and affects pyomelanin, but not DOPA melanin, production. In contrast to other genes of the tyrosine catabolic cluster, deletion of hpdA results in no growth within macrophages. This suggests that the ability to catabolise tyrosine is not required for macrophage infection and that HpdA has an additional novel role to that of tyrosine catabolism and pyomelanin production during growth in host cells.
| S-EPMC4374905 | biostudies-literature
Project description:Emergomyces africanus strain:CBS 136260 Genome sequencing and assembly
| PRJNA284519 | ENA
Project description:BACKGROUND:Tuberculosis (TB) is the leading cause of death in South Africa. The burden of disease varies by age, with peaks in TB notification rates in the HIV-negative population at ages 0-5, 20-24, and 45-49 years. There is little variation between age groups in the rates in the HIV-positive population. The drivers of this age pattern remain unknown. METHODS:We developed an age-structured simulation model of Mycobacterium tuberculosis (Mtb) transmission in Cape Town, South Africa. We considered five states of TB progression: susceptible, infected (latent TB), active TB, treated TB, and treatment default. Latently infected individuals could be re-infected; a previous Mtb infection slowed progression to active disease. We further considered three states of HIV progression: HIV negative, HIV positive, on antiretroviral therapy. To parameterize the model, we analysed treatment outcomes from the Cape Town electronic TB register, social mixing patterns from a Cape Town community and used literature estimates for other parameters. To investigate the main drivers behind the age patterns, we conducted sensitivity analyses on all parameters related to the age structure. RESULTS:The model replicated the age patterns in HIV-negative TB notification rates of Cape Town in 2009. Simulated TB notification rate in HIV-negative patients was 1000/100,000 person-years (pyrs) in children aged <5 years and decreased to 51/100,000 in children 5-15 years. The peak in early adulthood occurred at 25-29 years (463/100,000 pyrs). After a subsequent decline, simulated TB notification rates gradually increased from the age of 30 years. Sensitivity analyses showed that the dip after the early adult peak was due to the protective effect of latent TB and that retreatment TB was mainly responsible for the rise in TB notification rates from the age of 30 years. CONCLUSION:The protective effect of a first latent infection on subsequent infections and the faster progression in previously treated patients are the key determinants of the age-structure of TB notification rates in Cape Town.
| S-EPMC4791535 | biostudies-literature
Project description:Dimorphic plant and human mycopathogens require a switch from the usual yeast growth to filamentous growth for host tissue penetration, and the switch is controlled by multiple signaling systems other than the central developmental pathway. Unlike these fungi, dimorphic insect mycopathogens usually grow by hyphal extension, infect the host by hyphal penetration through the insect cuticle, and switch to unicellular blastospores from the penetrating hyphae only after entry into the host hemocoel, where blastospore propagation by yeast-like budding accelerates host mummification. Here, we report a dependence of the virulence-required dimorphic transition on the central pathway activators BrlA and AbaA in Beauveria bassiana Deletion of brlA or abaA abolished both aerial conidiation and submerged blastospore formation in vitro despite no negative impact on hyphal growth in various media, including a broth mimic of insect hemolymph. The hyphae of either deletion mutant lost insect pathogenicity through normal cuticle penetration, contrasting with a high infectivity of wild-type hyphae. The mutant hyphae injected into the host hemocoel failed to form blastospores, resulting in slower lethal action. Uncovered by transcriptomic analysis, several genes involved in host adhesion and cuticle degradation were sharply repressed in both deletion mutants versus wild type. However, almost all signaling genes homologous to those acting in the dimorphic switch of other fungi were not differentially expressed at a significant level and hence unlikely to be involved in shutting down the dimorphic switch of each deletion mutant. Therefore, like aerial conidiation, the submerged dimorphic switch in vitro and in vivo is a process of asexual development governed by the two central pathway activators in B. bassianaIMPORTANCE Dimorphic insect mycopathogens infect the host by hyphal penetration through the host cuticle and switch from the penetrating hyphae to unicellular blastospores after entry into the host hemocoel, where blastospore propagation by yeast-like budding accelerates host mummification to death. The fungal virulence-required dimorphic switch is confirmed as a process of asexual development directly regulated by BrlA and AbaA, two key activators of the central developmental pathway in an insect mycopathogen. This finding unveils a novel mechanism distinct from the control of the dimorphic switch by multiple signaling systems other than the central developmental pathway in dimorphic plant and human mycopathogens, which switch from the usual yeast growth to filamentous growth required for pathogenicity through host tissue penetration.
| S-EPMC6616149 | biostudies-literature