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Journal of Clinical Microbiology Jul 2022
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Journal of Clinical Microbiology Mar 2018
Topics: AIDS-Related Opportunistic Infections; Acquired Immunodeficiency Syndrome; HIV Infections; Histoplasma; Histoplasmosis; Humans
PubMed: 29472436
DOI: 10.1128/JCM.00912-17 -
MSphere Dec 2023is a primary fungal pathogen with the ability to infect otherwise healthy mammalian hosts, causing systemic and sometimes life-threatening disease. Thus far, molecular...
is a primary fungal pathogen with the ability to infect otherwise healthy mammalian hosts, causing systemic and sometimes life-threatening disease. Thus far, molecular genetic manipulation of this organism has utilized RNA interference, random insertional mutagenesis, and a homologous recombination protocol that is highly variable and often inefficient. Targeted gene manipulations have been challenging due to poor rates of homologous recombination events in . Interrogation of the virulence strategies of this organism would be highly accelerated by a means of efficiently generating targeted mutations. We have developed a recyclable CRISPR/Cas9 system that can be used to introduce gene disruptions in with high efficiency, thereby allowing disruption of multiple genes.
Topics: Animals; CRISPR-Cas Systems; Histoplasma; Homologous Recombination; Mutagenesis, Site-Directed; Mutagenesis, Insertional; Mammals
PubMed: 37819140
DOI: 10.1128/msphere.00370-23 -
MBio Aug 2023Peroxisomes are versatile eukaryotic organelles essential for many functions in fungi, including fatty acid metabolism, reactive oxygen species detoxification, and...
Peroxisomes are versatile eukaryotic organelles essential for many functions in fungi, including fatty acid metabolism, reactive oxygen species detoxification, and secondary metabolite biosynthesis. A suite of Pex proteins (peroxins) maintains peroxisomes, while peroxisomal matrix enzymes execute peroxisome functions. Insertional mutagenesis identified peroxin genes as essential components supporting the intraphagosomal growth of the fungal pathogen . Disruption of the peroxins Pex5, Pex10, or Pex33 in prevented peroxisome import of proteins targeted to the organelle via the PTS1 pathway. This loss of peroxisome protein import limited intracellular growth in macrophages and attenuated virulence in an acute histoplasmosis infection model. Interruption of the alternate PTS2 import pathway also attenuated virulence, although only at later time points of infection. The Sid1 and Sid3 siderophore biosynthesis proteins contain a PTS1 peroxisome import signal and localize to the peroxisome. Loss of either the PTS1 or PTS2 peroxisome import pathway impaired siderophore production and iron acquisition in , demonstrating compartmentalization of at least some biosynthetic steps for hydroxamate siderophore biosynthesis. However, the loss of PTS1-based peroxisome import caused earlier virulence attenuation than either the loss of PTS2-based protein import or the loss of siderophore biosynthesis, indicating additional PTS1-dependent peroxisomal functions are important for virulence. Furthermore, disruption of the Pex11 peroxin also attenuated virulence independently of peroxisomal protein import and siderophore biosynthesis. These findings demonstrate peroxisomes contribute to pathogenesis by facilitating siderophore biosynthesis and another unidentified role(s) for the organelle during fungal virulence. IMPORTANCE The fungal pathogen infects host phagocytes and establishes a replication-permissive niche within the cells. To do so, overcomes and subverts antifungal defense mechanisms which include the limitation of essential micronutrients. replication within host cells requires multiple distinct functions of the fungal peroxisome organelle. These peroxisomal functions contribute to pathogenesis at different times during infection and include peroxisome-dependent biosynthesis of iron-scavenging siderophores to enable fungal proliferation, particularly after activation of cell-mediated immunity. The multiple essential roles of fungal peroxisomes reveal this organelle as a potential but untapped target for the development of therapeutics.
Topics: Histoplasma; Virulence; Siderophores; Peroxins; Peroxisomes; Adaptation, Physiological
PubMed: 37432032
DOI: 10.1128/mbio.03284-22 -
Journal of Clinical Microbiology Jul 2022
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Journal of Microbiology, Immunology,... Dec 2020
Topics: Female; Histoplasma; Histoplasmosis; Humans; Middle Aged; Reinfection; Taiwan
PubMed: 32094075
DOI: 10.1016/j.jmii.2020.02.003 -
MBio May 2018In a recent article, Sepúlveda et al. (mBio 8:e01339-17, 2017, https://doi.org/10.1128/mBio.01339-17) investigated the genetic structure and evolutionary history of the...
In a recent article, Sepúlveda et al. (mBio 8:e01339-17, 2017, https://doi.org/10.1128/mBio.01339-17) investigated the genetic structure and evolutionary history of the human pathogen Using whole-genome resequencing data, Sepúlveda et al. found that the genus is composed of at least four strongly differentiated lineages. Their tour de force is to use a smart combination of population genomic approaches to show that the advanced stage of intraspecific divergence observed within does not simply reflect population structure, but instead results from previously unidentified speciation events. The four independently evolving lineages are elevated to the species status and assigned names. The newly described species exhibit medically important differences in phenotype, and these findings, therefore, have important epidemiological implications. This work provides a blueprint for phylogenomic species recognition in fungi, opening the way for a new age of enlightenment in which fungal species are diagnosed using highly discriminatory tools within a hypothesis-testing framework.
Topics: Biodiversity; Biological Evolution; Genetic Speciation; Histoplasma; Humans; Metagenomics; Phylogeny
PubMed: 29739908
DOI: 10.1128/mBio.00181-18 -
Diversification of Fungal Chitinases and Their Functional Differentiation in Histoplasma capsulatum.Molecular Biology and Evolution Apr 2021Chitinases enzymatically hydrolyze chitin, a highly abundant and utilized polymer of N-acetyl-glucosamine. Fungi are a rich source of chitinases; however, the...
Chitinases enzymatically hydrolyze chitin, a highly abundant and utilized polymer of N-acetyl-glucosamine. Fungi are a rich source of chitinases; however, the phylogenetic and functional diversity of fungal chitinases are not well understood. We surveyed fungal chitinases from 373 publicly available genomes, characterized domain architecture, and conducted phylogenetic analyses of the glycoside hydrolase (GH18) domain. This large-scale analysis does not support the previous division of fungal chitinases into three major clades (A, B, C) as chitinases previously assigned to the "C" clade are not resolved as distinct from the "A" clade. Fungal chitinase diversity was partly shaped by horizontal gene transfer, and at least one clade of bacterial origin occurs among chitinases previously assigned to the "B" clade. Furthermore, chitin-binding domains (including the LysM domain) do not define specific clades, but instead are found more broadly across clades of chitinases. To gain insight into biological function diversity, we characterized all eight chitinases (Cts) from the thermally dimorphic fungus, Histoplasma capsulatum: six A clade, one B clade, and one formerly classified C clade chitinases. Expression analyses showed variable induction of chitinase genes in the presence of chitin but preferential expression of CTS3 in the mycelial stage. Activity assays demonstrated that Cts1 (B-I), Cts2 (A-V), Cts3 (A-V), Cts4 (A-V) have endochitinase activities with varying degrees of chitobiosidase function. Cts6 (C-I) has activity consistent with N-acetyl-glucosaminidase exochitinase function and Cts8 (A-II) has chitobiase activity. These results suggest chitinase activity is variable even within subclades and that predictions of functionality require more sophisticated models.
Topics: Chitinases; Evolution, Molecular; Fungal Proteins; Genome, Fungal; Histoplasma; Protein Domains
PubMed: 33185664
DOI: 10.1093/molbev/msaa293 -
International Journal of Infectious... Sep 2019Histoplasmosis is a systemic disease caused by the dimorphic fungus Histoplasma capsulatum. Diagnosis is often delayed, or it is misdiagnosed as tuberculosis. In Brazil,...
BACKGROUND
Histoplasmosis is a systemic disease caused by the dimorphic fungus Histoplasma capsulatum. Diagnosis is often delayed, or it is misdiagnosed as tuberculosis. In Brazil, the infection is common and cases of histoplasmosis have been described in all regions of the country; however, the real problem is underestimated since notification of histoplasmosis is not mandatory.
METHODS
Human histoplasmosis cases diagnosed in Brazil and published up to December 2018 were identified through a search conducted in the PubMed/MEDLINE, SciELO, and Web of Science databases. Moreover, the isolation of H. capsulatum from animals or environmental sources in Brazil was also evaluated.
RESULTS
A total of 207 articles fulfilled the inclusion criteria and were evaluated, involving a total of 3530 patients with a diagnosis of histoplasmosis during the period studied. Of these patients, 78.3% were male, giving a male-to-female ratio of approximately 4:1. Histoplasmosis presented a higher frequency in individuals between the fourth and fifth decades of life. Disseminated disease was the most common form of histoplasmosis. Isolation of H. capsulatum on culture media and histopathology using staining methods were the diagnostic methods with the best efficiency. The best results in the identification of the H. capsulatum were achieved for samples from mononuclear phagocyte system components, skin and mucosa, and hematological samples. Regarding predisposing factors for histoplasmosis, HIV infection was the most common underlying condition. The overall mortality rate was 33.1%.
CONCLUSIONS
This study represents the first available systematic review demonstrating Brazilian cases of histoplasmosis in the literature and highlights that the disease is more widespread in the Brazilian territory than has previously been thought.
Topics: Animals; Brazil; Female; HIV Infections; Histoplasma; Histoplasmosis; Humans; Male
PubMed: 31330326
DOI: 10.1016/j.ijid.2019.07.009 -
Frontiers in Cellular and Infection... 2022Equine histoplasmosis commonly known as epizootic lymphangitis (EL) is a neglected granulomatous disease of equine that is endemic to Ethiopia. It is caused by variety...
Equine histoplasmosis commonly known as epizootic lymphangitis (EL) is a neglected granulomatous disease of equine that is endemic to Ethiopia. It is caused by variety , a dimorphic fungus that is closely related to variety c The objective of this study was to undertake a phylogenetic analysis of isolated from EL cases of horses in central Ethiopia and evaluate their relationship with isolates in other countries and/or clades using the internal transcribed spacer (ITS) region of rRNA genes. Clinical and mycological examinations, DNA extraction, polymerase chain reaction (PCR), Sanger sequencing, and phylogenetic analysis were used for undertaking this study. Additionally, sequence data of isolates were retrieved from GenBank and included for a comprehensive phylogenetic analysis. A total of 390 horses were screened for EL and 97 were positive clinically while was isolated from 60 horses and further confirmed with PCR, of which 54 were sequenced. BLAST analysis of these 54 isolates identified 29 isolates and 14 isolates from other fungal genera while the remaining 11 samples were deemed insufficient for further downstream analysis. The phylogenetic analysis identified five clades, namely, African, Eurasian, North American 1 and 2, and Latin American A and B. The Ethiopian isolates were closely aggregated with isolates of the Latin American A and Eurasian clades, whereas being distantly related to isolates from North American 1 and 2 clades as well as Latin American B clade. This study highlights the possible origins and transmission routes of Histoplasmosis in Ethiopia.
Topics: Animals; DNA, Fungal; Ethiopia; Genes, rRNA; Histoplasma; Histoplasmosis; Horses; Phylogeny
PubMed: 35909976
DOI: 10.3389/fcimb.2022.789157