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Current Opinion in Microbiology Aug 2015Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related... (Review)
Review
Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related microbes has been poorly understood. Several new studies of the host transcriptional response to microsporidia infection have found infection-induced regulation of genes involved in innate immunity, ubiquitylation, metabolism, and hormonal signaling. In addition, microsporidia have recently been shown to exploit host recycling endocytosis for exit from intestinal cells, and to interact with host degradation pathways. Microsporidia infection has also been shown to profoundly affect behavior in insect hosts. Altogether, these and other recent findings are providing much-needed insight into the underlying mechanisms of microsporidia interaction with host animals.
Topics: Animals; Disease Models, Animal; Host-Pathogen Interactions; Humans; Immunity, Innate; Insecta; Microsporidia; Microsporidiosis
PubMed: 25847674
DOI: 10.1016/j.mib.2015.03.006 -
Current Biology : CB Sep 2023In this Quick guide, Thomas Whelan and Naomi Fast introduce the microsporidia: obligate intracellular parasites with the most extremely reduced genomes known in...
In this Quick guide, Thomas Whelan and Naomi Fast introduce the microsporidia: obligate intracellular parasites with the most extremely reduced genomes known in eukaryotes.
Topics: Microsporidia; Eukaryota
PubMed: 37751700
DOI: 10.1016/j.cub.2023.06.076 -
Trends in Parasitology Aug 2022Microsporidian diversity is vast. There is a renewed drive to understand how microsporidian pathological, genomic, and ecological traits relate to their phylogeny. We... (Review)
Review
Microsporidian diversity is vast. There is a renewed drive to understand how microsporidian pathological, genomic, and ecological traits relate to their phylogeny. We comprehensively sample and phylogenetically analyse 125 microsporidian genera for which sequence data are available. Comparing these results with existing phylogenomic analyses, we suggest an updated taxonomic framework to replace the inconsistent clade numbering system, using informal taxonomic names: Glugeida (previously clades 5/3), Nosematida (4a), Enterocytozoonida (4b), Amblyosporida (3/5), Neopereziida (1), and Ovavesiculida (2). Cellular, parasitological, and ecological traits for 281 well-defined species are compared with identify clade-specific patterns across long-branch Microsporidia. We suggest that future taxonomic circumscriptions of Microsporidia should involve additional markers (SSU/ITS/LSU), and that a comprehensive suite of phenotypic and ecological traits help to predict broad microsporidian functional and lineage diversity.
Topics: Microsporidia; Phylogeny
PubMed: 35667993
DOI: 10.1016/j.pt.2022.05.007 -
Microbiology Spectrum Apr 2017Microsporidia are obligate intracellular pathogens related to Fungi. These organisms have a unique invasion organelle, the polar tube, which upon appropriate... (Review)
Review
Microsporidia are obligate intracellular pathogens related to Fungi. These organisms have a unique invasion organelle, the polar tube, which upon appropriate environmental stimulation rapidly discharges out of the spore, pierces a host cell's membrane, and serves as a conduit for sporoplasm passage into the host cell. Phylogenetic analysis suggests that microsporidia are related to the Fungi, being either a basal branch or sister group. Despite the description of microsporidia over 150 years ago, we still lack an understanding of the mechanism of invasion, including the role of various polar tube proteins, spore wall proteins, and host cell proteins in the formation and function of the invasion synapse. Recent advances in ultrastructural techniques are helping to better define the formation and functioning of the invasion synapse. Over the past 2 decades, proteomic approaches have helped define polar tube proteins and spore wall proteins as well as the importance of posttranslational modifications such as glycosylation in the functioning of these proteins, but the absence of genetic techniques for the manipulation of microsporidia has hampered research on the function of these various proteins. The study of the mechanism of invasion should provide fundamental insights into the biology of these ubiquitous intracellular pathogens that can be integrated into studies aimed at treating or controlling microsporidiosis.
Topics: Animals; Cytoplasm; Fungal Proteins; Glycosylation; Host-Pathogen Interactions; Humans; Life Cycle Stages; Microsporidia; Microsporidiosis; Organelles; Phylogeny; Protein Processing, Post-Translational; Proteomics; Spores, Fungal
PubMed: 28944750
DOI: 10.1128/microbiolspec.FUNK-0018-2016 -
PLoS Pathogens Nov 2016Microsporidia are strict obligate intracellular parasites that infect a wide range of eukaryotes including humans and economically important fish and insects. Surviving... (Review)
Review
Microsporidia are strict obligate intracellular parasites that infect a wide range of eukaryotes including humans and economically important fish and insects. Surviving and flourishing inside another eukaryotic cell is a very specialised lifestyle that requires evolutionary innovation. Genome sequence analyses show that microsporidia have lost most of the genes needed for making primary metabolites, such as amino acids and nucleotides, and also that they have only a limited capacity for making adenosine triphosphate (ATP). Since microsporidia cannot grow and replicate without the enormous amounts of energy and nucleotide building blocks needed for protein, DNA, and RNA biosynthesis, they must have evolved ways of stealing these substrates from the infected host cell. Providing they can do this, genome analyses suggest that microsporidia have the enzyme repertoire needed to use and regenerate the imported nucleotides efficiently. Recent functional studies suggest that a critical innovation for adapting to intracellular life was the acquisition by lateral gene transfer of nucleotide transport (NTT) proteins that are now present in multiple copies in all microsporidian genomes. These proteins are expressed on the parasite surface and allow microsporidia to steal ATP and other purine nucleotides for energy and biosynthesis from their host. However, it remains unclear how other essential metabolites, such as pyrimidine nucleotides, are acquired. Transcriptomic and experimental studies suggest that microsporidia might manipulate host cell metabolism and cell biological processes to promote nucleotide synthesis and to maximise the potential for ATP and nucleotide import. In this review, we summarise recent genomic and functional data relating to how microsporidia exploit their hosts for energy and building blocks needed for growth and nucleic acid metabolism and we identify some remaining outstanding questions.
Topics: Animals; Host-Parasite Interactions; Humans; Microsporidia; Nucleotides
PubMed: 27855212
DOI: 10.1371/journal.ppat.1005870 -
Parasitology Research May 2020The reduction and specialization of the energy metabolism system is a common trait in the evolution of intracellular parasites. One group of fungi-related parasites, the... (Review)
Review
The reduction and specialization of the energy metabolism system is a common trait in the evolution of intracellular parasites. One group of fungi-related parasites, the Microsporidia, seems to have developed this trait far more than other eukaryotes. As an extreme adaptation for a parasitic lifestyle, some of them have completely lost the ability to synthesize ATP, relying heavily upon the metabolic processes of host cells to ensure their own development and reproduction. For a long time, only fragmentary data on the functioning and evolution of the energy metabolism system in microsporidia was available. However, the recent discovery of microsporidia-related microorganisms, the Cryptomycota and Aphelida, alongside with the genome sequencing and new data about basal groups in the Microsporidia has shed new light on this problem. Here, we review recent data about functioning of the energy metabolism system in microsporidia and closely related organisms, and discuss possible evolutionary pathways in the group.
Topics: Energy Metabolism; Evolution, Molecular; Fungi; Genome, Fungal; Host-Parasite Interactions; Loss of Function Mutation; Microsporidia; Phylogeny
PubMed: 32200463
DOI: 10.1007/s00436-020-06657-9 -
Trends in Microbiology Jan 1998Microsporidia are obligate intracellular parasites that infect a wide range of eukaryotes, causing severe diseases in immunocompromised humans and losses to apiaries,... (Review)
Review
Microsporidia are obligate intracellular parasites that infect a wide range of eukaryotes, causing severe diseases in immunocompromised humans and losses to apiaries, fisheries and silk farms. They have often been considered to be primitive eukaryotes; however, more recent evidence suggests they are more closely related to fungi.
Topics: Animals; Eukaryotic Cells; Evolution, Molecular; Fungi; Genes, Protozoan; Microsporidia; Phylogeny
PubMed: 9481819
DOI: 10.1016/S0966-842X(97)01185-2 -
Advances in Parasitology 2013Parasitism, aptly defined as one of the 'living-together' strategies (Trager, 1986), presents a dynamic system in which the parasite and its host are under evolutionary... (Review)
Review
Parasitism, aptly defined as one of the 'living-together' strategies (Trager, 1986), presents a dynamic system in which the parasite and its host are under evolutionary pressure to evolve new and specific adaptations, thus enabling the coexistence of the two closely interacting partners. Microsporidia are very frequently encountered obligatory intracellular protistan parasites that can infect both animals and some protists and are a consummate example of various aspects of the 'living-together' strategy. Microsporidia, relatives of fungi in the superkingdom Opisthokonta, belong to the relatively small group of parasites for which the host cell cytoplasm is the site of both reproduction and maturation. The structural and physiological reduction of their vegetative stage, together with the manipulation of host cell physiology, enables microsporidia to live in the cytosolic environment for most of their life cycle in a way resembling endocytobionts. The ability to form structurally complex spores and the invention and assembly of a unique injection mechanism enable microsporidia to disperse within host tissues and between host organisms, resulting in long-lasting infections. Microsporidia have adapted their genomes to the intracellular way of life, evolved strategies how to obtain nutrients directly from the host and how to manipulate not only the infected cells, but also the hosts themselves. The enormous variability of host organisms and their tissues provide microsporidian parasites a virtually limitless terrain for diversification and ecological expansion. This review attempts to present a general overview of microsporidia, emphasising some less known and/or more recently discovered facets of their biology.
Topics: Animals; Cytoplasm; Host-Pathogen Interactions; Humans; Microsporidia; Microsporidiosis
PubMed: 23548087
DOI: 10.1016/B978-0-12-407706-5.00004-6 -
Cellular Microbiology Nov 2020Microsporidia are a large group of fungal-related obligate intracellular parasites. They are responsible for infections in humans as well as in agriculturally and... (Review)
Review
Microsporidia are a large group of fungal-related obligate intracellular parasites. They are responsible for infections in humans as well as in agriculturally and environmentally important animals. Although microsporidia are abundant in nature, many of the molecular mechanisms employed during infection have remained enigmatic. In this review, we highlight recent work showing how microsporidia invade, proliferate and exit from host cells. During invasion, microsporidia use spore wall and polar tube proteins to interact with host receptors and adhere to the host cell surface. In turn, the host has multiple defence mechanisms to prevent and eliminate these infections. Microsporidia encode numerous transporters and steal host nutrients to facilitate proliferation within host cells. They also encode many secreted proteins which may modulate host metabolism and inhibit host cell defence mechanisms. Spores exit the host in a non-lytic manner that is dependent on host actin and endocytic recycling proteins. Together, this work provides a fuller picture of the mechanisms that these fascinating organisms use to infect their hosts.
Topics: Adaptive Immunity; Animals; Cell Proliferation; Fungal Proteins; Host-Pathogen Interactions; Humans; Immunity, Innate; Microsporidia; Microsporidiosis; Spores, Fungal; Stress, Physiological
PubMed: 32748538
DOI: 10.1111/cmi.13247 -
Microbiology Spectrum Oct 2016Microsporidia comprise a phylum of obligate intracellular pathogens related to fungi that infect virtually all animals. Recently, the nematode Caenorhabditis elegans has... (Review)
Review
Microsporidia comprise a phylum of obligate intracellular pathogens related to fungi that infect virtually all animals. Recently, the nematode Caenorhabditis elegans has been developed as a convenient model for studying microsporidia infection in a whole-animal host through the identification and characterization of a natural microsporidian pathogen of this commonly studied laboratory organism. The C. elegans natural microsporidian pathogen is named Nematocida parisii, and it causes a lethal intestinal infection in C. elegans. Comparison of the genomes of N. parisii and its closely related species Nematocida sp. 1, together with the genomes of other microsporidian species, has provided insight into the evolutionary events that led to the emergence of the large, specialized microsporidia phylum. Cell biology studies of N. parisii infection in C. elegans have shown how N. parisii restructures host intestinal cells and, in particular, how it hijacks host exocytosis for nonlytic exit to facilitate transmission. Recent results also show how the host responds to infection with ubiquitin-mediated responses, and how a natural variant of C. elegans is able to clear N. parisii infection, but only during early life. Altogether, these studies provide insight into the mechanisms of microsporidia pathogenesis using a whole-animal host.
Topics: Animals; Caenorhabditis elegans; Host-Pathogen Interactions; Microsporidia
PubMed: 27763260
DOI: 10.1128/microbiolspec.FUNK-0003-2016