Structure of Microsporidia

Vávra, Jiří; Larsson, J.I. Ronny

doi:10.1002/9781118395264.ch1

Cited by 32 publications

(30 citation statements)

References 189 publications

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“…Of note, another exit mode was noted in the human gastrointestinal microsporidia Enterocytozoon bieneusi (in Clade IV like E . longa ), whereby the infected cell itself is extruded in the lumen [48–50]. Presumably, the cell then rapidly dies and the spores are released by disintegration of the enterocyte plasma membrane.…”

Section: Discussionmentioning

confidence: 99%

A Large Collection of Novel Nematode-Infecting Microsporidia and Their Diverse Interactions with Caenorhabditis elegans and Other Related Nematodes

Zhang

Sachse²,

Prévost³

et al. 2016

PLoS Pathog

176

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Microsporidia are fungi-related intracellular pathogens that may infect virtually all animals, but are poorly understood. The nematode Caenorhabditis elegans has recently become a model host for studying microsporidia through the identification of its natural microsporidian pathogen Nematocida parisii. However, it was unclear how widespread and diverse microsporidia infections are in C. elegans or other related nematodes in the wild. Here we describe the isolation and culture of 47 nematodes with microsporidian infections. N. parisii is found to be the most common microsporidia infecting C. elegans in the wild. In addition, we further describe and name six new species in the Nematocida genus. Our sampling and phylogenetic analysis further identify two subclades that are genetically distinct from Nematocida, and we name them Enteropsectra and Pancytospora. Interestingly, unlike Nematocida, these two genera belong to the main clade of microsporidia that includes human pathogens. All of these microsporidia are horizontally transmitted and most specifically infect intestinal cells, except Pancytospora epiphaga that replicates mostly in the epidermis of its Caenorhabditis host. At the subcellular level in the infected host cell, spores of the novel genus Enteropsectra show a characteristic apical distribution and exit via budding off of the plasma membrane, instead of exiting via exocytosis as spores of Nematocida. Host specificity is broad for some microsporidia, narrow for others: indeed, some microsporidia can infect Oscheius tipulae but not its sister species Oscheius sp. 3, and conversely some microsporidia found infecting Oscheius sp. 3 do not infect O. tipulae. We also show that N. ausubeli fails to strongly induce in C. elegans the transcription of genes that are induced by other Nematocida species, suggesting it has evolved mechanisms to prevent induction of this host response. Altogether, these newly isolated species illustrate the diversity and ubiquity of microsporidian infections in nematodes, and provide a rich resource to investigate host-parasite coevolution in tractable nematode hosts.

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Section: Discussionmentioning

confidence: 99%

A Large Collection of Novel Nematode-Infecting Microsporidia and Their Diverse Interactions with Caenorhabditis elegans and Other Related Nematodes

Zhang

Sachse²,

Prévost³

et al. 2016

PLoS Pathog

176

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“…The everting PT, and the PT within the intact spore, is not empty, but has been shown by several authors to be filled with electron-dense materials (Cali et al, 2002;Vavra and Larsson, 2014;Takvorian et al, 2019) which are thought by some to be unpolymerized PTPs and perhaps membranes (Kudo and Daniels, 1963;Weidner, 1972Weidner, , 1976. According to several ultrastructural observations eversion of the PT has been likened to a tube sliding within a tube (or a glove finger being turned inside out) and it has been further hypothesized that PTPs polymerize on the forming tube when they exit at the distal tip of the PT (Weidner, 1982;Weidner et al, 1995).…”

Section: Organismmentioning

confidence: 99%

“…During infection of host cells by microsporidia, the infectious sporoplasm is transported from spores via the PT, resulting in the transmission of the infection (Takvorian et al, 2005;Vavra and Larsson, 2014). During this process, the sporoplasm flows through the PT, appears as a droplet at the distal end of the PT and remains attached to the PT for several minutes (Korke, 1916;Ohshima, 1937;Gibbs, 1953;Lom, 1972;Weidner, 1972;Frixione et al, 1992;.…”

Section: Observations On the Sporoplasmmentioning

confidence: 99%

Invasion of Host Cells by Microsporidia

2020

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Microsporidia are found worldwide and both vertebrates and invertebrates can serve as hosts for these organisms. While microsporidiosis in humans can occur in both immune competent and immune compromised hosts, it has most often been seen in the immune suppressed population, e.g., patients with advanced HIV infection, patients who have had organ transplantation, those undergoing chemotherapy, or patients using other immune suppressive agents. Infection can be associated with either focal infection in a specific organ (e.g., keratoconjunctivitis, cerebritis, or hepatitis) or with disseminated disease. The most common presentation of microsporidiosis being gastrointestinal infection with chronic diarrhea and wasting syndrome. In the setting of advanced HIV infection or other cases of profound immune deficiency microsporidiosis can be extremely debilitating and carries a significant mortality risk. Microsporidia are transmitted as spores which invade host cells by a specialized invasion apparatus the polar tube (PT). This review summarizes recent studies that have provided information on the composition of the spore wall and PT, as well as insights into the mechanism of invasion and interaction of the PT and spore wall with host cells during infection.

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“…2C). This type of cyst is similar to a xenoparasitic complex (xenoma) found in several groups of microsporidia (Sprague et al, 1992) but unusual in the lack of a membranous sporophorous vesicle (SV) to contain the spores as commonly found in xenomas in fish (Vávra and Larsson, 2014) and some insects (Becnel and Andreadis, 2014). A persistent SV was produced by the sporont (Fig.…”

Section: Interfacementioning

confidence: 95%