Explore the vast range of titles available.

Microsporidia, as opportunistic parasitic pathogens, constitute a formidable threat to human health. Although the regulatory circuitry of the nucleus-targeted effector EnP1 remains highly intricate and only partially characterized, our study identifies histone H2A as a novel binding partner of EnP1. Furthermore, we demonstrate that both EnP1 overexpression and microsporidia infection induce monoubiquitination of H2A (H2Aub) through downregulation of BAP1 expression. Subsequent mechanistic analyses revealed that elevated H2Aub levels positively correlate with enhanced microsporidian proliferation, whereas attenuation of H2Aub markedly suppresses pathogen expansion. Furthermore, EnP1 orchestrates the enrichment of H2Aub at the SLC7A11 promoter, driving its transcriptional upregulation. Collectively, these findings underscore that EnP1 modulates the ferroptosis state of host cells through H2Aub-mediated epigenetic reprogramming, ultimately facilitating pathogen propagation. This study endeavors to elucidate the critical survival strategies of microsporidia within host cells mediated by EnP1 and to unravel the multifaceted interplay between these pathogens and their hosts.

A vertically transmitted microsporidian, Microsporidia MB , with the ability to disrupt Plasmodium development was reported in Anopheles arabiensis from Kenya, East Africa. To demonstrate its range of incidence, archived DNA samples from 7575 Anopheles mosquitoes collected from Ghana were screened. MB prevalence was observed at 1.8%. An. gambiae s.s constituted 87% of positive mosquitoes while the remaining were from An. coluzzii . Both sibling species had similar positivity rates (24% and 19%; p  = 0.42) despite the significantly higher number of An. gambiae s.s analysed ( An. gambiae s.s = 487; An. coluzzii  = 94; p  = 0.0005). The microsporidian was also more prevalent in emerged adults from field-collected larvae than field-caught adults ( p  < 0.0001) suggestive of an efficient vertical transmission and/or horizontal transfer among larvae. This is the first report of Microsporidia MB in Anopheles mosquitoes in West Africa. It indicates possible widespread among malaria vector species and warrants investigations into the symbiont’s diversity across sub-Saharan Africa.

Enterocytozoon bieneusi (E. bieneusi) is a pathogenic microsporidian that affects immunocompromised individuals, including those with HIV, and represents a major cause of diarrhea. It can severely impact human health, causing gastrointestinal disease, nutritional deficits, and life-threatening complications. However, the microbial mechanisms by which E. bieneusi affects host nutrition are not well understood. Wild rodents have long been considered valuable models for studying human diseases due to similarities in gut microbiota dynamics and immune responses, making them particularly relevant for investigating parasitic infections. Here, we assembled a comprehensive catalog of 9,929 non-redundant microbial genomes from wild rodent gut metagenomes and evaluated their potential for B vitamins and vitamin K biosynthesis using comparative functional genomics. We identified 2,307 genomes encoding complete pathways for de novo biosynthesis of at least one essential vitamin, though no single genome encoded all pathways, indicating a distributed metabolic capacity within the microbial community. Infection with E. bieneusi significantly altered the microbial composition and the potential for vitamin biosynthesis, with a notable expansion of Methanobacteriota and reprogramming of pyridoxine (vitamin B ) biosynthesis pathways. These changes reveal a functional shift in microbial metabolism in response to parasitic pressure. By elucidating the microbial basis of vitamin biosynthesis in wild rodents and the impact of E. bieneusi infection on microbial functions, this study provides new insights into the role of gut microbiota in maintaining host health and supporting nutrient provision under parasitic stress. Moreover, the findings will provide valuable insights into the prevention and control of E. bieneusi infection in a variety of host, including humans.

Microsporidia are a group of intracellular pathogens that actively manipulate host cell biological processes to facilitate their intracellular niche. Apoptosis is an important defense mechanism by which host cell control intracellular pathogens. Microsporidia modulating host cell apoptosis has been reported previously, however the molecular mechanism is not yet clear. In this report, we describe that the microsporidia Nosema bombycis inhibits apoptosis of Bombyx mori cells through a secreted protein NbSPN14, which is a serine protease inhibitor (Serpin). An immunofluorescent assay demonstrated that upon infection with N . bombycis , NbSPN14 was initially found in the B . mori cell cytoplasm and then became enriched in the host cell nucleus. Overexpression and RNA-interference (RNAi) of NbSPN14 in B . mori’ embryo cell confirmed that NbSPN14 inhibited host cells apoptosis. Immunofluorescent and Co-IP assays verified the co-localization and interaction of NbSPN14 with the BmICE, the Caspase 3 homolog in B . mori . Knocking out of BmICE or mutating the BmICE-interacting P1 site of NbSPN14, eliminated the localization of NbSPN14 into the host nucleus and prevented the apoptosis-inhibiting effect of NbSPN14, which also proved that the interaction between BmICE and NbSPN14 occurred in host cytoplasm and the NbSPN14 translocation into host cell nucleus depends on BmICE. These data elucidate that N . bombycis secretory protein NbSPN14 inhibits host cell apoptosis by directly inhibiting the Caspase protease BmICE, which provides an important insight for understanding pathogen-host interactions and a potential therapeutic target for N . bombycis proliferation.

Bile acids (BAs) are central to host-microbiota interactions, yet their metabolism in wild rodents remains poorly characterized. This study aimed to explore the genomic potential of gut microorganisms in wild rodents for BA metabolism and its implications for host adaptation and pathogen interactions. We reconstructed 6,332 genomes from the gut microbiota of wild rodents and performed genome-resolved metabolic profiling. Comparative analyses were conducted across host species, including humans, pigs, laboratory mice, and chickens. Functional enrichment was further assessed in relation to glycoside hydrolase families and Enterocytozoon bieneusi infection status. A total of 5,208 genomes were identified as participants in key BA metabolic pathways, including deconjugation, oxidation, and dihydroxylation, predominantly from Bacillota_A and Bacteroidota. Notably, Muribaculaceae and CAG-485 lineages within Bacteroidota encoded bile salt hydrolase (BSH). Cross-species comparisons revealed a striking absence of 7β-hydroxysteroid dehydrogenase (7β-HSDH) in laboratory mice, indicating their limited suitability for modeling intestinal BA metabolism. BSH-encoding genomes were significantly enriched in glycoside hydrolase families GH13 and GH16, suggesting a potential link between BA transformation and carbohydrate metabolism. Furthermore, Enterocytozoon bieneusi infection was associated with a marked increase in BA-related microbial taxa in wild rodents. Our findings highlight the intricate interconnections between gut microbial functions, BA metabolism, and pathogen interactions. The absence of 7β-HSDH in laboratory mice underscores wild rodents as potentially more suitable models for BA research. These results open new avenues for understanding microbiome-driven host adaptation and health.

Microsporidia are fungal-related obligate intracellular parasites that infect many types of animals. Microsporidia have exceptionally reduced genomes resulting in limited metabolic capabilities and are thought to be reliant on host metabolism to fuel their own growth. Here, we investigate the impact of microsporidia infection on host lipid metabolism using the nematode Caenorhabditis elegans along with its natural microsporidian pathogen Nematocida parisii . We show that infection causes an increase in the level of C. elegans lipid droplet associated lipase, ATGL-1, and a decrease in host fat levels. A mutation that decreases ATGL-1 activity and overexpression of ATGL-1 did not significantly change N. parisii infection levels. Using lipidomics we show that N. parisii infection decreases C. elegans triglyceride levels and results in increased ceramides that we speculate are synthesized by N. parisii . Mutations in host genes involved in ceramide synthesis did not significantly change the levels of N. parisii infection. Together these results show that microsporidia can cause changes to lipid metabolism of their hosts, but some individual mutations of C. elegans lipid enzymes do not alter microsporidian growth.

Molecular tools of the intracellular protozoan pathogens Apicomplexa and Kinetoplastida for manipulation of host cell machinery have been the focus of investigation for approximately two decades. Microsporidia, fungi-related microorganisms forming another large group of obligate intracellular parasites, are characterized by development in direct contact with host cytoplasm (the majority of species), strong minimization of cell machinery, and acquisition of unique transporters to exploit host metabolic system. All the aforementioned features are suggestive of the ability of microsporidia to modify host metabolic and regulatory pathways. Seven proteins of the microsporidium Antonospora (Paranosema) locustae with predicted signal peptides but without transmembrane domains were overexpressed in Escherichia coli. Western-blot analysis with antibodies against recombinant products showed secretion of parasite proteins from different functional categories into the infected host cell. Secretion of parasite hexokinase and α/β-hydrolase was confirmed by immunofluorescence microscopy. In addition, this method showed specific accumulation of A. locustae hexokinase in host nuclei. Expression of hexokinase, trehalase, and two leucine-rich repeat proteins without any exogenous signal peptide led to their secretion in the yeast Pichia pastoris. In contrast, α/β-hydrolase was not found in the culture medium, though a significant amount of this enzyme accumulated in the yeast membrane fraction. These results suggest that microsporidia possess a broad set of enzymes and regulatory proteins secreted into infected cells to control host metabolic processes and molecular programs.

Microsporidia are located at the base of the fungal evolutionary tree. They are obligate intracellular parasites and harness host metabolism to fuel their growth and proliferation. However, how the infestation of cells affects the whole organism and how the organism contributes to parasite proliferation remain poorly understood. Here, we have developed a Tubulinosema ratisbonensis systemic infection model in the genetically amenable Drosophila melanogaster host, in which parasite spores obtained in a mammalian cell culture infection system are injected into adult flies. The parasites proliferate within flies and ultimately kill their hosts. As commonly observed for microsporidia infecting insects, T.   ratisbonensis preferentially grows in the fat body and ultimately depletes the host metabolic stores. We find that supplementing the fly diet with yeast does not benefit the host but the parasite, which increases its proliferation. Unexpectedly, fatty acids and not carbohydrates or amino acids are the critical components responsible for this phenomenon. Our genetic dissection of host lipid metabolism identifies a crucial compound hijacked by T.   ratisbonensis : phosphatidic acid. We propose that phosphatidic acid is a limiting precursor for the synthesis of the parasite membranes and, hence, of its proliferation. A Drosophila melanogaster systemic infection model for the microsporidian Tubulinosema ratisbonensis reveals that the parasite hijacks host phosphatidic acid, which is a limiting precursor for synthesis of parasite membranes and therefore proliferation.

The horizontally-transmitted acanthocephalan parasite Polymorphus minutus and the vertically-transmitted microsporidian parasite Dictyocoela roeselum have both been shown to influence on the antitoxic responses of mono-infected Gammarus roeseli exposed to cadmium. The present study investigates the effect of this co-infection on the antitoxic defence responses of naturally infected females exposed to cadmium stress. Our results revealed that, depending on the cadmium dose, bi-infection induced only slight, significant increased cell damage in G. roeseli as compared to non-infection. In addition, the antitoxic defence pattern of cadmium-exposed bi-infected hosts was similar to the pattern of cadmium-exposed D. roeselum-infected hosts. Reduced glutathione concentrations, carotenoid levels and γ-glutamylcystein ligase activity decreased, while metallothionein concentrations increased. This similar pattern indicates that host physiology can be controlled to some extent by microsporidia under stress conditions. It supports the hypothesis of a disruption of acanthocephalan effects in the presence of microsporidia. However, the global negative effects of bi-infection on host condition should be tested on more biological models, since competition between parasites depends on life history trade-off.

In order to study the effects of Nosema ceranae infection on honey bee microRNA (miRNA) expression, we deep-sequenced honey bee miRNAs daily across a full 6-day parasite reproduction cycle. Seventeen miRNAs were differentially expressed in honey bees infected by N. ceranae that potentially target over 400 genes predicted to primarily involve ion binding, signaling, the nucleus, transmembrane transport and DNA binding. Based on Enzyme Code analysis, nine biological pathways were identified by screening target genes against the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, seven of which involved metabolism. Our results suggest that differentially expressed miRNAs regulate metabolism related genes of host honey bees in response to N. ceranae infection.