Persistent mirusvirus infection in the marine protist Aurantiochytrium

Persistent mirusvirus infection in the marine protist Aurantiochytrium | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Persistent mirusvirus infection in the marine protist Aurantiochytrium John Archibald, Dudley Chung, Nik Brask, Sari Matar, Lucie Gallot-Lavallée, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5686297/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 11 Nov, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract Mirusviruses are enigmatic double-stranded (ds) DNA viruses with a chimeric evolutionary history – they have informational genes of Nucleocytoviricota ancestry and virion module genes most like those of herpesviruses. Mirusvirus genomes were discovered in marine metagenomic data (1) but, despite their abundance and broad environmental distribution, their host range is unknown. The marine thraustochytrid protist Aurantiochytrium limacinum was recently found to possess two mirusvirus-like genomic elements, one a circular episome (AurliV-1) and the other (AurliV-2) a chromosomal integrant (2). Here we show that A. limacinum mirusvirus genes are expressed and virions are produced in all culture conditions examined, including standard growth medium. Of 66 AurIiV-1-encoded proteins detected using proteomics, 48 were up-regulated under starvation conditions, including major capsid protein and triplex proteins. Quantitative PCR showed that AurliV-1 DNA is packaged into virions, and transmission electron microscopy revealed ~140 nm virions in the nucleus, in cytoplasmic vesicles, between the plasma membrane and cell wall, and in the extracellular environment. Putative surface-localized, AurliV-1-encoded, arylsulfatase and alpha-galactosidase proteins may digest sulfated polysaccharides in the host cell wall. Our results establish Aurantiochytrium as the first model system for elucidating mirusvirus-host interactions and reframe the concept of persistent viral infection in microbial eukaryotes. Biological sciences/Microbiology/Virology/Viral evolution Biological sciences/Genetics/Eukaryote Biological sciences/Genetics/Genomics/Genome evolution Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Full Text Additional Declarations There is NO Competing Interest. Supplementary Files ChungMirusvirusProteinTableS1V4Dec20.csv Extended Data S1 ChungSIFigsV9Dec20.pdf Supplementary Figures S1 - S6 ChungetalSuppInfoDec20.pdf Supplementary Information Cite Share Download PDF Status: Published Journal Publication published 11 Nov, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5686297","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":395012013,"identity":"ee0b70c4-e2f1-4c05-9f31-5d5b505c806e","order_by":0,"name":"John 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