biostudies-literatureZhang DXEuropean Research CouncilDutch Research Council (NWO)Wellcome TrustBiotechnology and Biological Sciences Research Councileadx1178https://www.ebi.ac.uk/biostudies/studies/S-EPMC12494034biostudies-literatureUnknown11(40)While archaeal viruses show a stunning diversity of morphologies, many bear a notable resemblance to tailed bacterial phages. This raises fundamental questions: Do all tailed viruses share a common origin and do they infect their hosts in similar ways? Answering these questions requires high-resolution structural insights, yet no complete atomic models of archaeal viruses have been available. Here, we present the near-atomic resolution structure of Haloferax tailed virus 1 (HFTV1), an archaeal virus thriving in extreme salinity. Using cryo-electron microscopy, we resolve the architecture and assembly of all structural proteins and capture conformational transitions associated with DNA ejection. Our data reveal genome spooling within the capsid and identify putative receptor-binding and catScience advancesCryo-EM resolves the structure of the archaeal dsDNA virus HFTV1 from head to tail.PMC12494034803894101039446VI.Vidi.223.020BB/R000484/1202904/Z/16/Z206181/Z/17/ZIsupov MNDaum BGold VAMDavies RMMcLaren MOksanen HMQuax TEFSchwarzer SZhang DXStuart WSfalseCryo-EM resolves the structure of the archaeal dsDNA virus HFTV1 from head to tail.While archaeal viruses show a stunning diversity of morphologies, many bear a notable resemblance to tailed bacterial phages. This raises fundamental questions: Do all tailed viruses share a common origin and do they infect their hosts in similar ways? Answering these questions requires high-resolution structural insights, yet no complete atomic models of archaeal viruses have been available. Here, we present the near-atomic resolution structure of Haloferax tailed virus 1 (HFTV1), an archaeal virus thriving in extreme salinity. Using cryo-electron microscopy, we resolve the architecture and assembly of all structural proteins and capture conformational transitions associated with DNA ejection. Our data reveal genome spooling within the capsid and identify putative receptor-binding and cat2025-01-01T00:00:00Z2025 Oct2026-06-04T04:25:48.552Z2026-05-04T03:14:32.535ZS-EPMC124940344104286110.1126/sciadv.adx1178