<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly"^^ . "Influenza A virus (IAV) poses a persistent threat to human and animal health,\r\ncausing annual epidemics and devastating pandemics responsible for millions of deaths.\r\nThe emergence of pandemic variants is closely tied\r\nto co-infection events involving zoonotic and human IAVs,\r\nwhich can lead to reassortment of their segmented genomes.\r\nThis genetic exchange can produce new variants\r\nwith novel antigenic properties and enhanced host adaptation.\r\nThe increasingly intensive factory farming of poultry and swine\r\namplifies the chances for co-infection events,\r\nand each is a dice roll for a new pandemic strain.\r\nThis threat underscores the need to understand the molecular mechanisms\r\nof IAV assembly and reassortment.\r\n\r\nA critical aspect of the IAV replication cycle is the assembly process.\r\nEach progeny virus must incorporate all\r\neight unique genome segments to be replication competent.\r\nTo achieve this, it subverts the Rab11-regulated recycling endosome\r\nto transport viral ribonucleoproteins (vRNPs) from the nucleus, where they are replicated,\r\nto the plasma membrane, where budding occurs.\r\nOn this route, vRNPs undergo phase-separation and form liquid organelles\r\ncharacterized by high local concentrations of vRNPs.\r\nThis process has been extensively studied,\r\nyet key questions remain unanswered:\r\nWhere and how are vRNP bundles formed?\r\nWhat is the structural organization of this process?\r\nAre other viral or cellular components involved?\r\nThis thesis aims to address these questions using in situ cryo-electron tomography.\r\n\r\nSurprisingly, I discovered that the sites of vRNP clustering\r\nwere predominantly associated with intracellular membranes,\r\nlikely originating from endoplasmic reticulum,\r\nthat were heavily decorated with the viral glycoprotein hemagglutinin (HA).\r\nThe HA proteins engaged in head-to-head interactions,\r\ninducing a reorganization of the membranes into zipper-like\r\ndouble membrane structures that exhibited diverse morphologies and sizes.\r\nThis membrane remodeling was highly conserved and solely driven by HA.\r\nTo quantify vRNP clustering, I developed a cluster identification algorithm\r\nwhich revealed that vRNPs form clusters comprising fewer than eight vRNPs on these membranes.\r\nThis suggests that HA membranes serve as platforms for the formation of vRNP bundles.\r\n\r\nNotably, this study also yielded several intriguing serendipitous findings.\r\nMatrix protein 1, which determines the virus particle shape by forming a matrix layer in virions,\r\nformed multilayered, helical coils in the nuclei of infected cells\r\nthat disassembled in the cytoplasm.\r\nDuring budding, it initiated the formation of the matrix layer around vRNPs\r\nprior to attachment to the plasma membrane,\r\nwhich hints towards a mechanism to ensure that eight vRNPs are incorporated into budding virions.\r\n\r\nIn sum, this thesis highlights the power of high resolution, in situ imaging using cryo-electron tomography.\r\nBy directly visualizing cellular processes in their native environment,\r\nthis work has revealed fundamental mechanisms underlying of IAV assembly,\r\nlaying the groundwork for future research and opening new avenues for investigation."^^ . "2025" . . . . . . . "Moritz"^^ . "Wachsmuth-Melm"^^ . "Moritz Wachsmuth-Melm"^^ . . . . . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly (PDF)"^^ . . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly (Other)"^^ . . . . . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly (Other)"^^ . . . . . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly (Other)"^^ . . . . . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly (Other)"^^ . . . . . . "In Situ Cryo-Electron Tomography of Influenza A Virus Assembly (Other)"^^ . . . . . "HTML Summary of #36218 \n\nIn Situ Cryo-Electron Tomography of Influenza A Virus Assembly\n\n" . "text/html" . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .