title: Correlative scanning-transmission electron microscopy reveals that a chimeric flavivirus is released as individual particles in secretory vesicles.
abstract: The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.
authors.affiliation: Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Burlaud-Gaillard
authors.affiliation: Département Bioprocess, Upstream Platform, Sanofi Pasteur, Marcy l'Etoile, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Sellin
authors.affiliation: Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Georgeault
authors.affiliation: Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France.
authors.forename: Rustem
authors.initials: R
authors.lastname: Uzbekov
authors.affiliation: Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Lebos
authors.affiliation: Département Bioprocess, Upstream Platform, Sanofi Pasteur, Marcy l'Etoile, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Guillaume
authors.affiliation: Plate-Forme RIO des Microscopies, PPF ASB, Université François Rabelais and CHRU de Tours, Tours, France; INSERM U966, Université François Rabelais and CHRU de Tours, Tours, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Roingeard
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism / Q000821:virology; D003716:Dengue Virus / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D022142:Secretory Vesicles / Q000378:metabolism* / Q000821:virology*; D014709:Vero Cells