title: Surface structure of Uukuniemi virus.
abstract: Uukuniemi virus, grown in chicken embryo fibroblasts, has been studied by electron microscopy using negative staining, thin sectioning, and freeze-etching techniques. The spherical virus particle measures about 95 nm in diameter. Its envelope consists of a 5-nm thick membrane covered by 8- to 10-nm long surface projections. These are composed of two polypeptides species of about the same size. Both of them can be removed by digestion with the proteolytic enzyme thermolysin except for a small fragment. The enzyme-treated particles are smooth surfaced and extremely deformable. The glycopolypeptides are clustered to form hollow cylindrical morphological units, 10 to 12 nm in diameter, with a 5-nm central cavity. Both negative staining and freeze-etching suggest that these units are penton-hexon clusters arranged in a T = 12, P = 3, icosahedral surface lattice. The membrane to which the surface subunits are attached is probably a lipid bilayer as evidenced by its double-track appearance in thin sections and the tendency of the freeze fracturing to occur within it. The strand-like nucleoprotein appears from thin-sectioning results to be to a large part located in a zone underneath the membrane.
mesh_terms: D001103:Arboviruses / Q000032:analysis / Q000648:ultrastructure*; D046508:Culture Techniques; D005613:Freeze Etching; D006020:Glycopeptides / Q000032:analysis; D010455:Peptides / Q000032:analysis; D012367:RNA, Viral / Q000032:analysis; D013194:Staining and Labeling; D013820:Thermolysin / Q000378:metabolism; D014764:Viral Proteins / Q000032:analysis
chemical_list: D006020:Glycopeptides; D010455:Peptides; D012367:RNA, Viral; D014764:Viral Proteins; D013820:Thermolysin