title: Morphology and ultrastructure of retrovirus particles.
abstract: Retrovirus morphogenesis entails assembly of Gag proteins and the viral genome on the host plasma membrane, acquisition of the viral membrane and envelope proteins through budding, and formation of the core through the maturation process. Although in both immature and mature retroviruses, Gag and capsid proteins are organized as paracrystalline structures, the curvatures of these protein arrays are evidently not uniform within one or among all virus particles. The heterogeneity of retroviruses poses significant challenges to studying the protein contacts within the Gag and capsid lattices. This review focuses on current understanding of the molecular organization of retroviruses derived from the sub-nanometer structures of immature virus particles, helical capsid protein assemblies and soluble envelope protein complexes. These studies provide insight into the molecular elements that maintain the stability, flexibility and infectivity of virus particles. Also reviewed are morphological studies of retrovirus budding, maturation, infection and cell-cell transmission, which inform the structural transformation of the viruses and the cells during infection and viral transmission, and lead to better understanding of the interplay between the functioning viral proteins and the host cell.
authors.affiliation: Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA ; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN, USA ; Characterization Facility, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Wuhan Institute of Virology, Chinese Academy of Science, Wuhan, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Cao
authors.affiliation: Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA ; Pharmacology Graduate Program, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Martin
authors.affiliation: Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA ; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Joachim D
authors.initials: JD
authors.lastname: Mueller
authors.affiliation: Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA ; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN, USA ; Pharmacology Graduate Program, University of Minnesota, Minneapolis, MN, USA ; Department of Microbiology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Mansky
keywords: Gag lattice; capsid protein shell; cryo-electron microscopy; cryo-electron tomography; envelop protein complex; retrovirus structure; sub-tomogram averaging