title: Microscopic Characterization of the Brazilian Giant Samba Virus.
abstract: Prior to the discovery of the mimivirus in 2003, viruses were thought to be physically small and genetically simple. Mimivirus, with its ~750-nm particle size and its ~1.2-Mbp genome, shattered these notions and changed what it meant to be a virus. Since this discovery, the isolation and characterization of giant viruses has exploded. One of the more recently discovered giant viruses, Samba virus, is aMimivirusthat was isolated from the Rio Negro in the Brazilian Amazon. Initial characterization of Samba has revealed some structural information, although the preparation techniques used are prone to the generation of structural artifacts. To generate more native-like structural information for Samba, we analyzed the virus through cryo-electron microscopy, cryo-electron tomography, scanning electron microscopy, and fluorescence microscopy. These microscopy techniques demonstrated that Samba particles have a capsid diameter of ~527 nm and a fiber length of ~155 nm, making Samba the largestMimivirusyet characterized. We also compared Samba to a fiberless mimivirus variant. Samba particles, unlike those of mimivirus, do not appear to be rigid, and quasi-icosahedral, although the two viruses share many common features, including a multi-layered capsid and an asymmetric nucleocapsid, which may be common amongst theMimiviruses.
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824 MI, USA. schradja@msu.edu.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Schrad
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824 MI, USA. younge16@msu.edu.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Young
authors.affiliation: Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901 Minas Gerais, Brazil. jonatas.abrahao@gmail.com.|Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UM63 CNRS 7278 IRD 198 INSERM U1095, Aix-Marseille University, 13385 Marseille Cedex 05, France. jonatas.abrahao@gmail.com.
authors.forename: Jônatas S
authors.initials: JS
authors.lastname: Abrahão
authors.affiliation: Departamento de Virologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil. cortines@micro.ufrj.br.
authors.forename: Juliana R
authors.initials: JR
authors.lastname: Cortines
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, 48824 MI, USA. kparent@msu.edu.
authors.forename: Kristin N
authors.initials: KN
authors.lastname: Parent
mesh_terms: D001938:Brazil; D002213:Capsid / Q000648:ultrastructure; D008853:Microscopy; D056686:Mimiviridae / Q000302:isolation & purification / Q000648:ultrastructure*; D045483:Rivers / Q000821:virology
keywords: Megavirales; Mimiviridae; cryo-electron microscopy; cryo-electron tomography; fluorescence microscopy; giant viruses; mimivirus; nucleocytoplasmic large DNA virus (NCLDV); scanning electron microscopy