title: Unusual self-assembly properties of Norovirus Newbury2 virus-like particles.
abstract: In the Caliciviridae family of nonenveloped, positive-stranded RNA viruses, Noroviruses are major causes of human and animal gastroenteritis worldwide. The Norovirus T=3 icosahedral capsid is made of 180 copies of the VP1 protein, as exemplified in the crystal structure of the virus-like particle (VLP) of the human Norwalk virus (NV). It was previously shown that the ca 40-nm recombinant NV VLP can be disassembled and reassembled in vitro. Here we report on the disassembly and self-assembly properties for the related (VP1 sequence identity of 50%) bovine Newbury2 Norovirus (NB2) VLP. Using a panel of biophysical techniques, we show that while the NB2 VLP displays disassembly properties similar to the NV VLP, NB2-VP1 shows remarkable self-assembly properties heretofore unreported for NV-VP1 or any other calicivirus capsid protein. These properties include the capabilities of self-assembling not only into regular T=3 capsids but also into larger VLP (up to 76 nm in diameter) and of tolerating substitution of the spike domain for that of a distantly related Calicivirus. In conditions favoring the natural, T=3 capsid, NB2-VP1 reproducibly assembles by an apparent two-phase process. Our results establish a robust new system with which to probe the dynamics of viral capsid self-assembly.
authors.affiliation: Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, UMR, Orsay, France. guillaume.tresset@u-psud.fr
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tresset
authors.forename: Vincent
authors.initials: V
authors.lastname: Decouche
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Bryche
authors.forename: Annie
authors.initials: A
authors.lastname: Charpilienne
authors.forename: Clémence
authors.initials: C
authors.lastname: Le Cœur
authors.forename: Cécile
authors.initials: C
authors.lastname: Barbier
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Squires
authors.forename: Mehdi
authors.initials: M
authors.lastname: Zeghal
authors.forename: Didier
authors.initials: D
authors.lastname: Poncet
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bressanelli
mesh_terms: D003460:Crystallization / Q000379:methods; D019281:Dimerization; D029322:Norovirus / Q000737:chemistry*; D011487:Protein Conformation; D014771:Virion / Q000737:chemistry* / Q000648:ultrastructure*; D019065:Virus Assembly
keywords: Capsid self-assembly; Electron microscopy; Light scattering; Small-angle scattering; Virus assembly