3D reconstruction and capsid protein characterization of grass carp reovirus

Abstract

Grass carp reovirus (GCRV) is a relatively new virus first isolated in China and is a member of the Aquareovirus genus of the Reoviridae family. Recent report of genomic sequencing showed that GCRV shared high degree of homology with mammalian reovirus (MRV). As a step of our effort to understand the structural basis of GCRV pathogenesis, we determined the three-dimensional (3D) structure of GCRV capsid at 17 A resolution by electron cryomicroscopy. Each GCRV capsid has a multilayered organization, consisting of an RNA core, an inner, middle and outer protein layer. The outer layer is made up of 200 trimers that are arranged on an incomplete T=13 icosahedral lattice. A characteristic feature of this layer is the depression resulting from the absence of trimers around the peripentonal positions, revealing the underlying trimers on the middle layer. There are 120 subunits in the inner layer arranged with T=1 symmetry. These structural features are common to other members of the Reoviridae. Moreover, SDS-PAGE analysis showed that GCRV virions contain seven structural proteins (VP1-VP7). These structural proteins have a high degree of sequence homology to MRV, consistent with the structural similarities observed in our study. The high structural similarities of isolated GCRV and MRV suggest that future structural studies focusing on GCRV entering into and replicating within its host cell are necessary in order to fully understand the structural basis of GCRV pathogenesis.

Antigenic analysis of grass carp reovirus using single-chain variable fragment antibody against IgM from Ctenopharyngodon idella

“…It consists of an eleven segmented double-stranded RNA genome enclosed by two concentric icosahedral protein capsids, which consist of seven structural proteins VP1-VP7. The inner core layer is arranged with T=1 symmetry, is composed of five proteins, and possesses the enzymatic activities necessary for viral transcription and replication [9][10][11][12]. The remaining VP5 and VP7 proteins are outer capsid proteins arranged on an incomplete T=13 icosahedral lattice, which contains 200 trimers formed by VP5-VP7 heterodimers.…”

An improved RT-PCR assay for rapid and sensitive detection of grass carp reovirus

“…Like many other reoviruses, GCRV is a multilayered spherically structured particle that contains a genome of 11 segments of dsRNA (named S1-S11) that encode 7 structural proteins (VP1-VP7) and 5 nonstructural proteins (Attoui et al, 2002;Fang et al, 2005Fang et al, , 2008Cheng et al, 2008Cheng et al, , 2009). …”

VP5 autocleavage is required for efficient infection by in vitro-recoated aquareovirus particles

“…The 11 genome segments encode seven structural proteins (VP1-VP7) and five nonstructural proteins. Genome sequence analysis and threedimensional structural reconstructions by cryo-electron microscopy have indicated that there are great similarities between aquareoviruses and mammalian reoviruses (MRVs) in protein structure and particle organization (Cheng et al, 2008(Cheng et al, , 2010Fang et al, 2005). Similar to other reoviruses in the family Reoviridae, the GCRV particle is organized mainly into two layers: an outer capsid and an inner capsid.…”