ABSTRACT
Cryo-electron microscopy was applied to analyze mud crab reovirus (MCRV), which causes 'sleeping disease' in mud crab, Scylla serrata, a marine species cultured in China. We present here the three dimensional structure of MCRV at 13.8Å resolution. The outer capsid shell is composed of 260 trimers with complete T=13 icosahedral symmetry. A major difference between MCRV and previously reported aquareoviruses is that it lacks a pentameric turret structure. These results together with recently published molecular biological evidence (Deng et al., 2012) indicate that, from a structural perspective, MCRV should be classified as a new member of the family Reoviridae.
Subject(s)
Brachyura/virology , Reoviridae/classification , Reoviridae/ultrastructure , Virion/ultrastructure , Animals , China , Classification , Cryoelectron Microscopy , Reoviridae/isolation & purificationABSTRACT
Mud crab reovirus (MCRV) is the causative agent of a serious disease with high mortality in cultured mud crab (Scylla serrata). This study sequenced and analyzed 12 genome segments of MCRV. The 12 genome segments had a total length of 24.464 kb, showing a total G+C content of 41.29% and predicted 15 ORFs. Sequence analysis showed that the majority of MCRV genes shared low homology with the counterpart genes of other reoviruses, e.g., the amino acid identity of RNA-dependent RNA polymerase (RdRp) was lower than 13.0% compared to the RdRp sequences of other reoviruses. Nucleotide and amino acid sequences of RdRp and capping enzyme suggested MCRV as a single group. Further genome-based phylogenetical analysis of conserved termini and reovirus polymerase motif indicates that this MCRV belongs to a new genus of the Reoviridae family, tentatively named as Crabreovirus.
