Sequence analysis of 12 genome segments of mud crab reovirus (MCRV)

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.