Complete Genome Sequence of Macrobrachium rosenbergii Golda Virus (MrGV) from China

SIMPLE SUMMARY: Macrobrachium rosenbergii golda virus (MrGV) was first identified in Macrobrachium rosenbergii in Bangladesh with massive larva death. In this study, the variant of MrGV Mr-18 from China was accidentally found in a meta-transcriptome study of M. rosenbergii and compared with MrGV LH1-2018 reported in Bangladesh. Phylogenetic analysis has shown that these two variants belong to the same, yet unclassified, genus. At present, there has no evidence that MrGV Mr-18 causes disease in M. rosenbergii. However, we should be alert that MrGV may lead to the mass death of M. rosenbergii larvae; thus, surveillance of MrGV in Asia should be given priority. ABSTRACT: In a meta-transcriptome study of the giant freshwater prawn Macrobrachium rosenbergii sampled in 2018 from a hatchery, we identified a variant of Macrobrachium rosenbergii golda virus (MrGV) in postlarvae without clinical signs. The virus belongs to the family Roniviridae, and the genome of this MrGV variant, Mr-18, consisted of 28,957 nucleotides, including 4 open reading frames (ORFs): (1) ORF1a, encoding a 3C-like protein (3CLP) (4933 aa); (2) ORF1b, encoding a replicase polyprotein (2877 aa); (3) ORF2, encoding a hypothetical nucleocapsid protein (125 aa); and (4) ORF3, encoding a glycoprotein (1503 aa). ORF1a overlaps with ORF1b with 40 nucleotides, where a −1 ribosomal frameshift with slippage sequence 5′-G(14925)GGUUUU(14931)-3′ produces the pp1ab polyprotein. The genomic sequence of Mr-18 shared 97.80% identity with MrGV LH1-2018 discovered in Bangladesh. The amino acid sequence identities between them were 99.30% (ORF1a), 99.60% (ORF1b), 100.00% (ORF2), and 99.80% (ORF3), respectively. Phylogenetic analysis of the RNA-dependent RNA polymerase (RdRp) proteins revealed that they clustered together and formed a separate cluster from the genus Okavirus. The finding of MrGV in China warrants further studies to determine its pathogenicity and prevalence within the region.