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