A Novel RNA Virus, Macrobrachium rosenbergii Golda Virus (MrGV), Linked to Mass Mortalities of the Larval Giant Freshwater Prawn in Bangladesh

Abstract

Mass mortalities of the larval stage of the giant freshwater prawn, Macrobrachium rosenbergii, have been occurring in Bangladesh since 2011. Mortalities can reach 100% and have resulted in an 80% decline in the number of hatcheries actively producing M. rosenbergii. To investigate a causative agent for the mortalities, a disease challenge was carried out using infected material from a hatchery experiencing mortalities. Moribund larvae from the challenge were prepared for metatranscriptomic sequencing. De novo virus assembly revealed a 29 kb single‑stranded positive-sense RNA virus with similarities in key protein motif sequences to yellow head virus (YHV), an RNA virus that causes mass mortalities in marine shrimp aquaculture, and other viruses in the Nidovirales order. Primers were designed against the novel virus and used to screen cDNA from larvae sampled from hatcheries in the South of Bangladesh from two consecutive years. Larvae from all hatcheries screened from both years were positive by PCR for the novel virus, including larvae from a hatchery that at the point of sampling appeared healthy, but later experienced mortalities. These screens suggest that the virus is widespread in M. rosenbergii hatchery culture in southern Bangladesh, and that early detection of the virus can be achieved by PCR. The hypothesised protein motifs of Macrobrachium rosenbergii golda virus (MrGV) suggest that it is likely to be a new species within the Nidovirales order. Biosecurity measures should be taken in order to mitigate global spread through the movement of post-larvae within and between countries, which has previously been linked to other virus outbreaks in crustacean aquaculture.

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

“…One of the features in nidovirus is the presence of a −1 ribosomal shifting site, at which the ribosome shifts from ORF1a to ORF1b and produces a fused ORF1ab polypeptide. Within LH1-2018, the frameshift slippery sequence was 5′-GGGUUUU-3′, followed by a stem-loop stimulatory structure [ 8 ]. The same slippery sequence 5′-G 14925 GGUUUU 14931 -3′ and downstream stem-loop structure were found in the ORF1a of Mr-18, and the fused ORF1ab (7797 aa) had a 98.17% nucleotide sequence identity to that of LH1-2018.…”

“…PCR was initiated at 94 °C for 5 min, followed by 30 cycles of 94 °C 30 s, 57 °C 30 s, and 72 °C 30 s, ending at 72 °C for 10 min. Meanwhile, we used the published PCR detection method to detect 13 M. rosenbergii [ 8 ]. The reverse transcription process was performed as described earlier.…”

“…Recently, a new nidovirus named Macrobrachium rosenbergii golda virus (MrGV) LH1-2018 was reported in Bangladesh associated with high mortalities in M. rosenbergii hatcheries [ 8 , 9 ]. It shared a nucleotide sequence identity of 46.50% with YHV (EU487200).…”

Deep mining of the Sequence Read Archive reveals bipartite coronavirus genomes and inter-family Spike glycoprotein recombination

“…Following the emerging trend in virology, recently described nidoviruses have been discovered by bioinformatics analysis of next or third generation sequencing data from meta-genomic andtranscriptomics studies of diverse specimens [6,7,[21][22][23][24][25][26][27][28][29][30][31][32][33][34]. These data sets are composed of overlapping sequence fragments of variable lengths (so-called reads) of various origins that can be assembled into contigs, some of which may represent full-length or partial viral genomes.…”

Special Issue “Emerging Viruses 2020: Surveillance, Prevention, Evolution and Control”

“…The authors suggest, based on their analysis, that these posalike viruses may represent a new virus family within the order Pircornavirales , and they may have come from parasites infecting the guts of mammals and other animals. Also regarding viruses from invertebrates, in the next article Hooper et al [ 22 ] investigated a mass mortality event of giant freshwater prawn ( Macrobrachium rosenbergii ) larvae in Bangladesh. Using metatranscriptomic sequencing, the authors identified a new virus species within the Nidovirales order, baptized as Macrobrachium rosenbergii golda virus.…”