A Novel Virus of Flaviviridae Associated with Sexual Precocity in Macrobrachium rosenbergii

Abstract

The iron prawn syndrome (IPS), also described as sexual precocity, results in the reduced size of farmed prawns at harvest and significant economic losses. IPS has been frequently reported in populations of farmed Macrobrachium rosenbergii since 2010, but the cause was heretofore unknown.

Virome Analysis of Normal and Growth Retardation Disease-Affected Macrobrachiumrosenbergii

“…For the maturation of flavivirus particles, the polyprotein precursor is cleaved into structural proteins (capsid protein [C], premembrane protein [prM], and envelope protein [E]) and also nonstructural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, 2K, NS4B, and NS5) ( 39 ). Here, one 12,594-bp viral contig had 98.8% nucleotide identity with the previously identified infectious precocity virus (IPV) ( 28 ), tentatively named Infectious precocity virus strain ZJJS2019 (IPV strain ZJJS2019). IPV strain ZJJS2019 was obtained only from GRD-affected prawns, with high relative abundance (up to 91,141 RPM) ( Table 1 ).…”

“…IPV strain ZJJS2019 was obtained only from GRD-affected prawns, with high relative abundance (up to 91,141 RPM) ( Table 1 ). The genome of IPV strain ZJJS2019 presented the same site of programmed −1 ribosomal frameshifting (−1PRF) to produce a single polyprotein (3,707 amino acids) ( 28 ), sharing 99.62% amino acid identity across the polyprotein with IPV strain ZJJS2019 ( Fig. 8A and Table 1 ).…”

“…In recent years, GRD has continuously emerged in the main provinces of M. rosenbergii breeding, and the proportion of GRD-affected prawns in farming ponds reached 30 to 40% or even up to 80 to 90% in serious areas ( 27 ). Although mass mortalities have not occurred in GRD-affected ponds, GRD in M. rosenbergii has resulted in a production decline of more than 50%, causing substantial economic losses for M. rosenbergii aquaculture ( 28 ). Recently, a few studies have been performed to investigate the cause of GRD.…”

“…The high prevalence of Enterobacter cloacae in slow-growing giant freshwater prawns observed by Gao et al ( 29 ) suggested that the slow growth of M. rosenbergii is probably linked to E. cloacae . Dong et al ( 28 ) detected eight major shrimp pathogens, but none were found in diseased prawns. Furthermore, they have also characterized a novel flavivirus associated with sexual precocity.…”

Comparative analysis of genome-encoded viral sequences reveals the evolutionary history of flavivirids (family Flaviviridae)

“…Given the extent of uncharacterised flavivirid diversity and the accelerating rate of virus discovery, further expansion and revision of flavivirid taxonomy will no doubt be required as exploration of the virome proceeds - numerous novel and divergent flavivirids have been described since we originally submitted this report [34, 54] - the taxonomic system proposed above would provide a relatively open structure capable of accommodating novel flavivirid diversity.…”