Complete characterisation of the American grass carp reovirus genome (genus Aquareovirus: family Reoviridae) reveals an evolutionary link between aquareoviruses and coltiviruses

Abstract

An aquareovirus was isolated from several fish species in the USA (including healthy golden shiners) that is not closely related to members of species Aquareovirus A, B and C. The virus, which is atypical (does not cause syncytia in cell cultures at neutral pH), was implicated in a winter die-off of grass carp fingerlings and has therefore been called 'American grass carp reovirus' (AGCRV). Complete nucleotide sequence analysis of the AGCRV genome and comparisons to the other aquareoviruses showed that it is closely related to golden ide reovirus (GIRV) (>92% amino acid [aa] identity in VP5(NTPase) and VP2(Pol)). However, comparisons with grass carp reovirus (Aquareovirus C) and chum salmon reovirus (Aquareovirus A) showed only 22% to 76% aa identity in different viral proteins. These findings have formed the basis for the recognition of AGCRV and GIRV as members of a new Aquareovirus species 'Aquareovirus G' by ICTV. Further sequence comparisons to other members of the family Reoviridae suggest that there has been an 'evolutionary jump,' involving a change in the number of genome segments, between the aquareoviruses (11 segments) and coltiviruses (12 segments). Segment 7 of AGRCV encodes two proteins, from two distinct ORFs, which are homologues of two Coltivirus proteins encoded by genome segments 9 and 12. A similar model has previously been reported for the rotaviruses and seadornaviruses.

Virus genomes and virus-host interactions in aquaculture animals

“…At least 15 reovirus genomes have been completely sequenced (Table 2). Of these, 11 reoviruses are different isolates from cultured grass carp obtained in various years and from different regions [85,[87][88][89][90][91][92]; the other four reoviruses were isolated from cultured golden shiner, chum salmon, Atlantic salmon (Piscine reovirus), and turbot (Scophthalmus maximus reovirus), respectively [93][94][95].…”

Complete Genome Sequence of a Reovirus Isolated from Grass Carp, Indicating Different Genotypes of GCRV in China

“…It was assigned to the genus Aquareovirus because of its morphology and its genome, which is composed of 11 segments of double-stranded RNA (dsRNA) (7). Seven genetic groups were established, designated aquareovirus A to G (AQRV-A to AQRV-G), and GCRV 873 is considered to belong to AQRV-C (1,6). In order to understand the genetic diversity and molecular epidemiology of this virus, we report here the complete sequence of all 11 segments of GCRV strain HZ08, from Zhejiang Province, China, that was isolated in 2008.…”

Structure and function of S9 segment of grass carp reovirus Anhui strain

“…All members of Reoviridae family exhibit conserved terminal sequences which are similar among different species and have been used in reovirus classification [3,13]. Analysis of the 5 0 and 3 0 terminal sequences demonstrated that non-coding regions (NCRs) existed in S9 segment of GCRV-AH528, whose length was 22 nucleotides at the 5 0 end and 41 nucleotides at the 3 0 end.…”