Complete Genome Analysis of the Mandarin Fish Infectious Spleen and Kidney Necrosis Iridovirus

Abstract

The nucleotide sequence of the infectious spleen and kidney necrosis virus (ISKNV) genome was determined and found to comprise 111,362 bp with a G+C content of 54.78%. It contained 124 potential open reading frames (ORFs) with coding capacities ranging from 40 to 1208 amino acids. The analysis of the amino acid sequences deduced from the individual ORFs revealed that 35 of the 124 potential gene products of ISKNV show significant homology to functionally characterized proteins of other species. Some of the putative gene products of ISKNV showed significant homologies to proteins in the GenBank/EMBL/DDBJ databases including enzymes and structural proteins involved in virus replication, transcription, protein modification, and virus-host interaction. In addition, one major repeated sequence showing significant homology to the Red Sea bream iridovirus (RSIV) genome was identified. Based on the information obtained from biological properties (including histopathology, tissue tropisms, natural host range, and geographic distribution), physiochemical and physical properties, and genome analysis, we suggest that ISKNV, RSIV, sea bass iridovirus, grouper iridovirus, and African lampeye iridovirus may belong to a new genus of the Iridoviridae family and are tentatively referred to as cell hypertrophy iridoviruses.

Histological, ultrastructural, and in situ hybridization study on enlarged cells in grouper Epinephelus hybrids infected by grouper iridovirus in Taiwan (TGIV)

“…Similar viruses have been described for a number of fishes including ALIV from African lampeye, GIV from grouper Epinephelus malabaricus, SBIV from sea bass , an RSIV-like iridovirus from striped beakperch Oplegnathus fasciatus (Jung & Oh 2000, Kim et al 2002, and ISKNV from the mandarinfish Siniperca chuatsi (He et al 2001). These viruses were proposed to form a separate taxonomic unit, and were collectively termed 'cell hypertrophy iridoviruses' (He et al 2001). Phylogenetic trees derived from major capsid proteins, cytosine DNA methyltransferase, ATPase, and DNA polymerase suggest that these viruses differ from other iridoviruses.…”

“…Another grouper iridovirus, isolated from E. macabaricus (GIV, Miyata et al 1997) was reported in Thailand. This virus was closely related to RSIV and was molecularly clustered with other 'cell hypertrophy iridoviruses' (He et al 2001). ATPase gene-sequence analysis (Fig.…”

“…Grouper iridovirus in Taiwan (TGIV) was first reported in 1997 (Chao & Pang 1997), and has histological characteristics similar to the second group. He et al (2001) compared ATPase, DNA polymerase and RNA polymerase genes of selected members of Iridoviridae and suggested that RSIV, SBIV, ALIV, GIV and ISKNV may belong to a new genus, and tentatively referred to them as 'cell hypertrophy iridoviruses'. A research group led by T. Miyazaki also proposed the definition tropical iridovirus or 'Tropivirus' for these viruses (Sudthongkong et al 2002b).…”

Molecular basis and genetic improvement of economically important traits in aquaculture animals

“…Especially in infectious virus diseases, a lot of pathogenic viruses were identified from freshwater and marine culture animals [103], and the complete genomes of several viruses, such as grass carp hemorrhage virus (GCHV) [104], shrimp white spot syndrome virus (WSSV) [105], mandarin fish infectious spleen and kidney necrosis iridovirus (ISKNV) [106], and flounder lymphocystis disease virus isolated in China (LCDV-C) [107], were sequenced in China. Moreover, their structure proteins were characterized [108][109][110][111], and some of them were functionally analyzed [112,113].…”

Rana grylio virus thymidine kinase gene: an early gene of iridovirus encoding for a cytoplasmic protein

“…Based on the Eighth Report of the International Committee on Taxonomy of Virus (ICTV), the family Iridoviridae has been subdivided into five genera: Iridovirus, Chloriridovirus, Ranavirus, Lymphocystisvirus, and Megalocytivirus [3]. To date, 12 genome sequences of iridoviruses including at least one from each genus have been completely sequenced and analysed [2,[4][5][6][7][8][9][10][11][12][13][14]. These analyses show that iridoviruses encode a number of cellular protein homologues that may be mostly involved in nucleic acid metabolism, such as ribonucleotide reductase (RR), thymidylate synthase (TS), deoxyuridine triphosphatase (DUT), and purine nucleoside phosphorylase (PNP) [15].…”