Complete genome analysis of a red seabream iridovirus (RSIV) isolated from Asian seabass (Lates calcarifer) in India

Red sea bream iridovirus (RSIV) is the causative agent of the iridoviral disease with high mortality rates in cultured fish. Our laboratory reported the first case of RSIV infection in India which resulted in mass mortalities of Asian seabass, Lates calcarifer. The RSIV-LC strain isolated from infected fish was subjected to complete genome sequencing and analysis. The complete genome of RSIV-LC was found to be of 111,557 bp in size having a G + C content of 53 %. The complete genome has 114 open reading frames (ORFs) of which 38 ORFs were predicted as functional proteins while the rest were hypothetical proteins. Among the ORFs 26 were found to be core genes reported earlier to be homologous in iridovirus complete genomes. Phylogenetic tree constructed based on the 26 core gene sequences, major capsid protein and ATPase genes revealed RSIV-LC in this study to belong to the genus Megalocytivirus of the RSIV-Genotype II. The present study provides the first report of the complete genome sequence and annotation of the RSIV strain isolated from India.

Automated summary

This study reported the first case of RSIV infection in India, leading to mass mortalities of Asian seabass, Lates calcarifer. The complete genome of RSIV-LC was found to be 111,557 bp in size with 38 predicted functional proteins and 26 core genes homologous to iridovirus complete genomes. Phylogenetic analysis revealed RSIV-LC to belong to the Megalocytivirus genus of RSIV-Genotype II.