First documentation of whole genome sequence analysis for infectious spleen and kidney necrosis virus (ISKNV) isolated from angel fish (Pterophyllum scalare) in India

The study presents the first report of the ISKNV whole genome sequence isolated from angel fish (Pterophyllum scalare) in India, offering insights into gene composition, function, phylogeny, and potential vaccine development. The complete genome of AK-ISKNV was found to be of 110,460 bp with the GC content of 54.79 %. The complete genome has 122 open reading frames (ORFs) and 48 ORFs were predicted as functional proteins while the rest were hypothetical proteins. Phylogenetic tree constructed based on the major capsid protein and ATPase genes revealed AK-ISKNV in this study belong to the genus Megalocytivirus of the ISKNV-Genotype I. The whole genome exhibits a 99.81 % similarity, and the phylogenetic analysis indicates a close association with Angel Fish Iridovirus (AFIV), specifically identified as MK689685.1, originating from Australia. Further, phylogenetic analysis confirms the ISKNV genotype and its distinction from RSIV. The present study provides the first report of the complete genome sequence and annotation of the ISKNV strain (AK-ISKNV) isolated from India. Four proteins were selected as prospective vaccination candidates based on their high B-cell epitope score and antigenic locations. These proteins include myristylated membrane protein (ORF 105), main capsid protein (ORF 104), and two hypothetical proteins (ORF 11 and ORF 14). In conclusion, this research contributes vital genomic information essential for understanding and mitigating the impact of ISKNV, providing a foundation for targeted disease control measures in aquaculture. •First complete ISKNV strain (AK-ISKNV) genome sequenced from India (110,460 bp, 54.79 % GC).•AK-ISKNV closely related to Australian angel fish iridovirus (AFIV).•AK-ISKNV belongs to Megalocytivirus genus (ISKNV-Genotype I).•Four potential vaccine candidates identified (ORFs 105, 104, 11, 14).